SPECIFICATION PYRROLOPYRIDAZINONE COMPOUND TECHNICAL FIELD [0001] The present invention relates to a novel pyrrolo- pyridazinone compound and a pharmaceutically acceptable salt thereof useful as a medicine, and a pharmaceutical composition containing these. The pyrrolopyridazinone compound according to the present invention has a potent phosphodiesterase 4 (herein¬after abbreviated to as PDE4) inhibiting action, and controls function of cells restrainingly by causing increase in a cyclic adenosine monophosphate (cAMP) con¬centration in cells. PDE4 localizes in cells which participate in an inflammatory reaction, and further exists in bronchial smooth muscle cells, so that it causes restraint of functions of inflammatory cells and relaxation of bronchial smooth muscle, whereby it is useful, for _ example, as an anti-inflammatory agent or an inhibitor of respiratory tract contraction. BACKGROUND ART [0002] It has been known pyrrolopyridazinone compounds similar to the compound of the present invention (see Patent literature 1 and Non-patent literatures 1 to 3) , but it has been not known that these compounds have a PDE4 inhibitory activity. [0003] As a PDE4 inhibitor, it has already been known com¬pounds such as xanthine derivatives. Rolipram analogues, or nitroquazone derivatives, etc., but these inhibitors could not be used clinically since they causes severe vomit or nausea as side effects (see Non-patent literature 4). In recent years, PDE4 inhibitors improved in side effects such as vomit and nausea have been reported that they are useful for treatment of asthma, chronic obstructive pulmonary disease (hereinafter also referred to as COPD) and allergic coryza (see Non-patent literatures 5 to 7). However, it cannot be said that they have a clinically sufficient effects even in compounds in which vomit or nausea as side effects are improved with a certain extent. [4] Patent literature 1: WO 01/96336 pamphlet Non-patent literature 1: Chem. Pharm. Bull., 754 (2002) Non-patent literature 2: Heterocycles, 41, 1863 (1996) Non-patent literature 3: Heterocycles, £0, 2471 (2003) Non-patent literature 4: Exp. Opin. Ther. Patents, 7, 989 (1997) Non-patent literature 5: Lancet, 358, 265 (2001) Non-patent literature 6: J. Allergy Clin. Immunol., 108, 530 (2001) Non-patent literature 7: Eur. Respir. J., 10, 1008 (1997) DISCLOSURE OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION [5] The present inventors have intensively studied on syntheses and pharmacological effects of compounds having PDE4 inhibitory activity and less side effects, and as a result, they have found that a novel pyrrolopyridazinone compound is a compound having a potent PDE4 inhibitory activity, excellent oral absorbability and continuity of action, and causing less vomit or nausea as side effects, whereby the present invention has been accomplished. Accordingly, the present invention is to provide a novel pyrrolopyridazinone compound and a pharmaceutically acceptable salt thereof having a potent PDE4 inhibitory activity, excellent oral absorbability and continuity of action, and causing less vomit or nausea as side effects. and a pharmaceutical composition containing these. MEANS TO SOLVE THE PROBLEMS [0006] The present invention relates to a novel pyrrolopyrid- azinone compound and a pharmaceutically acceptable salt thereof, having a potent PDE4 inhibitory activity, excellent oral absorbability and continuity of action, and causing less vomit or nausea as side effects. [7] The "pyrrolopyridazinone compound" of the present invention means a compound represented by the following formula (1). (1) [0009] wherein R^ represents a C^-Cj alkyl group or a halogeno C^-Cj alkyl group, R^ represents a C3-C5 cycloalkyl group, a (C3-C5 cycloalkyl) C1-C2 alkyl group or a C1-C3 alkyl group, R^ represents a hydrogen atom, or a methylene group or a cis-vinylene group each of which is a group for constituting a substituted oxygen-con¬taining heterocyclic ring in combination with the group -0-R^, R^ represents a hydrogen atom, a halogen atom, a C^-Cg alkyl group, a C^-Cg alkenyl group, a C^-Cg alkynyl group, a hydroxy C3-CS alkenyl group, a hydroxy C3-C6 alkynyl group, a C^-C^ alkyl group substituted by a substituent(s) selected from Substituent group (a), a C3-C6 cycloalkyl group which may be substituted by a substituent(s) selected from Substituent group (b), "a C1-C3 alkyl group which is substituted by a Cj-Cg cyclo- alkyl group which may be substituted by a substitu¬ent (s) selected from Substituent group (b), and which may be substituted by a hydroxy group", an aromatic ring group or heteroaromatic ring group each of which may be substituted by a substituent(s) selected from Substituent group (c), or "a C^-Cj alkyl group which is substituted by an aromatic ring group or heteroaroma¬tic ring group each of which may be substituted by a substituent(s) selected from Substituent group (c), and which may be substituted by a hydroxy group", Substituent group (a) represents a halogen atom, a hydroxy group, a cyano group, a carboxy group, a C^- C5 alkoxy group, a halogeno C^-C^ alkoxy group, a Cj-Cg cycloalkoxy group, a (Cj-Cg cycloalkyl)C1-C2 alkoxy group, a C^-C^ alkoxycarbonyl group, a Cj-C^ alkanoyl group, a C2-C4 alkanoyloxy group or a C1-C4 alkyl-sub¬stituted amino group, Substituent group (b) represents a hydroxy group or a halogen atom, Substituent group (c) represents a halogen atom, a hydroxy group, a cyano group, a nitro group, a carboxy group, a C^-Cs alkoxy group, a C1-C4 alkoxycarbonyl group, a Cj-C^ alkanoyloxy group, a C1-C4 alkyl-substituted amino group or a C1-C4 alkyl group which may be substituted by a substituent(s) selected from the group consisting of (a halogen atom, a hydroxy group and a carboxy group), or a pharmaceutically acceptable salt thereof. BEST MODE TO CARRY OUT THE INVENTION [0010] In the compound represented by the above-mentioned formula (1), a "C^-Cj alkyl group", and a "C1-C2 alkyl group portion" of the halogeno C^-Cj alkyl group represented by a "C^-Cj alkyl group portion" of the (C3-C4 cycloalkyl) - Ci-C^ alkyl group represented by and a "C^-Cj alkyl group portion" in the "C^-Cj alkyl group which is substituted by an aromatic ring group or heteroaromatic ring group each of which may be substituted by a substituent(s) selected from Substituent group (c), and may be substituted by a hydroxy group" represented by R^ each means the "Ci-Cj alkyl group" having the same meaning, and such a "Ci-Cj alkyl group" may be mentioned, for example, a methyl or ethyl group, prefer¬ably a methyl group. [0011] The "halogeno portion" of the halogeno C^-Cj alkyl group represented by R^ means a halogen atom such as a fluorine or chlorine atom, etc., preferably a fluorine atom. As the "halogeno C^-Cj alkyl group" represented by R\ there may be mentioned, for example, a fluoromethyl, di- fluoromethyl, trifluoromethyl, 2-fluoroethyl, 2,2-difluoro- ethyl, 2,2,2-trifluoroethyl, chloromethyl, dichloromethyl, trichloromethyl, 2-chloroethyl, 2,2-dichloroethyl or 2,2,2- trichloroethyl group, etc., preferably a fluoromethyl, difluoromethyl, chloromethyl or dichloromethyl group, more preferably a difluoromethyl group. As R^, there may be preferably mentioned a methyl or difluoromethyl group, more preferably difluoromethyl group. [0012] As the "Cj-Cs cycloalkyl group" represented by R^, there may be mentioned, for example, a cyclopropyl, cyclo- butyl or cyclopentyl group, preferably a cyclopropyl or cyclobutyl group. As the "(C3-C5 cycloalkyl) Cj-Cj alkyl group" repre¬sented by R^, there may be mentioned, for example, a cyclo- propylmethyl, 1-cyclopropylethyl, 2-cyclopropylethyl, cyclobutylmethyl, 1-cyclobutylethyl, 2-cyclobutylethyl, cyclopentylmethyl, 1-cyclopentylethyl or 2-cyclopentylethyl group, preferably a cyclopropylmethyl or cyclobutylmethyl group. As the "C1-C3 alkyl group" represented by there may be mentioned, for example, a straight or branched C^-Cj alkyl group such as a methyl, ethyl, propyl or isopropyl group, preferably an ethyl or isopropyl group. As R^, there may be preferably mentioned a cyclo- propyl, cyclobutyl, cyclopentyl, cyclopropylmethyl, cyclo- butylmethyl, ethyl or isopropyl group, more preferably a cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylmethyl or isopropyl group, particularly preferably a cyclopropyl or cyclopropylmethyl group. [0013] R^ represents a hydrogen atom, or a methylene group or a cis-vinylene group for constituting a substituted oxygen- containing heterocyclic ring in combination with the group -0-R'. The substituted oxygen-containing hetero ring formed by R^ in combination with the group -0-R^ is a substituted oxygen-containing hetero ring constituted by a tetrahydro- furan ring or 3,6-dihydro-2H-pyran ring, and as a substi- tuent(s) on the ring, there may be mentioned, for example, a 1,2-ethylene, 1,3-propylene, 1,4-butylene, cyclopropyl, cyclobutyl or a methyl group, etc. A substituted position on the ring is at the carbon atom which directly binds to an oxygen atom of the group -0-R^. A number of the substituent(s) on the ring is 1 or 2, and when the substituents are of a plural number, they may be the same or different from each other. As the substituted oxygen-containing hetero ring formed by R^ in combination with the group -0-R^, there may be preferably mentioned a 2,2-(1,2-ethylene)-tetrahydro- furan ring, 2,2-(1,3-propylene)-tetrahydrofuran ring, 2,2- (1,4-butylene)-tetrahydrofuran ring, 2-cyclopropyl-tetra- hydrofuran ring, 2-cyclobutyl-tetrahydrofuran ring, 2,2- dimethyl-tetrahydrofuran ring, 6,6-(1,2-ethylene)-3,6- dihydro-2H-pyran ring, 6,6-(1,3-propylene)-3,6-dihydro-2H- pyran ring, 6,6-(1,4-butylene)-3,6-dihydro-2H-pyran ring. 6-cyclopropyl-3,6-dihydro-2H-pyran ring, 6-cyclobutyl-3,6- dihydro-2H-pyran ring or 6,6-dimethyl-3,6-dihydro-2H-pyran ring, more preferably a 2,2-(1,4-butylene)-tetrahydrofuran ring, 6,6-(1,3-propylene)-3,6-dihydro-2H-pyran ring, 6,6- (1,4-butylene)-3,6-dihydro-2H-pyran ring, 6-cyclopropyl- 3,6-dihydro-2H-pyran ring or 6,6-dimethyl-3,6-dihydro-2H- pyran ring. [14] As the "halogen atom" which is a substituent(s) of R^, there may be mentioned, for example, a fluorine, chlorine, bromine or iodine atom, preferably a chlorine, bromine or iodine atom, more preferably a chlorine or bromine atom. The halogen atoms which are a substituent(s) in Substituent group (a), Substituent group (b) and Substitu¬ent group (c) represented by and the halogen atom in "a C1-C4 alkyl group which may be substituted by a substitu¬ent (s) selected from the group consisting of (a halogen atom, a hydroxy group, and a carboxy group)" of Substituent group (c) each means "a halogen atom" having the same mean¬ings, and such a halogen atom may be mentioned, for example, a fluorine, chlorine, bromine or iodine atom, preferably a fluorine, chlorine or bromine atom, more preferably a fluorine or chlorine atom. [15] As the "C^^-Cg alkyl group" of R^, there may be mention¬ed, for example, a straight or branched alkyl group such as a methyl, ethyl, propyl, isopropyl, butyl, iso- butyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, 1-methylbutyl, 2-methylbutyl, 1,2-dimethyl- propyl, 1-ethylpropyl, hexyl, 1-methylpentyl, 2-methyl- pentyl, 3-methylpentyl, 4-methylpentyl, 1-ethylbutyl, 2- ethylbutyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3- dimethyIbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, heptyl, 1-methylhexyl, 2-methylhexyl, 3-methylhexyl, 4- methylhexyl, 5-methylhexyl, 1-ethylpentyl, 2-ethylpentyl, 3-ethylpentyl, 1,2-dimethylpentyl, 1,3-dimethylpentyl, 1,4- dimethyIpentyl, 2,3-dimethylpenty1, 2,4-dimethylpentyl, 3,4-dimethylpentyl, 1,1-dimethylpentyl, 2,2-dimethyIpentyl, 3,3-dimethyIpentyl, 4,4-dimethylpentyl, 1-methyl-2-ethyl- butyl, octyl, 1-methylheptyl, 2-methylheptyl, 3-methyl- heptyl, 4-methylheptyl, 5-methylheptyl, 6-methylheptyl, 1- ethylhexyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 1,2- dimethylhexyl, 1,3-dimethylhexyl, 1,4-dimethylhexyl, 1,5- dimethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5- dimethylhexyl, 3,4-dimethylhexyl, 3,5-dimethylhexyl, 1,1- dimethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 4,4- dimethylhexyl, 5,5-dimethylhexyl, 1-methyl-3-ethylpentyl, 2-methyl-3-ethylpentyl, 2-propyIpentyl or 2,2,3,3-tetra- methylbutyl group, etc., preferably a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl, 2-methylbutyl, hexyl, 2-methylpentyl, 3-methyl- pentyl, 4-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 2,3-dimethylbutyl, heptyl, 2-methyl- hexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 2,3- dimethylpentyl, 2,4-dimethylpentyl, 3,4-dimethylpentyl, 2.2- dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, octyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5- methylheptyl, 6-methylheptyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5- dimethylhexyl, 3,4-dimethylhexyl, 3,5-dimethylhexyl, 2,2- dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 5,5- dimethylhexyl, 2-methyl-3-ethylpentyl, 2-propylpentyl or 2,2,3,3-tetramethylbutyl group, more preferably a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, iso¬pentyl, neopentyl, hexyl, 2-ethylbutyl, 2,2-dimethylbutyl, 3.3- dimethylbutyl, heptyl, 2,2-dimethylpentyl, 3,3-di- methylpentyl, 4,4-dimethylpentyl, octyl, 4-ethylhexyl, 2,2- dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 5,5- dimethylhexyl, 2-propylpentyl or 2,2,3,3-tetramethylbutyl group, particularly preferably a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl, hexyl, 2-ethylbutyl, 2,2-dimethylbutyl and 3,3-dimethyl- butyl group. [0016] The "C1-C5 alkoxy group"s in Substituent group (a) and Substituent group (c) each means a "C^-Cg alkoxy group" having the same meanings, and such a "C1-C5 alkoxy group" may be mentioned a straight or branched C^-Cg alkoxy group such as a methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentoxy, isopentoxy, neopentoxy, tert-pentoxy, 1,2-dimethylpropoxy, 1-ethyl- propoxy, 1-methylbutoxy and 2-methylbutoxy group. [17] As the "halogeno C1-C4 alkoxy group" in Substituent group (a), there may be mentioned a straight or branched halogeno C^-C^ alkoxy group such as a difluoromethoxy, dichloromethoxy, dibromomethoxy, diiodomethoxy, trifluoro- methoxy, trichloromethoxy, 2 -fluoroethoxy, 2-chloroethoxy, 2-bromoethoxy, 2,2-difluoroethoxy, 2,2,2-trifluoroethoxy, perfluoroethoxy, 2,2-dichloroethoxy, 2,2,2 -trichloroethoxy, 2-fluoropropoxy, 3-fluoropropoxy, 3,3,3 -trifluoropropoxy, perfluoropropoxy, 2-fluoro-l-methylethoxy, 2,2-difluoro-l- methylethoxy, 2,2,2-trifluoro-l-methylethoxy, 4-fluoro- butoxy and perfluorobutoxy group, etc. As the "Cj-Cg cycloalkoxy group" in Substituent group (a), there may be mentioned, for example, a cyclopropoxy, cyclobutoxy, cyclopentoxy or cyclohexyloxy group. As the " (Cj-Cg cycloalkyl) C1-C2 alkoxy group" in Substituent group (a), there may be mentioned, for example, a cyclopropylmethoxy, 1-cyclopropylethoxy, 2-cyclopropyl- ethoxy, cyclobutylmethoxy, 1-cyclobutylethoxy, 2-cyclo- butylethoxy, cyclopentylmethoxy, 1-cyclopentylethoxy, 2- cyclopentylethoxy, cyclohexylmethoxy, 1-cyclohexylethoxy or 2-cyclohexylethoxy group. [18] The "C1-C4 alkoxycarbonyl group"s in Substituent group (a) and Substituent group (c) each means a "C^-C^ alkoxy¬carbonyl group" having the same meanings, and such a "C1-C4 alkoxycarbonyl group" may be mentioned, for example, a straight or branched C1-C4 alkoxycarbonyl group such as a methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isoprop- oxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, sec-butoxy- carbonyl and tert-butoxycarbonyl group. [19] As the "C2-C4 alkanoyl group" in Substituent group (a), there may be mentioned, for example, a straight or branched C^-C^ alkanoyl group such as an acetyl, propionyl, butyryl and isobutyryl group. The "C2-C4 alkanoyloxy group"s in Substituent group (a) and Substituent group (c) each means a "Cj-C^ alkanoyl¬oxy group" having the same meanings, and such a "C2-C4 alkanoyloxy group" may be mentioned, for example, a straight or branched C^-C^ alkanoyloxy group such as an acetyloxy, propionyloxy, butyryloxy and isobutyryloxy group. [20] The C1-C4 alkyl-substituted amino groups in Substi¬tuent group (a) and Substituent group (c) are an amino group which is substituted by 1 or 2 alkyl groups selected from a straight or branched C1-C4 alkyl group such as a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec- butyl and tert-butyl group (when 2 substituents are substi¬tuted, the respective alkyl groups may be the same or different from each other), and there may be mentioned, for example, a methylamino, ethylamino, propylamine, isopropyl- amino, butylamino, isobutylamino, sec-butylamino, tert- butylamino, dimethylamino, diethylamino, dipropylamino, dibutylamino, diisopropylamino, diisobutylamino, ethyl- methylamino, methylpropylamino, butylmethylamino, isoprop- ylmethylamino or isobutylmethylamino group, etc., prefer¬ably a dimethylamino, diethylamino, dipropylamino, dibutyl¬amino, diisopropylamino, diisobutylamino, ethylmethylamino, methylpropylamino, butylmethylamino, isopropylmethylamino or isobutylmethylamino group, more preferably a dimethyl- amino, diethylamino, dipropylamino, dibutylamino or diiso- propylamino group. [0021] As Substituent group (a), they are preferably a fluorine atom, chlorine atom, hydroxy, cyano, carboxy, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, l-ethylpropoxy, 2-fluoroethoxy, 2,2-difluoroethoxy, 2,2,2-trifluoroethoxy, cyclopropoxy, cyclobutoxy, cyclopropylmethoxy, 1-cyclopropylethoxy, 2- cyclopropylethoxy, cyclobutylmethoxy, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, acetyl, propionyl, butyryl, isobutyryl, acetyloxy, propionyloxy, butyryloxy, isobutyryloxy, dimethylamino, diethylamino, dipropylamino, dibutylamino, diisopropylamino, diisobutylamino, ethyl- methylamino, methylpropylamino, butylmethylamino, isoprop- ylmethylamino or isobutylmethylamino group, more preferably a fluorine atom, chlorine atom, hydroxy, cyano, carboxy, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, l-ethylpropoxy, 2-fluoroethoxy, 2,2,2-trifluoroethoxy, cyclopropoxy, cyclobutoxy, cyclo¬propylmethoxy, cyclobutylmethoxy, methoxycarbonyl, ethoxy¬carbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxy¬carbonyl, isobutoxycarbonyl, dimethylamino, diethylamino, dipropylamino, dibutylamino, diisopropylamino or diiso¬butylamino group, particularly preferably a fluorine atom, chlorine atom, hydroxy, carboxy, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, 1- ethylpropoxy, 2-fluoroethoxy, cyclobutoxy, cyclopropyl¬methoxy, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl or butoxycarbonyl group. A number of these substituent(s) of the C^-Cg alkyl group substituted by a substituent(s) selected from Substi¬tuent group (a) is, for example, 1 to 4, preferably 1 to 3, and when they are a plural number, these substituents may be the same or different from each other. [0022] As the "Ci-Cg alkyl group" of the C^-C^ alkyl group substituted by a substituent(s) selected from Substituent group (a) of R^, there may be mentioned, for example, a straight or branched C^-Cg alkyl group such as a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert- butyl, pentyl, isopentyl, neopentyl, tert-pentyl, 1-methyl- butyl, 2-methylbutyl, 1,2-dimethylpropyl, 1-ethylpropyl, hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4- methylpentyl, 1-ethylbutyl, 2-ethylbutyl, 1,1-dimethyl- butyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,3-dimethyl- butyl and 2,3-dimethylbutyl group, etc., preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, iso¬pentyl, 2-methylbutyl, hexyl, 2-methylpentyl, 3-methyl¬pentyl, 4-methylpentyl or 2-ethylbutyl group, more prefer¬ably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl or 2-ethylbutyl group, particu¬larly preferably methyl, ethyl, propyl, isopropyl, butyl, isobutyl, isopentyl or 2-ethylbutyl group. [0023] As the "Cj-Cg alkyl group substituted by a substitu¬ent (s) selected from Substituent group (a)" of R^, there may be mentioned, for example, trifluoromethyl, 2,2,2-tri- fluoroethyl, 3,3,3-trifluoropropyl, 2-chloroethyl, 2,2- dichloroethyl, 2,2,2-trichloroethyl, hydroxymethyl, 1- hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 2-hydroxy- propyl , 3-hydroxypropyl, 1-hydroxybutyl, 2-hydroxybutyl, 3- hydroxybutyl, 4-hydroxybutyl, 1-hydroxypentyl, 5-hydroxy- pentyl, 1-hydroxyhexyl, 6-hydroxyhexyl, 1-hydroxy-2-methyl- propyl, 2-hydroxy-2-methylpropyl, 1-hydroxy-3-methylbutyl, 3-hydroxy-3-methylbutyl, 1-hydroxy-4-methylpentyl, 4- hydroxy-4-methylpentyl, 2-ethyl-2-hydroxybutyl, cyano- methyl, 1-cyanoethyl, 2-cyanoethyl, 1-cyanopropyl, 2-cyano- propyl, 3 -cyanopropy1, 1-cyanobutyl, 2-cyanobutyl, 3-cyano- butyl, 4 -cyanobutyl, 1-cyanopentyl, 5-cyanopentyl, 1-cyano- hexyl, 6 -cyanohexyl, l-cyano-2-methylpropyl, 2-cyano-2- methylpropyl, l-cyano-3-methylbutyl, 3-cyano-3-methylbutyl, l-cyano-4-methylpentyl, 4-cyano-4-methylpentyl, 2-cyano-2- ethylbutyl, carboxymethyl, 1-carboxyethyl, 2-carboxyethyl, 1-carboxypropyl, 2-carboxypropyl, 3 -carboxypropyl, 1- carboxybutyl, 2-carboxybutyl, 3-carboxybutyl, 4-carboxy- butyl, 1-carboxypentyl, 5-carboxypentyl, 1-carboxyhexyl, 5- carboxyhexyl, 1-carboxy-2-methylpropyl, 2-carboxy-2-methyl- propyl, l-carboxy-3-methylbutyl, 3-carboxy-3-methylbutyl, 1- carboxy-4-methylpentyl, 4-carboxy-4-methylpentyl, 2- carboxy-2 -ethylbutyl, [0024] methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, 1-methoxy- propyl, 2-methoxypropyl, 3-methoxypropyl, 1-methoxybutyl, 2- methoxybutyl, 3-methoxybutyl, 4-methoxybutyl, 1-methoxy- pentyl, 5-methoxypentyl, 1-methoxyhexyl, 6-methoxyhexyl, 1- raethoxy-2-methylpropyl, 2-methoxy-2-methylpropyl, 1- methoxy-3-methylbutyl, 3-methoxy-3-methylbutyl, 1-methoxy- 4-methylpentyl, 4-methoxy-4-methylpentyl, 2-ethyl-2- methoxybutyl, ethoxymethyl, 1-ethoxyethyl, 2-ethoxyethyl, 1-ethoxypropyl, 2-ethoxypropyl, 3-ethoxypropyl, 1-ethoxy- butyl, 2-ethoxybutyl, 3-ethoxybutyl, 4-ethoxybutyl, 1- ethoxypentyl, 5-ethoxypentyl, 1-ethoxyhexyl, 6-ethoxyhexyl, 1- ethoxy-2-methylpropyl, 2-ethoxy-2-methylpropyl, 1-ethoxy- 3- methylbutyl, 3-ethoxy-3-methylbutyl, 1-ethoxy-4-methyl- pentyl, 4-ethoxy-4-methylpentyl, 2-ethoxy-2-ethylbutyl, propoxymethyl, 1-propoxyethyl, 2-propoxyethyl, 1-propoxy- propyl, 2-propoxypropyl, 3-propoxypropyl, 1-propoxybutyl, 2- propoxybutyl, 3-propoxybutyl, 4-propoxybutyl, 1-propoxy- pentyl, 5-propoxypentyl, 1-propoxyhexyl, 6-propoxyhexyl, 2- methyl-1-propoxypropyl, 2-methyl-2-propoxypropyl, 3-methyl- 1-propoxybutyl, 3-methyl-3-propoxybutyl, 4-methyl-1-prop- oxypentyl, 4-methyl-4-propoxypentyl, 2-ethyl-2-propoxy- butyl, butoxymethyl, 1-butoxyethyl, 2-butoxyethyl, 1- butoxypropy1, 2-butoxypropyl, 3-butoxypropyl, 1-butoxy- butyl, 2-butoxybutyl, 3-butoxybutyl, 4-butoxybutyl, 1- butoxypentyl, 5-butoxypentyl, 1-butoxyhexyl, 6-butoxyhexyl, l-butoxy-2-methylpropyl, 2-butoxy-2-methylpropyl, 1-butoxy- 3-methylbutyl, 3-butoxy-3-methylbutyl, l-butoxy-4-methyl- pentyl, 4-butoxy-4-methylpentyl, 2-butoxy-2-ethylbutyl, isopropoxyraethyl, 1-isopropoxyethyl, 2-isopropoxyethyl, 1- isopropoxypropyl, 2 -isopropoxypropyl, 3 -isopropoxypropyl, 1- isopropoxybutyl, 2-isopropoxybutyl, 3-isopropoxybutyl, 4- isopropoxybutyl, 1-isopropoxypentyl, 5-isopropoxypentyl, 1- isopropoxyhexyl, 6-isopropoxyhexyl, l-isopropoxy-2-methyl- propyl, 2-isopropoxy-2-methylpropyl, 1-isopropoxy-3-methyl- butyl, 3-isopropoxy-3-methylbutyl, 1-isopropoxy-4-methyl- pentyl, 4-isopropoxy-4-methylpentyl, 2-ethyl-2-isopropoxy¬butyl, isobutoxymethyl, 1-isobutoxyethyl, 2-isobutoxyethyl, sec-butoxymethyl, 1-(sec-butoxy)ethyl, 2-(sec-butoxy)ethyl, tert-butoxymethyl, 1-(tert-butoxy)ethyl, 2-(tert-butoxy)- ethyl, 1-ethylpropoxymethyl, 1-(1-ethylpropoxy)ethyl, 2-(1- ethylpropoxy)ethyl, [0025] 2- fluoroethoxymethyl, 1-(2-fluoroethoxy)ethyl, 2-(2-fluoro- ethoxy)ethyl, 1-(2-fluoroethoxy)propyl, 2-(2-fluoroethoxy)- propyl, 3-(2-fluoroethoxy)propyl, 1-(2-fluoroethoxy)butyl, 2- (2-fluoroethoxy)butyl, 3-(2-fluoroethoxy)butyl, 4-(2- fluoroethoxy)butyl, 1-(2-fluoroethoxy)pentyl, 5-(2-fluoro- ethoxy)pentyl, 1-(2-fluoroethoxy)hexyl, 6-(2-fluoroethoxy)- hexyl, 1-(2-fluoroethoxy)-2-methylpropyl, 2-(2-fluoro¬ethoxy) -2-methylpropyl, 1-(2-fluoroethoxy)-3-methylbutyl, 3- (2-fluoroethoxy)-3-methylbutyl, 1-(2-fluoroethoxy)-4- methylpentyl, 4-(2-fluoroethoxy)-4-methylpentyl, 2-ethyl-2- (2-fluoroethoxy)butyl, (2,2-difluoroethoxy)methyl, l-(2,2- difluoroethoxy)ethyl, 2-(2,2-difluoroethoxy)ethyl, l-(2,2- difluoroethoxy)propyl, 2-(2,2-difluoroethoxy)propyl, 3- (2,2-difluoroethoxy)propyl, 1-(2,2-difluoroethoxy)butyl, 2- (2,2-difluoroethoxy)butyl, 3-(2,2-difluoroethoxy)butyl, 4- (2,2-difluoroethoxy)butyl, 1-(2,2-difluoroethoxy)pentyl, 5- (2,2-difluoroethoxy)pentyl, 1-(2,2-difluoroethoxy)hexyl, 6- (2,2-difluoroethoxy)hexyl, 1-(2,2-difluoroethoxy)-2-methyl- propyl, 2-(2,2-difluoroethoxy)-2-methylpropyl, l-(2,2- difluoroethoxy)-3-methylbutyl, 3-(2,2-difluoroethoxy)-3- methylbutyl, 1-(2,2-difluoroethoxy)-4-methylpentyl, 4-(2,2- difluoroethoxy)-4-methylpentyl, 2-ethyl-2-(2,2-difluoro¬ethoxy) butyl , (2,2,2-trifluoroethoxy)methyl, l-(2,2,2- trifluoroethoxy)ethyl, 2 -(2,2,2-trifluoroethoxy)ethyl, 1- (2,2,2-trifluoroethoxy)propyl, 2-(2,2,2-trifluoroethoxy)- propyl, 3-(2,2,2-trifluoroethoxy)propyl, 1-(2,2,2-tri- f luoroethoxy) butyl , 2-(2,2,2-trifluoroethoxy)butyl, 3- (2,2,2-trifluoroethoxy)butyl, 4-(2,2,2-trifluoroethoxy)- butyl, 1-(2,2,2-trifluoroethoxy)pentyl, 5-(2,2,2-tri- fluoroethoxy)pentyl, 1-(2,2,2-trifluoroethoxy)hexyl, 6- (2,2,2-trifluoroethoxy)hexyl, 1-(2,2,2-trifluoroethoxy)-2- methylpropyl, 2-(2,2,2-trifluoroethoxy)-2-methylpropyl, 1- (2 , 2 , 2-trifluoroethoxy)-3-methylbutyl, 3-(2,2,2-trifluoro¬ethoxy) -3-methylbutyl, 1-(2,2,2-trifluoroethoxy)-4-methyl¬pentyl, 4-(2,2,2-trifluoroethoxy)-4-methylpentyl, 2-ethyl- 2-(2, 2,2-trifluoroethoxy)butyl, cyclopropoxymethyl, 1- cyclopropoxyethyl, 2-cyclopropoxyethyl, 1-cyclopropoxy- propyl, 2-cyclopropoxypropyl, 3-cyclopropoxypropyl, 1- cyclopropoxybutyl, 2-cyclopropoxybutyl, 3-cyclopropoxy- butyl, 4-cyclopropoxybutyl, 1-cyclopropoxypentyl, 5-cyclo- propoxypentyl, 1-cyclopropoxyhexyl, 6-cyclopropoxyhexyl, [0026] 1- cyclopropoxy-2-methylpropyl, 2 -cyclopropoxy-2-methyl- propyl, l-cyclopropoxy-3-methylbutyl, 3-cyclopropoxy-3- methylbutyl, 1-cyclopropoxy-4-methylpentyl, 4-cyclopropoxy- 4 -methylpentyl , 2-cyclopropoxy-2-ethylbutyl, cyclobutoxy- methyl, 1-cyclobutoxyethyl, 2-cyclobutoxyethyl, 1-cyclo- butoxypropyl, 2-cyclobutoxypropyl, 3-cyclobutoxypropyl, 1- cyclobutoxybutyl, 2-cyclobutoxybutyl, 3-cyclobutoxybutyl, 4-cyclobutoxybutyl, 1-cyclobutoxypentyl, 5-cyclobutoxy- pentyl, 1-cyclobutoxyhexyl, 6-cyclobutoxyhexyl, 1-cyclo- butoxy-2-methylpropyl, 2-cyclobutoxy-2-methylpropyl, 1- cyclobutoxy-3-methylbutyl, 3-cyclobutoxy-3-methylbutyl, 1- cyclobutoxy-4-methylpentyl, 4-cyclobutoxy-4-methylpentyl, 2- cyclobutoxy-2-ethylbutyl, cyclopropylmethoxymethyl, 1- cyclopropylmethoxyethyl, 2-cyclopropylmethoxyethyl, 1- cyclopropylmethoxypropyl, 2-cyclopropylmethoxypropyl, 3- cyclopropylmethoxypropyl, 1-cyclopropylmethoxybutyl, 2- cyclopropylmethoxybutyl, 3-cyclopropylmethoxybutyl, 4- cyclopropylmethoxybutyl, 1-cyclopropylmethoxypentyl, 5- cyclopropylmethoxypentyl, 1-cyclopropylmethoxyhexyl, 6- cyclopropylmethoxyhexyl, 1-cyclopropylmethoxy-2-methyl- propyl, 2-cyclopropylmethoxy-2-methylpropyl, 1-eyelopropy1- methoxy-3-methylbutyl, 3 -cyclopropylmethoxy-3-methylbutyl, l-cyclopropylmethoxy-4-methylpentyl, 4-cyclopropylmethoxy- 4 -methylpentyl , 2-cyclopropylmethoxy-2-ethylbutyl, cyclo- butylmethoxymethyl, 1-cyclobutylmethoxyethyl, 2-cyclobutyl- methoxyethyl, 1-cyclobutylmethoxypropyl, 2-cyclobutyl- methoxypropyl, 3-cyclobutylmethoxypropyl, 1-cyclobutyl- methoxybutyl, 2-cyclobutylmethoxybutyl, 3-cyclobutyl- methoxybutyl, 4-cyclobutylmethoxybutyl, 1-cyclobutyl- methoxypentyl, 5-cyclobutylmethoxypentyl, 1-cyclobutyl- methoxyhexyl, 6-cyclobutylmethoxyhexyl, 1-cyclobutyl- methoxy-2-methylpropyl, 2 -cyclobutylmethoxy-2-methylpropyl, 1- cyclobutylmethoxy-3-methylbutyl, 3 -cyclobutylmethoxy-3 - methylbutyl, 1-cyclobutylmethoxy-4-methylpentyl, 4-cyclo- butylmethoxy-4-methylpentyl, 2-cyclobutylmethoxy-2-ethyl- butyl, [0027] (1-cyclopropylethoxy)methyl, 2-(1-cyclopropylethoxy)ethyl, 2- (1-cyclopropylethoxy)propyl, 3-(1-cyclopropylethoxy)- propyl, 4-(1-cyclopropylethoxy)butyl, 5-(1-cyclopropyl¬ethoxy) pentyl , 6-(1-cyclopropylethoxy)hexyl, 2-(1-cyclo¬propylethoxy) -2-methylpropyl, 3-(1-cyclopropylethoxy)-3- methylbutyl, 4-(1-cyclopropylethoxy)-4-methylpentyl, 2-(1- cyclopropylethoxy)-2-ethylbutyl, (2-cyclopropylethoxy)- methyl, 2-(2-cyclopropylethoxy)ethyl, 2-(2-cyclopropyl¬ethoxy) propyl, 3-(2-cyclopropylethoxy)propyl, 4-(2-cyclo- propylethoxy)butyl, 5 -(2-cyclopropylethoxy)pentyl, 6-(2- cyclopropylethoxy)hexyl, 2-(2-cyclopropylethoxy)-2-methyl- propyl, 3-(2-cyclopropylethoxy)-3-methylbutyl, 4-(2-cyclo- propylethoxy)-4-methylpentyl, 2-(2-cyclopropylethoxy)-2- ethylbutyl, [0028] methoxycarbonylmethyl, 1-methoxycarbonylethyl, 2-methoxy- carbonylethyl, 1-methoxycarbonylpropyl, 2-methoxycarbonyl- propyl, 3-methoxycarbonylpropyl, 1-methoxycarbonylbutyl, 2- methoxycarbonylbutyl, 3-methoxycarbonylbutyl, 4-methoxy- carbonylbutyl, 1-methoxycarbonylpentyl, 5-methoxycarbonyl- pentyl, 1-methoxycarbonylhexyl, 6-methoxycarbonylhexyl, 1- tnethoxycarbonyl-2-methylpropyl, 2-methoxycarbonyl-2-raethyl- propyl, l-methoxycarbonyl-3-methylbutyl, 3-methoxycarbonyl- 3 -methylbutyl , l-methoxycarbonyl-4-methylpentyl, 4-methoxy- carbonyl-4-methylpentyl, 2 -ethyl-2-methoxycarbonylbutyl, ethoxycarbonylmethyl, 1-ethoxycarbonylethyl, 2-ethoxy- carbonylethyl, 1-ethoxycarbonylpropyl, 2-ethoxycarbonyl- propyl, 3-ethoxycarbonylpropyl, 1-ethoxycarbonylbutyl, 2- ethoxycarbonylbutyl, 3 -ethoxycarbonylbutyl, 4 -ethoxy- carbonyIbuty1, 1-ethoxycarbonylpentyl, 5-ethoxycarbonyl- pentyl, 1-ethoxycarbonylhexyl, 6 -ethoxycarbonylhexyl, 1- ethoxycarbonyl-2-methylpropyl, 2 -ethoxycarbonyl-2-methyl- propyl, 1-ethoxycarbonyl-3-methylbutyl, 3-ethoxycarbonyl-3- methylbutyl, 1-ethoxycarbonyl-4-methylpentyl, 4-ethoxy¬carbonyl -4-methylpentyl, 2 -ethoxycarbonyl-2 -ethylbutyl, propoxycarbonylmethyl, 1-propoxycarbonylethyl, 2-propoxy- carbonylethyl, 1-propoxycarbonylpropyl, 2-propoxycarbonyl- propyl, 3-propoxycarbonylpropyl, 1-propoxycarbonylbutyl, 2- propoxycarbonylbutyl, 3-propoxycarbonylbutyl, 4-propoxy- carbonylbutyl, 1-propoxycarbonylpentyl, 5-propoxycarbonyl- pentyl, 1-propoxycarbonylhexyl, 6-propoxycarbonylhexyl, 2- methyl-1-propoxycarbonylpropyl, 2-methyl-2-propoxycarbon¬ylpropyl, 3-methyl-1-propoxycarbonylbutyl, 3-methyl-3- propoxycarbonylbutyl, 4-methyl-1-propoxycarbonylpentyl, 4- methyl-4-propoxycarbonylpentyl, 2-ethyl-2-propoxycarbonyl¬butyl , [0029] butoxycarbonylmethyl, 1-butoxycarbonylethyl, 2-butoxy- carbonylethyl, 1-butoxycarbonylpropyl, 2-butoxycarbonyl- propyl , 3-butoxycarbonylpropyl, 1-butoxycarbonylbutyl, 2- butoxycarbonylbutyl, 3-butoxycarbonylbutyl, 4-butoxy- carbonylbutyl, 1-butoxycarbonylpentyl, 5-butoxycarbonyl- pentyl, 1-butoxycarbonylhexyl, 6-butoxycarbonylhexyl, 1- butoxycarbonyl-2-methylpropyl, 2-butoxycarbonyl-2-methyl- propyl, 1-butoxycarbonyl-3-methylbutyl, 3-butoxycarbonyl-3- methylbutyl, 1-butoxycarbonyl-4-methylpentyl, 4-butoxy¬carbonyl -4-methylpentyl, 2-butoxycarbonyl-2 -ethylbutyl, isopropoxycarbonylmethyl, 1-isopropoxycarbonylethyl, 2- isopropoxycarbonylethyl, 1-isopropoxycarbonylpropyl, 2- isopropoxycarbonylpropyl, 3-isopropoxycarbonylpropyl, 1- isopropoxycarbonylbutyl, 2-isopropoxycarbonylbutyl, 3- isopropoxycarbonylbutyl, 4-isopropoxycarbonylbutyl, 1- isopropoxycarbonylpentyl, 5 -isopropoxycarbonylpentyl, 1- isopropoxycarbonylhexyl, 6 -isopropoxycarbonylhexyl, 1- i sopropoxycarbonyl-2-methylpropyl, 2 -isopropoxycarbonyl-2 - methylpropyl, 1-isopropoxycarbonyl-3-methylbutyl, 3-iso- propoxycarbonyl-3-methylbutyl, 1-i sopropoxycarbonyl-4 - methylpentyl, 4-isopropoxycarbonyl-4-methylpentyl, 2-ethyl- 2-isopropoxycarbonylbutyl, [0030] isobutoxycarbonylmethyl, 1-isobutoxycarbonylethyl, 2-iso- butoxycarbonylethyl, 1-isobutoxycarbonylpropyl, 2-iso- butoxycarbonylpropyl, 3 -isobutoxycarbonylpropyl, 1-iso- butoxycarbonylbutyl, 2-isobutoxycarbonylbutyl, 3-isobutoxy- carbonylbutyl, 4 -isobutoxycarbonylbutyl, 1-isobutoxycarbon- ylpentyl, 5-isobutoxycarbonylpentyl, 1-isobutoxycarbonyl- hexyl, 6-isobutoxycarbonylhexyl, l-isobutoxycarbonyl-2- methylpropyl, 2-isobutoxycarbonyl-2-methylpropyl, 1-iso- butoxycarbonyl-3-methylbutyl, 3 -isobutoxycarbonyl-3-methyl- butyl, 1-isobutoxycarbonyl-4-methylpentyl, 4-isobutoxy- carbonyl-4-methylpentyl, 2 -ethyl-2 -isobutoxycarbonylbutyl, acetyloxymethyl, 1-acetyloxyethyl, 2-acetyloxyethyl, 1- acetyloxypropyl, 2-acetyloxypropyl, 3-acetyloxypropyl, 1- acetyloxybutyl, 2-acetyloxybutyl, 3-acetyloxybutyl, 4- acetyloxybutyl, 1-acetyloxypentyl, 5-acetyloxypentyl, 1- acetyloxyhexyl, 6-acetyloxyhexyl, 1-acetyloxy-2-methyl- propyl, 2-acetyloxy-2-raethylpropyl, 1-acetyloxy-3-methyl- butyl, 3-acetyloxy-3-methylbutyl, l-acetyloxy-4-methyl- pentyl, 4-acetyloxy-4-methylpentyl, 2-acetyloxy-2-ethyl- butyl, [31] propionyloxymethyl, 1-propionyloxyethyl, 2-propionyloxy- ethyl, 1-propionyloxypropyl, 2-propionyloxypropyl, 3- propionyloxypropyl, 1-propionyloxybutyl, 2-propionyloxy- butyl, 3-propionyloxybutyl, 4-propionyloxybutyl, 1-propion- yloxypentyl, 5-propionyloxypentyl, 1-propionyloxyhexyl, 6- propionyloxyhexyl, 2-methyl-1-propionyloxypropyl, 2-methyl- 2- propionyloxypropyl, 3-methyl-1-propionyloxybutyl, 3- methyl-3-propionyloxybutyl, 4-methyl-1-propionyloxypentyl, 4-methyl-4-propionyloxypentyl, 2-ethyl-2-propionyloxybutyl, butyryloxymethyl, 1-butyryloxyethyl, 2-butyryloxyethyl, 1- butyryloxypropyl, 2-butyryloxypropyl, 3-butyryloxypropyl, 1-butyryloxybutyl, 2-butyryloxybutyl, 3-butyryloxybutyl, 4- butyryloxybutyl, 1-butyryloxypentyl, 5-butyryloxypentyl, 1- butyryloxyhexyl, 6-butyryloxyhexyl, 1-butyryloxy-2-methyl- propyl, 2-butyryloxy-2-methylpropyl, 1-butyryloxy-3-methyl- butyl, 3-butyryloxy-3-methylbutyl, 1-butyryloxy-4-methyl- pentyl, 4-butyryloxy-4-methylpentyl, 2-butyryloxy-2-ethyl- butyl, acetylmethyl, 1-acetylethyl, 2-acetylethyl, 1- acetylpropyl, 2-acetylpropyl, 3-acetylpropyl, 1-acetyl- butyl, 2-acetylbutyl, 3-acetylbutyl, 4-acetylbutyl, 1- acetylpentyl, 5-acetylpentyl, 1-acetylhexyl, 6-acetylhexyl, 1-acetyl-2-methylpropyl, 2-acetyl-2-methylpropyl, 1-acetyl- 3- methylbutyl, 3-acetyl-3-methylbutyl, l-acetyl-4-methyl- pentyl, 4-acetyl-4-methylpentyl, 2-acetyl-2-ethylbutyl, [32] propionylmethyl, 1-propionylethyl, 2-propionylethyl, 1- propionylpropyl, 2-propionylpropyl, 3-propionylpropyl, 1- propionylbutyl, 2-propionylbutyl, 3-propionylbutyl, 4- propionylbutyl, 1-propionylpentyl, 5-propionylpentyl, 1- propionylhexyl, 6-propionylhexyl, 2-methyl-1-propionyl- propyl, 2-methyl-2-propionylpropyl, 3-methyl-1-propionyl- butyl, 3-methyl-3-propionylbutyl, 4-methyl-1-propionyl- pentyl, 4-methyl-4-propionylpentyl, 2-ethyl-2-propionyl- butyl, butyrylmethyl, 1-butyrylethyl, 2-butyrylethyl, 1- butyrylpropyl, 2-butyrylpropyl, 3-butyrylpropyl, 1-butyryl- butyl, 2-butyrylbutyl, 3-butyrylbutyl, 4-butyrylbutyl, 1- butyrylpentyl, 5-butyrylpentyl, 1-butyrylhexyl, 6-butyryl- hexyl, l-butyryl-2-methylpropyl, 2-butyryl-2-raethylpropyl, l-butyryl-3-methylbutyl, 3-butyryl-3-methylbutyl, 1- butyryl-4-methylpentyl, 4-butyryl-4-methylpentyl, 2- butyryl-2-ethylbutyl, dimethylaminomethyl, 2-dimethylamino- ethyl, 3 -dimethylaminopropyl, 4 -dimethylaminobuty1, 5- dimethylaminopentyl, 6-dimethylaminohexyl, diethylamino- methyl, 2-diethylaminoethyl, 3-diethylaminopropyl, 4- diethylaminobutyl, 5-diethylaminopentyl, 6-diethylamino- hexyl, dipropylaminomethyl, 2-dipropylaminoethyl, 3- dipropylaminopropyl, 4-dipropylaminobutyl, 5-dipropylamino- pentyl, 6 -dipropylaminohexyl, dibutylaminomethyl, 2 - dibutylaminoethyl, 3-dibutylaminopropyl, 4-dibutylamino- butyl, 5-dibutylaminopentyl, 6-dibutylaminohexyl, diiso- propylaminomethyl, 2-diisopropylaminoethyl, 3-diisopropyl- aminopropyl, 4-diisopropylaminobutyl, 5-diisopropylamino- pentyl or 6-diisopropylaminohexyl group, etc., [0033] preferably a trifluoromethyl, 2,2,2-trifluoroethyl, 3,3,3- trifluoropropyl, 2-chloroethyl, hydroxymethyl, 1-hydroxy- ethyl, 2-hydroxyethyl, 1-hydroxypropyl, 3-hydroxypropyl, 1- hydroxybutyl, 4-hydroxybutyl, 1-hydroxypentyl, 5-hydroxy- pentyl, 1-hydroxyhexy1, 6-hydroxyhexyl, 1-hydroxy-2-methyl- propyl, 2-hydroxy-2-methylpropyl, 1-hydroxy-3-methylbutyl, 3-hydroxy-3-methylbutyl, l-hydroxy-4-methylpentyl, 4- hydroxy-4-methylpentyl, 2-ethyl-2-hydroxybutyl, cyano- methyl, 2-cyanoethyl, 3 -cyanopropyl, 4 -cyanobutyl, 5-cyano- pentyl, 6-cyanohexyl, 2-cyano-2-methylpropyl, 3-cyano-3- methylbutyl, 4-cyano-4-methylpentyl, 2-cyano-2-ethylbutyl, carboxymethyl, 2 -carboxyethyl, 3 -carboxypropyl, 4 -carboxy- butyl, 5-carboxypentyl, 6-carboxyhexyl, 2-carboxy-2-methyl- propyl, 3-carboxy-3-methylbutyl, 4-carboxy-4-meth.ylpentyl, 2- carboxy-2-ethylbutyl, methoxymethyl, 2-methoxyethyl, 2- methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 5-methoxy- pentyl, 6-methoxyhexyl, 2-methoxy-2-methylpropyl, 3- methoxy-3-methylbutyl, 4-methoxy-4-methylpentyl, 2-ethyl-2- methoxybutyl, ethoxymethyl, 2-ethoxyethyl, 2-ethoxypropyl, 3- ethoxypropyl, 4-ethoxybutyl, 5-ethoxypentyl, 6-ethoxy- hexyl, 2-ethoxy-2-methylpropyl, 3-ethoxy-3-methylbutyl, 4- ethoxy-4-methylpentyl, 2-ethoxy-2-ethylbutyl, propoxy- methyl, 2-propoxyethyl, 3-propoxypropyl, 4-propoxybutyl, 5- propoxypentyl, 6-propoxyhexyl, 2-methyl-2-propoxypropyl, 3- methyl-3-propoxybutyl, 4-methyl-4-propoxypentyl, 2-ethyl-2- propoxybutyl, butoxymethyl, 2-butoxyethyl, 3-butoxypropyl, 4- butoxybutyl, 5-butoxypentyl, 6-butoxyhexyl, 2-butoxy-2- methylpropyl, 3-butoxy-3-methylbutyl, 4-butoxy-4-methyl- pentyl , 2-butoxy-2-ethylbutyl, [34] isopropoxymethyl, 2 -isopropoxyethyl, 3-isopropoxypropyl, 4- isopropoxybutyl, 5-isopropoxypentyl, 6-isopropoxyhexyl, 2- isopropoxy-2-methylpropyl, 3-isopropoxy-3-methylbutyl, 4- isopropoxy-4-methylpentyl, 2-ethyl-2-isopropoxybutyl, isobutoxymethyl, 2-isobutoxyethyl, sec-butoxymethyl, 2- (sec-butoxy)ethyl, tert-butoxymethyl, 2-(tert-butoxy)ethyl, 1- ethylpropoxymethyl, 2 -(1-ethylpropoxy)ethyl, [35] 2- fluoroethoxymethyl, 2-(2-fluoroethoxy)ethyl, 2-(2-fluoro- ethoxy)propyl, 3 -(2-fluoroethoxy)propyl, 4-(2-fluoro¬ethoxy) butyl, 5-(2-fluoroethoxy)pentyl, 6-(2-fluoroethoxy)- hexyl, 2-(2-fluoroethoxy)-2-methylpropyl, 3-(2-fluoro¬ethoxy) -3-methylbutyl, 4-(2-fluoroethoxy)-4-methylpentyl, 2-ethyl-2-(2-fluoroethoxy)butyl, (2,2,2-trifluoroethoxy)- methyl, 2-(2,2,2-trifluoroethoxy)ethyl, 2 -(2,2,2-trifluoro¬ethoxy) propyl, 3-(2,2,2-trifluoroethoxy)propyl, 4-(2,2,2- trifluoroethoxy)butyl, 5 -(2,2,2-trifluoroethoxy)pentyl, 6- (2,2,2-trifluoroethoxy)hexyl, 2-(2,2,2 -trifluoroethoxy)-2- methylpropyl, 3-(2,2,2-trifluoroethoxy)-3-methylbutyl, 4- (2,2,2-trifluoroethoxy)-4-methylpentyl, 2-ethyl-2-(2,2,2- trifluoroethoxy)butyl, cyclopropoxymethyl, 2-cyclopropoxy- ethyl, 2-cyclopropoxypropyl, 3-cyclopropoxypropyl, 4-cyclo- propoxybutyl, 5-cyclopropoxypentyl, 6-cyclopropoxyhexyl, 2- cyclopropoxy-2-methylpropyl, 3-cyclopropoxy-3-methylbutyl, 4 -cyclopropoxy-4-methylpentyl, 2 -cyclopropoxy-2-ethylbutyl, cyclobutoxymethyl, 2-cyclobutoxyethyl, 2-cyclobutoxypropyl, 3-cyclobutoxypropyl, 4-cyclobutoxybutyl, 5-cyclobutoxypent- yl , 6-cyclobutoxyhexyl, 2-cyclobutoxy-2-methylpropyl, 3- cyclobutoxy-3-methylbutyl, 4-cyclobutoxy-4-methylpentyl, 2- cyclobutoxy-2-ethylbutyl, cyclopropylmethoxymethyl, 2- cyclopropylmethoxyethyl, 2-cyclopropylmethoxypropyl, 3- cyclopropylmethoxypropyl, 4-cyclopropylmethoxybutyl, 5- cyclopropylmethoxypentyl, 6-cyclopropylmethoxyhexyl, 2- cyclopropylmethoxy-2-methylpropyl, 3 -cyclopropylmethoxy-3 - methylbutyl, 4-cyclopropylmethoxy-4-methylpentyl, 2-cyclo- propylmethoxy-2-ethylbutyl, cyclobutylmethoxymethyl, 2- cyclobutylmethoxyethyl, 2-cyclobutylmethoxypropyl, 3- cyclobutylmethoxypropyl, 4-cyclobutylmethoxybutyl, 5- cyclobutylmethoxypentyl, 6-cyclobutylmethoxyhexyl, 2- cyclobutylmethoxy-2-methylpropyl, 3-cyclobutylmethoxy-3- methylbutyl, 4-cyclobutylmethoxy-4-methylpentyl, 2-cyclo- butylmethoxy-2-ethylbutyl, methoxycarbonylmethyl, 2- methoxycarbonylethyl, 3-methoxycarbonylpropyl, 4-methoxy- carbonylbutyl, 5-methoxycarbonylpentyl, 6-methoxycarbonyl- hexyl, 2-methoxycarbonyl-2-methylpropyl, 3-methoxycarbonyl- 3-methylbutyl, 4-methoxycarbonyl-4-methylpentyl, 2-ethyl-2- methoxycarbonylbutyl, ethoxycarbonylmethyl, 2 -ethoxycarbon- ylethyl, 3-ethoxycarbonylpropyl, 4-ethoxycarbonylbutyl, 5- ethoxycarbonylpentyl, 6-ethoxycarbonylhexyl, 2-ethoxy- carbonyl-2-methylpropyl, 3-ethoxycarbonyl-3-methylbutyl, 4- ethoxycarbonyl-4-methylpentyl, 2 -ethoxycarbonyl-2 -ethyl- butyl, propoxycarbonylmethyl, 2-propoxycarbonylethyl, 3- propoxycarbonylpropyl, 4-propoxycarbonylbutyl, 5-propoxy- carbonylpentyl, 6-propoxycarbonylhexyl, 2-methyl-2-propoxy- carbonylpropyl, 3-tnethyl-3-propoxycarbonylbutyl, 4-methyl- 4-propoxycarbonylpentyl, 2 -ethyl-2-propoxycarbonylbutyl, butoxycarbonylmethyl, 2-butoxycarbonylethyl, 3-butoxy- carbonylpropyl, 4-butoxycarbonylbutyl, 5-butoxycarbonyl- pentyl, 6-butoxycarbonylhexyl, 2-butoxycarbonyl-2-methyl- propyl, 3-butoxycarbonyl-3-methylbutyl, 4-butoxycarbonyl-4- methylpentyl, 2-butoxycarbonyl-2-ethylbutyl, isopropoxy- carbonylmethyl, 2-isopropoxycarbonylethyl, 3-isopropoxy- carbonylpropyl, 4-isopropoxycarbonylbutyl, 5-isopropoxy- carbonylpenty1, 6 -i sopropoxycarbonyIhexy1, 2 -i sopropoxy- carbonyl-2-methylpropyl, 3 -isopropoxycarbonyl-3-methyl- butyl, 4-isopropoxycarbonyl-4-methylpentyl, 2-ethyl-2- isopropoxycarbonylbutyl, isobutoxycarbonylmethyl, 2-iso- butoxycarbonylethyl, 3-isobutoxycarbonylpropyl, 4-iso- butoxycarbonylbutyl, 5-isobutoxycarbonylpentyl, 6-iso- butoxycarbonylhexyl, 2-isobutoxycarbonyl-2-methylpropyl, 3- i sobutoxycarbonyl-3-methylbutyl, 4 -i sobutoxycarbonyl-4 - methylpentyl, 2-ethyl-2-isobutoxycarbonylbutyl, [0036] acetyloxymethyl, 2-acetyloxyethyl, 3-acetyloxypropyl, 4- acetyloxybutyl, 5-acetyloxypentyl, 6-acetyloxyhexyl, 2- acetyloxy-2-methylpropyl, 3-acetyloxy-3-methylbutyl, 4- acetyloxy-4-methylpentyl, 2-acetyloxy-2-ethylbutyl, propionyloxymethyl, 2-propionyloxyethyl, 3-propionyloxy- propyl, 4-propionyloxybutyl, 5-propionyloxypentyl, 6- propionyloxyhexyl, 2-methyl-2-propionyloxypropyl, 3-methyl- 3-propionyloxybutyl, 4-methyl-4-propionyloxypentyl, 2- ethyl-2-propionyloxybutyl, butyryloxymethyl, 2-butyryloxy- ethyl, 3-butyryloxypropyl, 4-butyryloxybutyl, 5-butyryl- oxypentyl, 6-butyryloxyhexyl, 2-butyryloxy-2-methylpropyl, 3- butyryloxy-3-methylbutyl, 4-butyryloxy-4-methylpentyl, 2- butyryloxy-2-ethylbutyl, acetylmethyl, 2-acetylethyl, 3- acetylpropyl, 4-acetylbutyl, 5-acetylpentyl, 6-acetylhexyl, 2-acetyl-2-methylpropyl, 3-acetyl-3-methylbutyl, 4-acetyl- 4- methylpentyl, 2-acetyl-2-ethylbutyl, propionylmethyl, 2- propionylethyl, 3-propionylpropyl, 4-propionylbutyl, 5- propionylpentyl, 6-propionylhexyl, 3-methyl-3-propionyl- butyl, 4-methyl-4-propionylpentyl, 2-ethyl-2-propionyl- butyl, butyrylmethyl, 2-butyrylethyl, 3-butyrylpropyl, 4- butyrylbutyl, 5-butyrylpentyl, 6-butyrylhexyl, 2-butyryl-2- methylpropyl, 3-butyryl-3-methylbutyl, 4-butyryl-4-methyl- pentyl, 2-butyryl-2-ethylbutyl, dimethylaminomethyl, 2- dimethylaminoethyl, 3-dimethylaminopropyl, 4-dimethyl- aminobutyl, diethylaminomethyl, 2-diethylaminoethyl, 3- diethylaminopropyl, 4-diethylaminobutyl, dipropylamino- methyl, 2-dipropylaminoethyl, 3-dipropylaminopropyl, 4- dipropylaminobutyl, dibutylaminomethyl, 2-dibutylamino- ethyl, 3-dibutylaminopropyl, 4-dibutylaminobutyl, diiso- propylaminomethyl, 2-diisopropylaminoethyl, 3-diisopropyl- aminopropyl or 4-diisopropylaminobutyl group, [0037] more preferably 2,2,2-trifluoroethyl, 3 , 3,3 -trifluoro- propyl, 2-chloroethyl, hydroxymethyl, 2-hydroxyethyl, 3- hydroxypropyl, 4-hydroxybutyl, B-hydroxypentyl, 6-hydroxy- hexyl, 2-hydroxy-2-methylpropyl, 3-hydroxy-3-methylbutyl, 4-hydroxy-4-methylpentyl, 2-ethyl-2-hydroxybutyl, 2-cyano- 2-methylpropyl, 3-cyano-3-methylbutyl, 4-cyano-4-methyl- pentyl, 2-cyano-2-ethylbutyl, 2-carboxy-2-methylpropyl, 3- carboxy-3-methylbutyl, 4-carboxy-4-methylpentyl, 2-carboxy- 2-ethylbutyl, methoxymethyl, 2-methoxyethyl, 3-methoxy- propyl, 4-methoxybutyl, 5-methoxypentyl, 6-methoxyhexyl, 2- methoxy-2-methylpropyl, 3-methoxy-3-methylbutyl, 4-methoxy- 4-methylpentyl, 2-ethyl-2-methoxybutyl, ethoxymethyl, 2- ethoxyethyl, 3-ethoxypropyl, 4-ethoxybutyl, 5-ethoxypentyl, 6-ethoxyhexyl, 2-ethoxy-2-methylpropyl, 3-ethoxy-3-methyl¬butyl, 4-ethoxy-4-methylpentyl, 2-ethoxy-2-ethylbutyl, propoxymethyl, 2-propoxyethyl, 3-propoxypropyl, 4-propoxy- butyl, 2-methyl-2-propoxypropyl, 3-methyl-3-propoxybutyl, 4-methyl-4-propoxypentyl, 2-ethyl-2-propoxybutyl, butoxy- methyl, 2-butoxyethyl, 3-butoxypropyl, 4-butoxybutyl, 2- butoxy-2-methylpropyl, 3-butoxy-3-methylbutyl, 4-butoxy-4- methylpentyl, 2-butoxy-2-ethylbutyl, isopropoxymethyl, 2- isopropoxyethyl, 3-isopropoxypropyl, 4-isopropoxybutyl, isobutoxymethyl, sec-butoxymethyl, tert-butoxymethyl, 1- ethylpropoxymethyl, 2-fluoroethoxymethyl, 2-(2-fluoro- ethoxy)ethyl, 3-(2-fluoroethoxy)propyl, 4-(2-fluoroethoxy)- butyl, 5-(2-fluoroethoxy)pentyl, 6 -(2-fluoroethoxy)hexyl, 2- (2-fluoroethoxy)-2-methylpropyl, 3-(2-fluoroethoxy)-3- methylbutyl, 4-(2-fluoroethoxy)-4-methylpentyl, 2-ethyl-2- (2-fluoroethoxy)butyl, (2,2,2-trifluoroethoxy)methyl, cyclopropoxymethyl, cyclobutoxymethyl, 2-cyclobutoxyethyl, 3- cyclobutoxypropyl, 4-cyclobutoxybutyl, 5-cyclobutoxy- pentyl, 6-cyclobutoxyhexyl, 2-cyclobutoxy-2-methylpropyl, 3- cyclobutoxy-3-methylbutyl, 4-cyclobutoxy-4-methylpentyl, 2-cyclobutoxy-2-ethylbutyl, cyclopropylmethoxymethyl, 2- cyclopropylmethoxyethyl, 3-cyclopropylmethoxypropyl, 4- cyclopropylraethoxybutyl, 5-cyclopropylmethoxypentyl, 6- cyclopropylmethoxyhexyl, 2 -cyclopropylmethoxy-2-methyl- propyl, 3-cyclopropylmethoxy-3-methylbutyl, 4-cyclopropyl¬methoxy- 4 -methylpentyl , 2-cyclopropylmethoxy-2-ethylbutyl, cyclobutylmethoxymethyl, [0038] methoxycarbonylmethyl, 2-methoxycarbonylethyl, 3-methoxy- carbonylpropyl, 4-methoxycarbonylbutyl, 2-methoxycarbonyl- 2-methylpropyl, 3-methoxycarbonyl-3-methylbutyl, 4-methoxy¬carbonyl -4 -methylpentyl , 2-ethyl-2-methoxycarbonylbutyl, ethoxycarbonylmethyl, 2-ethoxycarbonylethyl, 3-ethoxy- carbonylpropyl, 4-ethoxycarbonylbutyl, 2-ethoxycarbonyl-2- methylpropyl, 3-ethoxycarbonyl-3-methylbutyl, 4-ethoxy- carbonyl-4-methylpentyl, 2-ethoxycarbonyl-2-ethylbutyl, propoxycarbonylmethyl, 2-propoxycarbonylethyl, 3-propoxy- carbonylpropyl, 4-propoxycarbonylbutyl, 2-methyl-2-propoxy- carbonylpropyl, 3-methyl-3-propoxycarbonylbutyl, 4-methyl- 4- propoxycarbonylpentyl, 2 -ethyl-2-propoxycarbonylbutyl, butoxycarbonylmethyl, 2-butoxycarbonylethyl, 3-butoxy- carbonylpropyl, 4-butoxycarbonylbutyl, 2-butoxycarbonyl-2 - methylpropyl, 3-butoxycarbonyl-3-methylbutyl, 4-butoxy- carbonyl-4-methylpentyl, 2-butoxycarbonyl-2-ethylbutyl, isopropoxycarbonylmethyl, 2-isopropoxycarbonylethyl, 3- isopropoxycarbonylpropyl, 4-isopropoxycarbonylbutyl, 2- isopropoxycarbonyl-2-methylpropyl, 3 -isopropoxycarbonyl-3 - methylbutyl, 4-isopropoxycarbonyl-4-methylpentyl, 2-ethyl- 2-isopropoxycarbonylbutyl, isobutoxycarbonylmethyl, 2-iso- butoxycarbonylethyl, 3-isobutoxycarbonylpropyl, 4-iso- butoxycarbonylbutyl, acetyloxymethyl, 2 -acetyloxyethyl, 3 - acetyloxypropyl, 4-acetyloxybutyl, 5-acetyloxypentyl, 6- acetyloxyhexyl, 2-acetyloxy-2-methylpropyl, 3-acetyloxy-3- methylbutyl, 4-acetyloxy-4-methylpentyl, 2-acetyloxy-2- ethylbutyl, propionyloxymethyl, 2-propionyloxyethyl, 3- propionyloxypropyl, 4-propionyloxybutyl, 5-propionyloxy- pentyl, acetylmethyl, 2-acetylethyl, 3-acetylpropyl, 4- acetylbutyl, 5-acetylpentyl, 6-acetylhexyl, 2-acetyl-2- methylpropyl, 3-acetyl-3-methylbutyl, 4-acetyl-4-methyl- pentyl, 2-acetyl-2-ethylbutyl, propionylmethyl, 2-pro- pionylethyl, 3-propionylpropyl, 4-propionylbutyl, 5- propionylpentyl, dimethylaminomethyl, 2-dimethylaminoethyl, diethylaminomethyl, 2-diethylaminoethyl, dipropylamino- methyl, 2-dipropylaminoethyl, 2-dibutylaminoethyl, 3- dibutylaminopropyl, diisopropylaminomethyl or 2-diiso- propylaminoethyl group, [39] particularly preferably 2,2,2-trifluoroethyl, 3,3,3-tri- fluoropropyl, 2-chloroethyl, hydroxymethyl, 2-hydroxy-2- methylpropyl, 3-hydroxy-3-methylbutyl, 4-hydroxy-4-methyl- pentyl, 2-ethyl-2-hydroxybutyl, 2-cyano-2-methylpropyl, 3- cyano-3-methylbutyl, 2-carboxy-2-methylpropyl, 3-carboxy-3- methylbutyl, 4-carboxy-4-methylpentyl, methoxymethyl, 2- methoxyethyl, ethoxymethyl, 2-ethoxyethyl, isopropoxy- methyl, 2-isopropoxyethyl, isobutoxymethyl, sec-butoxy- methyl, tert-butoxymethyl, 1-ethylpropoxymethyl, 2-fluoro- ethoxymethyl, cyclobutoxymethyl, cyclopropylmethoxymethyl or dimethylamino group. [40] The "Cj-Cg cycloalkyl group" of the Cj-Cg cycloalkyl group which may be substituted by a substituent(s) selected from Substituent group (b) and the "Cj-Cg cycloalkyl group" of the C^-C:^ alkyl group which is substituted by a Cj-Cg cycloalkyl group which may be substituted by a substitu¬ent (s) selected from Substituent group (b), and may be substituted by a hydroxy group of R^ each mean a "C3-CS cycloalkyl group" having the same meaning, and such a "C3- Cg cycloalkyl group" may be mentioned, for example, a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group. As Substituent group (b), there may be mentioned, for example, a hydroxy group, a fluorine, chlorine, bromine or iodine atom, preferably a hydroxy group, a fluorine, chlorine or bromine atom, more preferably a hydroxy group, a fluorine or chlorine atom. A number of substituents of the Cj-Cg cycloalkyl group substituted by these substituent(s) selected from Substi¬tuent group (b) is, for example, 1 to 5, preferably 1 to 3, and the substituents in the case of a plural numer may be the same or different from each other. As the Cj-Cg cycloalkyl group which may be substituted by a substituent(s) selected from Substituent group (b), there may be mentioned, for example, a cyclopropyl, 1- hydroxycyclopropy1, cyclobutyl, 1-hydroxycyclobutyl, cyclopentyl, 3,3-difluoro-l-hydroxycyclopentyl, cyclohexyl, 3,3-difluoro-l-hydroxycyclohexyl or 4,4-difluoro-l-hydroxy- cyclohexyl group, etc., preferably a cyclopropyl, 1- hydroxycyclopropyl, cyclobutyl or 1-hydroxycyclobutyl group. [0041] As the "C1-C3 alkyl group portion" of the "C^-Cj alkyl group which is substituted by a C3-CS cycloalkyl group which may be substituted by a substituent(s) selected from Substituent group (b), and may be substituted by a hydroxy group" of there may be mentioned, for example, a straight or branched C1-C3 alkyl group such as a methyl. ethyl, propyl and isopropyl group, preferably a methyl, ethyl or propyl group. [42] As the "C1-C3 alkyl group which is substituted by a C3- Cg cycloalkyl group which may be substituted by a substitu- ent(s) selected from Substituent group (b), and may be substituted by a hydroxy group" of there may be men¬tioned, for example, a eyelopropyImethyl, (1-hydroxycyclo- propyl)methyl, cyclobutylmethyl, (1-hydroxycyclobutyl)- methyl, cyclopentylmethyl, (3,3-difluoro-l-hydroxycyclo- pentyl)methyl, cyclohexylmethyl, (3,3-difluoro-l-hydroxy- cyclohexyl) methyl , (4,4-difluoro-l-hydroxycyclohexyl)- methyl, cyclopropylhydroxymethyl, hydroxy(1-hydroxycyclo- propyl)methyl, cyclobutylhydroxymethyl, hydroxy(1-hydroxy- cyclobutyl)methyl, cyclopentylhydroxymethyl, (3,3-difluoro- 1- hydroxycyclopentyl )hydroxymethyl, eyelohexylhydroxy- methyl, (3,3-difluoro-l-hydroxyeyelohexyl)hydroxymethyl, (4,4-difluoro-l-hydroxycyelohexyl)hydroxymethyl, 1-eyelo- propylethyl, 2-eyclopropylethyl, 1-(1-hydroxycyclopropyl)- ethyl, 2-(1-hydroxycyelopropyl)ethyl, 1-cyclobutylethyl, 2- cyclobutylethyl, 1-(1-hydroxycyclobutyl)ethyl, 2-(1- hydroxycyclobutyl)ethyl, 1-cyclopentylethyl, 2-cyclopentyl- ethyl, 1-(3,3-difluoro-l-hydroxycyclopentyl)ethyl, 2-(3,3- difluoro-l-hydroxycyclopentyl)ethyl, 1-cyclohexylethyl, 2- cyclohexylethyl, 1-(3,3-difluoro-l-hydroxycyclohexyl)ethyl, 2- (3 , 3-difluoro-l-hydroxycyclohexyl)ethyl, 1-(4,4-difluoro- 1-hydroxycyclohexyl)ethyl, 2-(4,4-difluoro-l-hydroxycyclo- hexyl) ethyl, [43] 1-cyclopropylpropyl, 3-cyclopropylpropyl, 1-(1-hydroxy¬cyclopropyl) propyl, 3-(1-hydroxycyclopropyl)propyl, 1- cyclobutylpropyl, 3-cyclobutylpropyl, 1-(1-hydroxycyclo¬butyl) propyl , 3-(1-hydroxycyclobutyl)propyl, 1-cyclopentyl- propyl, 3-cyclopentylpropyl, 1-(3,3-difluoro-l-hydroxy¬cyclopentyl) propyl , 3-(3,3-difluoro-l-hydroxycyclopentyl)- propyl, 1-cyclohexylpropyl, 3-cyclohexylpropyl, l-(3,3- difluoro-l-hydroxycyclohexyl)propyl, 3-(3,3-difluoro-l- hydroxycyclohexyl) propyl , 1-(4,4-difluoro-l-hydroxycyclo- hexyDpropyl, 3-(4,4-difluoro-l-hydroxycyclohexyl)propyl, 1-eyelopropy1-1-hydroxysthy1, 2 -eyelopropy1-2-hydroxysthy1, 1-hydroxy-l-(1-hydroxyeyclopropyl)ethyl, 2-hydroxy-2-(1- hydroxyeyclopropyl)ethyl, 1-eyclobutyl-l-hydroxyethyl, 2- eyclobutyl-2-hydroxyethyl, l-hydroxy-1-(1-hydroxycyelo- butyDethyl, 2-hydroxy-2 - (1-hydroxyeyelobutyl) ethyl, 1- cyelopentyl-1-hydroxyethyl, 2-cyclopentyl-2-hydroxyethyl, 1-(3,3-difluoro-l-hydroxycyclopentyl)-1-hydroxyethyl, 2- (3,3-difluoro-l-hydroxycyelopentyl)-2-hydroxyethyl, 1- eyelohexyl-1-hydroxyethyl, 2-eyelohexyl-2-hydroxyethyl, 1- (3,3-difluoro-l-hydroxycyelohexyl)-1-hydroxyethyl, 2-(3,3- difluoro-l-hydroxyeyelohexyl)-2-hydroxyethyl, 1-(4,4- difluoro-l-hydroxyeyelohexyl)-1-hydroxyethyl, 2-(4,4- di fluoro-1-hydroxyeyelohexyl)-2 -hydroxyethyl, [44] 1-eye1opropy1-1-hydroxypropy1, 3 -eye1opropy1-3 -hydroxy- propyl, 1-hydroxy-l-(1-hydroxycyclopropyl)propyl, 3- hydroxy-3-(1-hydroxyeyclopropyl)propyl, 1-cyclobutyl-l- hydroxypropyl, 3-cyclobutyl-3-hydroxypropyl, 1-hydroxy-1- (1-hydroxycyclobutyl)propyl, 3-hydroxy-3-(1-hydroxyeyelo¬butyl) propyl , 1-cyelopentyl-l-hydroxypropyl, 3-cyelopentyl- 3 -hydroxypropyl , 1-(3,3-difluoro-l-hydroxycyelopentyl)-1- hydroxypropyl, 3-(3,3-difluoro-l-hydroxycyclopentyl)-3- hydroxypropyl, 1-cyclohexyl-l-hydroxypropyl, 3-cyelohexyl- 3-hydroxypropyl, 1-(3,3-difluoro-l-hydroxycyclohexyl)-1- hydroxypropy1, 3-(3,3-difluoro-l-hydroxycyclohexyl)-3- hydroxypropy1, 1-(4,4-difluoro-l-hydroxycyclohexyl)-1- hydroxypropyl, 3-(4,4-difluoro-l-hydroxycyclohexyl)-3- hydroxypropyl, 1-eyclopropyl-l-methylethyl, 2-eye1opropy1- 1-methylethyl, 1-eyclobutyl-l-methylethyl, 2-cyclobutyl-l- methylethyl, 1-(1-hydroxyeyclopropyl)-1-methylethyl or 2- cyclopropyl-2-hydroxy-l-methylethyl group, etc., [45] preferably a cyelopropylmethyl, (1-hydroxycyclopropyl)- methyl, cyclobutylmethyl, (1-hydroxycyclobutyl)methyl, cyclopropylhydroxymethyl, hydroxy(1-hydroxycyclopropyl)- methyl, cyclobutylhydroxymethyl, hydroxy(1-hydroxycyclo¬butyl) methyl , 2-cyclopropylethyl, 2-(1-hydroxycyclopropyl)- ethyl, 2-cyclobutylethyl, 2-(1-hydroxycyclobutyl)ethyl, 3- cyclopropylpropyl, 3-(1-hydroxycyclopropyl)propyl, 3-cyclo- butylpropyl, 3-(1-hydroxycyclobutyl)propyl, 2-cyclopropyl- hydroxyethyl, 2-hydroxy-2-(1-hydroxycyclopropyl)ethyl, 2- cyclobutyl-2-hydroxyethyl, 2-hydroxy-2-(l-hydroxycyclo- butyDethyl, 3-cyclopropyl-3-hydroxypropyl, 3-hydroxy-3-(1- hydroxycyclopropyl)propyl, 3-eyelobutyl-3-hydroxypropyl or hydroxy-3-(1-hydroxycyclobutyl)propyl group, more prefer¬ably cyclopropylmethyl, (1-hydroxycyclopropyl)methyl, cyclobutylmethyl, (1-hydroxycyclobutyl)methyl, cyclopropyl¬hydroxymethyl, hydroxy(1-hydroxycyclopropyl)methyl, cyclo¬butylhydroxymethyl, hydroxy(1-hydroxycyclobutyl)methyl, 2- cyclopropylethyl, 2-(1-hydroxycyclopropyl)ethyl, 2-cyclo- butylethyl or 2-(1-hydroxycyclobutyl)ethyl group. [0046] As the "Cj-Cg alkenyl group" of R^, there may be mentioned, for example, a straight or branched Cj-Cg alkenyl group such as vinyl, 1-propenyl, 2-propenyl, 1- butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3- pentenyl, 4-pentenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4- hexenyl, 5-hexenyl, 1-methyl-1-propenyl, 2-methyl-1- propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl, 1- methyl-l-butenyl, 2-methyl-1-butenyl, 3-methyl-1-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1-methyl-3-butenyl, 2-methyl-3-butenyl, 3-methyl-3-butenyl, 1-methyl-1-pentenyl, 2-methyl-1-pentenyl, 3-methyl-1- pentenyl, 4-methyl-1-pentenyl, 1-methyl-2-pentenyl, 2- methyl-2-pentenyl, 3-methyl-2-pentenyl, 4-methyl-2-penten¬yl , 1-methyl-3-pentenyl, 2-methyl-3-pentenyl, 3-methyl-3- pentenyl, 4-methyl-3-pentenyl, l-methyl-4-pentenyl, 2- methyl-4-pentenyl, 3-methyl-4-pentenyl, 4-methyl-4-pentenyl and 2,3-dimethyl-2-butenyl group, etc., preferably 2- propenyl, 2-butenyl, 3-butenyl, 2-pentenyl, 3-pentenyl, 4- pentenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 2- methyl-2-propenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 2-methyl-3-butenyl, 3-methyl-3-butenyl, 2-methyl-2-penten¬yl , 3-methyl-2-pentenyl, 4-methyl-2-pentenyl, 2-methyl-3- pentenyl, 3-methyl-3-pentenyl, 4-methyl-3-pentenyl, 2- methyl-4-pentenyl, 3-methyl-4-pentenyl, 4-methyl-4-pentenyl or 2,3-dimethyl-2-butenyl group, more preferably 2-propen- yl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-methyl-2-propenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 2-methyl-2-penten¬yl, 3-methyl-2-pentenyl, 4-methyl-2-pentenyl or 2,3-di¬methyl -2 -butenyl group, particularly preferably 2-propenyl, 2-butenyl, 2-methyl-2-propenyl, 2-methyl-2-butenyl, 3- methyl-2-butenyl and 2,3-dimethyl-2-butenyl group. [47] As the "Cj-Cg alkynyl group" of R'*, there may be men¬tioned, for example, a straight or branched Cj-Cg alkynyl group such as an ethynyl, 1-propynyl, 2-propynyl, 1-butyn- yl, 2-butynyl, 3-butynyl, 1-methyl-2-propynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 3-methyl-1-butynyl, 1- methyl-2-butynyl, 1-methyl-3-butynyl, 2-methyl-3-butynyl, 1- hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 3- methyl-l-hexynyl, 4-methyl-1-pentynyl, 1-methyl-2-pentynyl, 4-methyl-2-pentynyl, 1-methyl-3-pentynyl, 2-methyl-3- pentynyl, 1-methyl-4-pentynyl, 2-methyl-4-pentynyl, 3- methyl-4-pentynyl and 2,2-dimethyl-3-butynyl group, etc., preferably an ethynyl, 2-propynyl, 2-butynyl, 3-butynyl, 2- pentynyl, 3-pentynyl, 4-pentynyl, 2-methyl-3-butynyl, 2- hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 4-methyl-2- pentynyl, 2-methyl-3-pentynyl, 2-methyl-4-pentynyl, 3- methyl-4-pentynyl or 2,2-dimethyl-3-butynyl group, more preferably an ethynyl, 2-propynyl, 2-butynyl, 2-pentynyl, 2- hexynyl or 4-methyl-2-pentynyl group, particularly preferably an ethynyl, 2-propynyl, 2-butynyl and 4-methyl- 2-pentynyl group. [48] 6 The "hydroxy C^-Cg alkenyl group" of R^ means a C3-C6 alkenyl group in which a hydroxy group is substituted on a carbon which is other carbon atoms than those constituting a double bond, and there may be mentioned, for example, a 3-hydroxy-1-propenyl, 1-hydroxy-2-propenyl, 3-hydroxy-1- butenyl, 4-hydroxy-1-butenyl, l-hydroxy-2-butenyl, 4- hydroxy-2-butenyl, 1-hydroxy-3-butenyl, 2-hydroxy-3-buten¬yl , 3-hydroxy-1-pentenyl, 1-hydroxy-2-pentenyl, 2-hydroxy- 3-pentenyl, 3-hydroxy-4-pentenyl, 3-hydroxy-1-hexenyl, 1- hydroxy-2-hexenyl, 2-hydroxy-3-hexenyl, 3-hydroxy-4-hexenyl or 4-hydroxy-5-hexenyl group, etc., preferably a 1-hydroxy- 2-propenyl, l-hydroxy-2-butenyl, 2-hydroxy-3-butenyl, 1- hydroxy-2-pentenyl, 2-hydroxy-3-pentenyl, 3-hydroxy-4- pentenyl, l-hydroxy-2-hexenyl, 2-hydroxy-3-hexenyl, 3- hydroxy-4-hexenyl or 4-hydroxy-5-hexenyl group, more pre¬ferably a l-hydroxy-2-propenyl, l-hydroxy-2-butenyl, 1- hydroxy-2-pentenyl or l-hydroxy-2-hexenyl group, particu¬larly preferably a l-hydroxy-2-propenyl or 1-hydroxy-2- butenyl group. [0049] The "hydroxy C3-C6 alkynyl group" of R means a C3-C alkynyl group in which a hydroxy group is substituted on a carbon which is other carbon atoms than those constituting a triple bond, and there may be mentioned, for example, a 3-hydroxy-1-propynyl, 1-hydroxy-2-propynyl, 3-hydroxy-l- butynyl, 4-hydroxy-1-butynyl, 1-hydroxy-2-butynyl, 4- hydroxy-2-butynyl, 1-hydroxy-3-butynyl, 2-hydroxy-3-butyn- yl, 3-hydroxy-1-pentynyl, 1-hydroxy-2-pentynyl, 2-hydroxy- 3-pentynyl, 3-hydroxy-4-pentynyl, 3-hydroxy-1-hexynyl, 1- hydroxy-2-hexynyl, 2-hydroxy-3-hexynyl, 3-hydroxy-4-hexynyl or 4-hydroxy-5-hexynyl group, etc., preferably a 1-hydroxy- 2-propynyl, l-hydroxy-2-butynyl, 2-hydroxy-3-butynyl, 1- hydroxy-2-pentynyl, 2-hydroxy-3-pentynyl, 3-hydroxy-4- pentynyl, l-hydroxy-2-hexynyl, 2-hydroxy-3-hexynyl, 3- hydroxy-4-hexynyl or 4-hydroxy-5-hexynyl group, more preferably a 1-hydroxy-2-propynyl, 1-hydroxy-2-butynyl, 1- hydroxy-2-pentynyl or 1-hydroxy-2-hexynyl group, particu¬larly preferably a 1-hydroxy-2-propynyl or 1-hydroxy-2- butynyl group. [50] The "aromatic ring group or heteroaromatic ring group" of the aromatic ring group or heteroaromatic ring group which may be substituted by a substituent(s) selected from Substituent group (c) of there may be mentioned, for example, a phenyl, naphthyl, thienyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, imidazolyl, pyrazolyl, pyridyl, pyridazinyl, pyrimidinyl or pyrazinyl group, etc., prefer¬ably a phenyl, thienyl, thiazolyl, pyrazolyl, pyridyl, pyridazinyl or pyrimidinyl group, more preferably a phenyl, thienyl, thiazolyl, pyrazolyl or pyridyl group. [51] A number of substituent(s) of the C^-C^ alkyl group substituted by a substituent(s) selected from (a halogen atom, a hydroxy group or a carboxy group) in the "C1-C4 alkyl group which may be substistuted by a substituent(s) selected from the group consisting of (a halogen atom, a hydroxy group and a carboxy group)" of Substituent group (c) is, for example, 1 to 9, preferably 1 to 6, more pre¬ferably 1 to 3, and the substituents in the case of a plural number may be the same or different from each other. [52] As the "C1-C4 alkyl group portion" in the C^-C^ alkyl group which may be substituted by a substituent(s) selected from the group consisting of (a halogen atom, a hydroxy group and a carboxy group) of Substituent group (c), there may be mentioned, for example, a methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl or tert-butyl group, preferably a methyl, ethyl, propyl or isopropyl group. [53] As the "C1-C4 alkyl group which may be substituted by a substituent(s) selected from the group consisting of (a halogen atom, a hydroxy group and a carboxy group)" of Substituent group (c), there may be mentioned, for example, a trifluoromethyl, 2,2,2-trifluoroethyl, 3,3,3-trifluoro- propyl, 2-chloroethyl, 2,2-dichloroethyl, 2,2,2-trichloro- ethyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1- hydroxypropy1, 2 -hydroxypropy1, 3 -hydroxypropy1, 2,2,2- trifluoro-1-hydroxy-1-trifluoromethylethyl, 1-hydroxy-1- methylethyl, 1-hydroxybutyl, 2-hydroxybutyl, 3-hydroxy- butyl, 4-hydroxybutyl, 1-hydroxy-2-methylpropyl, 2-hydroxy- 2-methylpropyl, carboxymethyl, 1-carboxyethyl, 2-carboxy- ethyl, 1-carboxypropyl, 2-carboxypropyl, 3-carboxypropyl, 1- carboxybutyl, 2-carboxybutyl, 3-carboxybutyl, 4-carboxy- butyl, 1-carboxy-2-methylpropyl or 2-carboxy-2-methylpropyl group, etc., preferably a trifluoromethyl, 2,2,2-trifluoro¬ethyl, 2-chloroethyl, 2,2-dichloroethyl, hydroxymethyl, 2- hydroxyethyl, 2-hydroxypropy1, 3-hydroxypropy1, 2,2,2-tri- fluoro-1-hydroxy-1-1ri fluoromethylethyl, 1-hydroxy-1- methylethyl, 2-hydroxybutyl, 3-hydroxybutyl, 4"hydroxy¬butyl , 1-hydroxy-2-methylpropyl, 2-hydroxy-2-methylpropyl, carboxymethyl, 2-carboxyethyl, 2-carboxypropyl, 3-carboxy¬propyl, 2-carboxybutyl, 3-carboxybutyl, 4-carboxybutyl or 2- carboxy-2-methylpropyl group, more preferably a tri- fluoromethyl, 2,2,2-trifluoroethyl, hydroxymethyl, 2- hydroxyethyl, 3-hydroxypropy1, 2,2,2-trifluoro-1-hydroxy-l- trifluoromethylethyl, 1-hydroxy-1-methylethyl, 3-hydroxy- butyl, 4-hydroxybutyl, 1-hydroxy-2-methylpropyl, 2-hydroxy- 2-methylpropyl, carboxymethyl, 2-carboxyethyl, 3-carboxy¬propyl, 3-carboxybutyl, 4-carboxybutyl or 2-carboxy-2- methylpropyl group. [54] A number of the substituent(s) of the aromatic ring group or heteroaromatic ring group each of which is substituted by a substituent(s) selected from Substituent group (c) is, for example, 1 to 4, preferably 1 to 3, and the substituents in a plural number may be the same or different from each other. As the "aromatic ring group or heteroaromatic ring group which may be substituted by a substituent(s) selected from Substituent group (c)" of R^, there may be mentioned, for example, a phenyl, 2-fluorophenyl, 3-fluorophenyl, 4- fluorophenyl, 2,4-difluorophenyl, 2,6-difluorophenyl, 3,4- difluorophenyl, 2,4,6-trifluorophenyl, 2-chlorophenyl, 3- chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 2,6- dichlorophenyl, 3,4-dichlorophenyl, 2,4,6-trichlorophenyl, 2 -hydroxypheny1, 3 -hydroxypheny1, 4 -hydroxypheny1, 2,6- dihydroxyphenyl, 2,4-dihydroxyphenyl, 3,4-dihydroxypheny1, 2,4,6-trihydroxyphenyl, 3,4,5-trihydroxyphenyl, 2-cyano- phenyl, 3 -cyanophenyl, 4 -cyanophenyl, 2-nitrophenyl, 3- nitrophenyl, 4-nitrophenyl, 2 -carboxyphenyl, 3-carboxy- phenyl, 4 -carboxyphenyl, 2-methylphenyl, 3-methylphenyl, 4- methylphenyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, 3,4- dimethylphenyl, 2,4,6-trimethylphenyl, 2-trifluoromethyl- phenyl, 3 -trifluoromethylphenyl, 4 -trifluoromethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 3-propylphenyl, 4-propyl- phenyl, 3-isopropylphenyl, 4-isopropylphenyl, 3-butyl- phenyl, 4-butylphenyl, 3 -isobutylphenyl, 4-isobutylphenyl, 3- (1-hydroxy-1-methylethyl)phenyl, 4-(1-hydroxy-1-methyl- ethyl)phenyl, 3-(2,2,2-trifluoro-1-hydroxy-1-ethyl)phenyl, 4- (2,2,2-trifluoro-1-hydroxy-1-trifluoromethylethyl)phenyl, 3 -(1-carboxy-1-methylethyl)phenyl, 4 -(1-carboxy-1-methyl- ethyl)phenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxy- phenyl, 2,6-dimethoxyphenyl, 2,4-dimethoxyphenyl, 3,4- dimethoxyphenyl, 2,4,6 -trimethoxyphenyl, 3,4,5-trimethoxy- phenyl, [0056] 2- ethoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 2,6-di- ethoxyphenyl, 2,4-diethoxyphenyl, 3,4-diethoxyphenyl, 2- propoxyphenyl, 3-propoxyphenyl, 4-propoxyphenyl, 2-butoxy- phenyl, 3-butoxypheny1, 4-butoxypheny1, 2-isopropoxyphenyl, 3- isopropoxyphenyl, 4-isopropoxyphenyl, 2-methoxycarbonyl- phenyl, 3-methoxycarbonylphenyl, 4-methoxycarbonylphenyl, 2,6-dimethoxycarbonylphenyl, 2,4-dimethoxycarbonylphenyl, 3,4-dimethoxycarbonylphenyl, 2,4,6-trimethoxycarbonyl- phenyl, 3,4,5-1rimethoxycarbonylphenyl, 2 -ethoxycarbonyl- phenyl, 3 -ethoxycarbonylphenyl, 4 -ethoxycarbonylphenyl, 2,6-diethoxycarbonylphenyl, 2,4-diethoxycarbonylphenyl, 3,4-diethoxycarbonylphenyl, 2-propoxycarbonylphenyl, 3 - propoxycarbonylphenyl, 4-propoxycarbonylphenyl, 2-butoxy- carbonylphenyl, 3-butoxycarbonylphenyl, 4-butoxycarbonyl- phenyl, 2-isopropoxycarbonylphenyl, 3-isopropoxycarbonyl- phenyl, 4-isopropoxycarbonylphenyl, 3-acetoxyphenyl, 4- acetoxyphenyl, 3-propionyloxyphenyl, 4-propionyloxyphenyl, 3- butyryloxyphenyl, 4-butyryloxyphenyl, 3-dimethylamino- phenyl , 4-dimethylaminophenyl, 3-diethylaminophenyl, 4- diethylaminophenyl, 3-dipropylaminophenyl, 4-dipropylamino- phenyl, 3-dibutylaminophenyl, 4-dibutylaminophenyl, 3-di- isopropylaminophenyl, 4-diisopropylaminophenyl, 1-naphthyl, 2-naphthyl, [0057] 2-thienyl, 3-cyano-2-thienyl, 4-cyano-2-thienyl, 5-cyano-2- thienyl, 3-carboxy-2-thienyl, 4-carboxy-2-thienyl, 5- carboxy-2-thienyl, 3-methyl-2-thienyl, 4-methyl-2-thienyl, 5-methyl-2-thienyl, 3-trifluoromethyl-2-thienyl, 4-tri- fluoromethyl-2-thienyl, 5-trifluoromethyl-2-thienyl, 3,4- dimethyl-2-thienyl, 3,5-dimethyl-2-thienyl, 4,5-dimethyl-2- thienyl, 4-ethyl-2-thienyl, 5-ethyl-2-thienyl, 4-propyl-2- thienyl, 5-propyl-2-thienyl, 4-isopropyl-2-thienyl, 5- isopropyl-2-thienyl, 4-butyl-2-thienyl, 5-butyl-2-thienyl, 4- isobutyl-2-thienyl, 5-isobutyl-2-thienyl, 4-(1-hydroxy-l- methylethyl)-2-thienyl, 5-(1-hydroxy-1-methylethyl)-2- thienyl, 4-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl- ethyl)-2-thienyl, 5-(2,2,2-trifluoro-l-hydroxy-l-trifluoro- methylethyl)-2-thienyl, 4-(1-carboxy-1-methylethyl)-2- thienyl, 5-(1-carboxy-l-methylethyl)-2-thienyl, 3-methoxy- carbonyl-2-thienyl, 4-methoxycarbonyl-2-thienyl, 5-methoxy- carbonyl-2-thienyl, 3-ethoxycarbonyl-2-thienyl, 4-ethoxy¬carbonyl -2 -thienyl , 5-ethoxycarbonyl-2-thienyl, 3-propoxy- carbonyl-2-thienyl, 4-propoxycarbonyl-2-thienyl, 5-propoxy- carbonyl-2-thienyl, 3-butoxycarbonyl-2-thienyl, 4-butoxy- carbonyl-2-thienyl, 5-butoxycarbonyl-2-thienyl, 3-isoprop- oxycarbonyl-2-thienyl, 4-isopropoxycarbonyl-2-thienyl, 5- isopropoxycarbonyl-2 -thienyl, [0058] 3- thienyl, 2-cyano-3-thienyl, 4-cyano-3-thienyl, 5-cyano-3- thienyl, 2-carboxy-3-thienyl, 4-carboxy-3-thienyl, 5- carboxy-3-thienyl, 2-methyl-3-thienyl, 4-methyl-3-thienyl, 5-methyl-3-thienyl, 2-trifluoromethyl-3-thienyl, 4-tri- fluoromethyl-3-thienyl, 5-trifluoromethyl-3-thienyl, 2,4- dimethyl-3-thienyl, 2,5-dimethyl-3-thienyl, 4,5-dimethyl-3- thienyl, 5-ethyl-3-thienyl, 5-propyl-3-thienyl, 5-isoprop- yl-3-thienyl, 5-butyl-3-thienyl, 5-isobutyl-3-thienyl, 5- (1-hydroxy-1-methylethyl)-3-thienyl, 5-(2,2,2-trifluoro-1- hydroxy-l-trifluoromethylethyl)-3-thienyl, 5-(1-carboxy-l- methylethyl)-3-thienyl, 5-methoxycarbonyl-3-thienyl, 5- ethoxycarbonyl-3-thienyl, 5-propoxycarbonyl-3-thienyl, 5- butoxycarbonyl-3 -thienyl, 5-i sopropoxycarbonyl-3 -thienyl, 4- oxazolyl, 5-oxazolyl, 4-isoxazolyl, 5-isoxazolyl, 4- thiazolyl, 2-cyano-4-thiazolyl, 2-carboxy-4-thiazolyl, 2- methyl-4-thiazolyl, 2-ethyl-4-thiazolyl, 2-propyl-4- thiazolyl, 2-isopropyl-4-thiazolyl, 2-trifluoromethyl-4- thiazolyl, 2-(1-hydroxy-l-methylethyl)-4-thiazolyl, 2- (2,2,2-trifluoro-1-hydroxy-1-trifluoromethylethyl)-4- thiazolyl, 2-(1-carboxy-l-methylethyl)-4-thiazolyl, 2- methoxycarbonyl-4 -thiazolyl, 2 -ethoxycarbonyl-4 -thiazolyl, 2-propoxycarbony1-4 -thiazolyl, 2 -i sopropoxycarbonyl-4 - thiazolyl, 5-thiazolyl, 2-cyano-5-thiazolyl, 2-carboxy-5- thiazolyl, 2-methyl-5-thiazolyl, 2-ethyl-5-thiazolyl, 2- propyl-5-thiazolyl, 2-isopropyl-5-thiazolyl, 2-trifluoro- methyl-5-thiazolyl, 2-(1-hydroxy-l-methylethyl)-5-thiazol¬yl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl) -5- thiazolyl, 2-(1-carboxy-l-methylethyl)-5-thiazolyl, 2- methoxycarbonyl-5 -thiazolyl, 2 -ethoxycarbonyl- 5-thiazolyl, 2-propoxycarbonyl-5-thiazolyl, 2 -isopropoxycarbonyl-5- thiazolyl, 4-isothiazolyl, 5-isothiazolyl, 2-imidazolyl, 4- imidazolyl, 4-pyrazolyl, 1-methyl-4-pyrazolyl, l-ethyl-4- pyrazolyl, 1-propyl-4-pyrazolyl, 1-isopropyl-4-pyrazolyl, 1-butyl-4-pyrazolyl, [59] 3-pyrazolyl, 1-methyl-3-pyrazolyl, 1-ethyl-3-pyrazolyl, 1- propyl-3-pyrazolyl, 1-isopropyl-3-pyrazolyl, 1-butyl-3- pyrazolyl, 2-pyridyl, 6-cyano-2-pyridyl, 6-carboxy-2- pyridyl, 6-trifluoromethyl-2-pyridyl, 6-methoxy-2-pyridyl, 6-ethoxy-2-pyridyl, 6-propoxy-2-pyridyl, 6 -isopropoxy-2- pyridyl, 6-butoxy-2-pyridyl, 6-methoxycarbonyl-2-pyridyl, 6-ethoxycarbonyl-2-pyridyl, 6-propoxycarbonyl-2-pyridyl, 6- i sopropoxycarbonyl-2-pyridyl, 6-butoxycarbonyl-2-pyridyl, 6-(1-hydroxy-1-methylethyl)-2-pyridyl, 6-(2,2,2-trifluoro- 1-hydroxy-1-trifluoromethylethyl)-2-pyridyl, 6-(1-carboxy- 1- methylethyl)-2-pyridyl, 3-pyridyl, 6-cyano-3-pyridyl, 6- carboxy-3-pyridyl, 6-trifluoromethyl-3-pyridyl, 6-methoxy- 3- pyridyl, 6-ethoxy-3-pyridyl, 6-propoxy-3-pyridyl, 6- isopropoxy-3-pyridyl, 6-butoxy-3-pyridyl, 6-methoxycarbon¬yl -3 -pyridyl , 6-ethoxycarbonyl-3-pyridyl, 6-propoxycarbon- yl-3-pyridyl, 6-isopropoxycarbonyl-3-pyridyl, 6-butoxy- carbonyl-3-pyridyl, 6-(1-hydroxy-1-methylethyl)-3-pyridyl, 6-(2,2,2-trifluoro-1-hydroxy-1-trifluoromethylethyl)-3 - pyridyl, 6-(1-carboxy-l-methylethyl)-3-pyridyl, 2-cyano-3- pyridyl, 2-carboxy-3-pyridyl, 2-trifluoromethyl-3-pyridyl, 2- methoxy-3-pyridyl, 2-ethoxy-3-pyridyl, 2-propoxy-3- pyridyl, 2-isopropoxy-3-pyridyl, 2-butoxy-3-pyridyl, 2- methoxycarbonyl-3-pyridyl, 2-ethoxycarbonyl-3-pyridyl, 2- propoxycarbonyl-3-pyridyl, 2 -isopropoxycarbonyl-3-pyridyl, 2-butoxycarbonyl-3-pyridyl, 2-(1-hydroxy-1-methylethyl)-3- pyridyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl- ethyl)-3-pyridyl, 2-(1-carboxy-l-methylethyl)-3-pyridyl, [60] 4- pyridyl, 2-cyano-4-pyridyl, 2-carboxy-4-pyridyl, 2-tri¬fluoromethyl -4 -pyridyl , 2-methoxy-4-pyridyl, 2-ethoxy-4- pyridyl, 2-propoxy-4-pyridyl, 2 -isopropoxy-4-pyridyl, 2- butoxy-4-pyridyl, 2-methoxycarbonyl-4-pyridyl, 2-ethoxy- carbonyl-4-pyridyl, 2-propoxycarbonyl-4-pyridyl, 2-iso- propoxycarbonyl-4-pyridyl, 2-butoxycarbonyl-4-pyridyl, 2- {1-hydroxy-1-methylethyl)-4-pyridyl, 2-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl) -4-pyridyl, 2-(1-carboxy-l- methylethyl)-4-pyridyl, 3-pyridazinyl, 4-pyridazinyl, 2- pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl or 2-pyrazinyl group, etc., [0061] preferably a phenyl, 2-fluorophenyl, 3-fluorophenyl, 4- fluorophenyl, 2,4-difluorophenyl, 2,6-difluorophenyl, 3,4- difluorophenyl, 2,4,6-trifluorophenyl, 2-chlorophenyl, 3- chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 2,6- dichlorophenyl, 3,4-dichlorophenyl, 2,4,6 -trichlorophenyl, 3- hydroxyphenyl, 4-hydroxyphenyl, 3 -cyanophenyl, 4-cyano- phenyl, 3-nitrophenyl, 4-nitrophenyl, 3-carboxyphenyl, 4- carboxyphenyl, 3-methylphenyl, 4-methylphenyl, 3-trifluoro- methylphenyl, 4-trifluoromethylphenyl, 3-ethylphenyl, 4- ethylphenyl, 3-propylphenyl, 4-propylphenyl, 3 -isopropyl- phenyl, 4-isopropylphenyl, 3-(1-hydroxy-1-methylethyl)- phenyl, 4-(1-hydroxy-1-methylethyl)phenyl, 3-(2,2,2-tri- fluoro-l-hydroxy-l-trifluoromethylethyl)phenyl, 4- (2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)phenyl, 3-(1- carboxy-1-methylethyl)phenyl, 4-(1-carboxy-1-methylethyl)- phenyl, 3-methoxyphenyl, 4-methoxyphenyl, 3-ethoxyphenyl, 4- ethoxyphenyl, 3-propoxyphenyl, 4-propoxyphenyl, 3-butoxy- phenyl, 4-butoxyphenyl, 3-isopropoxyphenyl, 4-isopropoxy- phenyl, 3-methoxycarbonylphenyl, 4-methoxycarbonylphenyl, 3-ethoxycarbonylphenyl, 4-ethoxycarbonylphenyl, 3-acetoxy- phenyl, 4-acetoxyphenyl, 3-dimethylaminophenyl, 4-dimethyl- aminophenyl, 3-diethylaminophenyl, 4-diethylaminophenyl, 3- dipropylaminophenyl, 4 -dipropylaminophenyl, [0062] 2-thienyl, 4-cyano-2-thienyl, 5-cyano-2-thienyl, 4-carboxy- 2-thienyl, 5-carboxy-2-thienyl, 4-methyl-2-thienyl, 5- methyl-2-thienyl, 4-trifluoromethyl-2-thienyl, 5-trifluoro- methyl-2-thienyl, 4-ethyl-2-thienyl, 5-ethyl-2-thienyl, 4- propyl-2-thienyl, 5-propyl-2-thienyl, 4-isopropyl-2- thienyl, 5-isopropyl-2-thienyl, 4-(1-hydroxy-l-methyl- ethyl) -2-thienyl, 5-(1-hydroxy-l-methylethyl)-2-thienyl, 4- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-2- thienyl, 5-(2,2,2-trifluoro-1-hydroxy-1-trifluoromethyl- ethyl)-2-thienyl, 4-(1-carboxy-l-methylethyl)-2-thienyl, 5- (1-carboxy-1-methylethyl)-2 -thienyl, 4-methoxycarbonyl-2 - thienyl, 5-methoxycarbonyl-2-thienyl, 4-ethoxycarbonyl-2- thienyl, 5-ethoxycarbonyl-2-thienyl, 4-propoxycarbonyl-2- thienyl, 5-propoxycarbonyl-2-thienyl, 4-butoxycarbonyl-2- thienyl, 5-butoxycarbonyl-2-thienyl, 4-isopropoxycarbonyl- 2-thienyl, 5-isopropoxycarbonyl-2-thienyl, 3-thienyl, 4- cyano-3-thienyl, 5-cyano-3-thienyl, 4-carboxy-3-thienyl, 5- carboxy-3-thienyl, 4-methyl-3-thienyl, 5-methyl-3-thienyl, 4- trifluoromethyl-3-thienyl, 5-trifluoromethyl-3-thienyl, 5- ethyl-3-thienyl, 5-propyl-3-thienyl, 5-isopropyl-3- thienyl, 5-(1-hydroxy-l-methylethyl)-3-thienyl, 5-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-3-thienyl, 5- (1-carboxy-1-methylethyl)-3 -thienyl, 5-methoxycarbonyl-3 - thienyl, 5-ethoxycarbonyl-3-thienyl, 4-thiazolyl, 2-cyano- 4- thiazolyl, 2-carboxy-4-thiazolyl, 2-methyl-4-thiazolyl, 2-ethyl-4-thiazolyl, 2-propyl-4-thiazolyl, 2-isopropyl-4- thiazolyl, 2-trifluoromethyl-4-thiazolyl, 2-(1-hydroxy-l- methylethyl) -4-thiazolyl, 2-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl) -4-thiazolyl, 2-(1-carboxy-1-methyl- ethyl) -4-thiazolyl, 2-methoxycarbonyl-4-thiazolyl, 2- ethoxycarbonyl-4 -thiazolyl, [0063] 5- thiazolyl, 2-cyano-5-thiazolyl, 2-carboxy-5-thiazolyl, 2- methyl-5-thiazolyl, 2-ethyl-5-thiazolyl, 2-propyl-5- thiazolyl, 2-isopropyl-5-thiazolyl, 2-trifluoromethyl-5- thiazolyl, 2-(1-hydroxy-l-methylethyl)-5-thiazolyl, 2- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-5- thiazolyl, 2-(1-carboxy-l-methylethyl)-5-thiazolyl, 2- methoxycarbonyl-5 -thiazolyl, 2 -ethoxycarbonyl-5-thiazolyl, 2-propoxycarbonyl-5-thiazolyl, 2 -isopropoxycarbonyl-5 - thiazolyl, 4-pyrazolyl, 1-methyl-4-pyrazolyl, l-ethyl-4- pyrazolyl, 3-pyrazolyl, 1-methyl-3-pyrazolyl, l-ethyl-3- pyrazolyl, 6-cyano-2-pyridyl, 6-carboxy-2-pyridyl, 6- trifluoromethyl-2-pyridyl, 6-methoxy-2-pyridyl, 6-ethoxy-2- pyridyl, 6-methoxycarbonyl-2-pyridyl, 6-ethoxycarbonyl-2- pyridyl, 6-(1-hydroxy-l-methylethyl)-2-pyridyl, 6-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-2-pyridyl, 6- (1-carboxy-l-methylethyl)-2-pyridyl, 6-cyano-3-pyridyl, 6- carboxy-3-pyridyl, 6-trifluoromethyl-3-pyridyl, 6-methoxy- 3- pyridyl, 6-ethoxy-3-pyridyl, 6-methoxycarbonyl-3-pyridyl, 6-ethoxycarbonyl-3-pyridyl, 6-(1-hydroxy-l-methylethyl)-3- pyridyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl¬ethyl) -3 -pyridyl, 6-(1-carboxy-l-methylethyl)-3-pyridyl, 2- cyano-3-pyridyl, 2-carboxy-3-pyridyl, 2-trifluoromethyl-3- pyridyl, 2-methoxy-3-pyridyl, 2-ethoxy-3-pyridyl, 2- propoxy-3-pyridyl, 2-methoxycarbonyl-3-pyridyl, 2-ethoxy- carbonyl-3-pyridyl, 2-propoxycarbonyl-3-pyridyl, 2-(1- hydroxy-l-methylethyl)-3-pyridyl, 2-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl) -3-pyridyl, 2-(1-carboxy-l- methylethyl ) -3 -pyridyl , 2-cyano-4-pyridyl, 2-carboxy-4- pyridyl, 2-trifluoromethyl-4-pyridyl, 2-methoxy-4-pyridyl, 2-ethoxy-4-pyridyl, 2-propoxy-4-pyridyl, 2-methoxycarbonyl- 4- pyridyl, 2-ethoxycarbonyl-4-pyridyl, 2-(1-hydroxy-1- methylethyl)-4-pyridyl, 2-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl) -4-pyridyl or 2-(1-carboxy-l-methyl- ethyl) -4-pyridyl group, [0064] more preferably a phenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2,4-difluorophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 2-chlorophenyl, 3-chlorophenyl, 4- chlorophenyl, 2,4-dichlorophenyl, 2,6-dichlorophenyl, 3,4- dichlorophenyl, 3-cyanophenyl, 4-cyanophenyl, 3-nitro- phenyl, 4-nitrophenyl, 3-carboxyphenyl, 4-carboxyphenyl, 3- trifluoromethylphenyl, 4-trifluoromethylphenyl, 3-(l- hydroxy-l-methylethyl)phenyl, 4-(1-hydroxy-l-methylethyl)- phenyl, 3 -(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl- ethyl)phenyl, 4-(2,2,2-trifluoro-l-hydroxy-l-trifluoro- methylethyl)phenyl, 3 -(1-carboxy-1-methylethyl)phenyl, 4 - (1-carboxy-l-methylethyl)phenyl, 3-methoxyphenyl, 4- methoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 3-methoxy- carbonylphenyl, 4-methoxycarbonylphenyl, 3-ethoxycarbonyl- phenyl, 4-ethoxycarbonylphenyl, 2-thienyl, 4-cyano-2- thienyl, 5-cyano-2-thienyl, 4-carboxy-2-thienyl, 5-carboxy- 2- thienyl, 4-methyl-2-thienyl, 5-methyl-2-thienyl, 4-tri- fluoromethyl-2-thienyl, 5-trifluoromethyl-2-thienyl, 4-(1- hydroxy-1-methylethyl)-2-thienyl, 5-(1-hydroxy-1-methyl- ethyl)-2-thienyl, 4-(2,2,2-trifluoro-l-hydroxy-l-tri- fluoromethylethyl)-2-thienyl, 5-(2,2,2-trifluoro-l-hydroxy- 1- trif luoromethylethyl) -2-thienyl, 4-(1-carboxy-1-methyl- ethyl)-2-thienyl, 5-(1-carboxy-l-methylethyl)-2-thienyl, [0065] 3- thienyl, 4-cyano-3-thienyl, 5-cyano-3-thienyl, 4-carboxy- 3- thienyl, 5-carboxy-3-thienyl, 4-methyl-3-thienyl, 5- methyl-3-thienyl, 4-trifluoromethyl-3-thienyl, 5-trifluoro- methyl-3-thienyl, 5-ethyl-3-thienyl, 5-(1-hydroxy-l-methyl- ethyl) -3-thienyl, 5-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl) -3-thienyl, 5-{1-carboxy-l-methylethyl)-3- thienyl, 5-methoxycarbonyl-3-thienyl, 4-thiazolyl, 2-cyano- 4- thiazolyl, 2-carboxy-4-thiazolyl, 2-methyl-4-thiazolyl, 2- ethyl-4-thiazolyl, 2-propyl-4-thiazolyl, 2-isopropyl-4- thiazolyl, 2-trifluoromethyl-4-thiazolyl, 2-(1-hydroxy-l- methylethyl)-4-thiazolyl, 2-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl ) -4-thiazolyl, 2-(1-carboxy-1-methyl- ethyl)-4-thiazolyl, 2-methoxycarbonyl-4-thiazolyl, 5- thiazolyl, 2-cyano-5-thiazolyl, 2-carboxy-5-thiazolyl, 2- methyl-5-thiazolyl, 2-ethyl-5-thiazolyl, 2-trifluoromethyl- 5- thiazolyl, 2-(1-hydroxy-l-methylethyl)-5-thiazolyl, 2- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-5- thiazolyl, 2-(1-carboxy-l-methylethyl)-5-thiazolyl, 2- methoxycarbonyl-5-thiazolyl, 2 -ethoxycarbonyl-5-thiazolyl, 2-propoxycarbonyl-5 -thiazolyl, 2 -isopropoxycarbonyl-5- thiazolyl, 4-pyrazolyl, 6-cyano-2-pyridyl, 6-carboxy-2- pyridyl, 6-trifluoromethyl-2-pyridyl, 6-methoxy-2-pyridyl, 6-ethoxy-2-pyridyl, 6-methoxycarbonyl-2-pyridyl, 6-ethoxy- carbonyl-2-pyridyl, 6-(1-hydroxy-1-methylethyl)-2-pyridyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-2- pyridyl, 6-(1-carboxy-l-methylethyl)-2-pyridyl, 6-cyano-3- pyridyl, 6-carboxy-3-pyridyl, 6-trifluoromethyl-3-pyridyl, 6-methoxy-3-pyridyl, 6-ethoxy-3-pyridyl, 6-methoxycarbonyl- 3-pyridyl, 6-ethoxycarbonyl-3-pyridyl, 6-(l-hydroxy-l- methylethyl) -3-pyridyl, 6-(2,2,2-trifluoro-l-hydroxy-1- trifluoromethylethyl)-3-pyridyl, 6-(1-carboxy-l-methyl¬ethyl )-3-pyridyl, [0066] 2- cyano-3-pyridyl, 2-carboxy-3-pyridyl, 2-trifluoromethyl- 3- pyridyl, 2-methoxy-3-pyridyl, 2-ethoxy-3-pyridyl, 2- propoxy-3-pyridyl, 2-methoxycarbonyl-3-pyridyl, 2-ethoxy- carbonyl-3-pyridyl, 2-propoxycarbonyl-3-pyridyl, 2-(1- hydroxy-1-methylethyl)-3-pyridyl, 2-(2,2,2-trifluoro-1- hydroxy-l-trifluoromethylethyl)-3-pyridyl, 2-(1-carboxy-l- methylethyl) -3-pyridyl, 2-cyano-4-pyridyl, 2-carboxy-4- pyridyl, 2-trifluoromethyl-4-pyridyl, 2-methoxy-4-pyridyl, 2- ethoxy-4-pyridyl, 2-propoxy-4-pyridyl, 2-methoxycarbonyl- 4- pyridyl, 2-ethoxycarbonyl-4-pyridyl, 2-(l-hydroxy-l- methylethyl) -4-pyridyl, 2-(2,2,2-trifluoro-l-hydroxy-1- trifluoromethylethyl)-4-pyridyl or 2-(1-carboxy-l-methyl- ethyl)-4-pyridyl group, [0067] particularly preferably a phenyl, 2-fluorophenyl, 4-fluoro- phenyl, 2,4-difluorophenyl, 2-chlorophenyl, 4-chlorophenyl, 4-cyanophenyl, 4-nitrophenyl, 4-carboxyphenyl, 4-trifluoro- methylphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 4-methoxy- carbonylphenyl, 2-thienyl, 5-cyano-2-thienyl, 5-carboxy-2- thienyl, 5-methyl-2-thienyl, 5-trifluoromethyl-2-thienyl, 3- thienyl, 5-cyano-3-thienyl, 5-carboxy-3-thienyl, 5- methyl-3-thienyl, 5-trifluoromethyl-3-thienyl, 4-thiazolyl, 2-cyano-4-thiazolyl, 2-carboxy-4-thiazolyl, 2-methyl-4- thiazolyl, 2-trifluoromethyl-4-thiazolyl, 2-(1-hydroxy-l- methylethyl)-4-thiazolyl, 2-(2,2,2-trifluoro-l-hydroxy-1- trifluoromethylethyl)-4-thiazolyl, 5-thiazolyl, 2-cyano-5- thiazolyl, 2-carboxy-5-thiazolyl, 2-methyl-5-thiazolyl, 2- trifluoromethyl-5-thiazolyl, 2-(1-hydroxy-1-methylethyl)-5- thiazolyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl- ethyl)-5-thiazolyl, 4-pyrazolyl, 6-cyano-2-pyridyl, 6- carboxy-2-pyridyl, 6-trifluoromethyl-2-pyridyl, 6-methoxy- 2- pyridyl, 6-(1-hydroxy-l-methylethyl)-2-pyridyl, 6-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-2-pyridyl, 6- cyano-3-pyridyl, 6-carboxy-3-pyridyl, 6-trifluoromethyl-3- pyridyl, 6-methoxy-3-pyridyl, 6-(1-hydroxy-l-methylethyl)- 3- pyridyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl¬ethyl) -3 -pyridyl , 2-cyano-4-pyridyl, 2-carboxy-4-pyridyl, 2-trifluoromethyl-4-pyridyl, 2-methoxy-4-pyridyl, 2-(l- hydroxy-1-methylethyl)-4-pyridyl or 2-(2,2,2-trifluoro-l- hydroxy-1-trifluoromethylethyl)-4-pyridyl group. [0068] As the "C^-Cj alkyl group which is substituted by an aromatic ring group or heteroaromatic ring group each of which may be substituted by a substituent(s) selected from Substituent group (c), and may be substituted by a hydroxy group" of R^, there may be mentioned, for example, a benzyl, 2-fluorobenzyl, 3-fluorobenzyl, 4-fluorobenzyl, 2,4-difluorobenzyl, 2,6-difluorobenzyl, 3,4-difluorobenzyl, 2- chlorobenzyl, 3-chlorobenzyl, 4-chlorobenzyl, 2,4-di- chlorobenzyl, 2,6-dichlorobenzyl, 3,4-dichlorobenzyl, 2- cyanobenzyl, 3-cyanobenzyl, 4-cyanobenzyl, 3-nitrobenzyl, 4- nitrobenzyl, 3-carboxybenzyl, 4-carboxybenzyl, 3-tri- fluoromethylbenzyl, 4-trifluoromethylbenzyl, 3-(1-hydroxy- l-methylethyl) benzyl, 4-(1-hydroxy-l-methylethyl)benzyl, 3- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)benzyl, 4-(2,2, 2-trifluoro-l-hydroxy-l-trifluoromethylethyl)benzyl, 3- (1-carboxy-l-methylethyl)benzyl, 4-(1-carboxy-l-methyl- ethyl)benzyl, 3-methoxybenzyl, 4-methoxybenzyl, 3-ethoxy- benzyl, 4-ethoxybenzyl, 3-methoxycarbonylbenzyl, 4-methoxy- carbonylbenzyl, 3-ethoxycarbonylbenzyl, 4-ethoxycarbonyl- benzyl, 1-naphthylmethyl, 2-naphthylmethyl, 2-thienyl- methyl, 4-cyano-2-thienylmethyl, 5-cyano-2-thienylmethyl, 4- carboxy-2-thienylmethyl, 5-carboxy-2-thienylmethyl, 4- methyl-2-thienylmethyl, 5-methyl-2-thienylmethyl, 4-tri- fluoromethyl-2 -thienylmethyl, 5 -1ri fluoromethyl-2 -thienyl- methyl, 4-(1-hydroxy-l-methylethyl)-2-thienylmethyl, 5-(1- hydroxy-l-methylethyl)-2-thienylmethyl, 4-(2,2,2-trifluoro- 1-hydroxy-1-trifluoromethylethyl)-2-thienylmethyl, 5- (2,2, 2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-2- thienylmethyl, 4-(1-carboxy-1-methylethyl)-2-thienylmethyl, 5- (1-carboxy-1-methylethyl)-2-thienylmethyl, [0069] 3- thienylmethyl, 4-cyano-3-thienylmethyl, 5-cyano-3-thien¬ylmethyl, 4-carboxy-3-thienylmethyl, 5-carboxy-3-thienyl¬methyl, 4-methyl-3-thienylmethyl, 5-methyl-3-thienylmethyl, 4- trifluoromethyl-3-thienylmethyl, 5-trifluoromethyl-3- thienylmethyl, 5-ethyl-3-thienylmethyl, 5-(1-hydroxy-l- methylethyl) -3-thienylmethyl, 5-(2,2,2-trifluoro-l-hydroxy- l-trif luoromethylethyl) -3-thienylmethyl, 5-(1-carboxy-1- raethylethyl)-3-thienylmethyl, 5-methoxycarbonyl-3-thienyl¬methyl, 4-oxazolylmethyl, 5-oxazolylmethyl, 4-isoxazolyl- methyl, 5-isoxazolylmethyl, 4-thiazolylmethyl, 2-cyano-4- thiazolylmethyl, 2-carboxy-4 -thiazolylmethyl, 2-methyl-4- thiazolylmethyl, 2-ethyl-4-thiazolylmethyl, 2-propyl-4- thiazolylmethyl, 2-isopropyl-4-thiazolylmethyl, 2-tri- fluoromethyl-4-thiazolylmethyl, 2-(1-hydroxy-l-methyl¬ethyl) -4-thiazolylmethyl, 2-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl) -4-thiazolylmethyl, 2-(1-carboxy-l- methylethyl)-4 -thiazolylmethyl, 2-methoxycarbonyl-4 - thiazolylmethyl, 5-thiazolylmethyl, 2-cyano-5-thiazolyl¬methyl, 2-carboxy-5-thiazolylmethyl, 2-methyl-5-thiazol¬ylmethyl, 2-ethyl-5-thiazolylmethyl, 2-trifluoromethyl-5- thiazolylmethyl, 2-(1-hydroxy-l-methylethyl)-5-thiazolyl- methyl, 2 -(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl¬ethyl )- 5-thiazolylmethyl, 2-(1-carboxy-1-methylethyl)- 5- thiazolylmethyl, 2-methoxycarbonyl-5 -thiazolylmethyl, 2- ethoxycarbonyl-5-thiazolylmethyl, 2-propoxycarbonyl-5 - thiazolylmethyl, 2-isopropoxycarbonyl-5-thiazolylmethyl, 4- isothiazolylraethyl, S-isothiazolylmethyl, 2-imidazolyl- raethyl, 4-imidazolylmethyl, 3-pyrazolylmethyl, 4-pyrazol- ylmethyl, [70] 2- pyridylmethyl, 6-cyano-2-pyridylmethyl, 6-carboxy-2- pyridylmethyl, 6 -trifluoromethyl-2-pyridylmethyl, 6- methoxy-2-pyridylmethyl, 6-ethoxy-2-pyridylmethyl, 6- methoxycarbonyl-2-pyridylmethyl, 6 -ethoxycarbonyl-2 - pyridylmethyl, 6-(1-hydroxy-1-methylethyl)-2-pyridylmethyl, 6-(2,2,2-trifluoro-1-hydroxy-1-trifluoromethylethyl)-2- pyridylmethyl, 6-(1-carboxy-1-methylethyl)-2-pyridylmethyl, 3- pyridylmethyl, 6-cyano-3-pyridylmethyl, 6-carboxy-3- pyridylmethyl, 6-trifluoromethyl-3-pyridylmethyl, 6- methoxy-3-pyridylmethyl, 6-ethoxy-3-pyridylmethyl, 6- methoxycarbonyl-3-pyridylmethyl, 6 -ethoxycarbonyl-3 - pyridylmethyl, 6-(1-hydroxy-1-methylethyl)-3-pyridylmethyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-3- pyridylmethyl, 6 -(1-carboxy-1-methylethyl)-3-pyridylmethyl, 2-cyano-3-pyridylmethyl, 2-carboxy-3-pyridylmethyl, 2- trifluoromethyl-3-pyridylmethyl, 2-methoxy-3-pyridylmethyl, 2-ethoxy-3-pyridylmethyl, 2-propoxy-3-pyridylmethyl, 2- methoxycarbonyl-3-pyridylmethyl, 2 -ethoxycarbonyl-3 - pyridylmethyl, 2-propoxycarbonyl-3-pyridylmethyl, 2-(1- hydroxy-1-methylethyl)-3-pyridylmethyl, 2-(2,2,2-trifluoro- 1- hydroxy-l-trif luoromethylethyl) -3-pyridylmethyl, 2-(1- carboxy-1-methylethyl)-3-pyridylmethyl, 4-pyridylmethyl, 2- cyano-4-pyridylmethyl, 2-carboxy-4-pyridylmethyl, 2-tri- fluoromethyl-4-pyridylmethyl, 2-methoxy-4-pyridylmethyl, 2- ethoxy-4-pyridylmethyl, 2-propoxy-4-pyridylmethyl, 2- methoxycarbonyl-4-pyridylmethyl, 2-ethoxycarbonyl-4- pyridylmethyl, 2-(1-hydroxy-1-methylethyl)-4-pyridylmethyl, 2- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-4- pyridylmethyl, 2-(1-carboxy-1-methylethyl)-4-pyridylmethyl, [71] 3-pyridazinylmethyl, 4-pyridazinylmethyl, 2-pyrimidinyl- methyl, 4-pyrimidinylmethyl, 5-pyrimidinylmethyl, 2- pyrazinylmethyl, phenethyl, 2-fluorophenethyl, 3-fluoro- phenethyl, 4-fluorophenethyl, 2,4-difluorophenethyl, 2,6- difluorophenethyl, 3,4-difluorophenethyl, 2-chlorophen- ethyl, 3-chlorophenethyl, 4-chlorophenethyl, 2,4-dichloro- phenethyl, 2,6-dichlorophenethyl, 3,4-dichlorophenethyl, 3- cyanophenethyl, 4-cyanophenethyl, 3-nitrophenethyl, 4- nitrophenethyl, 3-carboxyphenethyl, 4-carboxyphenethyl, 3- trifluoromethylphenethyl, 4-trifluoromethylphenethyl, 3-(l- hydroxy-l-methylethyl)phenethyl, 4-(1-hydroxy-1-methyl- ethyl) phenethyl , 3-(2,2,2-trifluoro-l-hydroxy-l-trifluoro- methylethyl)phenethyl, 4-(2,2,2-trifluoro-1-hydroxy-1-tri- fluoromethylethyl)phenethyl, 3-(1-carboxy-l-methylethyl)- phenethyl, 4 -(1-carboxy-1-methylethyl)phenethyl, 3-methoxy- phenethyl, 4-methoxyphenethyl, 3-ethoxyphenethyl, 4-ethoxy- phenethyl, 3-methoxycarbonylphenethyl, 4-methoxycarbonyl- phenethyl, 3-ethoxycarbonylphenethyl, 4-ethoxycarbonyl- phenethyl, 2-(2-thienyl)ethyl, 2-(4-cyano-2-thienyl)ethyl, 2-(5-cyano-2-thienyl)ethyl, 2-(4-carboxy-2-thienyl)ethyl, 2 -(5-carboxy-2 -thienyl)ethyl, 2 -(4-methyl-2 -thienyl)ethyl, 2- (5-methyl-2-thienyl)ethyl, 2-(4-trifluoromethyl-2- thienyl)ethyl, 2-(5-trifluoromethyl-2-thienyl)ethyl, 2-(4- (1-hydroxy-1-methylethyl)-2-thienyl)ethyl, 2-(5-(1-hydroxy- 1-methylethyl)-2-thienyl)ethyl, 2-(4-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl) -2-thienyl)ethyl, 2-(5- (2,2,2-trifluoro-1-hydroxy-1-1 ri fluoromethylethyl)-2 - thienyl)ethyl, 2-(4-(1-carboxy-l-methylethyl)-2-thienyl)- ethyl, 2-(5-(1-carboxy-l-methylethyl)-2-thienyl)ethyl, 2- (3-thienyl)ethyl, 2-(4-cyano-3-thienyl)ethyl, 2-(5-cyano-3- thienyl)ethyl, 2 -(4 -carboxy-3 -thienyl)ethyl, 2 -(5 -carboxy- 3- thienyl)ethyl, 2-(4-methyl-3-thienyl)ethyl, 2-(5-methyl- 3-thienyl)ethyl, 2 -(4-trifluoromethyl-3-thienyl)ethyl, 2- (5-trifluoromethyl-3-thienyl)ethyl, 2-(5-ethyl-3-thienyl)- ethyl, 2-(5-(1-hydroxy-1-methylethyl)-3-thienyl)ethyl, [0072] 2-(5-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-3- thienyl)ethyl, 2-(5-(1-carboxy-l-methylethyl)-3-thienyl)- ethyl, 2-(5-methoxycarbonyl-3-thienyl)ethyl, 2-(4-thiazol- yl)ethyl, 2-(2-cyano-4-thiazolyl)ethyl, 2-(2-carboxy-4- thiazolyl)ethyl, 2-(2-methyl-4-thiazolyl)ethyl, 2-(2-ethyl- 4-thiazolyl)ethyl, 2 -(2-propyl-4-thiazolyl)ethyl, 2-(2- isopropyl-4-thiazolyl)ethyl, 2-(2-trifluoromethyl-4- thiazolyl)ethyl, 2-(2-(1-hydroxy-1-methylethyl)-4-thiazol- yl)ethyl, 2-(2-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl )-4 -thiazolyl)ethyl, 2 -(2 -(1-carboxy-1-methyl- ethyl)-4-thiazolyl)ethyl, 2-(2-methoxycarbonyl-4-thiazol- yl)ethyl, 2-(5-thiazolyl)ethyl, 2-(2-cyano-5-thiazolyl)- ethyl, 2-(2-carboxy-5-thiazolyl)ethyl, 2-(2-methyl-5- thiazolyl)ethyl, 2-(2-ethyl-5-thiazolyl)ethyl, 2-(2- trifluoromethyl-5-thiazolyl)ethyl, 2-(2-(1-hydroxy-l- methylethyl)-5-thiazolyl)ethyl, 2-(2-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl) -5-thiazolyl)ethyl, 2-(2- (1- carboxy-1-methylethyl)-5-thiazolyl)ethyl, 2-(2-methoxy- carbonyl-5-thiazolyl)ethyl, 2-(2-ethoxycarbonyl-5-thiazol¬yl) ethyl, 2-(2-propoxycarbonyl-5-thiazolyl)ethyl, 2-(2- isopropoxycarbonyl- 5 -thiazolyl)ethyl, [0073] 2-(4-pyrazolyl)ethyl, 2-(6-cyano-2-pyridyl)ethyl, 2-(6- carboxy-2-pyridyl)ethyl, 2-(6-trifluoromethyl-2-pyridyl)- ethyl, 2-(6-methoxy-2-pyridyl)ethyl, 2-(6-ethoxy-2-pyrid- yl)ethyl, 2-(6-methoxycarbonyl-2-pyridyl)ethyl, 2-(6- ethoxycarbonyl-2-pyridyl)ethyl, 2-(6-(1-hydroxy-1-methyl- ethyl)-2-pyridyl)ethyl, 2-(6-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl ) -2-pyridyl)ethyl, 2-(6-(1-carboxy-l- methylethyl) -2-pyridyl)ethyl, 2-(6-cyano-3-pyridyl)ethyl, 2-(6-carboxy-3-pyridyl)ethyl, 2-(6-trifluoromethyl-3- pyridyl)ethyl, 2-(6-methoxy-3-pyridyl)ethyl, 2 -(6-ethoxy-3- pyridyl)ethyl, 2-(6-methoxycarbonyl-3-pyridyl)ethyl, 2-(6- ethoxycarbonyl-3-pyridyl)ethyl, 2-(6-(1-hydroxy-1-methyl- ethyl)-3-pyridyl)ethyl, 2-(6-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl) ethyl , 2- (6-(1-carboxy-l-methylethyl)- 3-pyridyl)ethyl, 2-(2-cyano-3-pyridyl)ethyl, 2-(2-carboxy- 3 -pyridyl) ethyl , 2-(2-trifluoromethyl-3-pyridyl)ethyl, 2- (2-methoxy-3-pyridyl)ethyl, 2-(2-ethoxy-3-pyridyl)ethyl, 2- (2-propoxy-3-pyridyl)ethyl, 2 -(2-methoxycarbonyl-3-pyrid¬yl) ethyl, 2-(2-ethoxycarbonyl-3-pyridyl)ethyl, 2-(2- propoxycarbonyl-3-pyridyl)ethyl, 2-(2-(1-hydroxy-1-methyl- ethyl)-3-pyridyl)ethyl, 2-(2-(2,2,2-trifluoro-1-hydroxy-l- trif luoromethylethyl) ethyl, 2-(2-(1-carboxy-l-methylethyl)- 3-pyridyl)ethyl, 2-(2-cyano-4-pyridyl)ethyl, 2-(2-carboxy- 4 -pyridyl) ethyl , 2-(2-trifluoromethyl-4-pyridyl)ethyl, 2- (2-methoxy-4-pyridyl)ethyl, 2-(2-ethoxy-4-pyridyl)ethyl, 2- (2-propoxy-4-pyridyl)ethyl, 2-(2-methoxycarbonyl-4- pyridyl)ethyl, 2-(2-ethoxycarbonyl-4-pyridyl)ethyl, 2-(2- (1-hydroxy-1-methylethyl)-4-pyridyl)ethyl, 2 -(2 -(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-4-pyridyl)- ethyl, 2-(2-(1-carboxy-l-methylethyl)-4-pyridyl)ethyl, [0074] hydroxyphenylmethyl, (2-fluorophenyl)hydroxymethyl, (3- fluoropheny1)hydroxymethyl, (4 -fluoropheny1)hydroxymethyl, (2, 4-difluorophenyl)hydroxymethyl, (2,6-difluorophenyl)- hydroxymethyl, (3,4-difluorophenyl)hydroxymethyl, (2- chlorophenyl)hydroxymethyl, (3 -chlorophenyl)hydroxymethyl, (4-chlorophenyl)hydroxymethyl, (2,4-dichlorophenyl)- hydroxyImethyl, (2,6-dichlorophenyl)hydroxymethyl, (3,4- dichlorophenyl)hydroxymethyl, (3 -cyanophenyl)hydroxymethyl, (4-cyanophenyl)hydroxymethyl, hydroxy(3-nitrophenyl)methyl, hydroxy(4-nitrophenyl)methyl, (3-carboxyphenyl)hydroxy¬methyl, (4-carboxyphenyl)hydroxymethyl, hydroxy(3-tri- fluoromethylphenyl)methyl, hydroxy(4-trifluoromethyl- phenyl)methyl, hydroxy(3-methoxyphenyl)methyl, hydroxy(4- methoxyphenyl)methyl, (3 -ethoxyphenyl)hydroxymethyl, (4- ethoxyphenyl)hydroxymethyl, hydroxy(3-methoxycarbonyl- phenyl)methyl, hydroxy(4-methoxycarbonylphenyl)methyl, (3- ethoxycarbonylphenyl)hydroxymethyl, (4-ethoxycarbonyl- phenyl)hydroxymethyl, hydroxy(2-thienyl)methyl, hydroxy(5- methyl-2-thienyl)methyl or hydroxy(5-trifluoromethyl-2- thienyl)methyl group, etc., [75] preferably a benzyl, 2-fluorobenzyl, 3-fluorobenzyl, 4- fluorobenzyl, 2,4 -di fluorobenzyl, 2,6 -di fluorobenzyl, 3,4- difluorobenzyl, 2-chlorobenzyl, 3-chlorobenzyl, 4-chloro- benzyl, 2,4-dichlorobenzyl, 2,6-dichlorobenzyl, 3,4-di- chlorobenzyl, 2-cyanobenzyl, 3-cyanobenzyl, 4-cyanobenzyl, 3-nitrobenzyl, 4-nitrobenzyl, 3-carboxybenzyl, 4-carboxy- benzyl, 3-trifluoromethylbenzyl, 4-trifluoromethylbenzyl, (1-hydroxy-1-methylethyl)benzyl, 4-(1-hydroxy-1-methyl- ethyl)benzyl, 3-(2,2,2-trifluoro-1-hydroxy-1-trifluoro- methylethyl)benzyl, 4-(2,2,2-trifluoro-1-hydroxy-1-tri- fluoromethylethyl)benzyl, 3-(1-carboxy-1-methylethyl)- benzyl, 4 -(1-carboxy-1-methylethyl)benzyl, 3-methoxybenzyl, methoxybenzyl, 3-ethoxybenzyl, 4-ethoxybenzyl, 3-methoxy- carbonylbenzyl, 4-methoxycarbonylbenzyl, 3-ethoxycarbonyl- benzyl, 4-ethoxycarbonylbenzyl, 2-thienylmethyl, 4-cyano-2- thienylmethyl, 5-cyano-2-thienylmethyl, 4-carboxy-2- thienylmethyl, 5 -carboxy-2 -thienylmethyl, [76] 4-methyl-2-thienylmethyl, 5-methyl-2-thienylmethyl, 4-tri- fluoromethyl-2 -thienylmethyl, 5-1rifluoromethyl-2 -thienyl- methyl, 4-(1-hydroxy-1-methylethyl)-2-thienylmethyl, 5-(l- hydroxy-1-methylethyl)-2-thienylmethyl, 4-(2,2,2-trifluoro- 1-hydroxy-1-trifluoromethylethyl)-2-thienylmethyl, 5- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-2- thienylmethyl, 4-(1-carboxy-1-methylethyl)-2-thienylmethyl, 5 -(1-carboxy-1-methylethyl)-2 -thienylmethyl, 3 -thienyl- methyl, 4-cyano-3-thienylmethyl, 5-cyano-3-thienylmethyl, 4-carboxy-3-thienylmethyl, 5-carboxy-3-thienylmethyl, 4- methyl-3-thienylmethyl, 5-methyl-3-thienylmethyl, 4-tri- fluoromethyl-3-thienylmethyl, 5-trifluoromethyl-3-thienyl¬methyl, 5-ethyl-3-thienylmethyl, 5-(1-hydroxy-1-methyl¬ethyl) -3-thienylmethyl, 5-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl) -3-thienylmethyl, 5-(1-carboxy-1- methylethyl)-3 -thienylmethyl, 5-methoxycarbonyl-3 -thienyl- methyl, 4-thiazolylmethyl, 2-cyano-4-thiazolylmethyl, 2- carboxy-4-thiazolylmethyl, 2-methyl-4-thiazolylmethyl, 2- ethyl-4-thiazolylmethyl, 2-propyl-4-thiazolylmethyl, 2-iso- propyl-4-thiazolylmethyl, 2-trifluoromethyl-4-thiazolyl- methyl, 2-(1-hydroxy-l-methylethyl)-4-thiazolylmethyl, 2- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-4-thia- zolylmethyl, 2 -(1-carboxy-1-methylethyl)-4 -thiazolylmethyl, 2-methoxycarbonyl-4-thiazolylmethyl, [77] 5-thiazolylmethyl, 2-cyano-5-thiazolylmethyl, 2-carboxy-5- thiazolylmethyl, 2-methyl-5-thiazolylmethyl, 2-ethyl-5- thiazolylmethyl, 2-trifluoromethyl-5-thiazolylmethyl, 2-(l- hydroxy-1-methylethyl)-5-thiazolylmethyl, 2-(2,2,2-tri¬fluoro-l-hydroxy-l-trif luoromethylethyl) -5-thiazolylmethyl, 2 -(1-carboxy-1-methylethyl)-5-thiazolyl, 2-methoxycarbonyl- 5-thiazolylmethyl, 4-pyrazolylmethyl, 6-cyano-2-pyridyl- methyl, 6-carboxy-2-pyridylmethyl, 6-trifluoromethyl-2- pyridylmethyl, 6-methoxy-2-pyridylmethyl, 6-ethoxy-2-pyrid- ylmethyl, 6-methoxycarbonyl-2-pyridylmethyl, 6-ethoxy- carbonyl-2-pyridylmethyl, 6-(1-hydroxy-l-methylethyl)-2- pyridylmethyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl) -2-pyridylmethyl, 6-(1-carboxy-1-methylethyl)- 2-pyridylmethyl, 6-cyano-3-pyridylmethyl, 6-carboxy-3- pyridylmethyl, 6-trifluoromethyl-3-pyridylmethyl, 6- methoxy-3-pyridylmethyl, 6-ethoxy-3-pyridylmethyl, 6- methoxycarbonyl-3-pyridylmethyl, 6-ethoxycarbonyl-3-pyrid¬ylmethyl, 6-(1-hydroxy-l-methylethyl)-3-pyridylmethyl, 6- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-3-pyrid- ylmethyl, 6 -(1-carboxy-1-methylethyl)-3-pyridylmethyl, [78] 2-cyano-3-pyridylmethyl, 2-carboxy-3-pyridylmethyl, 2-tri- fluoromethyl-3-pyridylmethyl, 2-methoxy-3-pyridylmethyl, 2- ethoxy-3-pyridylmethyl, 2-propoxy-3-pyridylmethyl, 2- methoxycarbonyl-3-pyridylmethyl, 2-ethoxycarbonyl-3-pyrid¬ylmethyl, 2-propoxycarbonyl-3-pyridylmethyl, 2-(1-hydroxy- l-methylethyl) -3-pyridylmethyl, 2-(2,2,2-trifluoro-1- hydroxy-l-trifluoromethylethyl)-3-pyridylmethyl, 2-(1- carboxy-l-methylethyl)-3-pyridylmethyl, 2-cyano-4-pyridyl¬methyl, 2-carboxy-4-pyridylmethyl, 2-trifluoromethyl-4- pyridylmethyl, 2-methoxy-4-pyridylmethyl, 2-ethoxy-4-pyrid¬ylmethyl, 2-propoxy-4-pyridylmethyl, 2-methoxycarbonyl-4- pyridylmethyl, 2-ethoxycarbonyl-4-pyridylmethyl, 2-(1- hydroxy-l-methylethyl)-4-pyridylmethyl, 2-(2,2,2-trifluoro- 1- hydroxy-l-trifluoromethylethyl)-4-pyridylmethyl, 2-(1- carboxy-l-methylethyl)-4-pyridylmethyl, phenethyl, 2- fluorophenethyl, 3 -fluorophenethyl, 4 -fluorophenethyl, 3- chlorophenethyl, 3-cyanophenethyl, 3-carboxyphenethyl, 3- methoxyphenethyl, 2-(2-thienyl)ethyl, 2-(3-thienyl)ethyl, 2- (4-thiazolyl)ethyl, 2-(5-thiazolyl)ethyl, 2-(4-pyrazol- yl)ethyl, 2-(6-cyano-2-pyridyl)ethyl, 2 -(6-carboxy-2- pyridyl)ethyl, 2-(6-methoxy-2-pyridyl)ethyl, 2-(6-cyano-3- pyridyl)ethyl, 2-(6-carboxy-3-pyridyl)ethyl, 2-(6-methoxy- 3- pyridyl)ethyl, 2-(2-cyano-3-pyridyl)ethyl, 2-(2-carboxy- 3- pyridyl) ethyl , 2-(2-methoxy-3-pyridyl)ethyl, hydroxyl- phenylmethyl, (2 -fluorophenyl)hydroxymethyl, (3-fluoro- phenyl)hydroxymethyl, (4-fluorophenyl)hydroxymethyl, (3- chlorophenyl)hydroxymethyl, (3,4-difluorophenyl)hydroxy¬methyl, (2,4-difluorophenyl)hydroxymethyl, (3-cyano- phenyl)hydroxymethyl, hydroxy(3-trifluoromethylphenyl)- methyl or hydroxy(2-thienyl)methyl group, [0079] more preferably a benzyl, 2-fluorobenzyl, 3-fluorobenzyl, 4- fluorobenzyl, 2,4-difluorobenzyl, 3,4-difluorobenzyl, 2- chlorobenzyl, 3-chlorobenzyl, 4-chlorobenzyl, 2,4-dichloro- benzyl, 3,4-dichlorobenzyl, 2-cyanobenzyl, 3-cyanobenzyl, 4-cyanobenzyl, 3-nitrobenzyl, 3-carboxybenzyl, 4-carboxy- benzyl, 3 -trifluoromethylbenzyl, 4 -trifluoromethylbenzyl, 3-(1-hydroxy-1-methylethyl)benzyl, 4-(1-hydroxy-1-methyl- ethyl) benzyl, 3-(2,2,2-trifluoro-l-hydroxy-1-trifluoro- methylethyl)benzyl, 4-(2,2,2-trifluoro-1-hydroxy-1-tri- fluoromethylethyl)benzyl, 4-(1-carboxy-1-methylethyl)- benzyl, 3-methoxybenzyl, 4-methoxybenzyl, 3-methoxycarbon- ylbenzyl, 4-methoxycarbonylbenzyl, 2 -thienylmethyl, 5- cyano-2-thienylmethyl, 5-carboxy-2-thienylmethyl, 5-methyl- 2- thienylmethyl, 5-trifluoromethyl-2-thienylmethyl, 5-(1- hydroxy-l-methylethyl)-2-thienylmethyl, 5- (2,2,2-trifluoro- 1-hydroxy-1-trifluoromethylethyl)-2-thienylmethyl, 4-(1- carboxy-l-methylethyl)-2-thienylmethyl, 3-thienylmethyl, 5- cyano-3-thienylmethyl, 5-carboxy-3-thienylmethyl, 5-methyl- 3- thienylmethyl, 5-trifluoromethyl-3-thienylmethyl, 5-(l- hydroxy-l-methylethyl)-3-thienylmethyl, 5-(2,2,2-trifluoro- 1- hydroxy-l-trifluoromethylethyl)-3-thienylmethyl, 4- thiazolylmethyl, 2-cyano-4-thiazolylmethyl, 2-carboxy-4- thiazolylmethyl, 2-methyl-4-thiazolylmethyl, 2-trifluoro- methyl-4-thiazolylmethyl, 2-(1-hydroxy-1-methylethyl)-4- thiazolylmethyl, 2-(2,2,2-trifluoro-l-hydroxy-1-trifluoro¬methylethyl) -4- thiazolylmethyl , 5-thiazolylmethyl, 2-cyano- 5- thiazolylmethyl, 2-carboxy-5-thiazolylmethyl, 2-methyl-5- thiazolylmethyl, 2-trifluoromethyl-5-thiazolylmethyl, 2-(1- hydroxy-1-methylethyl)-5-thiazolylmethyl, 2- (2,2,2-tri- fluoro-1-hydroxy-1-trifluoromethylethyl)-5 -thiazolylmethyl, 4- pyrazolylmethyl, 6-cyano-2-pyridylmethyl, 6-carboxy-2- pyridylmethyl, 6-trifluoromethyl-2-pyridylmethyl, 6- methoxy-2-pyridylmethyl, 6-(1-hydroxy-1-methylethyl)-2- pyridylmethyl, 6-(2,2,2-trifluoro-1-hydroxy-1-trifluoro¬methylethyl) -2-pyridylmethyl, [0080] 6- cyano-3-pyridylmethyl, 6-carboxy-3-pyridylmethyl, 6 -tri¬fluoromethyl-3-pyridylmethyl, 6-methoxy-3-pyridylmethyl, 6- (1-hydroxy-1-methylethyl)-3-pyridylmethyl, 6-(2,2,2-tri- fluoro-1-hydroxy-1-trifluoromethylethyl)-3-pyridylmethyl, 2- cyano-3-pyridylmethyl, 2-carboxy-3-pyridylmethyl, 2-tri- fluoromethyl-3-pyridylmethy1, 2-methoxy-3-pyridylmethyl, 2- (1-hydroxy-1-methylethyl)-3-pyridylmethyl, 2-(2,2,2-tri- fluoro-1-hydroxy-1-trifluoromethylethyl)-3-pyridylmethyl, 2-cyano-4-pyridylmethyl, 2-carboxy-4-pyridylmethyl, 2-tri- fluoromethyl-4-pyridylmethyl, 2-methoxy-4-pyridylmethyl, 2- (1-hydroxy-1-methylethyl)-4-pyridylmethyl, 2- (2,2,2-tri- fluoro-1-hydroxy-1-trifluoromethylethyl)-4-pyridylmethyl, phenethyl, 2-fluorophenethyl, 3-fluorophenethyl, 4-fluoro- phenethyl, 3-chlorophenethyl, 3-cyanophenethyl, 3-carboxy- phenethyl, 3-methoxyphenethyl, 2 -(2-thienyl)ethyl, 2-(3- thienyl)ethyl, 2 -(6-cyano-2-pyridyl)ethyl, 2 -(6-methoxy-2- pyridyl)ethyl, 2 -(6-cyano-3-pyridyl)ethyl, 2-(e-methoxy-S- pyridyl) ethyl, 2-(2-cyano-3-pyridyl)ethyl, 2 -(2-methoxy-3- pyridyl)ethyl, hydroxyphenylmethyl, (2-fluorophenyl)- hydroxymethyl, (3-fluorophenyl)hydroxymethyl, (4-fluoro- phenyl)hydroxymethyl, (3,4-difluorophenyl)hydroxymethyl or hydroxy(2-thienyl)methyl group, [0081] particularly preferably a benzyl, 2-fluorobenzyl, 3-fluoro- benzyl, 4-fluorobenzyl, 2,4-difluorobenzyl, 3,4-difluoro¬benzyl, 2-chlorobenzyl, 3-chlorobenzyl, 2-cyanobenzyl, 3- cyanobenzyl, 3-carboxybenzyl, 4-carboxybenzyl, 3-trifluoro- methylbenzyl, 4-methoxybenzyl, 3-methoxycarbonylbenzyl, 2- thienylmethyl, 5-cyano-2-thienylmethyl, 5-carboxy-2-thien- ylmethyl, 5-trifluoromethyl-2-thienylmethyl, 3-thienyl- methyl, 5-cyano-3-thienylmethyl, 5-carboxy-3-thienylmethyl, 5- trifluoromethyl-3-thienylmethyl, 4-thiazolylmethyl, 2- cyano-4-thiazolylmethyl, 2-carboxy-4-thiazolylmethyl, 2-(1- hydroxy-1-methylethyl)-4-thiazolylmethyl, 2-(2,2,2-tri- fluoro-1-hydroxy-1-trifluoromethylethyl)-4-thiazolylmethyl, 2- cyano-5-thiazolylmethyl, 2-carboxy-5-thiazolylmethyl, 2- (1-hydroxy-1-methylethyl)-5-thiazolylmethyl, 2- (2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-5-thiazolyl- methyl, 6-cyano-2-pyridylmethyl, 6-carboxy-2-pyridylmethyl, 6- methoxy-2-pyridylmethyl, 6-(1-hydroxy-1-methylethyl)-2- pyridylmethyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl ) -2 -pyridylmethyl , 6-cyano-3-pyridylmethyl, 6- carboxy-3-pyridylmethyl, 6-methoxy-3-pyridylmethyl, 6-(1- hydroxy-1-methylethyl)-3-pyridylmethyl, 6-(2,2,2-trifluoro- l-hydroxy-l-trif luoromethylethyl) -3-pyridylmethyl, 2-cyano- 3- pyridylmethyl, 2-carboxy-3-pyridylmethyl, 2-methoxy-3- pyridylmethyl, 2-(1-hydroxy-1-methylethyl)-3-pyridylmethyl, 2-(2, 2, 2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-3- pyridylmethyl, 2-cyano-4-pyridylmethyl, 2-carboxy-4-pyrid- ylmethyl, 2-methoxy-4-pyridylmethyl, 2-(1-hydroxy-l-methyl- ethyl)-4-pyridylmethyl, 2-(2,2,2-trifluoro-1-hydroxy-1- trifluoromethylethyl)-4-pyridylmethyl, phenethyl, 2-fluoro- phenethyl, 3-fluorophenethyl, 4-fluorophenethyl, 3-cyano- phenethyl, 2-(2-thienyl)ethyl, 2-(6-cyano-2-pyridyl)ethyl, 2-(6-cyano-3-pyridyl)ethyl, 2-(2-cyano-3-pyridyl)ethyl, hydroxyphenylmethyl, (3-fluorophenyl)hydroxymethyl, (4- fluorophenyl)hydroxymethyl or hydroxy(2-thienyl)methyl group. [0082] As R^, there may be preferably mentioned a hydrogen atom, chlorine atom, bromine atom, iodine atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, iso- pentyl, neopentyl, 2-methylbutyl, hexyl, 2-methylpentyl, 3- methylpentyl, 4-methylpentyl, 2-ethylbutyl, 2,2-dimethyl- butyl, 3,3-dimethylbutyl, 2,3-dimethylbutyl, heptyl, 2- methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 3,4-dimethylpentyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, octyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5- methylheptyl, 6-methylheptyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5- dimethylhexyl, 3,4-dimethylhexyl, 3,5-dimethylhexyl, 2,2- dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 5,5- dimethylhexyl, 2-methyl-3-ethylpentyl, 2-propylpentyl, 2,2,3,3-tetramethylbutyl, trifluoromethyl, 2,2,2-trifluoro- ethyl, 3,3,3-trifluoropropyl, 2-chloroethyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 3-hydroxy- propyl, 1-hydroxybutyl, 4-hydroxybutyl, 1-hydroxypentyl, 5- hydroxypentyl, 1-hydroxyhexyl, 6-hydroxyhexyl, 1-hydroxy-2- methylpropyl, 2-hydroxy-2-methylpropyl, 1-hydroxy-3-methyl- butyl, 3-hydroxy-3-methylbutyl, l-hydroxy-4-methylpentyl, 4-hydroxy-4-methylpentyl, 2-ethyl-2-hydroxybutyl, cyano- methyl, 2-cyanoethyl, 3 -cyanopropyl, 4 -cyanobutyl, 5-cyano- pentyl, 6-cyanohexy1, 2-cyano-2-methylpropyl, 3-cyano-3- methylbutyl, 4-cyano-4-methylpentyl, 2-cyano-2-eth.ylbutyl, carboxymethyl, 2-carboxyethyl, 3-carboxypropyl, 4-carboxy- butyl, 5-carboxypentyl, 6-carboxyhexyl, 2-carboxy-2-methyl- propyl, 3-carboxy-3-methylbutyl, 4-carboxy-4-methylpentyl, 2- carboxy-2-ethylbutyl, methoxymethyl, 2-methoxyethyl, 2- methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 5-methoxy- pentyl, 6-methoxyhexyl, 2-methoxy-2-methylpropyl, 3- methoxy-3-methylbutyl, 4-methoxy-4-methylpentyl, 2-ethyl-2- methoxybutyl, [0083] ethoxyraethyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxy- propyl, 4-ethoxybutyl, 5-ethoxypentyl, 6-ethoxyhexyl, 2- ethoxy-2-methylpropyl, 3-ethoxy-3-methylbutyl, 4-ethoxy-4- methylpentyl, 2-ethoxy-2-ethylbutyl, propoxymethyl, 2- propoxyethyl, 3-propoxypropyl, 4-propoxybutyl, 5-propoxy- pentyl, 6-propoxyhexyl, 2-methyl-2-propoxypropyl, 3-methyl- 3- propoxybutyl, 4-methyl-4-propoxypentyl, 2-ethyl-2-prop- oxybutyl, butoxymethyl, 2-butoxyethyl, 3-butoxypropyl, 4- butoxybutyl, 5-butoxypentyl, 6-butoxyhexyl, 2-butoxy-2- methylpropyl, 3-butoxy-3-methylbutyl, 4-butoxy-4-methyl- pentyl, 2-butoxy-2-ethylbutyl, isopropoxymethyl, 2-isoprop- oxyethyl, 3-isopropoxypropyl, 4-isopropoxybutyl, 5-isoprop- oxypentyl, 6-isopropoxyhexyl, 2-isopropoxy-2-methylpropyl, 3-isopropoxy-3-methylbutyl, 4-isopropoxy-4-methylpentyl, 2- ethyl-2-isopropoxybutyl, isobutoxymethyl, 2-isobutoxyethyl, sec-butoxymethyl, 2-(sec-butoxy)ethyl, tert-butoxymethyl, 2 -(tert-butoxy)ethyl, 1-ethylpropoxymethyl, 2-(1-ethylprop- oxy)ethyl, 2-fluoroethoxymethyl, 2-(2-fluoroethoxy)ethyl, 2-(2-fluoroethoxy)propyl, 3-(2-fluoroethoxy)propyl, 4-(2- fluoroethoxy)butyl, 5-(2-fluoroethoxy)pentyl, 6-(2-fluoro¬ethoxy) hexyl , 2-(2-fluoroethoxy)-2-methylpropyl, 3-(2- fluoroethoxy)-3-methylbutyl, 4-(2-fluoroethoxy)-4-methyl- pentyl, 2-ethyl-2-(2-fluoroethoxy)butyl, (2,2,2-trifluoro¬ethoxy) methyl , 2-(2,2,2-trifluoroethoxy)ethyl, 2-(2,2,2- trifluoroethoxy)propyl, 3-(2,2,2-trifluoroethoxy)propyl, 4- (2,2, 2-trifluoroethoxy)butyl, 5-(2,2,2-trifluoroethoxy)- pentyl, 6-(2,2,2-trifluoroethoxy)hexyl, 2 -(2,2,2-trifluoro¬ethoxy) -2-methylpropyl, 3-(2,2,2-trifluoroethoxy)-3-methyl- butyl, 4-(2,2,2-trifluoroethoxy)-4-methylpentyl, 2-ethyl-2- (2 , 2 , 2-trifluoroethoxy)butyl, cyclopropoxyraethyl, 2-cyclo- propoxyethyl, 2-cyclopropoxypropyl, 3-cyclopropoxypropyl, 4- cyclopropoxybutyl, 5-cyclopropoxypentyl, 6-cyclopropoxy- hexyl, 2-cyclopropoxy-2-methylpropyl, 3-cyclopropoxy-3- methylbutyl, 4-cyclopropoxy-4-methylpentyl, 2-cyclopropoxy- 2-ethylbutyl, cyclobutoxymethyl, 2-cyclobutoxyethyl, 2- cyclobutoxypropyl, 3-cyclobutoxypropyl, 4-cyclobutoxybutyl, 5- cyclobutoxypentyl, 6-cyclobutoxyhexyl, 2-cyclobutoxy-2- methylpropyl, 3-cyclobutoxy-3-methylbutyl, 4-cyclobutoxy-4- methylpentyl, 2-cyclobutoxy-2-ethylbutyl, cyclopropyl- methoxymethyl, 2-eyelopropyImethoxyethyl, 2-cyclopropyl- methoxypropyl, 3-cyclopropylmethoxypropyl, 4-cyclopropyl- methoxybutyl, 5-cyclopropylmethoxypentyl, 6-cyclopropyl- methoxyhexyl, 2-cyclopropylmethoxy-2-methylpropyl, 3- cyclopropyImethoxy-3-methylbutyl, 4 -cyclopropyImethoxy-4 - methylpentyl, 2-cyclopropylmethoxy-2-ethylbutyl, cyclo- butylmethoxymethyl, 2-cyclobutylmethoxyethyl, 2-cyclobutyl- methoxypropyl, 3-cyclobutylmethoxypropyl, 4-cyclobutyl- methoxybutyl, 5-cyclobutylmethoxypentyl, 6-cyclobutyl- methoxyhexyl, 2-cyclobutyImethoxy-2-methylpropyl, 3-cyclo- butylmethoxy-3-methylbutyl, 4-cyclobutylmethoxy-4-methyl- pentyl, 2-eyelobutylmethoxy-2-ethylbutyl, methoxycarbonyl- methyl, 2-methoxyearbonylethyl, 3-methoxyearbonylpropyl, 4- methoxycarbonylbutyl, 5-methoxyearbonylpentyl, 6-methoxy- carbonylhexyl, 2-methoxycarbonyl-2-methylpropyl, 3-methoxy- carbonyl-3-methylbutyl, 4-methoxycarbonyl-4-methylpentyl, 2-ethyl-2-methoxyearbonylbutyl, ethoxycarbonylmethyl, 2- ethoxyearbonylethyl, 3-ethoxyearbonylpropyl, 4-ethoxy- carbonylbutyl, 5-ethoxyearbonylpentyl, 6-ethoxyearbonyl- hexyl, 2-ethoxycarbonyl-2-methylpropyl, 3-ethoxycarbonyl-3- methylbutyl, 4-ethoxycarbonyl-4-methylpentyl, 2-ethoxy¬carbonyl -2 -ethylbutyl, propoxycarbonylmethyl, 2-propoxy- carbonylethyl, 3-propoxycarbonylpropyl, 4-propoxycarbonyl- butyl, 5-propoxycarbonylpentyl, 6-propoxycarbonylhexyl, 2- methyl-2-propoxycarbonylpropyl, 3-methyl-3-propoxycarbonyl- butyl, 4-methyl-4-propoxycarbonylpentyl, 2-ethyl-2-propoxy- carbonylbutyl, [0084] butoxycarbonylmethyl, 2-butoxycarbonylethyl, 3-butoxy- carbonylpropyl, 4-butoxycarbonylbutyl, 5-butoxycarbonyl- pentyl, 6-butoxycarbonylhexyl, 2-butoxycarbonyl-2-methyl- propyl, 3-butoxycarbonyl-3-methylbutyl, 4-butoxycarbonyl-4- methylpentyl, 2-butoxycarbonyl-2-ethylbutyl, isopropoxy- carbonylmethyl, 2-isopropoxycarbonylethyl, 3 -isopropoxy- carbonylpropyl, 4-isopropoxycarbonylbutyl, 5-isopropoxy- carbonylpentyl, 6-isopropoxycarbonylhexyl, 2-isopropoxy- carbonyl-2-methylpropyl, 3 -isopropoxycarbonyl-3-methyl- butyl, 4-isopropoxycarbonyl-4-methylpentyl, 2-ethyl-2-iso- propoxycarbonylbutyl, isobutoxycarbonylmethyl, 2-isobutoxy- carbonylethyl, 3-isobutoxycarbonylpropyl, 4-isobutoxy- carbonylbutyl, 5-isobutoxycarbonylpentyl, 6-isobutoxy- carbonylhexyl, 2-isobutoxycarbonyl-2-methylpropyl, 3-iso- butoxycarbonyl-3-methylbutyl, 4 -isobutoxycarbonyl-4-methyl- pentyl, 2-ethyl-2-isobutoxycarbonylbutyl, acetyloxymethyl, 2-acetyloxyethyl, 3-acetyloxypropyl, 4-acetyloxybutyl, 5- acetyloxypentyl, 6-acetyloxyhexyl, 2-acetyloxy-2-methyl¬propyl , 3-acetyloxy-3-methylbutyl, 4-acetyloxy-4-methyl- pentyl, 2-acetyloxy-2-ethylbutyl, propionyloxymethyl, 2- propionyloxyethyl, 3-propionyloxypropyl, 4-propionyloxy- butyl, 5-propionyloxypentyl, 6-propionyloxyhexyl, 2-methyl- 2-propionyloxypropyl, 3-methyl-3-propionyloxybutyl, 4- methyl-4-propionyloxypentyl, 2-ethyl-2-propionyloxybutyl, butyryloxymethyl, 2-butyryloxyethyl, 3-butyryloxypropyl, 4- butyryloxybutyl, 5-butyryloxypentyl, 6-butyryloxyhexyl, 2- butyryloxy-2-methylpropyl, 3-butyryloxy-3-methylbutyl, 4- butyryloxy-4-methylpentyl, 2-butyryloxy-2 -ethylbutyl, acetylmethyl, 2-acetylethyl, 3-acetylpropyl, 4-acetylbutyl, 5-acetylpentyl, 6-acetylhexyl, 2-acetyl-2-methylpropyl, 3- acetyl-3-methylbutyl, 4-acetyl-4-methylpentyl, 2-acetyl-2- ethylbutyl, [85] propionylmethyl, 2-propionylethyl, 3-propionylpropyl, 4- propionylbutyl, 5-propionylpentyl, 6-propionylhexyl, 3- propionyl-3-methylbutyl, 4-propionyl-4-methylpentyl, 2- ethyl-2-propionylbutyl, butyrylmethyl, 2-butyrylethyl, 3- butyrylpropyl, 4-butyrylbutyl, 5-butyrylpentyl, 6-butyryl- hexyl, 2-butyryl-2-methylpropyl, 3-butyryl-3-methylbutyl, 4-butyryl-4-methylpentyl, 2-butyryl-2-ethylbutyl, dimethyl- aminomethyl, 2-dimethylaminoethyl, 3-dimethylarainopropyl, 4-dimethylaminobutyl, diethylaminomethyl, 2-diethylamino- ethyl, 3-diethylaminopropyl, 4-diethylaminobutyl, dipropyl- aminomethyl, 2-dipropylaminoethyl, 3-dipropylaminopropyl, 4-dipropylaminobutyl, dibutylarainomethyl, 2-dibutylamino- ethyl , 3-dibutylaminopropyl, 4-dibutylaminobutyl, diiso- propylaminomethyl, 2-diisopropylaminoethyl, 3-diisopropyl- aminopropyl, 4-diisopropylaminobutyl, cyclopropyl, 1- hydroxycyclopropyl, cyclobutyl, 1-hydroxycyclobutyl, cyclo- propylmethyl, (1-hydroxycyclopropyl)methyl, cyclobutyl- methyl, (1-hydroxycyclobutyl)methyl, cyclopropylhydroxy- methyl, hydroxy(1-hydroxycyclopropyl)methyl, cyclobutyl- hydroxymethyl, hydroxy(1-hydroxycyclobutyl)methyl, 2-cyclo- propylethyl, 2-(1-hydroxycyclopropyl)ethyl, 2-cyclobutyl- ethyl, 2-(1-hydroxycyclobutyl)ethyl, 3-cyclopropylpropyl, 3-(1-hydroxycyclopropyl)propyl, 3-cyclobutylpropyl, 3-(l- hydroxycyclobutyl)propyl, 2-cyclopropyl-2-hydroxyethyl, 2- hydroxy-2-(1-hydroxycyclopropyl)ethyl, [86] 2-cyclobutyl-2-hydroxyethyl, 2-hydroxy-2-(1-hydroxycyclo- butyl)ethyl, 3-cyclopropyl-3-hydroxypropyl, 3-hydroxy-3-(l- hydroxycyclopropyl) propyl , 3-cyclobutyl-3-hydroxypropyl, 3- hydroxy-3-(1-hydroxycyclobutyl)propyl, 2-propenyl, 2- butenyl, 3-butenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 2- hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 2-methyl-2- propenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 2-methyl- 3- butenyl, 3-methyl-3-butenyl, 2-methyl-2-pentenyl, 3- methyl-2-pentenyl, 4-methyl-2-pentenyl, 2-methyl-3-penten- yl, 3-methyl-3-pentenyl, 4-methyl-3-pentenyl, 2-methyl-4- pentenyl, 3-methyl-4-pentenyl, 4-methyl-4-pentenyl, 2,3- dimethyl-2-butenyl, ethynyl, 2-propynyl, 2-butynyl, 3- butynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 2-methyl-3- butynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl, 4- methyl-2-pentynyl, 2-methyl-3-pentynyl, 2-methyl-4- pentynyl, 3-methyl-4-pentynyl, 2 , 2-d.imethyl-3-butynyl, 1- hydroxy-2-propenyl, l-hydroxy-2-butenyl, 2-hydroxy-3- butenyl, 1-hydroxy-2-pentenyl, 2-hydroxy-3-pentenyl, 3- hydroxy-4-pentenyl, 1-hydroxy-2-hexenyl, 2-hydroxy-3- hexenyl, 3-hydroxy-4-hexenyl, 4-hydroxy-5-hexenyl, 1- hydroxy-2-propynyl, 1-hydroxy-2-butynyl, 2-hydroxy-3- butynyl, 1-hydroxy-2-pentynyl, 2-hydroxy-3-pentynyl, 3- hydroxy-4-pentynyl, 1-hydroxy-2-hexynyl, 2-hydroxy-3- hexynyl, 3-hydroxy-4-hexynyl, 4-hydroxy-5-hexynyl, [0087] phenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2,4-difluorophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 2,4,6-trifluorophenyl, 2-chlorophenyl, 3-chlorophenyl, 4- chlorophenyl, 2,4-dichlorophenyl, 2,6-dichlorophenyl, 3,4- dichlorophenyl, 2,4,6-trichlorophenyl, 3-hydroxyphenyl, 4- hydroxyphenyl, 3-cyanophenyl, 4-cyanopheny1, 3-nitrophenyl, 4- nitrophenyl, 3-carboxyphenyl, 4-carboxyphenyl, 3-methyl- phenyl, 4-methylphenyl, 3-trifluoromethylphenyl, 4-tri- fluoromethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 3-propyl- phenyl, 4-propylphenyl, 3-isopropylphenyl, 4-isopropyl- phenyl, 3 -(1-hydroxy-l-methylethyl)phenyl, 4-(1-hydroxy-l- methylethyl) phenyl, 3-(2,2,2-trifluoro-l-hydroxy-l-tri- f luoromethylethyl) phenyl , 4-(2,2,2-trifluoro-1-hydroxy-l- trifluoromethylethyl)phenyl, 3-(1-carboxy-l-methylethyl)- phenyl, 4-(1-carboxy-l-methylethyl)phenyl, 3-methoxyphenyl, 4-methoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 3-propoxy- phenyl, 4-propoxyphenyl, 3-butoxyphenyl, 4-butoxyphenyl, 3- isopropoxyphenyl, 4-isopropoxyphenyl, 3-methoxycarbonyl- phenyl, 4-methoxycarbonylphenyl, 3-ethoxycarbonylphenyl, 4- ethoxycarbonylphenyl, 3-acetoxyphenyl, 4-acetoxyphenyl, 3- dimethylaminophenyl, 4-dimethylaminophenyl, 3-diethylamino- phenyl, 4-diethylaminophenyl, 3-dipropylarainophenyl, 4- dipropylaminophenyl, [0088] 2-thienyl, 4-cyano-2-thienyl, 5-cyano-2-thienyl, 4-carboxy- 2-thienyl, 5-carboxy-2-thienyl, 4-methyl-2-thienyl, 5- methyl-2-thienyl, 4-trifluoromethyl-2-thienyl, 5-trifluoro- methyl-2-thienyl, 4-ethyl-2-thienyl, 5-ethyl-2-thienyl, 4- propyl-2-thienyl, 5-propyl-2-thienyl, 4-isopropyl-2-thien¬yl, 5-isopropyl-2-thienyl, 4-(1-hydroxy-l-methylethyl)-2- thienyl, 5-(1-hydroxy-l-methylethyl)-2-thienyl, 4-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-2-thienyl, 5- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-2- thienyl, 4-(1-carboxy-l-methylethyl)-2-thienyl, 5-(1- carboxy-l-methylethyl)-2-thienyl, 4-methoxycarbonyl-2- thienyl, 5-methoxycarbonyl-2 -thienyl, 4-ethoxycarbonyl-2- thienyl, 5-ethoxycarbonyl-2-thienyl, 4-propoxycarbonyl-2- thienyl, 5-propoxycarbonyl-2-thienyl, 4-butoxycarbonyl-2- thienyl, 5-butoxycarbonyl-2-thienyl, 4-isopropoxycarbonyl- 2-thienyl, 5-isopropoxycarbonyl-2-thienyl, 3-thienyl, 4- cyano-3-thienyl, 5-cyano-3-thienyl, 4-carboxy-3-thienyl, 5- carboxy-3-thienyl, 4-methyl-3-thienyl, 5-methyl-3-thienyl, 4- trifluoromethyl-3 -thienyl, 5 -1ri fluoromethyl-3 -thienyl, 5- ethyl-3-thienyl, 5-propyl-3-thienyl, 5-isopropyl-3- thienyl, 5-(1-hydroxy-l-methylethyl)-3-thienyl, 5-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-3-thienyl, 5- (1-carboxy-l-methylethyl)-3-thienyl, 5-methoxycarbonyl-3- thienyl, 5-ethoxycarbonyl-3 -thienyl, [0089] 4-thiazolyl, 2-cyano-4-thiazolyl, 2-carboxy-4-thiazolyl, 2- methyl-4-thiazolyl, 2-ethyl-4-thiazolyl, 2-propyl-4- thiazolyl, 2-isopropyl-4-thiazolyl, 2-trifluoromethyl-4- thiazolyl, 2-(1-hydroxy-l-methylethyl)-4-thiazolyl, 2- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-4- thiazolyl, 2 -(1-carboxy-1-methylethyl)-4 -thiazolyl, 2 - methoxycarbonyl-4 -thiazolyl, 2 -ethoxycarbonyl-4 -thiazolyl, 5- thiazolyl, 2-cyano-5-thiazolyl, 2-carboxy-5-thiazolyl, 2- methyl-5-thiazolyl, 2-ethyl-5-thiazolyl, 2-propyl-5- thiazolyl, 2-isopropyl-5-thiazolyl, 2-trifluoromethyl-5- thiazolyl, 2-(l-hydroxy-l-methylethyl)-5-thiazolyl, 2- (2,2,2-trifluoro-1-hydroxy-1-trifluoromethylethyl)-5- thiazolyl, 2 -(1-carboxy-1-methylethyl)- 5-thiazolyl, 2 - methoxycarbonyl-5 -thiazolyl, 2 -ethoxycarbonyl-5-thiazolyl, 2-propoxycarbonyl- 5 -thiazolyl, 2 -isopropoxycarbonyl- 5- thiazolyl, 4-pyrazolyl, 1-methyl-4-pyrazolyl, l-ethyl-4- pyrazolyl, 3-pyrazolyl, 1-methyl-3-pyrazolyl, 1-ethyl-3- pyrazolyl, 6-cyano-2-pyridyl, 6-carboxy-2-pyridyl, 6- trifluoromethyl-2-pyridyl, 6-methoxy-2-pyridyl, 6-ethoxy-2- pyridyl, 6-methoxycarbonyl-2-pyridyl, 6-ethoxycarbonyl-2- pyridyl, 6-(l-hydroxy-l-methylethyl)-2-pyridyl, 6-(2,2,2- trifluoro-1-hydroxy-1-trifluoromethylethyl)-2-pyridyl, 6- (1-carboxy-1-methylethyl)-2-pyridyl, [0090] 6- cyano-3-pyridyl, 5-carboxy-3-pyridyl, 6-trifluoromethyl- S-pyridyl, 6-methoxy-3-pyridyl, 6-ethoxy-3-pyridyl, 6- methoxycarbonyl-3-pyridyl, 6-ethoxycarbonyl-3-pyridyl, 6- (l-hydroxy-l-methylethyl)-3-pyridyl, 6-(2,2,2-trifluoro-1- hydroxy-1-trifluoromethylethyl)-3-pyridyl, 6-(1-carboxy-l- methylethyl)-3-pyridyl, 2-cyano-3-pyridyl, 2-carboxy-3- pyridyl, 2-trifluoromethyl-3-pyridyl, 2-methoxy-3-pyridyl, 2- ethoxy-3-pyridyl, 2-propoxy-3-pyridyl, 2-methoxycarbonyl- 3- pyridyl, 2-ethoxycarbonyl-3-pyridyl, 2-propoxycarbonyl-3- pyridyl, 2-(1-hydroxy-1-methylethyl)-3-pyridyl, 2-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-3-pyridyl, 2- (1-carboxy-1-methylethyl)-3-pyridyl, 2-cyano-4-pyridyl, 2- carboxy-4-pyridyl, 2-trifluoromethyl-4-pyridyl, 2-methoxy- 4- pyridyl, 2-ethoxy-4-pyridyl, 2-propoxy-4-pyridyl, 2- methoxycarbonyl-4-pyridyl, 2-ethoxycarbonyl-4-pyridyl, 2- (1-hydroxy-1-methylethyl)-4-pyridyl, 2-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl) -4-pyridyl, 2-(1-carboxy-l- methylethyl)-4-pyridyl, benzyl, 2-fluorobenzyl, 3-fluoro- benzyl, 4-fluorobenzyl, 2,4-difluorobenzyl, 2,6-difluoro¬benzyl, 3,4-difluorobenzyl, 2-chlorobenzyl, 3-chlorobenzyl, 4- ch.lorobenzyl, 2 , 4-dichlorobenzyl, 2 , 6-dichlorobenzyl, 3,4-dichlorobenzyl, 2-cyanobenzyl, 3-cyanobenzyl, 4-cyano- benzyl, 3-nitrobenzyl, 4-nitrobenzyl, 3-carboxybenzyl, 4- carboxybenzyl, 3-trifluoromethylbenzyl, 4-trifluoromethyl- benzyl, 3-(1-hydroxy-l-methylethyl)benzyl, 4-(1-hydroxy-l- methylethyl)benzyl, [0091] 3 -(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)benzyl, 4 -(2,2,2-trifluoro-1-hydroxy-1-trifluoromethylethyl)benzyl, 3-(1-carboxy-l-methylethyl)benzyl, 4-(1-carboxy-1-methyl- ethyl)benzyl, 3-methoxybenzyl, 4-methoxybenzyl, 3-ethoxy- benzyl, 4-ethoxybenzyl, 3-methoxycarbonylbenzyl, 4-methoxy- carbonylbenzyl, 3-ethoxycarbonylbenzyl, 4-ethoxycarbonyl- benzyl, 2-thienylmethyl, 4-cyano-2-thienylmethyl, 5-cyano- 2-thienylmethyl, 4-carboxy-2-thienylmethyl, 5-carboxy-2- thienylmethyl, 4-methyl-2-thienylmethyl, 5-methyl-2- thienylmethyl, 4-trifluoromethyl-2-thienylmethyl, 5-tri- fluoromethyl-2-thienylmethyl, 4-(1-hydroxy-l-methylethyl) - 2-thienylmethyl, 5-(1-hydroxy-l-methylethyl)-2-thienyl¬methyl , 4-(2,2,2-trifluoro-1-hydroxy-1-trifluoromethyl¬ethyl) -2-thienylmethyl, 5-(2,2,2-trifluoro-l-hydroxy-1- trifluoromethylethyl)-2-thienylmethyl, 4-(1-carboxy-l- methylethyl)-2 -thienylmethyl, 5 -(1-carboxy-1-methylethyl)- 2-thienylmethyl, 3-thienylmethyl, 4-cyano-3-thienylmethyl, 5- cyano-3-thienylmethyl, 4-carboxy-3-thienylmethyl, 5- carboxy-3-thienylmethyl, 4-methyl-3-thienylmethyl, 5- methyl-3-thienylmethyl, 4-trifluoromethyl-3-thienylmethyl, 5 -1ri fluoromethyl-3 -thienylmethyl, 5 -ethyl-3 -thienylmethyl, 5-(1-hydroxy-l-methylethyl)-3-thienylmethyl, 5- (2,2,2- trifluoro-1-hydroxy-1-trifluoromethylethyl)-3 -thienyl- methyl, 5-(1-carboxy-l-methylethyl)-3-thienylmethyl, 5- methoxycarbonyl-3-thienylmethyl, 4 -thiazolylmethyl, 2- cyano-4-thiazolylmethyl, 2-carboxy-4-thiazolylmethyl, 2- methyl-4-thiazolylmethyl, 2-ethyl-4-thiazolylmethyl, 2- propyl-4-thiazolylTnethyl, 2 - isopropyl-4 - thiazolylmethyl, 2- trifluoromethyl-4-thiazolylmethyl, 2-(1-hydroxy-1-methyl- ethyl)-4-thiazolylmethyl, 2-(2,2,2-trifluoro-1-hydroxy-1- trifluoromethylethyl)-4-thiazolylmethyl, 2-(1-carboxy-l- methylethyl)-4 -thiazolylmethyl, 2-methoxycarbonyl-4 - thiazolylmethyl, [0092] 5- thiazolylmethyl, 2-cyano-5-thiazolylmethyl, 2-carboxy-5- thiazolylmethyl, 2-methyl-5-thiazolylmethyl, 2-ethyl-5- thiazolylmethyl, 2-trifluoromethyl-5-thiazolylmethyl, 2-(l- hydroxy-l-methylethyl)-5-thiazolylmethyl, 2-(2,2,2-tri- f luoro- 1 -hydroxy- 1-trifluoromethylethyl)-5 -thiazolylmethyl, 2 -(1-carboxy-1-methylethyl)- 5 -thiazolylmethyl, 2-methoxy- carbonyl-5-thiazolylmethyl, 4-pyrazolylmethyl, 6-cyano-2- pyridylmethyl, 6-carboxy-2-pyridylmethyl, 6-trifluoro- methyl-2-pyridylmethyl, 6-methoxy-2-pyridylmethyl, 6- ethoxy-2-pyridylmethyl, 6-methoxycarbonyl-2-pyridylmethyl, 6- ethoxycarbonyl-2-pyridylmethyl, 6-(1-hydroxy-1-methyl¬ethyl ) -2-pyridylmethyl, 6-(2,2,2-trifluoro-l-hydroxy-1- trifluoromethylethyl)-2-pyridylmethyl, 6-(1-carboxy-l- methylethyl)-2-pyridylmethyl, 6-cyano-3-pyridylmethyl, 6- carboxy-3-pyridylmethyl, 6-trifluoromethyl-3-pyridylmethyl, 6-methoxy-3-pyridylmethyl, 6-ethoxy-3-pyridylmethyl, 6- methoxycarbonyl-3-pyridylmethyl, 6-ethoxycarbonyl-3 - pyridylmethyl, 6-(1-hydroxy-1-methylethyl)-3-pyridylmethyl, 6-(2,2,2-trifluoro-l-hydroxy-1-trifluoromethylethyl)-3 - pyridylmethyl, 6-(1-carboxy-1-methylethyl)-3-pyridylmethyl, 2-cyano-3-pyridylmethyl, 2-carboxy-3-pyridylmethyl, 2- trifluoromethyl-3-pyridylmethyl, 2-methoxy-3-pyridylmethyl, 2-ethoxy-3-pyridylmethyl, 2-propoxy-3-pyridylmethyl, 2- methoxycarbonyl-3-pyridylmethyl, 2 -ethoxycarbonyl-3 - pyridylmethyl, 2-propoxycarbonyl-3-pyridylmethyl, 2-(1- hydroxy-1-methylethyl)-3-pyridylmethyl, 2-(2,2,2-trifluoro- l-hydroxy-1- trif luoromethylethyl) -3-pyridylmethyl, 2-(1- carboxy-1-methylethyl)-3-pyridylmethyl, 2-cyano-4-pyridylmethyl, 2-carboxy-4-pyridylmethyl, 2- trifluoromethyl-4-pyridylmethyl, 2-methoxy-4-pyridylmethyl, 2-ethoxy-4-pyridylmethyl, 2-propoxy-4-pyridylmethyl, 2- methoxycarbonyl-4-pyridylmethyl, 2 -ethoxycarbonyl-4 - pyridylmethyl, 2-(1-hydroxy-1-methylethyl)-4-pyridyl, 2- (2,2 , 2-trifluoro-l-hydroxy-1-trifluoromethylethyl)-4- pyridylmethyl, 2-(1-carboxy-l-methylethyl)-4-pyridylmethyl, phenethyl, 2 -fluorophenethyl, 3-fluorophenethyl, 4-fluoro- phenethyl, 3 -chlorophenethyl, 3 -cyanophenethyl, 3 -carboxy- phenethy1, 3-methoxyphenethyl, 2 -(2 -thienyl)ethyl, 2 -(3 - thienyl)ethyl, 2-(4-thiazolyl)ethyl, 2-(5-thiazolyl)ethyl, 2-(4-pyrazolyl)ethyl, 2-(6-cyano-2-pyridyl)ethyl, 2-(6- carboxy-2-pyridyl)ethyl, 2-(6-methoxy-2-pyridyl)ethyl, 2- (6-cyano-3-pyridyl)ethyl, 2-(6-carboxy-3-pyridyl)ethyl, 2- (6-methoxy-3-pyridyl)ethyl, 2-(2-cyano-3-pyridyl)ethyl, 2- (2-carboxy-3-pyridyl)ethyl, 2-(2-methoxy-3-pyridyl)ethyl, hydroxyphenylmethyl, (2-fluorophenyl)hydroxymethyl, (3- fluorophenyl)hydroxymethyl, {4 -fluorophenyl)hydroxymethyl, (3 -chlorophenyl)hydroxymethyl, (3,4 -di fluorophenyl)hydroxy¬methyl, (2,4-difluorophenyl)hydroxymethyl, (3-cyanophenyl)- hydroxymethyl, hydroxy(3-trifluoromethylphenyl)methyl or hydroxy(2-thienyl)methyl group, more preferably a hydrogen atom, chlorine atom, bromine atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl, hexyl, 2-ethylbutyl, 2,2- dimethylbutyl, 3,3-dimethylbutyl, heptyl, 2,2-dimethyl- pentyl, 3 , 3-dimethylpentyl, 4,4-dimethylpentyl, octyl, 4- ethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 4,4- dimethylhexyl, 5,5-dimethylhexyl, 2-propylpentyl, 2,2,3,3- tetramethylbutyl, 2,2,2-trifluoroethyl, 3,3,3-trifluoro- propyl, 2-chloroethyl, hydroxyethyl, 2-hydroxyethyl, 3- hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6-hydroxy- hexyl, 2-hydroxy-2-methylpropyl, 3-hydroxy-3-methylbutyl, 4-hydroxy-4-methylpentyl, 2-ethyl-2-hydroxybutyl, 2-cyano- 2-methylpropyl, 3-cyano-3-methylbutyl, 4-cyano-4-methyl- pentyl, 2-cyano-2-ethylbutyl, 2-carboxy-2-methylpropyl, 3- carboxy-3-methylbutyl, 4-carboxy-4-methylpentyl, 2-carboxy- 2-ethylbutyl, methoxyraethyl, 2-methoxyethyl, 3-methoxy- propyl, 4-methoxybutyl, 5-methoxypentyl, 6-methoxyhexyl, 2- methoxy-2-methylpropyl, 3-methoxy-3-methylbutyl, 4-methoxy- 4-methylpentyl, 2-ethyl-2-methoxybutyl, ethoxymethyl, 2- ethoxyethyl, 3-ethoxypropyl, 4-ethoxybutyl, 5-ethoxypentyl, 6-ethoxyhexyl, 2-ethoxy-2-methylpropyl, 3-ethoxy-3-methyl- butyl, 4-ethoxy-4-methylpentyl, 2-ethoxy-2-ethylbutyl, propoxymethyl, 2-propoxyethyl, 3-propoxypropyl, 4-propoxy- butyl, 2-methyl-2-propoxypropyl, 3-methyl-3-propoxybutyl, 4-methyl-4-propoxypentyl, 2 -ethyl-2-propoxybutyl, [0095] butoxymethyl, 2-butoxyethyl, 3-butoxypropyl, 4-butoxybutyl, 2-butoxy-2-methylpropyl, 3-butoxy-3-methylbutyl, 4-butoxy- 4- methylpentyl, 2-butoxy-2-ethylbutyl, isopropoxymethyl, 2- isopropoxyethyl, 3-isopropoxypropyl, 4-isopropoxybutyl, isobutoxymethyl, sec-butoxymethyl, tert-butoxymethyl, 1- ethylpropoxymethyl, 2-fluoroethoxymethyl, 2-(2-fluoro- ethoxy)ethyl, 3-{2-fluoroethoxy)propyl, 4-(2-fluoro- ethoxy)butyl, 5 -(2-fluoroethoxy)pentyl, 6-(2-fluoro- ethoxy)hexyl, 2-(2-fluoroethoxy)-2-methylpropyl, 3-(2- fluoroethoxy)-3-methylbutyl, 4-(2-fluoroethoxy)-4-methyl- pentyl, 2-ethyl-2-(2-fluoroethoxy)butyl, (2,2,2-trifluoro¬ethoxy) methyl , cyclopropoxymethyl, cyclobutoxymethyl, 2- cyclobutoxyethyl, 3-cyclobutoxypropyl, 4-cyclobutoxybutyl, 5- cyclobutoxypentyl, 6-cyclobutoxyhexyl, 2-cyclobutoxy-2- methylpropyl, 3-cyclobutoxy-3-methylbutyl, 4-cyclobutoxy-4- methylpentyl, 2-cyclobutoxy-2-ethylbutyl, cyclopropyl- methoxymethyl, 2-cyclopropylmethoxyethyl, 3-cyclopropyl- methoxypropyl, 4-cyclopropylmethoxybutyl, 5-cyclopropyl- methoxypentyl, 6-cyclopropylmethoxyhexyl, 2-cyclopropyl- methoxy-2-methylpropyl, 3 -eyelopropylmethoxy-3-methylbutyl, 4 -cyclopropylmethoxy-4-methylpentyl, 2-cyclopropylmethoxy- 2-ethylbutyl, cyclobutylmethoxymethyl, methoxycarbonyl- methyl, 2-methoxycarbonylethyl, 3-methoxycarbonylpropyl, 4- methoxycarbonylbutyl, 2-methoxycarbonyl-2-methylpropyl, 3- methoxycarbonyl-3-methylbutyl, 4-methoxycarbonyl-4-methyl- pentyl, 2-ethyl-2-methoxycarbonylbutyl, ethoxycarbonyl- methyl, 2-ethoxycarbonylethyl, 3-ethoxycarbonylpropyl, 4- ethoxycarbonylbutyl, 2-ethoxycarbonyl-2-methylpropyl, 3- ethoxycarbonyl-3-methylbutyl, 4 -ethoxycarbonyl-4-methyl- pentyl, 2-ethoxycarbonyl-2-ethylbutyl, propoxycarbonyl- methyl, 2-propoxycarbonylethyl, 3-propoxycarbonylpropyl, 4- propoxycarbonylbutyl, 2-methyl-2-propoxycarbonylpropyl, 3 - methyl-3-propoxycarbonylbutyl, 4-methyl-4-propoxycarbonyl- pentyl, 2-ethyl-2-propoxycarbonylbutyl, butoxycarbonyl- methyl, 2-butoxycarbonylethyl, 3-butoxycarbonylpropyl, 4- butoxycarbonylbutyl, 2-butoxycarbonyl-2-methylpropyl, 3- butoxycarbonyl-3-methylbutyl, 4-butoxycarbonyl-4-methyl- pentyl, 2-butoxycarbonyl-2-ethylbutyl, isopropoxycarbonyl- methyl, 2-isopropoxycarbonylethyl, 3-isopropoxycarbonyl- propyl, 4-isopropoxycarbonylbutyl, 2-isopropoxycarbonyl-2- methylpropyl, 3-isopropoxycarbonyl-3-methylbutyl, 4-iso- propoxycarbonyl-4-methylpentyl, 2 -ethyl-2 -isopropoxycarbon¬ylbutyl, isobutoxycarbonylmethyl, 2-isobutoxycarbonylethyl, 3 -isobutoxycarbonylpropyl, 4 -isobutoxycarbonylbutyl, acetyloxymethyl, 2-acetyloxyethyl, 3-acetyloxypropyl, 4- acetyloxybutyl, 5-acetyloxypentyl, 6-acetyloxyhexyl, 2- acetyloxy-2-methylpropyl, 3-acetyloxy-3-methylbutyl, 4- acetyloxy-4-methylpentyl, 2-acetyloxy-2-ethylbutyl, propionyloxymethyl, 2-propionyloxyethyl, 3-propionyloxy- propyl, 4-propionyloxybutyl, 5-propionyloxypentyl, acetyl- methyl, 2-acetylethyl, 3-acetylpropyl, 4-acetylbutyl, 5- acetylpentyl, 6-acetylhexyl, 2-acetyl-2-methylpropyl, 3- acetyl-3-methylbutyl, 4-acetyl-4-methylpentyl, 2-acetyl-2- ethylbutyl, [0096] propionylmethyl, 2-propionylethyl, 3-propionylpropyl, 4- propionylbutyl, 5-propionylpentyl, dimethylaminomethyl, 2- dimethylaminoethyl, diethylaminomethyl, 2-diethylamino- ethyl, dipropylaminomethyl, 2-dipropylaminoethyl, 2- dibutylaminomethyl, 3-dibutylaminoethyl, diisopropylamino- methyl, 2-diisopropylaminoethyl, cyclopropyl, 1-hydroxy- cyclopropyl, cyclobutyl, 1-hydroxycyclobutyl, cyclopropyl- methyl, (1-hydroxycyclopropyl)methyl, cyclobutylmethyl, (1- hydroxycyclobutyl)methyl, cyclopropylhydroxymethyl, hydroxy(1-hydroxycyclopropyl)methyl, cyclobutylhydroxy- methyl, hydroxy(1-hydroxycyclobutyl)methyl, 2-cyclopropyl- ethyl, 2-(1-hydroxycyclopropyl)ethyl, 2-cyclobutylethyl, 2- (1-hydroxycyclobutyl)ethyl, 2-propenyl, 2-butenyl, 2- pentenyl, 2-hexenyl, 2-methyl-2-propenyl, 2-methyl-2- butenyl, 3-methyl-2-butenyl, 2-methyl-2-pentenyl, 3-methyl- 2- pentenyl, 4-methyl-2-pentenyl, 2,3-dimethyl-2-butenyl, ethynyl, 2-propynyl, 2-butynyl, 2-pentynyl, 2-hexynyl, 4- methyl-2-pentynyl, l-hydroxy-2-propenyl, l-hydroxy-2- butenyl, 1-hydroxy-2-pentenyl, 1-hydroxy-2-hexenyl, 1- hydroxy-2-propynyl, 1-hydroxy-2-butynyl, l-hydroxy-2- pentynyl, 1-hydroxy-2-hexynyl, phenyl, 2-fluorophenyl, 3- fluorophenyl, 4-fluorophenyl, 2,4-difluorophenyl, 2,6- difluorophenyl, 3,4-difluorophenyl, 2-chlorophenyl, 3- chlorophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, 2,6- dichlorophenyl, 3,4-dichlorophenyl, 3-cyanophenyl, 4- cyanophenyl, 3-nitrophenyl, 4-nitrophenyl, 3-carboxyphenyl, 4-carboxyphenyl, 3-trifluoromethylphenyl, 4-trifluoro- methylphenyl, 3-(1-hydroxy-1-methylethyl)phenyl, [0097] 4-(1-hydroxy-1-methylethyl)phenyl, 3-(2,2,2-trifluoro-l- hydroxy-1- trif luoromethylethyl ) phenyl , 4-(2,2,2-trifluoro- l-hydroxy-l-trifluoromethylethyl)phenyl, 3-(1-carboxy-l- methylethyl)phenyl, 4 -(1-carboxy-1-methylethyl)phenyl, 3 - methoxyphenyl, 4-methoxyphenyl, 3-ethoxyphenyl, 4-ethoxy- phenyl, 3-methoxycarbonylphenyl, 4-methoxycarbonylphenyl, 3- ethoxycarbonylphenyl, 4-ethoxycarbonylphenyl, 2-thienyl, 4- cyano-2-thienyl, 5-cyano-2-thienyl, 4-carboxy-2-thienyl, 5- carboxy-2-thienyl, 4-methyl-2-thienyl, 5-methyl-2- thienyl, 4-trifluoromethyl-2-thienyl, 5-trifluoromethyl-2- thienyl, 4-(1-hydroxy-l-methylethyl)-2-thienyl, 5-(1- hydroxy-1-methylethyl)-2-thienyl, 4-(2,2,2-trifluoro-1- hydroxy-l-trifluoromethylethyl)-2-thienyl, 5-(2,2,2-tri- fluoro-1-hydroxy-1-trifluoromethylethyl)-2-thienyl, 4-(1- carboxy-l-methylethyl)-2-thienyl, 5-(1-carboxy-1-methyl- ethyl)-2-thienyl, 3-thienyl, 4-cyano-3-thienyl, 5-cyano-3- thienyl, 4-carboxy-3-thienyl, 5-carboxy-3-thienyl, 4- methyl-3-thienyl, 5-methyl-3-thienyl, 4-trifluoromethyl-3- thienyl, 5-trifluoromethyl-3-thienyl, 5-ethyl-3-thienyl, 5- (1-hydroxy-1-methylethyl)-3-thienyl, 5-(2,2,2 -trifluoro-1- hydroxy-l-trifluoromethylethyl)-3-thienyl, 5-(1-carboxy-1- methylethyl)-3 -thienyl, 5-methoxycarbonyl-3 -thienyl, [98] 4-thiazolyl, 2-cyano-4-thiazolyl, 2-carboxy-4-thiazolyl, 2- methyl-4-thiazolyl, 2-ethyl-4-thiazolyl, 2-propyl-4- thiazolyl, 2-isopropyl-4-thiazolyl, 2-trifluoromethyl-4- thiazolyl, 2-(1-hydroxy-l-methylethyl)-4-thiazolyl, 2- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-4- thiazolyl, 2 -(1-carboxy-1-methylethyl)-4 -thiazolyl, 2- methoxycarbonyl-4-thiazolyl, 5-thiazolyl, 2-cyano-5- thiazolyl, 2-carboxy-5-thiazolyl, 2-methyl-5-thiazolyl, 2- ethyl-5-thiazolyl, 2-trifluoromethyl-5-thiazolyl, 2-(1- hydroxy-1-methylethyl)-5-thiazolyl, 2-(2,2,2-trifluoro-1- hydroxy-1-trifluoromethylethyl)-5-thiazolyl, 2-(1-carboxy- 1- methylethyl)-5-thiazolyl, 2-methoxycarbonyl-5-thiazolyl, 2 -ethoxycarbonyl-5-thiazolyl, 2-propoxycarbonyl-5-thiazol- yl, 2-isopropoxycarbonyl-5-thiazolyl, 4-pyrazolyl, 6-cyano- 2- pyridyl, 6-carboxy-2-pyridyl, 6-trifluoromethyl-2- pyridyl, 6-methoxy-2-pyridyl, 6-ethoxy-2-pyridyl, 6- methoxycarbonyl-2-pyridyl, 6-ethoxycarbonyl-2-pyridyl, 6- (1-hydroxy-l-methylethyl)-2-pyridyl, 6-(2,2,2-trifluoro-1- hydroxy-1-trifluoromethylethyl)-2-pyridyl, 6-(1-carboxy-l- methylethyl)-2-pyridyl, [99] 6-cyano-3-pyridyl, 6-carboxy-3-pyridyl, 6-trifluoromethyl- 3- pyridyl, 6-methoxy-3-pyridyl, 6-ethoxy-3-pyridyl, 6- methoxycarbonyl-3-pyridyl, 6-ethoxycarbonyl-3-pyridyl, 6- (1-hydroxy-1-methylethyl)-3-pyridyl, 6-(2,2,2-trifluoro-1- hydroxy-l-trifluoromethylethyl)-3-pyridyl, 6- (1-carboxy-l- methylethyl)-3-pyridyl, 2-cyano-3-pyridyl, 2-carboxy-3- pyridyl, 2-trifluoromethyl-3-pyridyl, 2-methoxy-3-pyridyl, 2- ethoxy-3-pyridyl, 2-propoxy-3-pyridyl, 2-methoxycarbonyl- 3- pyridyl, 2-ethoxycarbonyl-3-pyridyl, 2-propoxycarbonyl-3- pyridyl, 2-(1-hydroxy-1-methylethyl)-3-pyridyl, 2-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-3-pyridyl, 2- (1-carboxy-1-methylethyl)-3-pyridyl, 2-cyano-4-pyridyl, 2- carboxy-4-pyridyl, 2-trifluoromethyl-4-pyridyl, 2-methoxy- 4- pyridyl, 2-ethoxy-4-pyridyl, 2-propoxy-4-pyridyl, 2- methoxycarbonyl-4-pyridyl, 2-ethoxycarbonyl-4-pyridyl, 2- (1-hydroxy-1-methylethyl)-4-pyridyl, 2-(2,2,2-trifluoro-1- hydroxy-1-trifluoromethylethyl)-4-pyridyl, 2-(1-carboxy-l- methylethyl)-4-pyridyl, benzyl, 2-fluorobenzyl, 3-fluoro- benzyl, 4-fluorobenzyl, 2,4-difluorobenzyl, 3,4-difluoro¬benzyl, 2-chlorobenzyl, 3-chlorobenzyl, 4-chlorobenzyl, 2,4-dichlorobenzyl, 3,4-dichlorobenzyl, 2-cyanobenzyl, 3- cyanobenzyl, 4-cyanobenzyl, 3-nitrobenzyl, 3-carboxybenzyl, 4-carboxybenzyl, 3-trifluoromethylbenzyl, 4-trifluoro- methylbenzyl, 3-(1-hydroxy-1-methylethyl)benzyl, 4-(l- hydroxy-1-methylethyl)benzyl, 3-(2,2,2-trifluoro-l-hydroxy- 1- trif luoromethylethyl) benzyl , 4-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl) benzyl, 4-(1-carboxy-l- methylethyl)benzyl, 3-methoxybenzyl, 4-methoxybenzyl, 3- methoxycarbonylbenzyl, 4-methoxycarbonylbenzyl, [0100] 2- thienylmethyl, 5-cyano-2-thienylmethyl, 5-carboxy-2- thienylmethyl, 5-methyl-2-thienylmethyl, 5-trifluoromethyl- 2-thienylmethyl, 5-(1-hydroxy-1-methylethyl)-2-thienyl¬methyl, 5-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl¬ethyl )-2 -thienylmethyl, 4 -(1-carboxy-1-methylethyl)-2 - thienylmethyl, 3-thienylmethyl, 5-cyano-3-thienylmethyl, 5- carboxy-3-thienylmethyl, 5-methyl-3-thienylmethyl, 5- trifluoromethyl-3-thienylmethyl, 5-(1-hydroxy-1-methyl- ethyl) -3-thienylmethyl, 5-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl) -3-thienylmethyl, 4-thiazolylmethyl, 2-cyano-4-thiazolylmethyl, 2-carboxy-4-thiazolylmethyl, 2- methyl-4-thiazolylmethyl, 2-trifluoromethyl-4-thiazolyl- methyl, 2-(1-hydroxy-l-methylethyl)-4-thiazolylmethyl, 2- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl) -4- thiazolylmethyl, 5 -thiazolylmethyl, 2-cyano-5-thiazolyl¬methyl, 2-carboxy-5-thiazolylmethyl, 2-methyl-5-thiazolyl¬methyl, 2-trifluoromethyl-5-thiazolylmethyl, 2-(1-hydroxy- 1- methylethyl) -5-thiazolylmethyl, 2-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl) -5-thiazolylmethyl, 4- pyrazolylmethyl, 6-cyano-2-pyridylmethyl, 6-carboxy-2- pyridylmethyl, 6-trifluoromethyl-2-pyridylmethyl, 6- methoxy-2-pyridylmethyl, 6-(1-hydroxy-l-methylethyl)-2- pyridylmethyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl) -2-pyridylmethyl, [0101] 5-cyano-3-pyridylmethyl, 6-carboxy-3-pyridylmethyl, 6-tri- fluoromethyl-3-pyridylmethyl, 6-methoxy-3-pyridylmethyl, 6- (1-hydroxy-l-methylethyl)-3-pyridylmethyl, 6- (2,2,2-tri- fluoro-l-hydroxy-l-trifluoromethylethyl)-3-pyridylmethyl, 2- cyano-3-pyridylmethyl, 2-carboxy-3-pyridylmethyl, 2- trifluoromethyl-3-pyridylmethyl, 2-methoxy-3-pyridylmethyl, 2-(1-hydroxy-l-methylethyl)-3-pyridylmethyl, 2-(2,2,2- tri fluoro-1-hydroxy-1-tri fluoromethylethyl)-3-pyridyl- methyl, 2-cyano-4-pyridylmethyl, 2-carboxy-4-pyridylmethyl, 2-trifluoromethyl-4-pyridylmethyl, 2-methoxy-4-pyridyl- methyl, 2-(1-hydroxy-l-methylethyl)-4-pyridyl, 2-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-4-pyridyl¬methyl, phenethyl, 2-fluorophenethyl, 3-fluorophenethyl, 4- fluorophenethyl, 3-chlorophenethyl, 3-cyanophenethyl, 3- carboxyphenethyl, 3-methoxyphenethyl, 2-(2-thienyl)ethyl, 2-(3-thienyl)ethyl, 2-(6-cyano-2-pyridyl)ethyl, 2-(6- methoxy-2-pyridyl)ethyl, 2-(6-cyano-3-pyridyl)ethyl, 2-(6- methoxy-3-pyridyl)ethyl, 2-(2-cyano-3-pyridyl)ethyl, 2-(2- methoxy-3-pyridyl)ethyl, hydroxyphenylmethyl, (2-fluoro- phenyl)hydroxymethyl, (3-fluorophenyl)hydroxymethyl, (4- fluorophenyl)hydroxymethyl, (3,4-difluorophenyl)hydroxy¬methyl or hydroxy(2-thienyl)methyl group, [0102] more preferably a hydrogen atom, chlorine atom, bromine atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl, hexyl, 2-ethylbutyl, 2,2- dimethylbutyl, 3,3-dimethylbutyl, 2,2,2 -trifluoroethyl, 3,3,3-trifluoropropyl, 2-chloroethyl, hydroxymethyl, 2- hydroxy-2-methylpropyl, 3-hydroxy-3-methylbutyl, 4-hydroxy- 4-methylpentyl, 2-ethyl-2-hydroxybutyl, 2-cyano-2-methyl- propyl, 3-cyano-3-methylbutyl, 2-carboxy-2-methylpropyl, 3- carboxy-3-methylbutyl, 4-carboxy-4-methylpentyl, methoxy- methyl, ethoxymethyl, isopropoxymethyl, 2-methoxyethyl, 2- ethoxyethyl, 2-isopropoxyethyl, isobutoxymethyl, see- but oxymethyl , tert-butoxymethyl, 1-ethylpropoxymethyl, 2- fluoroethoxymethyl, cyclobutoxymethyl, cyclopropylmethoxy- methyl, dimethylaminomethyl, cyclopropyl, 1-hydroxycyclo- propyl, cyclobutyl, 1-hydroxycyclobutyl, cyclopropylmethyl, (1-hydroxycyclopropyl)methyl, cyclobutylmethyl, (1-hydroxy- cyclobutyl)methyl, cyclopropylhydroxymethyl, hydroxy(1- hydroxycyclopropyl)methyl, cyclobutylhydroxymethyl, hydroxy(1-hydroxycyclobutyl)methyl, 2-cyclopropylethyl, 2- (1-hydroxycyclopropyl)ethyl, 2-cyclobutylethyl, 2-(l- hydroxycyclobutyl)ethyl, 2-propenyl, 2-butenyl, 2-methyl-2- propenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 2,3- dimethyl-2-butenyl, ethynyl, 2-propynyl, 2-butynyl, 4- methyl-2-pentynyl, 1-hydroxy-2-propenyl, 1-hydroxy-2- butenyl, 1-hydroxy-2-propynyl, 1-hydroxy-2-butynyl, [0103] phenyl, 2-fluorophenyl, 4-fluorophenyl, 2,4-difluorophenyl, 2-chlorophenyl, 4-chlorophenyl, 4 -cyanophenyl, 4-nitro- phenyl, 4-carboxypheny1, 4-trifluoromethylphenyl, 3- methoxyphenyl, 4-methoxyphenyl, 4-methoxycarbonylphenyl, 2- thienyl, 5-cyano-2-thienyl, 5-carboxy-2-thienyl, 5-methyl- 2-thienyl, 5-trifluoromethyl-2-thienyl, 3-thienyl, 5-cyano- 3-thienyl, 5-carboxy-3-thienyl, 5-methyl-3-thienyl, 5-tri- fluoromethyl-3-thienyl, 4-thiazolyl, 2-cyano-4-thiazolyl, 2-carboxy-4-thiazolyl, 2-methyl-4-thiazolyl, 2-trifluoro- methyl-4-thiazolyl, 2-(1-hydroxy-1-methylethyl)-4-thiazol¬yl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl) -4- thiazolyl, 5-thiazolyl, 2-cyano-5-thiazolyl, 2-carboxy-5- thiazolyl, 2-methyl-5-thiazolyl, 2-trifluoromethyl-5- thiazolyl, 2 -(1-hydroxy-1-methylethyl)-5-thiazolyl, 2 - (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-5- thiazolyl, 4-pyrazolyl, 6-cyano-2-pyridyl, 6-carboxy-2- pyridyl, 6-trifluoromethyl-2-pyridyl, 6-methoxy-2-pyridyl, 6-(1-hydroxy-1-methylethyl)-2-pyridyl, 6-(2,2,2-trifluoro- 1- hydroxy-l-trif luoromethylethyl) -2-pyridyl, 6-cyano-3- pyridyl, 6-carboxy-3-pyridyl, 6-trifluoromethyl-3-pyridyl, 6-methoxy-3-pyridyl, 6-(1-hydroxy-1-methylethyl)-3-pyridyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-3 - pyridyl, 2-cyano-4-pyridyl, 2-carboxy-4-pyridyl, 2-tri- fluoromethyl-4-pyridyl, 2-methoxy-4-pyridyl, 2-(l-hydroxy- l -methylethyl ) -4-pyridyl, 2-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl ) -4 -pyridyl , benzyl, 2-fluorobenzyl, 3- fluorobenzyl, 4-fluorobenzyl, 2,4-difluorobenzyl, 3,4-di- fluorobenzyl, 2-chlorobenzyl, 3-chlorobenzyl, 2-cyanobenz- yl, 3-cyanobenzyl, 3-carboxybenzyl, 4-carboxybenzyl, 3- trifluoromethylbenzyl, 4-methoxybenzyl, 3-methoxycarbonyl- benzyl, [0104] 2- thienylmethyl, 5-cyano-2-thienylmethyl, 5-carboxy-2- thienylmethyl, 5-trifluoromethyl-2-thienylmethyl, 3- thienylmethyl, 5-cyano-3-thienylmethyl, 5-carboxy-3- thienylmethyl, 5-trifluoromethyl-3-thienylmethyl, 4- thiazolylmethyl, 2-cyano-4-thiazolylmethyl, 2-carboxy-4- thiazolylmethyl, 2-(1-hydroxy-1-methylethyl)-4-thiazolyl- methyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl¬ethyl) -4 -thiazolylmethyl , 2-cyano-5-thiazolylmethyl, 2- carboxy-5-thiazolylmethyl, 2-(1-hydroxy-1-methylethyl)-5- thiazolylmethyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoro- methylethyl)-5-thiazolylmethyl, 6-cyano-2-pyridylmethyl, 6- carboxy-2-pyridylmethyl, 6-methoxy-2-pyridylmethyl, 6-(1- hydroxy-1-methylethyl)-2-pyridylmethyl, 6-(2,2,2-trifluoro- 1-hydroxy-1-trifluoromethylethyl)-2-pyridylmethyl, 6-cyano- 3-pyridylmethyl, 6-carboxy-3-pyridylmethyl, 6-methoxy-3- pyridylmethyl, 6-(1-hydroxy-1-methylethyl)-3-pyridylmethyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-3- pyridylmethyl, 2-cyano-3-pyridylmethyl, 2-carboxy-3- pyridylmethyl, 2-methoxy-3-pyridylmethyl, 2 -(1-hydroxy-l- methylethyl)-3-pyridylmethyl, 2-(2,2,2-trifluoro-l-hydroxy- l-trif luoromethylethyl) -3-pyridylmethyl, 2-cyano-4-pyridyl- methyl, 2-carboxy-4-pyridylmethyl, 2-methoxy-4-pyridyl¬methyl, 2-(1-hydroxy-l-methylethyl)-4-pyridyl, 2-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-4-pyridyl¬methyl, phenethyl, 2-fluorophenethyl, 3-fluorophenethyl, 4- fluorophenethyl, 3-cyanophenethyl, 2-(2-thienyl)ethyl, 2- (6-cyano-2-pyridyl)ethyl, 2-(6-cyano-3-pyridyl)ethyl, 2-(2- cyano-3-pyridyl)ethyl, hydroxyphenylmethyl, (3-fluoro- phenyl)hydroxymethyl, (4 -fluorophenyl)hydroxymethyl or hydroxy(2-thienyl)methyl group, [0105] further more preferably a hydrogen atom, chlorine atom, bromine atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl, hexyl, 2-ethyl- butyl, 2,2,2-trifluoroethyl, 3,3,3 -trifluoropropyl, 2- chloroethyl, hydroxymethyl, methoxymethyl, ethoxymethyl, isopropoxymethyl, 2-methoxyethyl, 2-ethoxyethyl, 2- isopropoxyethyl, isobutoxymethyl, sec-butoxymethyl, tert- butoxymethyl, 1-ethylpropoxymethyl, 2-fluoroethoxymethyl, cyclobutoxymethyl, cyclopropylmethoxymethyl, dimethyl- aminomethyl, cyclopropyl, cyclobutyl, cyclopropylmethyl, cyclobutylmethyl, eyelopropyIhydroxymethyl, cyclobutyl- hydroxymethyl, 2-cyclopropylethyl, 2-cyclobutylethyl, 2- propenyl, 2-butenyl, 2-methyl-2-propenyl, 2-methyl-2- butenyl, 3-methyl-2-butenyl, 2,3-dimethyl-2-butenyl, ethynyl, 2-propynyl, 2-butynyl, 4-methyl-2-pentynyl, 1- hydroxy-2-propenyl, phenyl, 2-fluorophenyl, 4-fluorophenyl, 2 , 4-difluorophenyl, 2-chlorophenyl, 4-chlorophenyl, 4- cyanophenyl, 2-thienyl, 3-thienyl, 4-thiazolyl, 5-thiazol- yl, 4-pyrazolyl, 6-methoxy-2-pyridyl, 6-methoxy-3-pyridyl, benzyl, 2-fluorobenzyl, 3-fluorobenzyl, 4-fluorobenzyl, 2,4-difluorobenzyl, 3,4-difluorobenzyl, 2-chlorobenzyl, 3- chlorobenzyl, 2-cyanobenzyl, 3-cyanobenzyl, 3-carboxy- benzyl, 4-carboxybenzyl, 2-thienylmethyl, 5-cyano-2- thienylmethyl, 5-carboxy-2-thienylmethyl, 3 -thienylmethyl, 5-cyano-3-thienylmethyl, 5-carboxy-3-thienylmethyl, 2- carboxy-4-thiazolylmethyl, 6-cyano-2-pyridylmethyl, 6- carboxy-2-pyridylmethyl, 6-methoxy-2-pyridylmethyl, 6- cyano-3-pyridylmethyl, 6-carboxy-3-pyridylmethyl, 6- methoxy-3-pyridylmethyl, 2-cyano-3-pyridylmethyl, 2- carboxy-3-pyridylmethyl, 2-cyano-4-pyridylmethyl, 2- carboxy-4-pyridylmethyl, phenethyl, 2-fluorophenethyl, 3- fluorophenethyl, 4-fluorophenethyl, 3-cyanophenethyl, 2-(2- thienyl)ethyl, 2-(6-cyano-2-pyridyl)ethyl, 2-(6-cyano-3- pyridyl)ethyl, 2-(2-cyano-3-pyridyl)ethyl, hydroxyphenyl- methyl, (2-fluorophenyl)hydroxymethy1, (3-fluorophenyl)- hydroxymethyl or (4-fluorophenyl)hydroxymethy1 group, [0106] particularly preferably a hydrogen atom, chlorine atom, bromine atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, 2-ethylbutyl, 2,2,2- trifluoroethyl, 3,3,3 -trifluoropropyl, 2-chloroethyl, hydroxymethyl, methoxymethyl, ethoxymethyl, isopropoxy- methyl, 2-methoxyethyl, 2-ethoxyethyl, 2-isopropoxyethyl, isobutoxymethyl, sec-butoxymethyl, tert-butoxymethyl, 1- ethylpropoxymethyl, 2-fluoroethoxymethyl, cyclobutoxy- methyl, cyclopropylmethoxymethyl, dimethylaminomethyl, cyclopropyl, cyclopropylmethyl, cyclopropylhydroxymethyl, 2-cyclopropylethyl, 2-propenyl, 2-butenyl, 2-methyl-2- propenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 2,3- dimethyl-2-butenyl, ethynyl, 2-propynyl, 2-butynyl, 4- methyl-2-pentynyl, 1-hydroxy-2-propenyl, phenyl, 2-thienyl, 3-thienyl, 4-pyrazolyl, benzyl, 2-fluorobenzyl, 3-fluoro- benzyl, 4-fluorobenzyl, 2,4-difluorobenzyl, 3,4-difluoro¬benzyl, 2-chlorobenzyl, 3-chlorobenzyl, 2-cyanobenzyl, 3- cyanobenzyl, 3-carboxybenzyl, 2-thienylmethyl, 3-thienyl- methyl, 6-raethoxy-2-pyridylmethyl, 6-methoxy-3-pyridyl- methyl, phenethyl, hydroxyphenylmethyl, (2-fluorophenyl)- hydroxymethyl, (3-fluorophenyl)hydroxymethyl or (4-fluoro¬phenyl )hydroxymethyl group, [107] most preferably a hydrogen atom, chlorine atom, bromine atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, hydroxymethyl, methoxymethyl, ethoxymethyl, isopropoxymethyl, 2-methoxyethyl, 2-ethoxy- ethyl, isobutoxymethyl, sec-butoxymethyl, tert-butoxy- methyl, 1-ethylpropoxymethyl, 2-fluoroethoxymethyl, cyclobutoxymethyl, cyclopropylmethoxymethyl, dimethyl- aminomethyl, cyclopropyl, cyclopropylmethyl, 2-cyclopropyl- ethyl, 2-propenyl, ethynyl, 2-propynyl, 2-butynyl, 4- methyl-2-pentynyl, 1-hydroxy-2-propenyl, phenyl, 4- pyrazolyl, benzyl, 2-fluorobenzyl, 3-fluorobenzyl, 4- fluorobenzyl, 2-cyanobenzyl, 3-cyanobenzyl, 3-carboxy¬benzyl, 6-methoxy-2-pyridylmethyl, 6-methoxy-3-pyridyl- methyl, phenethyl or hydroxyphenylmethyl group. [108] In the substituent(s) referred to in the present invention, respective atoms or respective rings are also included. When geometric isomers or optical isomers exist in the pyrrolopyridazinone compound represented by the formula (1) of the present invention, these isomers are included in the scope of the present invention, and also, when proton tautomers exist, these tautomers are included in the scope of the present invention. The pyrrolopyridazinone compound of the present invention can exist as a hydrate or a solvate, or a HCl adduct, and these are included in the present invention. In the pyrrolopyridazinone compound represented by the formula (1) of the present invention, preferred are (1) a compound wherein R^ is a methyl or difluoromethyl group, (2) a compound wherein R^ is a difluoromethyl group, (3) a compound wherein R^ is a cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylmethyl, cyclobutylmethyl, ethyl or isopropyl group, (4) a compound wherein R^ is a cyclopropyl, cyclobutyl, cyclopentyl, cyclopropylmethyl or isopropyl group, (5) a compound wherein R^ is a cyclopropyl or cyclo¬propylmethyl group, (6) a compound wherein R^ is a hydrogen atom or a substi¬tuted oxygen-containing hetero ring formed in combination with the group -0-R^ (a 2,2-(1,2-ethylene)-tetrahydrofuran ring, 2,2-(1,3-propylene)-tetrahydrofuran ring, 2,2-(1,4- butylene)-tetrahydrofuran ring, 2-cyclopropyl-tetrahydro¬furan ring, 2-cyclobutyl-tetrahydrofuran ring, 2,2- dimethyl-tetrahydrofuran ring, 6,6-(1,2-ethylene)-3,6- dihydro-2H-pyran ring, 6,6-(1,3-propylene)-3,6-dihydro-2H- pyran ring, 5,6-(1,4-butylene)-3,6-dihydro-2H-pyran ring, 6-cyclopropyl-3,6-dihydro-2H-pyran ring, 6-cyclobutyl-3,6- dihydro-2H-pyran ring or 6,6-dimethyl-3,6-dihydro-2H-pyran ring), (7) a compound wherein R^ is a hydrogen atom or a substi¬tuted oxygen-containing hetero ring formed in combination with the group -0-R^ (a 2,2-(1,4-butylene)-tetrahydrofuran ring, 6,6-(1,3-propylene)-3,6-dihydro-2H-pyran ring, 6,6- (1,4-butylene)-3,6-dihydro-2H-pyran ring, 6-cyclopropyl- 3,6-dihydro-2H-pyran ring or 6,6-dimethyl-3,6-dihydro-2H- pyran ring), [110] (8) a compound wherein R^ is a hydrogen atom, chlorine atom, bromine atom, iodine atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl. 2-methylbutyl, hexyl, 2-methylpentyl, 3-methylpentyl, 4- methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, 3,3-di- methylbutyl, 2,3-dimethylbutyl, heptyl, 2-methylhexyl, 3- methylhexyl, 4-methylhexyl, 5-methylhexyl, 2,3-dimethyl- pentyl, 2,4-dimethylpentyl, 3,4-dimethylpentyl, 2,2-di- methylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, octyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5- methylheptyl, 6-methylheptyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 2,5- dimethylhexyl, 3,4-dimethylhexyl, 3,5-dimethylhexyl, 2,2- dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 5,5- dimethylhexyl, 2-methyl-3-ethylpentyl, 2-propylpentyl, 2,2,3,3-tetramethylbutyl, trifluoromethyl, 2,2,2-trifluoro- ethyl, 3,3,3 -trifluoropropyl, 2-chloroethyl, hydroxymethyl, 1- hydroxyethyl, 2-hydroxyethyl, 1-hydroxypropyl, 3-hydroxy- propyl , 1-hydroxybuty1, 4 -hydroxybuty1, 1-hydroxypenty1, 5 - hydroxypentyl, 1-hydroxyhexyl, 6-hydroxyhexyl, l-hydroxy-2- methylpropyl, 2-hydroxy-2-methylpropyl, 1-hydroxy-3-methyl- butyl, 3-hydroxy-3-methylbutyl, l-hydroxy-4-methylpentyl, 4-hydroxy-4-methylpentyl, 2-ethyl-2-hydroxybutyl, cyano- methyl, 2-cyanoethyl, 3-cyanopropyl, 4 -cyanobutyl, 5-cyano- pentyl, 6-cyanohexy1, 2-cyano-2-methylpropyl, 3-cyano-3- methylbutyl, 4-cyano-4-methylpentyl, 2-cyano-2-ethylbutyl, carboxymethyl, 2-carboxyethyl, 3-carboxypropyl, 4-carboxy- butyl, 5-carboxypentyl, 6-carboxyhexyl, 2-carboxy-2-methyl- propyl, 3-carboxy-3-methylbutyl, 4-carboxy-4-methylpentyl, 2- carboxy-2-ethylbutyl, methoxymethyl, 2-methoxyethyl, 2- methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 5-methoxy- pentyl, 6-methoxyhexyl, 2-methoxy-2-methylpropyl, 3- methoxy-3-methylbutyl, 4-methoxy-4-methylpentyl, 2-ethyl-2- methoxybutyl, [0111] ethoxymethyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxy- propyl, 4-ethoxybutyl, 5-ethoxypentyl, 6-ethoxyhexyl, 2- ethoxy-2-methylpropyl, 3-ethoxy-3-methylbutyl, 4-ethoxy-4- methylpentyl, 2-ethoxy-2-ethylbutyl, propoxymethyl, 2- propoxyethyl, 3-propoxypropyl, 4-propoxybutyl, 5-propoxy- pentyl, 6-propoxyhexyl, 2-methyl-2-propoxypropyl, 3-methyl- 3- propoxybutyl, 4-methyl-4-propoxypentyl, 2-ethyl-2- propoxybutyl, butoxymethyl, 2-butoxyethyl, 3-butoxypropyl, 4- butoxybutyl, 5-butoxypentyl, 6-butoxyhexyl, 2-butoxy-2- methylpropyl, 3-butoxy-3-methylbutyl, 4-butoxy-4-methyl- pentyl, 2-butoxy-2-ethylbutyl, isopropoxymethyl, 2-isoprop- oxyethyl, 3-isopropoxypropyl, 4-isopropoxybutyl, 5-isoprop- oxypentyl, 6-isopropoxyhexyl, 2-isopropoxy-2-methylpropyl, 3-isopropoxy-3-methylbutyl, 4-isopropoxy-4-methylpentyl, 2- ethyl-2-isopropoxybutyl, 2-fluoroethoxymethyl, 2-(2-fluoro- ethoxy)ethyl, isobutoxymethyl, 2-isobutoxyethyl, sec- butoxymethyl, 2 -(sec-butoxy)ethyl, tert-butoxymethyl, 2- (tert-butoxy)ethyl, 1-ethylpropoxymethyl, 2-(1-ethylprop- oxy)ethyl, 2-(2-fl-uoroethoxy)propyl, 3 - (2-f luoroethoxy)- propyl, 4-(2-fluoroethoxy)butyl, 5-(2-fluoroethoxy)pentyl, 6-(2-fluoroethoxy)hexyl, 2-(2-fluoroethoxy)-2-methylpropyl, 3 -(2-fluoroethoxy)-3-methylbutyl, 4 -(2 -fluoroethoxy)-4 - methylpentyl, 2-ethyl-2 -(2-fluoroethoxy)butyl, (2,2,2- trifluoroethoxy)methyl, 2-(2,2,2-trifluoroethoxy)ethyl, 2- (2,2,2-trifluoroethoxy)propyl, 3 -(2,2,2-trifluoroethoxy)- propyl, 4-(2,2,2-trifluoroethoxy)butyl, 5-(2,2,2-trifluoro¬ethoxy) pentyl , 6-(2,2,2-trifluoroethoxy)hexyl, 2-(2,2,2- trifluoroethoxy)-2-methylpropyl, 3-(2,2,2-trifluoroethoxy)- 3-methylbutyl, 4-(2,2,2-trifluoroethoxy)-4-methylpentyl, 2- ethyl-2-(2,2,2-trifluoroethoxy)butyl, cyclopropoxymethyl, 2-cyclopropoxyethyl, 2-cyclopropoxypropyl, 3-cyclopropoxy- propyl , 4-cyclopropoxybutyl, 5-cyclopropoxypentyl, 6-cyclo- propoxyhexyl, 2-cyclopropoxy-2-methylpropyl, 3-cycloprop- oxy-3-methylbutyl, 4-cyclopropoxy-4-methylpentyl, 2-cyclo- propoxy-2-ethylbutyl, cyclobutoxymethyl, 2-cyclobutoxy- ethyl, 2-cyclobutoxypropyl, 3-cyclobutoxypropyl, 4-cyclo- butoxybutyl, 5-cyclobutoxypentyl, 6-cyclobutoxyhexyl, 2- cyclobutoxy-2-methylpropyl, 3-cyclobutoxy-3-methylbutyl, 4- cyclobutoxy-4-methylpentyl, 2 -cyclobutoxy-2 -ethylbutyl, cyclopropylmethoxymethyl, 2-cyclopropylmethoxyethyl, 2- cyclopropylmethoxypropyl, 3-cyclopropylmethoxypropyl, 4- cyclopropylmethoxybutyl, 5-cyclopropylmethoxypentyl, 6- cyclopropylmethoxyhexyl, 2-cyclopropylmethoxy-2-methyl- propyl, 3-cyclopropylmethoxy-3-methylbutyl, 4-cyclopropyl- methoxy-4-methylpentyl, 2-cyclopropylmethoxy-2-ethylbutyl, cyclobutylmethoxymethyl, 2-cyclobutylmethoxyethyl, 2-cyclo- butylmethoxypropyl, 3-cyclobutylmethoxypropyl, 4-cyclo- butylmethoxybutyl, 5-cyclobutylmethoxypentyl, 6-cyclobutyl- methoxyhexyl, 2-cyclobutylmethoxy-2-methylpropyl, 3-cyclo- butylmethoxy-3-methylbutyl, 4-cyclobutylmethoxy-4-methyl- pentyl , 2-cyclobutylmethoxy-2-ethylbutyl, methoxycarbonyl- methyl, 2-methoxycarbonylethyl, 3-methoxycarbonylpropyl, 4- methoxycarbonylbutyl, 5-methoxycarbonylpentyl, 6-methoxy- carbonylhexyl, 2-methoxycarbonyl-2-methylpropyl, 3-methoxy- carbonyl-3-methylbutyl, 4-methoxycarbonyl-4-methylpentyl, 2- ethyl-2-methoxycarbonylbutyl, ethoxycarbonylmethyl, 2- ethoxycarbonylethyl, 3-ethoxycarbonylpropyl, 4-ethoxy- carbonylbutyl, 5-ethoxycarbonylpentyl, 6-ethoxycarbonyl- hexyl, 2-ethoxycarbonyl-2-methylpropyl, 3-ethoxycarbonyl-3- methylbutyl, 4-ethoxycarbonyl-4-methylpentyl, 2-ethoxy- carbonyl-2-ethylbutyl, propoxycarbonylmethyl, 2-propoxy- carbonylethyl, [0112] 3- propoxycarbonylpropyl, 4-propoxycarbonylbutyl, 5-propoxy- carbonylpentyl, 6-propoxycarbonylhexyl, 2-methyl-2-propoxy- carbonylpropyl, 3-methyl-3-propoxycarbonylbutyl, 4-methyl- 4- propoxycarbonylpentyl, 2-ethyl-2-propoxycarbonylbutyl, butoxycarbonylmethyl, 2-butoxycarbonylethyl, 3-butoxy- carbonylpropyl, 4-butoxycarbonylbutyl, 5-butoxycarbonyl- pentyl, 6-butoxycarbonylhexyl, 2-butoxycarbonyl-2-methyl¬propyl, 3-butoxycarbonyl-3-methylbutyl, 4-butoxycarbonyl-4- methylpentyl, 2-butoxycarbonyl-2-ethylbutyl, isopropoxy- carbonylmethyl, 2-isopropoxycarbonylethyl, 3-isopropoxy- carbonylpropyl, 4-isopropoxycarbonylbutyl, 5-isopropoxy- carbonylpentyl, 6-isopropoxycarbonylhexyl, 2-isopropoxy- carbonyl-2-methylpropyl, 3 -isopropoxycarbonyl-3-methyl- butyl, 4-isopropoxycarbonyl-4-methylpentyl, 2-ethyl-2-iso- propoxycarbonylbutyl, isobutoxycarbonylmethyl, 2-isobutoxy- carbonylethyl, 3-isobutoxycarbonylpropyl, 4-isobutoxy- carbonylbutyl, 5-isobutoxycarbonylpentyl, 6-isobutoxy- carbonylhexyl, 2-isobutoxycarbonyl-2-methylpropyl, 3-iso- butoxycarbonyl-3-methylbutyl, 4 -isobutoxycarbonyl-4-methyl- pentyl, 2-ethyl-2-isobutoxycarbonylbutyl, acetyloxymethyl, 2-acetyloxyethyl, 3-acetyloxypropyl, 4-acetyloxybutyl, 5- acetyloxypentyl, 6-acetyloxyhexyl, 2-acetyloxy-2-methyl¬propyl, 3-acetyloxy-3-methylbutyl, 4-acetyloxy-4-methyl- pentyl, 2-acetyloxy-2-ethylbutyl, propionyloxymethyl, 2- propionyloxyethyl, 3-propionyloxypropyl, 4-propionyloxy- butyl, 5-propionyloxypentyl, 6-propionyloxyhexyl, 2-methyl- 2-propionyloxypropyl, 3-methyl-3-propionyloxybutyl, 4- methyl-4-propionyloxypentyl, 2-ethyl-2-propionyloxybutyl, butyryloxymethyl, 2-butyryloxyethyl, 3-butyryloxypropyl, 4- butyryloxybutyl, 5-butyryloxypentyl, 6-butyryloxyhexyl, 2- butyryloxy-2-methylpropyl, 3-butyryloxy-3-methylbutyl, 4- butyryloxy-4-methylpentyl, 2-butyryloxy-2-ethylbutyl, [0113] acetylmethyl, 2-acetylethyl, 3-acetylpropyl, 4-acetylbutyl, 5-acetylpentyl, 6-acetylhexyl, 2-acetyl-2-methylpropyl, 3- acetyl-3-methylbutyl, 4-acetyl-4-methylpentyl, 2-acetyl-2- ethylbutyl, propionylmethyl, 2-propionylethyl, 3-propionyl- propyl, 4-propionylbutyl, 5-propionylpentyl, 6-propionyl- hexyl, 3-propionyl-3-methylbutyl, 4-propionyl-4-methyl¬pentyl, 2-ethyl-2-propionylbutyl, butyrylmethyl, 2-butyryl- ethyl, 3-butyrylpropyl, 4-butyrylbutyl, 5-butyrylpentyl, 6- butyrylhexyl, 2-butyryl-2-methylpropyl, 3-butyryl-3-methyl¬butyl, 4-butyryl-4-methylpentyl, 2-butyryl-2-ethylbutyl, dimethylaminomethyl, 2-dimethylaminoethyl, 3-dimethylamino- propyl, 4-dimethylaminobutyl, diethylaminomethyl, 2-di- ethylaminoethyl, 3-diethylaminopropyl, 4-diethylaminobutyl, dipropylaminomethyl, 2-dipropylaminoethyl, 3-dipropylamino- propyl, 4-dipropylaminobutyl, dibutylaminomethyl, 2-di- butylaminoethyl, 3-dibutylaminopropyl, 4-dibutylaminobutyl, diisopropylaminomethyl, 2-diisopropylaminoethyl, 3-diiso- propylaminopropyl, 4-diisopropylaminobutyl, cyclopropyl, 1- hydroxycyclopropyl, cyclobutyl, 1-hydroxycyclobutyl, cyclo- propylmethyl, (1-hydroxycyclopropyl)methyl, cyclobutyl- methyl, (1-hydroxycyclobutyl)methyl, cyclopropylhydroxy- methyl, hydroxy(1-hydroxycyclopropyl)methyl, cyclobutyl- hydroxymethyl, hydroxy(1-hydroxycyclobutyl)methyl, 2-cyclo- propylethyl, 2-(1-hydroxycyclopropyl)ethyl, 2-cyclobutyl- ethyl, 2 -(1-hydroxycyclobutyl)ethyl, 3-cyclopropylpropyl, 3-(1-hydroxycyclopropyl)propyl, 3-cyclobutylpropyl, 3-(l- hydroxycyclobutyl)propyl, 2-cyclopropyl-2-hydroxyethyl, 2- hydroxy-2-(1-hydroxycyclopropyl)ethyl, [0114] 2- cyclobutyl-2-hydroxyethyl, 2-hydroxy-2-(1-hydroxyeyelo- butyDethyl, 3-cyclopropyl-3-hydroxypropyl, 3-hydroxy-3-(1- hydroxycyclopropyl)propyl, 3-cyclobutyl-3-hydroxypropyl, 3- hydroxy-3-(1-hydroxycyclobutyl)propyl, 2-propenyl, 2- butenyl, 3-butenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 2- hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 2-methyl-2- propenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 2-methyl- 3- butenyl, 3-methyl-3-butenyl, 2-methyl-2-pentenyl, 3- methyl-2-pentenyl, 4-methyl-2-pentenyl, 2-methyl-3- pentenyl, 3-methyl-3-pentenyl, 4-methyl-3-pentenyl, 2- methyl-4-pentenyl, 3-methyl-4-pentenyl, 4-methyl-4- pentenyl, 2,3-dimethyl-2-butenyl, ethynyl, 2-propynyl, 2- butynyl, 3-butynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 2- methyl-3-butynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5- hexynyl, 4-methyl-2-pentynyl, 2-methyl-3-pentynyl, 2- methyl-4-pentynyl, 3-methyl-4-pentynyl, 2,2-dimethyl-3- butynyl, 1-hydroxy-2-propenyl, 1-hydroxy-2-butenyl, 2- hydroxy-3-butenyl, 1-hydroxy-2-pentenyl, 2-hydroxy-3- pentenyl, 3-hydroxy-4-pentenyl, 1-hydroxy-2-hexenyl, 2- hydroxy-3-hexenyl, 3-hydroxy-4-hexenyl, 4-hydroxy-5- hexenyl, 1-hydroxy-2-propynyl, 1-hydroxy-2-butynyl, 2- hydroxy-3-butynyl, 1-hydroxy-2-pentynyl, 2-hydroxy-3- pentynyl, 3-hydroxy-4-pentynyl, 1-hydroxy-2-hexynyl, 2- hydroxy-3 -hexyny1, 3 -hydroxy-4 -hexyny1, 4-hydroxy-5- hexynyl, [0115] phenyl, 2-fluorophenyl, 3-fluorophenyl, 4 -fluorophenyl, 2,4-difluorophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 2,4 , 6-trifluorophenyl, 2-chlorophenyl, 3-chlorophenyl, 4- chlorophenyl, 2,4-dichlorophenyl, 2,6-dichlorophenyl, 3,4- dichlorophenyl, 2,4,6 -trichlorophenyl, 3-hydroxyphenyl, 4- hydroxyphenyl, 3-cyanopheny1, 4-cyanopheny1, 3-nitrophenyl, 4-nitrophenyl, 3-carboxyphenyl, 4-carboxyphenyl, 3-methyl- phenyl, 4-tnethylphenyl, 3 - trif luoromethylphenyl, 4-tri- fluoromethylphenyl, 3-ethylphenyl, 4-ethylphenyl, 3-propyl- phenyl, 4-propylphenyl, 3-isopropylphenyl, 4-isopropyl- phenyl, 3-(1-hydroxy-1-methylethyl)phenyl, 4-(1-hydroxy-l- methylethyl)phenyl, 3-(2,2,2-trifluoro-1-hydroxy-1-tri- fluoromethylethyl)phenyl, 4-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl ) phenyl , 3-(1-carboxy-1-methylethyl)- phenyl, 4-(1-carboxy-1-methylethyl)phenyl, 3-methoxyphenyl, 4-methoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 3-propoxy- phenyl, 4-propoxyphenyl, 3-butoxyphenyl, 4-butoxyphenyl, 3- isopropoxyphenyl, 4-isopropoxyphenyl, 3-methoxycarbonyl- phenyl , 4-methoxycarbonylphenyl, 3 -ethoxycarbonylphenyl, 4 - ethoxycarbonylphenyl, 3-acetoxyphenyl, 4-acetoxyphenyl, 3- dimethylaminophenyl, 4-dimethylaminophenyl, 3-diethylamino- phenyl, 4-diethylaminophenyl, 3-dipropylaminophenyl, 4- dipropylaminophenyl, 2-thienyl, 4-cyano-2-thienyl, 5-cyano- 2-thienyl, 4-carboxy-2-thienyl, 5-carboxy-2-thienyl, 4- methyl-2-thienyl, 5-methyl-2-thienyl, 4-trifluoromethyl-2- thienyl, 5-trifluoromethyl-2-thienyl, 4-ethyl-2-thienyl, 5- ethyl-2-thienyl, 4-propyl-2-thienyl, 5-propyl-2-thienyl, 4- isopropyl-2-thienyl, 5-isopropyl-2-thienyl, 4-(1-hydroxy-l- methylethyl)-2-thienyl, 5-(1-hydroxy-1-methylethyl)-2- thienyl, 4-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl¬ethyl) -2-thienyl, 5-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl) -2-thienyl, 4-(1-carboxy-1-methylethyl)-2- thienyl, 5-(1-carboxy-1-methylethyl)-2-thienyl, 4-methoxy- carbonyl-2-thienyl, 5-methoxycarbonyl-2-thienyl, 4-ethoxy- carbonyl-2 -thienyl, 5 -ethoxycarbonyl-2 -thienyl, [0116] 4-propoxycarbonyl-2 -thienyl, 5-propoxycarbonyl-2 -thienyl, 4-butoxycarbonyl-2-thienyl, 5-butoxycarbonyl-2-thienyl, 4- isopropoxycarbonyl-2 -thienyl, 5-isopropoxycarbonyl-2 - thienyl, 3-thienyl, 4-cyano-3-thienyl, 5-cyano-3-thienyl, 4- carboxy-3-thienyl, 5-carboxy-3-thienyl, 4-methyl-3- thienyl, 5-methyl-3-thienyl, 4-trifluoromethyl-3-thienyl, 5- trifluoromethyl-3-thienyl, 5-ethyl-3-thienyl, 5-propyl-3- thienyl, 5-isopropyl-3-thienyl, 5-(1-hydroxy-l-methyl- ethyl) -3-thienyl, 5-(2,2,2-trifluoro-l-hydroxy-l-trifluoro- methylethyl)-3-thienyl, 5-(1-carboxy-l-methylethyl)-3- thienyl, B-methoxycarbonyl-3-thienyl, 5-ethoxycarbonyl-3- thienyl, 4-thiazolyl, 2-cyano-4-thiazolyl, 2-carboxy-4- thiazolyl, 2-methyl-4-thiazolyl, 2-ethyl-4-thiazolyl, 2- propyl-4-thiazolyl, 2-isopropyl-4-thiazolyl, 2-trifluoro- methyl-4-thiazolyl, 2-(1-hydroxy-1-methylethyl)-4-thiazol¬yl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-4- thiazolyl, 2-(1-carboxy-l-methylethyl)-4-thiazolyl, 2- methoxycarbonyl-4-thiazolyl, 2-ethoxycarbonyl-4-thiazolyl, 5- thiazolyl, 2-cyano-5-thiazolyl, 2-carboxy-5-thiazolyl, 2- methyl-5-thiazolyl, 2-ethyl-5-thiazolyl, 2-propyl-5- thiazolyl, 2-isopropyl-5-thiazolyl, 2-trifluoromethyl-5- thiazolyl, 2-(1-hydroxy-l-methylethyl)-5-thiazolyl, 2- (2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-5- thiazolyl, 2-(l-carboxy-l-methylethyl)-5-thiazolyl, 2- methoxycarbonyl-5-thiazolyl, 2-ethoxycarbonyl-5-thiazolyl, 2-propoxycarbonyl- 5 -thiazolyl, 2 -isopropoxycarbonyl-5- thiazolyl, 4-pyrazolyl, 1-methyl-4-pyrazolyl, l-ethyl-4- pyrazolyl, 3-pyrazolyl, 1-methyl-3-pyrazolyl, 1-ethyl-3- pyrazolyl, [0117] 6- cyano-2-pyridyl, 6-carboxy-2-pyridyl, 6-trifluoromethyl- 2-pyridyl, 6-methoxy-2-pyridyl, 6-ethoxy-2-pyridyl, 6- methoxycarbonyl-2-pyridyl, 6-ethoxycarbonyl-2-pyridyl, 6- (1-hydroxy-1-methylethyl)-2-pyridyl, 6-(2,2,2-trifluoro-l- hydroxy-l-trifluoromethylethyl)-2-pyridyl, 6-(1-carboxy-l- methylethyl)-2-pyridyl, 6-cyano-3-pyridyl, 6-carboxy-3- pyridyl, 6-trifluoromethyl-3-pyridyl, 6-methoxy-3-pyridyl, 6-ethoxy-3-pyridyl, 6-methoxycarbonyl-3-pyridyl, 6-ethoxy- carbonyl-3-pyridyl, 6-(1-hydroxy-1-methylethyl)-3-pyridyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethylethyl)-3- pyridyl, 6-(1-carboxy-1-methylethyl)-3-pyridyl, 2-cyano-3- pyridyl, 2-carboxy-3-pyridyl, 2-trifluoromethyl-3-pyridyl, 2-methoxy-3-pyridyl, 2-ethoxy-3-pyridyl, 2-propoxy-3- pyridyl, 2-methoxycarbonyl-3-pyridyl, 2-ethoxycarbonyl-3- pyridyl, 2-propoxycarbonyl-3-pyridyl, 2-(1-hydroxy-l- methylethyl)-3-pyridyl, 2-(2,2,2-trifluoro-l-hydroxy-l- trif luoromethylethyl) -3-pyridyl, 2-(1-carboxy-1-methyl¬ethyl) -3 -pyridyl , 2-cyano-4-pyridyl, 2-carboxy-4-pyridyl, 2- trifluoromethyl-4-pyridyl, 2-methoxy-4-pyridyl, 2-ethoxy- 4-pyridyl, 2-propoxy-4-pyridyl, 2-methoxycarbonyl-4- pyridyl, 2-ethoxycarbonyl-4-pyridyl, 2-(1-hydroxy-l-methyl- ethyl)-4-pyridyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl) -4-pyridyl, 2-{1-carboxy-1-methylethyl)-4- pyridyl, benzyl, 2-fluorobenzyl, 3-fluorobenzyl, 4-fluoro- benzyl, 2,4-difluorobenzyl, 2,6-difluorobenzyl, 3,4-di- fluorobenzyl, 2-chlorobenzyl, 3-chlorobenzyl, 4-chloro- benzyl, 2,4-dichlorobenzyl, 2,6-dichlorobenzyl, 3,4-di- chlorobenzyl, 2-cyanobenzyl, 3-cyanobenzyl, 4-cyanobenzyl, 3- nitrobenzyl, 4-nitrobenzyl, 3-carboxybenzyl, 4-carboxy- benzyl, 3-trifluoromethylbenzyl, 4-trifluoromethylbenzyl, [0118] 3- (1-hydroxy-1-methylethyl)benzyl, 4-(1-hydroxy-1-methyl- ethyl)benzyl, 3 -(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl) benzyl, 4- (2,2,2-trifluoro-l-hydroxy-l-tri- fluoromethylethyl)benzyl, 3-(1-carboxy-1-methylethyl)- benzyl, 4-(1-carboxy-1-methylethyl)benzyl, 3-methoxybenzyl, 4- methoxybenzyl, 3-ethoxybenzyl, 4-ethoxybenzyl, 3-methoxy- carbonylbenzyl, 4-methoxycarbonylbenzyl, 3-ethoxycarbonyl- benzyl, 4-ethoxycarbonylbenzyl, 2 -thienylmethyl, 4-cyano-2- thienylmethyl, 5-cyano-2-thienylmethyl, 4-carboxy-2-thien- ylmethyl, 5-carboxy-2-thienylmethyl, 4-methyl-2-thienyl¬methyl, 5-methyl-2-thienylmethyl, 4-trifluoromethyl-2- thienylmethyl , 5-trifluoromethyl-2-thienylmethyl, 4-(l- hydroxy-l-methylethyl)-2-thienylmethyl, 5-(1-hydroxy-1- methylethyl)-2-thienylmethyl, 4-(2,2,2-trifluoro-1-hydroxy- 1-trifluoromethylethyl)-2-thienylmethyl, 5-(2,2,2-tri- fluoro-1-hydroxy-1-1ri fluoromethylethyl)-2 -thienylmethyl, 4-(1-carboxy-1-methylethyl)-2-thienylmethyl, 5-(1-carboxy- 1-methylethyl)-2-thienylmethyl, 3-thienylmethyl, 4-cyano-3- thienylmethyl, 5-cyano-3-thienylmethyl, 4-carboxy-3-thien¬ylmethyl , 5-carboxy-3-thienylmethyl, 4-methyl-3-thienyl¬methyl, 5-methyl-3-thienylmethyl, 4-trifluoromethyl-3- thienylmethyl, 5-trifluoromethyl-3-thienylmethyl, 5-ethyl- 3- thienylmethyl, 5-(1-hydroxy-1-methylethyl)-3-thienyl¬methyl, 5-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl¬ethyl )-3 -thienylmethyl, 5 -(1-carboxy-1-methylethyl)-3 - thienylmethyl, 5-methoxycarbonyl-3 -thienylmethyl, [0119] 4- thiazolylmethyl, 2-cyano-4-thiazolylmethyl, 2-carboxy-4- thiazolylmethyl, 2-methyl-4-thiazolylmethyl, 2-ethyl-4- thiazolylmethyl, 2-propyl-4-thiazolylmethyl, 2-isopropyl-4- thiazolylmethyl, 2-trifluoromethyl-4-thiazolylmethyl, 2-(l- hydroxy-1-methylethyl)-4-thiazolylmethyl, 2-(2,2,2-tri- fluoro-1-hydroxy-1-trifluoromethylethyl)-4-thiazolylmethyl, 2 -(1-carboxy-1-methylethyl)-4 -thiazolylmethyl, 2-methoxy- carbonyl-4-thiazolylmethyl, 5-thiazolylmethyl, 2-cyano-5- thiazolylmethyl, 2-carboxy-5-thiazolylmethyl, 2-methyl-5- thiazolylmethyl, 2-ethyl-5-thiazolylmethyl, 2-trifluoro- methyl-5-thiazolylmethyl, 2-(1-hydroxy-1-methylethyl)-5- thiazolylmethyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl )-5 -thiazolylmethyl, 2 -(1-carboxy-1-methyl- ethyl)-5 -thiazolylmethyl, 2-methoxycarbonyl-5 -thiazolyl- methyl, 4-pyrazolylmethyl, 6-cyano-2-pyridylmethyl, 6- carboxy-2-pyridylmethyl, 6-trifluoromethyl-2-pyridylmethyl, 6-methoxy-2-pyridylmethyl, 6-ethoxy-2-pyridylmethyl, 6- methoxycarbonyl-2-pyridylmethyl, 6 -ethoxycarbonyl-2 - pyridylmethyl, 6-(1-hydroxy-1-methylethyl)-2-pyridylmethyl, 6-(2,2,2-trifluoro-1-hydroxy-1-trifluoromethylethyl)-2- pyridylmethyl, 6-(1-carboxy-1-methylethyl)-2-pyridylmethyl, 6-cyano-3-pyridylmethyl, 6-carboxy-3-pyridylmethyl, 6- tri fluoromethyl-3-pyridylmethyl, 6-methoxy-3-pyridylmethyl, 6 -ethoxy-3-pyridylmethyl, 6-methoxycarbonyl-3-pyridyl- methyl, 6-ethoxycarbonyl-3-pyridylmethyl, 6-(1-hydroxy-l- methylethyl) -3-pyridylmethyl, 6-(2,2,2-trifluoro-l-hydroxy- 1- trifluoromethylethyl)-3-pyridylmethyl, 6-(1-carboxy-1- methylethyl)-3-pyridylmethyl, 2-cyano-3-pyridylmethyl, 2- carboxy-3-pyridylmethyl, [0120] 2 -1ri fluoromethyl-3-pyridylmethyl, 2-methoxy-3-pyridyl- methyl, 2-ethoxy-3-pyridylmethyl, 2-propoxy-3-pyridyl¬methyl, 2-methoxycarbonyl-3-pyridylmethyl, 2-ethoxycarbon¬yl -3 -pyridylmethyl , 2-propoxycarbonyl-3-pyridylmethyl, 2- (1-hydroxy-l-methylethyl)-3-pyridylmethyl, 2-(2,2,2-tri- fluoro-1-hydroxy-1-trifluoromethylethyl)-3-pyridylmethyl, 2- (1-carboxy-1-methylethyl)-3-pyridylmethyl, 2-cyano-4- pyridylmethyl, 2-carboxy-4-pyridylmethyl, 2-trifluoro¬me thyl -4 -pyridylmethyl , 2-methoxy-4-pyridylmethyl, 2- ethoxy-4-pyridylmethyl, 2-propoxy-4-pyridylmethyl, 2- methoxycarbonyl-4-pyridylmethyl, 2 -ethoxycarbonyl-4 - pyridylmethyl, 2-(1-hydroxy-l-methylethyl)-4-pyridyl, 2- (2,2, 2-trifluoro-1-hydroxy-1-trifluoromethylethyl)-4- pyridylmethyl, 2-(1-carboxy-1-methylethyl)-4-pyridylmethyl, phenethyl, 2 -fluorophenethyl, 3-fluorophenethyl, 4-fluoro- phenethyl, 3-chlorophenethyl, 3-cyanophenethyl, 3-carboxy- phenethyl, 3-methoxyphenethyl, 2-(2-thienyl)ethyl, 2-(3- thienyl)ethyl, 2 -(4-thiazolyl)ethyl, 2-(5-thiazolyl)ethyl, 2-(4-pyrazolyl)ethyl, 2-(6-cyano-2-pyridyl)ethyl, 2-(6- carboxy-2-pyridyl)ethyl, 2-(6-methoxy-2-pyridyl)ethyl, 2- (6-cyano-3-pyridyl)ethyl, 2-(6-carboxy-3-pyridyl)ethyl, 2- (6-methoxy-3-pyridyl)ethyl, 2 -(2-cyano-3-pyridyl)ethyl, 2- (2-carboxy-3-pyridyl)ethyl, 2-(2-methoxy-3-pyridyl)ethyl. hydroxyphenylmethyl, (2-fluorophenyl)hydroxymethyl, (3- fluorophenyl)hydroxymethyl, (4-fluorophenyl)hydroxymethyl, (3-chlorophenyl)hydroxymethyl, (3,4-difluorophenyl)hydroxy¬methyl, (2,4-difluorophenyl)hydroxymethyl, (3-cyanophenyl)- hydroxymethyl, hydroxy(3-trifluoromethylphenyl)methyl or hydroxy(2-thienyl)methyl group, [0121] (9) a compound wherein R^ is a hydrogen atom, chlorine atom, bromine atom, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, neopentyl, hexyl, 2- ethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, heptyl, 2,2-dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, octyl, 4-ethylhexyl, 2,2-dimethylhexyl, 3,3-dimethylhexyl, 4,4-dimethylhexyl, 5,5-dimethylhexyl, 2-propylpentyl, 2,2,3,3-tetramethylbutyl, 2,2,2 -trifluoroethyl, 3,3,3- trifluoropropyl, 2-chloroethyl, hydroxyethyl, 2-hydroxy- ethyl, 3-hydroxypropyl, 4-hydroxybutyl, 5-hydroxypentyl, 6- hydroxyhexyl, 2-hydroxy-2-methylpropyl, 3-hydroxy-3-methyl- butyl, 4-hydroxy-4-methylpentyl, 2-ethyl-2-hydroxybutyl, 2- cyano-2-methylpropyl, 3-cyano-3-methylbutyl, 4-cyano-4- methylpentyl, 2-cyano-2-ethylbutyl, 2-carboxy-2-methyl- propyl , 3-carboxy-3-methylbutyl, 4-carboxy-4-methylpentyl, 2-carboxy-2-ethylbutyl, methoxymethyl, 2-methoxyethyl, 3- methoxypropyl, 4-methoxybutyl, 5-methoxypentyl, 6-methoxy- hexyl, 2-methoxy-2-methylpropyl, 3-methoxy-3-methylbutyl, 4-methoxy-4-methylpentyl, 2-ethyl-2-methoxybutyl, ethoxy- methyl, 2-ethoxyethyl, 3-ethoxypropyl, 4-ethoxybutyl, 5- ethoxypentyl, 6-ethoxyhexyl, 2-ethoxy-2-methylpropyl, 3- ethoxy-3-methylbutyl, 4-ethoxy-4-methylpentyl, 2-ethoxy-2- ethylbutyl, propoxymethyl, 2-propoxyethyl, 3-propoxypropyl, 4-propoxybutyl, 2-methyl-2-propoxypropyl, 3-methyl-3- propoxybutyl, 4-methyl-4-propoxypentyl, 2-ethyl-2-propoxy- butyl, butoxymethyl, 2-butoxyethyl, 3-butoxypropyl, 4- butoxybutyl, 2-butoxy-2-methylpropyl, 3-butoxy-3-methyl- butyl, 4-butoxy-4-methylpentyl, 2-butoxy-2-ethylbutyl, [0122] isopropoxymethyl, 2-isopropoxyethyl, 3 -isopropoxypropyl, 4- isopropoxybutyl, isobutoxymethyl, sec-butoxymethyl, tert- butoxymethyl, 1-ethylpropoxymethyl, 2-fluoroethoxymethyl, 2-(2-fluoroethoxy)ethyl, 3-(2-fluoroethoxy)propyl, 4-(2- fluoroethoxy)butyl, 5-(2-fluoroethoxy)pentyl, 6-(2-fluoro- ethoxy)hexyl, 2-(2-fluoroethoxy)-2-methylpropyl, 3-(2- fluoroethoxy)-3-methylbutyl, 4-(2-fluoroethoxy)-4-methyl- pentyl, 2-ethyl-2-(2-fluoroethoxy)butyl, (2,2,2-trifluoro¬ethoxy) methyl , cyclopropoxymethyl, cyclobutoxymethyl, 2- cyclobutoxyethyl, 3-cyclobutoxypropyl, 4-cyclobutoxybutyl, 5-cyclobutoxypentyl, 6-cyclobutoxyhexyl, 2-cyclobutoxy-2- methylpropyl, 3-cyclobutoxy-3-methylbutyl, 4-cyclobutoxy-4- methylpentyl, 2-cyclobutoxy-2-ethylbutyl, cyclopropyl- methoxymethyl, 2-cyclopropylmethoxyethyl, 3-cyclopropyl- methoxypropyl , 4-cyclopropylmethoxybutyl, 5-cyclopropyl- methoxypentyl, 6-cyclopropylmethoxyhexyl, 2-eyelopropy1- methoxy-2-methylpropyl, 3-cyclopropylmethoxy-3-methylbutyl, 4-cyclopropylmethoxy-4-methylpentyl, 2-cyclopropylmethoxy- 2-ethylbutyl , cyclobutylmethoxymethyl, methoxycarbonyl- methyl, 2-methoxycarbonylethyl, 3-methoxycarbonylpropyl, 4- raethoxycarbonylbutyl, 2-methoxycarbonyl-2-methylpropyl, 3- methoxycarbony1-3-methylbutyl, 4-methoxycarbonyl-4-methyl- pentyl, 2-ethyl-2-methoxycarbonylbutyl, ethoxycarbonyl- methyl, 2-ethoxycarbonylethyl, 3-ethoxycarbonylpropyl, 4- ethoxycarbonylbutyl, 2-ethoxycarbonyl-2-methylpropyl, 3- ethoxycarbonyl-3-methylbutyl, 4 -ethoxycarbonyl-4-methyl- pentyl, 2-ethoxycarbonyl-2-ethylbutyl, propoxycarbonyl- methyl, 2-propoxycarbonylethyl, 3-propoxycarbonylpropyl, 4- propoxycarbonylbutyl, 2-methyl-2-propoxycarbonylpropyl, 3 - methyl-3-propoxycarbonylbutyl, 4-methyl-4-propoxycarbonyl- pentyl, 2-ethyl-2-propoxycarbonylbutyl, butoxycarbonyl- methyl, 2-butoxycarbonylethyl, 3-butoxycarbonylpropyl, 4- butoxycarbonylbutyl, 2-butoxycarbonyl-2-methylpropyl, 3- butoxycarbonyl-3-methylbutyl, 4-butoxycarbonyl-4-methyl- pentyl, 2-butoxycarbonyl-2-ethylbutyl, isopropoxycarbonyl- methyl, 2-isopropoxycarbonylethyl, 3-isopropoxycarbonyl- propyl, 4-isopropoxycarbonylbutyl, 2-isopropoxycarbonyl-2- methylpropyl, 3-isopropoxycarbonyl-3-methylbutyl, 4-iso- propoxycarbonyl-4-methylpentyl, 2-ethyl-2-isopropoxy- carbonylbutyl, isobutoxycarbonylmethyl, 2-isobutoxy- carbonylethyl, 3-isobutoxycarbonylpropyl, 4-isobutoxy- carbonylbutyl, acetyloxymethyl, 2-acetyloxyethyl, 3-acetyl- oxypropyl, 4-acetyloxybutyl, 5-acetyloxypentyl, 6-acetyl- oxyhexyl, 2-acetyloxy-2-methylpropyl, 3-acetyloxy-3-methyl- butyl, 4-acetyloxy-4-methylpentyl, 2-acetyloxy-2-ethyl- butyl, propionyloxymethyl, 2-propionyloxyethyl, 3-propion- yloxypropyl, 4-propionyloxybutyl, 5-propionyloxypentyl, acetylmethyl, 2-acetylethyl, 3-acetylpropyl, 4-acetylbutyl, 5-acetylpentyl, 6-acetylhexyl, 2-acetyl-2-methylpropyl, 3- acetyl-3-methylbutyl, 4-acetyl-4-methylpentyl, 2-acetyl-2- ethylbutyl, propionylmethyl, 2-propionylethyl, 3-propionyl- propyl, 4-propionylbutyl, 5-propionylpentyl, [0123] dimethylaminomethyl, 2-dimethylaminoethyl, diethylamino- methyl, 2-diethylaminoethyl, dipropylaminomethyl, 2-di- propylaminoethyl, 2-dibutylaminomethyl, 3-dibutylamino- ethyl, diisopropylaminomethyl, 2-diisopropylaminoethyl, cyclopropyl, 1-hydroxycyclopropyl, cyclobutyl, 1-hydroxy- cyclobutyl, cyclopropylmethyl, (1-hydroxycyclopropyl)- methyl, cyclobutylmethyl, (1-hydroxycyclobutyl)methyl, cyclopropylhydroxymethyl, hydroxy(1-hydroxycyclopropyl)- methyl, cyclobutylhydroxymethyl, hydroxy(1-hydroxycyclo- butyl)methyl, 2-cyclopropylethyl, 2-(1-hydroxycyclopropyl)- ethyl, 2-cyclobutylethyl, 2-(1-hydroxycyclobutyl)ethyl, 2- propenyl, 2-butenyl, 2-pentenyl, 2-hexenyl, 2-methyl-2- propenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 2-methyl- 2-pentenyl, 3-methyl-2-pentenyl, 4-methyl-2-pentenyl, 2,3- dimethyl-2-butenyl, ethynyl, 2-propynyl, 2-butynyl, 2- pentynyl, 2-hexynyl, 4-methyl-2-pentynyl, l-hydroxy-2- propenyl, 1-hydroxy-2-butenyl, 1-hydroxy-2-pentenyl, 1- hydroxy-2-hexenyl, 1-hydroxy-2-propynyl, 1-hydroxy-2- butynyl, 1-hydroxy-2-pentynyl, 1-hydroxy-2-hexynyl, phenyl. 2- fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2,4- difluorophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 2- chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,4-dichloro- phenyl, 2,6-dichlorophenyl, 3,4-dichlorophenyl, 3-cyano- phenyl, 4 -cyanophenyl, 3-nitrophenyl, 4-nitrophenyl, 3- carboxyphenyl, 4-carboxyphenyl, 3-trifluoromethylphenyl, 4- trifluoromethylphenyl, [124] 3- (1-hydroxy-1-methylethyl)phenyl, 4-(1-hydroxy-1-methyl- ethyl) phenyl , 3-(2,2,2-trifluoro-1-hydroxy-1-trifluoro- methylethyl)phenyl, 4 -(2,2,2-trifluoro-1-hydroxy-1-tri- fluoromethylethyl)phenyl, 3-(1-carboxy-1-methylethyl)- phenyl, 4-(1-carboxy-1-methylethyl)phenyl, 3-methoxyphenyl, 4- methoxyphenyl, 3-ethoxyphenyl, 4-ethoxyphenyl, 3-methoxy- carbonylphenyl, 4-methoxycarbonylphenyl, 3 -ethoxycarbonyl- phenyl, 4-ethoxycarbonylphenyl, 2-thienyl, 4-cyano-2- thienyl, 5-cyano-2-thienyl, 4-carboxy-2-thienyl, 5-carboxy- 2-thienyl, 4-methyl-2-thienyl, 5-methyl-2-thienyl, 4- trifluoromethyl-2-thienyl, 5-trifluoromethyl-2-thienyl, 4- (1-hydroxy-1-methylethyl)-2-thienyl, 5-(1-hydroxy-1- methylethyl)-2-thienyl, 4-(2,2,2-trifluoro-l-hydroxy-l- trifluoromethylethyl)-2-thienyl, 5-(2,2,2-trifluoro-1- hydroxy-l-trifluoromethylethyl)-2-thienyl, 4-(1-carboxy-1- methylethyl)-2-thienyl, 5-(1-carboxy-1-methylethyl)-2- thienyl, 3-thienyl, 4-cyano-3-thienyl, 5-cyano-3-thienyl, 4- carboxy-3-thienyl, 5-carboxy-3-thienyl, 4-methyl-3- thienyl, 5-methyl-3-thienyl, 4-trifluoromethyl-3-thienyl, 5- trifluoromethyl-3-thienyl, 5-ethyl-3-thienyl, 5-(1- hydroxy-1-methylethyl)-3-thienyl, 5-(2,2,2-trifluoro-1- hydroxy-1-trifluoromethylethyl)-3-thienyl, 5-(1-carboxy-1- methylethyl)-3-thienyl, 5-methoxycarbonyl-3-thienyl, 4- thiazolyl, 2-cyano-4-thiazolyl, 2-carboxy-4-thiazolyl, 2- methyl-4-thiazolyl, 2-ethyl-4-thiazolyl, 2-propyl-4- thiazolyl, 2-isopropyl-4-thiazolyl, 2-trifluoromethyl-4- thiazolyl, [125] 2-(1-hydroxy-1-methylethyl)-4-thiazolyl, 2-(2,2,2-tri- fluoro-l-hydroxy-l-trifluoromethylethyl)-4-thiazolyl, 2-(1- carboxy-1-methylethyl)-4-thiazolyl, 2-methoxycarbonyl-4- thiazolyl, 5-thiazolyl, 2-cyano-5-thiazolyl, 2-carboxy-5- thiazolyl, 2-methyl-5-thiazolyl, 2-ethyl-5-thiazolyl, 2- trifluoromethyl-5-thiazolyl, 2-(1-hydroxy-1-methylethyl)-5- thiazolyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl- ethyl)-5-thiazolyl, 2-(1-carboxy-1-methylethyl)-5-thiazol- yl, 2-methoxycarbonyl-5-thiazolyl, 2-ethoxycarbonyl-5- thiazolyl, 2-propoxycarbonyl- 5-thiazolyl, 2 -isopropoxy- carbonyl-5-thiazolyl, 4-pyrazolyl, 6-cyano-2-pyridyl, 6- carboxy-2-pyridyl, 6-trifluoromethyl-2-pyridyl, 6-methoxy- 2-pyridyl, 6-ethoxy-2-pyridyl, 6-methoxycarbonyl-2-pyridyl, 6-ethoxycarbonyl-2-pyridyl, 6-(1-hydroxy-1-methylethyl)-2- pyridyl, 6-(2,2,2-trifluoro-l-hydroxy-l-trifluoromethyl¬ethyl) -2 -pyridyl , 6-(1-carboxy-l-methylethyl)-2-pyridyl, 6- cyano-3-pyridyl, 6-carboxy-3-pyridyl, 6-trifluoromethyl-3- pyridyl, 6-methoxy-3-pyridyl, 6-ethoxy-3-pyridyl, 6- methoxycarbonyl-3-pyridyl, 6-ethoxycarbonyl-3-pyridyl, 6- (1-hydroxy-1-methylethyl)-3-pyridyl, 6-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl) -3-pyridyl, 6-(1-carboxy-l- methylethyl ) -3 -pyridyl , 2-cyano-3-pyridyl, 2-carboxy-3- pyridyl, 2-trifluoromethyl-3-pyridyl, 2-methoxy-3-pyridyl, 2- ethoxy-3-pyridyl, 2-propoxy-3-pyridyl, 2-methoxycarbonyl- 3- pyridyl, 2-ethoxycarbonyl-3-pyridyl, 2-propoxycarbonyl-3- pyridyl, 2-(1-hydroxy-1-methylethyl)-3-pyridyl, 2-(2,2,2- trifluoro-l-hydroxy-l-trifluoromethylethyl)-3-pyridyl, 2- (1-carboxy-l-methylethyl)-3-pyridyl, 2-cyano-4-pyridyl, 2- carboxy-4-pyridyl, 2-trifluoromethyl-4-pyridyl, 2-methoxy- 4- pyridyl, 2-ethoxy-4-pyridyl, 2-propoxy-4-pyridyl, 2- methoxycarbonyl-4-pyridyl, 2-ethoxycarbonyl-4-pyridyl, 2- (1-hydroxy-1-methylethyl)-4-pyridyl, 2-(2,2,2-trifluoro-l- hydroxy-l-trif luoromethylethyl ) -4-pyridyl, 2-(1-carboxy-l- methylethyl) -4-pyridyl, [0126] benzyl, 2-fluorobenzyl, 3-fluorobenzyl, 4-fluorobenzyl, 2,4-difluorobenzyl, 3,4-difluorobenzyl, 2-chlorobenzyl, 3- chlorobenzyl, 4-chlorobenzyl, 2,4-dichlorobenzyl, 3,4- dichlorobenzyl, 2-cyanobenzyl, 3-cyanobenzyl, 4-cyano- benzyl, 3-nitrobenzyl, 3-carboxybenzyl, 4-carboxybenzyl, 3- trifluoromethylbenzyl, 4-trifluoromethylbenzyl, 3-(1- hydroxy-l-methylethyl)benzyl, 4-(1-hydroxy-1-methylethyl)- benzyl, 3-(2,2,2-trifluoro-1-hydroxy-1-trifluoromethyl- ethyl)benzyl, 4-(2,2,2-trifluoro-1-hydroxy-1-1rifluoro- methylethyl)benzyl, 4-(1-carboxy-1-methylethyl)benzyl, 3- methoxybenzyl, 4-methoxybenzyl, 3-methoxycarbonylbenzyl, 4- methoxycarbonylbenzyl, 2-thienylmethyl, 5-cyano-2-thienyl- methyl, 5-carboxy-2-thienylmethyl, 5-methyl-2-thienyl¬methyl, 5-trifluoromethyl-2-thienylmethyl, 5-(1-hydroxy-l- methylethyl) -2-thienylmethyl, 5-(2,2,2-trifluoro-l-hydroxy- 1-trifluoromethylethyl)-2-thienylmethyl, 4-(1-carboxy-l- methylethyl)-2-thienylmethyl, 3-thienylmethyl, 5-cyano-3- thienylmethyl, 5-carboxy-3-thienylmethyl, 5-methyl-3- thienylmethyl, 5-trifluoromethyl-3-thienylmethyl, 5-(1- hydroxy-1-methylethyl)-3-thienylmethyl, 5-(2,2,2-trifluoro- 1- hydroxy-1-trifluoromethylethyl)-3-thienylmethyl, 4- thiazolylmethyl, 2-cyano-4-thiazolylmethyl, 2-carboxy-4- thiazolylmethyl, 2-methyl-4-thiazolylmethyl, 2-trifluoro- methyl-4-thiazolylmethyl, 2-(1-hydroxy-1-methylethyl)-4- thiazolylmethyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl) -4-thiazolylmethyl, [0127] 5-thiazolylmethyl, 2-cyano-5-thiazolylmethyl, 2-carboxy-5- thiazolylmethyl, 2-methyl-5-thiazolylmethyl, 2 -trifluoro- methyl-5-thiazolylmethyl, 2-(1-hydroxy-1-methylethyl)-5- thiazolylmethyl, 2-(2,2,2-trifluoro-l-hydroxy-l-trifluoro¬methylethyl )- 5 - thiazolylmethyl , 4-pyrazolylmethyl, 6-cyano- 2- pyridylmethyl, 6-carboxy-2-pyridylmethyl, 6-trifluoro- methyl-2-pyridylmethyl, 6-methoxy-2-pyridylmethyl, 6-(l- hydroxy-1-methylethyl)-2-pyridylmethyl, 6-(2,2,2-trifluoro- l-hydroxy-l-trif luoromethylethyl) -2-pyridylmethyl, 6-cyano- 3- pyridylmethyl, 6-carboxy-3-pyridylmethyl, 6-trifluoro- methyl-3-pyridylmethyl, 6-methoxy-3-pyridylmethyl, 6-(1- hydroxy-l-methylethyl)-3-pyridylmethyl, 6-(2,2,2-trifluoro- 1-hydroxy-l-trifluoromethylethyl)-3-pyridylmethyl, 2-cyano- 3- pyridylmethyl, 2-carboxy-3-pyridylmethyl, 2-trifluoro- methyl-3-pyridylmethyl, 2-methoxy-3-pyridylmethyl, 2-(1- hydroxy-l-methylethyl)-3-pyridylmethyl, 2-(2,2,2-trifluoro- 1- hydroxy-1-trifluoromethylethyl)-3-pyridylmethyl, 2-cyano- 4- pyridylmethyl, 2-carboxy-4-pyridylmethyl, 2-trifluoro- methyl-4-pyridylmethyl, 2-methoxy-4-pyridylmethyl, 2-(l- hydroxy-l-methylethyl) -4-p>yldj=< , (Step 28B) d R^ O R2 R2 (69) (70) (4a) [0352] wherein rS R^, R^ and X have the same meanings as defined above. Preparation method 2 8 is a method for preparing Compound (4a) wherein Z of the above-mentioned compound (4) is a 4,4,5,5-tetramethyl-[1,3,2]dioxaborolanyl group by using Compound (69) as a starting compound. Step 2 8A is a step for preparing a lithiated compound (70) by reacting Compound (69) with an organolithium compound in an inert solvent. Compound (69) is a compound which is conventionally known, or can be prepared by either of the following mentioned "Preparation method 32", "Preparation method 36", "Preparation method 37", "Preparation method 38", "Preparation method 39" or "Preparation method 4 0". As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an ether such as diethyl ether, tetrahydrofuran or 1,2-dimethoxyethane, etc.; an aliphatic saturated hydrocarbon such as pentane, hexane, cyclohexane or heptane, etc.; an aromatic hydro¬carbon such as benzene or toluene, etc.; or a mixed solvent of an optional combination of the above, etc., preferably diethyl ether or tetrahydrofuran. As the organolithium compound, there may be mentioned, for example, an organolithium compound such as butyl lithium or sec-butyl lithium, etc. An amount of the organolithium compound to be used is generally 0.9 to 1.5- fold mol amount, preferably 1 to 1.1-fold mol amount based on 1 mol of Compound (69). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of -80°C to 20°C, preferably -70°C to 0°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 12 hours, preferably 3 0 minutes to 6 hours. In this step, the lithiated compound (70) can be applied to the next Step 2 8B without isolation from the reaction mixture. [354] step 28B is a step for preparing a boronic acid ester compound (4a) by reacting the lithiated compound (70) with 2-isopropoxy-4,4,5,5-tetramethyl[1,3,2]dioxaborolane in an inert solvent. The inert solvent to be used in this step is the same solvents as those used in the above-mentioned "Step 28A". An amount of the 2-isopropoxy-4,4,5,5-tetramethyl- Ll, 3 , 2] dioxaborolane to be used is generally 1 to 2-fold mol amount, preferably 1 to 1.5-fold mol amount based on 1 mol of Compound (69) or Compound (70). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of -80°C to 50°C, preferably -70°C to 30°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 30 minutes to 6 hours, preferably 3 0 minutes to 3 hours. [Preparation method 29] [0355] Palladium catalyst r^ (Step 29) [356] wherein R^, R^, R^ and X have the same meanings as defined above. Preparation method 29 is another method for preparing a boronic acid ester compound (4a) described in the above- mentioned "Preparation method 28" . [357] Step 29 is a step for preparing a boronic acid ester compound (4a) by reacting Compound (69) with bis(pinaco- lato)diboron in an inert solvent in the presence of a palladium catalyst. This step is carried out in the same manner as in the above-mentioned "Step lA" except for selecting 1,4-dioxane as an inert solvent, l,l'-bis(di- phenylphosphino)ferrocene palladium chloride as a palladium catalyst and potassium acetate as a base, respectively, and using Compound (69) in place of Compound (3), and bis- (pinacolato)diboron in place of Compound (4), respectively. [Preparation method 3 0] [0358] Paladium catalyst (Step 30) O R^ (69) [359] wherein R^, R^, R^ and X have the same meanings as defined above. Preparation method 3 0 is another method for preparing a boronic acid ester compound (4a) described in the above- mentioned "Preparation method 28". Step 30 is a step for preparing a boronic acid ester compound (4a) by reacting Compound (69) with pinacol borane in an inert solvent in the presence of a palladium catalyst. This step is carried out in the same manner as in the above-mentioned "Step lA" except for selecting 1,4- dioxane, 1,2-dimethoxyethane or toluene as an inert solvent, selecting 1,1'-bis(diphenylphosphino)ferrocene palladium chloride as a palladium catalyst and selecting triethylamine or N,N-diisopropylethylamine as a base, respectively, and using Compound (69) in place of Compound (3) and using pinacol borane in place of Compound (4). [Preparation method 31] [361] OH H OH O \ (Step 31 A) )=< (Step 31B) (4b) (4c) [362] wherein R^ and R^ have the same meanings as defined above. Preparation method 31 is a method for preparing Compound (4c) wherein Z in the above-mentioned boronic acid compound (4) is a dihydroxyboryl group and using a boronic acid ester compound (4a) as a starting compound. [363] Step 31A is a step for preparing a boronic acid amine complex compound (4b) by reacting Compound (4a) with diethanolamine in an inert solvent. Compound (4a) can be prepared by either method of the above-mentioned "Prepara¬tion method 28", "Preparation method 29" or "Preparation method 3 0". As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an alcohol such as methanol, ethanol, propanol, isopropanol, butanol or tert- butanol, etc., and the like, preferably isopropanol. An amount of diethanolamine to be used is generally 1 to 20-fold mol amount, preferably 3 to 10-fold mol amount based on 1 mol of Compound (4a). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of -10°C to 50°C, preferably 0°C to 30°C. R A reaction time may vary depending on a reaction temperature, etc., and is generally for 30 minutes to 48 hours, preferably 1 hour to 24 hours. [364] Step 3IB is a step for preparing a boronic acid compound (4c) by hydrolyzing Compound (4b) in an inert solvent under acidic conditions. As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an ether such as tetrahydrofuran or 1,4-dioxane, etc.; an organic acid such as formic acid, acetic acid, propionic acid or trifluoro- acetic acid, etc.; water; or a mixed solvent of an optional combination of the above, etc., preferably water. As the acid to be used, there may be mentioned, for example, hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, phosphoric acid, p-toluenesulfonic acid, methanesulfonic acid or trifluoroacetic acid , etc., preferably hydrochloric acid. An amount of the acid to be used is generally 10 to 2000-fold mol amount, preferably 30 to 300-fold mol amount based on 1 mol of Compound (4b). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of 0°C to 100°C, preferably 15°C to 50°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 48 hours, preferably 1 hour to 24 hours. [Preparation method 32] R'—X (73) HO-np b^p^Br Bromine (Step 32B) (Step 32A) HO—^""^-Br (72) (71) (69a) (Step 32C) F2HC O O Difluoromethylating agent (74) (69b) [366] wherein R^, R^ and X have the same meanings as defined above. Preparation method 32 is another method for preparing Compound (69a) wherein X in the above-mentioned compound (69) is a bromine atom, or Compound (69b) wherein X is a bromine atom, and R^ is a difluoromethyl group, respec¬tively. [367] Step 32A is a step for preparing Compound (72) by reacting Compound (71) with bromine in an inert solvent. Compound (71) is conventionally known or can be prepared by the following mentioned "Preparation method 33" . As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an alcohol such as methanol, ethanol, propanol or isopropanol, etc.; a nitrile such as acetonitrile or propionitrile, etc.; an ether such as tetrahydrofuran, 1,2-dimethoxyethane or 1,4-dioxane, etc.; a halogenated aliphatic hydrocarbon such as dichloro- methane, chloroform or 1,2-dichloroethane, etc.; or a mixed solvent of an optional combination of the above, etc., preferably dichloromethane or 1,4-dioxane. An amount of bromine to be used is generally 1 to 1.5- fold mol amount, preferably 1 to 1.05-fold mol amount based on 1 mol of Compound (71). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of -80°C to 50°C, preferably -60°C to 20°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 6 hours, preferably 3 0 minutes to 3 hours. [0368] Step 32B is a step for preparing Compound (69a) by reacting Compound (72) with a halogen compound (73) in an inert solvent in the presence of a base. As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, a ketone such as acetone, methyl ethyl ketone or methyl isobutyl ketone, etc.; a nitrile such as acetonitrile or propionitrile, etc.; an amide such as N,N-dimethylformamide, N,N-dimethyl- acetamide or N-methylpyrrolidone, etc.; or a sulfoxide such as dimethylsulfoxide, etc., preferably acetone or N,N- dimethylformamide. The halogen compound (73) is a known compound such as methyl iodide, etc., or a compound which can be prepared from a known compound according to a known method. An amount of the halogen compound (73) to be used is generally 1 to 5-fold mol amount, preferably 1 to 1.5-fold mol amount based on 1 mol of Compound (72). As the base to be used, there may be mentioned, for example, an alkali metal carbonate such as sodium carbon¬ate, potassium carbonate or cesium carbonate, etc.; an alkali metal alkoxide such as sodium methoxide, sodium ethoxide, sodium tert-butoxide or potassium tert-butoxide, etc.; or an alkali metal hydride such as sodium hydride, etc., preferably sodium carbonate or potassium carbonate. An amount of the base to be used is generally 1 to 5-fold mol amount, preferably 1 to 3-fold mol amount based on 1 mol of Compound (72). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of 0°C to 100°C, preferably 10°C to 50°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 24 hours, preferably 1 hour to 12 hours. [0369] Step 32C is a step for preparing Compound (69b) by reacting Compound (72) with a difluoromethylating agent (74) in an inert solvent in the presence of a base. As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an alcohol such as methanol, ethanol, propanol or isopropanol, etc.; a nitrile such as acetonitrile or propionitrile, etc.; an amide such as N,N-dimethylformamide, N,N-dimethylacetamide or N- methylpyrrolidone, etc.; a sulfoxide such as dimethylsulf- oxide, etc.; an ether such as tetrahydrofuran, 1,2-di- methoxyethane or 1,4-dioxane, etc.; a halogenated aliphatic hydrocarbon such as dichloromethane, chloroform or 1,2- dichloroethane, etc.; an aromatic hydrocarbon such as benzene or toluene, etc.; water; or a mixed solvent of an optional combination of the above, etc., preferably dichloromethane, 1,4-dioxane or toluene-water mixed solvent. As the difluoromethylating agent (74) to be used, there may be mentioned, for example, chlorodifluoromethane, chlorodifluoroacetic acid, sodium chlorodifluoroacetate, methyl chlorodifluoroacetate or ethyl chlorodifluoro¬acetate, etc., preferably chlorodifluoromethane or sodium chlorodifluoroacetate. An amount of the difluoromethylat- ing agent (74) to be used is generally 1 to 10-fold mol amount, preferably 1 to 3-fold mol amount based on 1 mol of Compound (72). As the base to be used, there may be mentioned, for example, an alkali metal hydroxide such as lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.; or an alkali metal carbonate such as sodium carbonate, potassium carbonate or cesium carbonate, etc., preferably sodium hydroxide or sodium carbonate. An amount of the base to be used is generally 1 to 10-fold mol amount, preferably 1 to 3-fold mol amount based on 1 mol of Compound (72) . Incidentally, when toluene-water mixed solvent is used as an inert solvent, a phase-transfer catalyst such as tetraethylammonium chloride or tetrabutylammonium bromide, etc. may be used. An amount of the phase-transfer catalyst to be used is generally 0.05 to 10-fold mol amount, preferably 0.1 to 1- fold mol amount based on 1 mol of Compound (72). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of 20°C to 150°C, preferably 50°C to 100°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 12 hours, preferably 1 hour to 6 hours. [Preparation method 33] [0370] X (76) HO-^ o (Step 33A) (71) wherein R^, R^ and X have the same meanings as defined above, R^^ represents a methyl group, benzyl group, 4- methoxybenzyl group, cyclopropylmethyl group, MEM group, MOM group or BOM group. Preparation method 3 3 is another method for preparing a starting compound (71) described in the above-mentioned "Preparation method 32". [372] Step 33A is a step for preparing Compound (77) by reacting Compound (75) with Compound (76). Compound (75) is a known compound such as 2-methoxyphenol or 2-benzyloxy- phenol, etc., or a compound which can be prepared from a known compound according to a known method. Compound (76) is a known compound such as methyl iodide or cyclopropyl¬methyl bromide, etc., or a compound which can be prepared from a known compound according to a known method. This step is carried out in the same manner as in the above- mentioned "Step 32B" except for using Compound (75) in place of Compound (72), and using Compound (76) in place of Compound (73), respectively. [373] Step 3 3B is a step for preparing Compound (71) by removing R^^ which is a protective group of Compound (77). With regard to removal of the protective group, it can be carried out easily by referring to conventionally known literatures (W.Greene and P.G.H.Wuts "Protective Groups in Organic Synthesis" Ed., John Wiley & Sons), etc. For example, when R^' is a methyl group, it is carried out by a method using boron tribromide or sodium ethylthiolate; when R^' is a 4-methoxybenzyl group, cyclopropylmethyl group, MEM group, MOM group or BOM group, by a method of applying acid treatment; or when R^' is a benzyl group, 4-methoxy¬benzyl group or BOM group, by a method of hydrogenation decomposition using a palladium catalyst, respectively. [Preparation method 34] [374] 1) (CF3C0)20 Br )=/ (Step 34A) )=/ (Step 34B) HO HO O^ R (75) (79) HO— Deprotection (Step 34C) (72) [375] wherein R^, R^, R^'' and X have the same meanings as defined above. Preparation method 34 is another method for preparing an intermediate compound (72) described in the above- mentioned "Preparation method 32". [376] Step 34A is a step for preparing Compound (78) by reacting Compound (75) with trifluoroacetic anhydride in an inert solvent in the presence of a base catalyst, then brominating the product using N-bromosuccineimide, and further treating the reaction mixture with water. This step is carried out according to the method described in WO 01/19785. [377] Step 34B is a step for preparing Compound (79) by reacting Compound (78) with Compound (76) . This step is carried out in the same manner as in the above-mentioned "Step 32B" except for using Compound (78) in place of Compound (72), and using Compound (76) in place of Compound (73), respectively. [378] step 34C is a step for preparing Compound (72) by- removing R^'' which is a protective group of Compound (79) . This step is carried out in the same manner as in the above-mentioned "Step 33B" except for using Compound (79) in place of Compound (77). [Preparation method 35] [0379] R^^—X HO )=/ (Step 35A) )=/ (Step 35B) OHC OHC HO (80) (82) (78) [380] wherein R^, R^, R^' and X have the same meanings as defined above. Preparation method 3 5 is another method for preparing Compound (78) described in the above-mentioned "Preparation method 34" using the known compound (80) as a starting compound. [381] Step 3 5A is a step for preparing Compound (82) by reacting Compound (80) with Compound (81) in the presence of a base. As Compound (81), there may be mentioned, for example, known compounds such as methyl iodide, benzyl bromide, cyclopropylmethyl chloride, cyclopropylmethyl bromide, methoxymethyl chloride and methoxyethoxymethyl chloride, etc. This step is carried out in the same manner as in the above-mentioned "Step 32B" except for using Compound (80) in place of Compound (72), and using Compound (81) in place of Compound (73), respectively. [382] Step 35B is a step for preparing Compound (78) by applying Compound (82) to Baeyer-Villiger oxidation in an inert solvent. As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, a halogenated aliphatic hydrocarbon such as dichloromethane, chloroform or 1,2-dichloroethane, etc., and the like, preferably dichloromethane. As the oxidizing agent to be used, there may be men¬tioned, for example, an oxidizing agent such as m-chloro- perbenzoic acid and hydrogen peroxide, etc., preferably m- chloroperbenzoic acid. An amount of the oxidizing agent to be used is generally 1 to 10-fold mol amount, preferably 1 to 1.5-fold mol amount based on 1 mol of Compound (82). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of 0°C to 100°C, preferably 10°C to 50°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 1 day to 7 days, preferably 1 day to 3 days. [Preparation method 36] [0383] Ph =P-Ph I Ph (85) (Step 36B) [384] wherein R^, R^^ and X have the same meanings as defined above. Preparation method 3 6 is a method for preparing Compound (69c) wherein an oxygen-containing heterocyclic ring formed by ring fusion of R^ and R^ of the above-men¬tioned compound (69) is a 2,2-(1,4-butylene)-tetrahydro- furan ring by using Compound (78) as a starting compound. [385] Step 36A, Step 36B, Step 36C and Step 36D are carried out according to the method described in WO 96/03399. Compound (78) can be prepared, for example, by the above- mentioned "Preparation method 35". Step 3 6E is a step for preparing a phenol compound (89) by removing R" which is a protective group of Compound (88). This step is carried out in the same manner as in the above-mentioned "Step 33B" except for using Compound (88) in place of Compound (77). Step 3 6F is a step for preparing Compound (69c) by- reacting Compound (89) with a halogen compound (73). This step is carried out in the same manner as in the above- mentioned "Step 3 2B" except for using Compound (89) in place of Compound (72). [Preparation method 3 7] [388] r18 19 R (Step 37D) (Step 370) HO (91) (Step 37 A) [389] wherein R^ and W have the same meanings as defined above, R^® and R^® each represents a hydrogen atom, methyl group or cyclopropyl group (provided that R^® and R" do not represent hydrogen atoms or cyclopropyl groups simultane¬ously) . Also, R^® and R^® may form a cyclic C2-C4 alkylene group in combination. [390] Preparation method 3 7 is a method for preparing Compound (69d) wherein an oxygen-containing heterocyclic ring formed by ring fusion of R^ and R^ of the above- mentioned compound (69) is a 3,6-dihydro-2H-pyran ring by using Compound (90) as a starting compound. [391] Step 3 7A is a step for preparing Compound (92) by reacting Compound (90) with Compound (91). Compound (90) can be prepared, for example, in the same manner as in the above-mentioned "Preparation method 35" except for using Compound (73) of the above-mentioned "Step 32B" in place of Compound (81). As Compound (91), there may be mentioned, for example, known compounds such as 3-butyn-2-ol, 2- methyl-3-butyn-2-ol, l-cyclopropyl-2-propyn-l-ol, 1- ethynylcyclopropanol, 1-ethynylcyclobutanol and 1-ethynyl- cyclopentanol, etc. This step is carried out in the same method as described in WO 97/43288. [392] Step 3 7B is a step for preparing Compound (92') by reacting Compound (90) with Compound (91')- As Compound (91'), there may be mentioned, for example, known compounds such as 4-trimethylsilyl-3-butyn-2-ol, 2-methyl-4-tri- methylsilyl-3-butyn-2-ol, l-cyclopropyl-3-trimethylsilyl-2- propyn-l-ol, 1-trimethylsilylethynylcyclopropanol, 1-tri- methylsilylethynylcyclobutanol and 1-trimethylsilylethynyl- cyclopentanol, etc. This step is carried out according to the method described in WO 97/43288 similarly as in the above- mentioned "Step 37A". [393] Step 3 7C is a step for preparing Compound (92) by removing a protective group at the end of the ethynyl group of Compound (92') . This step is carried out in the same manner as in the above-mentioned "Step 9A1" except for using Compound (92') in place of Compound (6h). HO' (91) (Step 38B) Step 3 7B is a step for preparing Compound (6 9d) by intramolecular cyclization of Compound (92). This step is carried out according to the method described in WO 97/43288 similarly as in the above-mentioned "Step 3 7A". [Preparation method 38] b-nQ-Br HO (Step 38A) (78) HO-/ R^-X b^f Vsr Deprotection (73) THT (Step38C) W R 1,19 (95) (Step 38D) (69d) [396] wherein R^, R^^, R^® and R^® have the same meanings as defined above. Preparation method 3 8 is another method for preparing Compound (69d) wherein an oxygen-containing heterocyclic ring formed by ring fusion of R^ and R^ of the above- mentioned compound (69) is a 3,6-dihydro-2H-pyran ring by using Compound (78) as a starting compound. [397] Step 3 8A and Step 3 8B are carried out in the same method as described in WO 97/43288. Compound (78) can be prepared, for example, by the above-mentioned "Preparation method 3 5". Step 3 8C is a step for preparing Compound (95) by removing R^^ which is a protective group of Compound (94) . This step is carried out in the same manner as in the above-mentioned "Step 33B" except for using Compound (94) in place of Compound (77). [399] Step 3 8D is a step for preparing Compound (6 9d) by reacting Compound (95) with a halogen Compound (73). This step is carried out in the same manner as in the above- mentioned "Step 32B" except for using Compound (95) in place of Compound (72). [Preparation method 3 9] [0400] Dfluoromethylating agent (74) (Step 39) (69e) [401] wherein R^® and R^® have the same meanings as defined above. Preparation method 3 9 is a method for preparing Compound (69e) wherein an oxygen-containing heterocyclic ring formed by ring fusion of R^ and R^ of the above- mentioned compound (69) is a 3,6-dihydro-2H-pyran ring and R^ is a difluoromethyl group by using Compound (95) as a starting compound. [402] Step 3 9 is a step for preparing Compound (69e) by reacting Compound (95) with a difluoromethylating agent (74) in an inert solvent in the presence of a base. Compound (95) can be prepared by the above-mentioned "Step 3 8C". Step 3 9 is carried out in the same manner as in the above-mentioned "Step 32C" except for using Compound (95) in place of Compound (72). [Preparation method 40] 1) BuLi 2) Iodine 1 Br > (Step 40A) (97) (Step 40B) hohQ R^—X (73) Deprotection (Step40C)' Bromine (Step 40D) O I >^(100) (Step 40E) HoX= (101) (103) (Step 40G) [404] wherein R^, R^® and R^^ have the same meanings as defined above. Preparation method 4 0 is a method for preparing Compound (69d) wherein an oxygen-containing heterocyclic ring formed by ring fusion of R^ and R^ of the above- mentioned compound (69) is a 3,6-dihydro-2H-pyran ring by using the known compound (96) as a starting compound. [405] Step 4OA is a step for preparing Compound (97) by reacting the known compound (96) with cyclopropylmethyl bromide in an inert solvent in the presence of a base. This step is carried out in the same manner as in the above-mentioned "Step 32B" except for using Compound (96) in place of Compound (72), and using cyclopropylmethyl bromide in place of the halogen compound (73). In this case, it is particularly preferred that N,N-dimethylform- amide is selected as an inert solvent, and potassium carbonate as a base, respectively, and amounts thereof are 1-fold mol amount based on 1 mol of Compound (96), a reaction temperature is 8 0°C, and a reaction time is 2 hours. [406] Step 40B is a step for preparing an iodized compound (98) after subjecting the bromine atom of Compound (97) to bromine atom-lithium metal exchange by using butyl lithium. This step is carried out in the same manner as in the above-mentioned "Preparation method 28" except for using Compound (97) in place of Compound (69) , and using iodine in place of 2-isopropoxy-4,4,5,5-tetramethyl[1,3,2]dioxa- borolane, respectively. Step 4 0C is a step for preparing a phenol compound (99) by removing a MOM group which is a protective group of Compound (98) . This step is carried out in the same manner as in the above-mentioned "Step 33B" except for using Compound (98) in place of Compound (77). [408] Step 4 0D is a step for preparing a brominated compound (100) by reacting Compound (99) with bromine. This step is carried out in the same manner as in the above-mentioned "Step 32A" except for using Compound (99) in place of Compound (71). [409] Step 4 0E is a step for preparing Compound (101) by reacting Compound (100) with a halogen compound (73). This step is carried out in the same manner as in the above- mentioned "Step 32B" except for using Compound (100) in place of Compound (72). [410] Step 40F is a step for preparing Compound (102) by removing a cyclopropylmethyl group which is a protective group of Compound (101). This step is carried out in the same manner as in the above-mentioned "Step 33B" except for using Compound (101) in place of Compound (77). [411] step 4 0G is a step for preparing Compound (69d) by reacting Compound (102) with Compound (103) in the presence of a palladium catalyst. As Compound (103), there may be mentioned, for example, known compounds such as 3-buten-2- ol, 2-methyl-3-buten-2-ol, l-cyclopropyl-2-propen-l-ol, 1- vinylcyclopropanol, 1-vinylcyclobutanol and 1-vinylcyclo- pentanol, etc. This step is carried out in the same method as described in WO 01/83476. [Preparation method 41] [0412] CO2 (Step 41) (7) [413] wherein R^, R^ and R^ have the same meanings as defined above. Preparation method 41 is a method for preparing Compound (7) in the above-mentioned "Preparation method 3". [414] Step 41 is a step for preparing Compound (7) to which a carboxy group is introduced by reacting a lithiated compound (70) with carbon dioxide. Compound (70) can be prepared by the above-mentioned "Step 28A" . This step is carried out in the same manner as in the above-mentioned "Step 2 8B" except for using carbon dioxide in place of 2- isopropoxy-4,4,5,5-tetramethyl[1,3,2]dioxaborolane. [Preparation method 42] H H (9) O rV /wCOOH (Step 42) (10) [416] wherein R^, R^' and M have the same meanings as defined above. Preparation method 42 is another method for preparing Compound (10) of the above-mentioned "Preparation method 3" . Step 42 is a step for preparing Compound (10) by- reacting a benzoic acid compound (7) with an organometallic compound (9) in an inert solvent. Compound (7) can be prepared by, for example, the above-mentioned "Preparation method 41" . This step is carried out in the same manner as in the above-mentioned "Step 3B" except for using Compound (7) in place of Compound (8). [Preparation method 43] (7) O bk A^^R'' (105) R' I R 20 (106) X.N (Step 43A) (104) I ivj'*^ Reductbn (Step 43D) ^20 R22 R O O Halogenating agent (21) . (Step 43E) R^^M (108) (Step 430) (110) (109) I jN f- o X ^N 20 wherein R^ X and M have the same meanings as defined above, represents a BOM group, 4-methoxybenzyl group or SEM group, R^^ represents a hydrogen atom, BOM group or SEM group, and R^^ represents a C^-Cg alkyl group, "a Cj-Cg cycloalkyl group which may be substituted by a substitu- ent(s) selected from Substituent group (b)" or "an aromatic ring group or heteroaromatic ring group each may be substi¬tuted by a substituent(s) selected from Substituent group (d)". (the Ci-Cg alkyl group of R^^ has the same meaning as the unsubstituted alkyl group in the "C^-Cg alkyl group substituted by a substituent(s) selected from Substi¬tuent group (a)".) [419] Preparation method 43 is a method for preparing Compound (111) wherein R® and R® of the above-mentioned compound (3) are each a SEM group or BOM group, and R^ is an ethyl group substituted by R^^, or R® of the above-men- tioned compound (3a) is a SEM group or BOM group, and R^ is an ethyl group substituted by R^^. [420] Step 43A is a step for preparing a vinyl ether compound (106) by reacting Compound (104) with Compound (105) in an inert gas atmosphere in an inert solvent and in the presence of a palladium catalyst and a base. Compound (104) is a compound wherein R® and R® of the above-mention¬ed compound (41a) are each a SEM group, 4-methoxybenzyl group or BOM group, and X is a bromine atom, or a compound wherein R^ of the above-mentioned compound (41b) is a SEM group, 4-methoxybenzyl group or BOM group, and X is a bromine atom, and can be prepared by the above-mentioned "Step 141" or "Step 14K". Compound (105) is a compound which is a known compound such as methylvinyl ether, ethylvinyl ether, propylvinyl ether, butylvinyl ether and tert-butylvinyl ether, etc., or can be prepared from a known compound according to the known method. This step is carried out in the same manner as in the above-mentioned "Step llAl" except for using Compound (104) in place of Compound (6f) and using Compound (105) in place of Compound (24), respectively, using 1,3-bis(diphenylphosphino)propane in place of triphenylphosphine or tri(o-tolyl)phosphine as a phosphine derivative which is preferably co-present, using N,N-diisopropylethylamine as a preferred base, and using thallium acetate to control selectivity of the reaction. An amount of the thallium acetate to be used to control selectivity of the reaction is generally 0.5 to 3- fold mol amount, preferably 1 to 1.5-fold mol amount based on Compound (104). [0421] Step 43B is a step for preparing Compound (107) having an acetyl group by hydrolyzing a vinyl ether compound (106) in an inert solvent in the presence of an acid catalyst. As the inert solvent to be used, there may be mention¬ed, for example, an aliphatic hydrocarbon such as pentane, hexane or heptane, etc.; an aromatic hydrocarbon such as benzene or toluene, etc.; an ether such as tetrahydrofuran, 1,2-dimethoxyethane or 1,4-dioxane, etc.; an alcohol such as methanol, ethanol, propanol or isopropanol, etc.; an ester such as methyl acetate or ethyl acetate, etc.; an amide such as N,N-dimethylformamide, N,N-dimethylacetamide or N-methylpyrrolidone, etc.; a sulfoxide such as dimethyl- sulfoxide, etc.; a nitrile such as acetonitrile or propio- nitrile, etc.; water; or a mixed solvent of an optional combination of the above, etc., preferably a mixed solvent of hexane-ethyl acetate or methanol. As the acid catalyst to be used, there may be men¬tioned a solid acid such as silica gel, etc.; an ion exchange resin such as Amberlite 15 (trade name), etc.; an inorganic acid such as hydrochloric acid, hydrobromic acid, sulfuric acid or phosphoric acid, etc.; an organic acid such as formic acid, acetic acid, propionic acid or tri- fluoroacetic acid, etc.; or a sulfonic acid such as methanesulfonic acid or p-toluenesulfonic acid, etc., preferably silica gel or hydrochloric acid. An amount of the acid catalyst to be used is generally 0.5 to 3-fold mol amount, preferably 1 to 1.5-fold mol amount based on 1 mol of Compound (106) . Provided that in the case of the solid acid, it is generally 1 to 20 kg, preferably 5 to 15 kg based on 1 mol of Compound (106). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of 0°C to 200°C, preferably 10°C to 50°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 72 hours, preferably 1 hour to 24 hours. [422] Step 43C is a step for preparing Compound (109) having a hydroxy group by reacting Compound (10 7) having an acetyl group with an organometallic compound (108) in an inert solvent. As the organometallic compound (108) to be used, there may be mentioned, for example, an organolithium reagent such as methyl lithium, butyl lithium or phenyl lithium, etc.; or an organomagnesium reagent (Grignard reagent) such as methyl magnesium chloride, methyl magne¬sium bromide, ethyl magnesium chloride, ethyl magnesium bromide, propyl magnesium chloride, propyl magnesium bromide, butyl magnesium chloride, butyl magnesium bromide, cyclopropyl magnesium chloride, cyclopropyl magnesium bromide, phenyl magnesium chloride or phenyl magnesium bromide, etc. Step 43C is carried out in the same manner as in the above-mentioned "Step 3B" except for using Compound (107) in place of Compound (8), and using an organometallic compound (108) in place of the organo¬metallic compound (9), respectively. [423] Step 43D is a step for preparing Compound (110) by reducing Compound (10 9) having a hydroxy group using an organosilane compound or organotin compound in an inert solvent in the presence of an acid or a Lewis acid. Step 43D is carried out in the same manner as in the above- mentioned "Step 12C1" except for using Compound (109) in place of Compound (6q). [424] Step 43E is a step for preparing Compound (111) wherein the 2-position of the pyrrolopyridazinone ring is halogenated by reacting Compound (110) with a halogenating agent (21) . This step is carried out in the same manner as in the above-mentioned "Step 6A" except for using Compound (110) in place of Compound (2e). [Preparation method 44] I O 0 0 OH O agent (Step 44B) agent (Step 44A) I ■M ^cA-nAN-''^^ Hal^^ating Reding X-^XA R N I I (106) ^20 (113) (112) O A O Base (Step 44Q MeOH O (Step 44D) (Step 44^ N ^20 ^20 (114) O I ^20 (116) [426] wherein R', and R^^ have the same meanings as defined above, R" represents a C^-C^ alkyl group having the same meaning as defined above or a (Cj-Cg cycloalkyl) C^-Cj alkyl group having the same meaning as defined above, X" represents a chlorine atom or bromine atom. [427] Preparation method 44 is a method for preparing Compound (119) wherein R^ of the above-mentioned compound (3) is an ethyl group substituted by a group-OR". [0428] Step 44A is a step for preparing a haloacetyl deriva¬tive (112) by reacting Compound (106) with a halogenating agent in an inert solvent. Compound (106) can be prepared by the above-mentioned "Step 43A". As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an aromatic hydrocarbon such as benzene or toluene, etc.; an ether such as diethyl ether, tetrahydrofuran, 1,2-dimethoxyethane or 1,4-dioxane, etc.; an alcohol such as methanol, ethanol, propanol or isopropanol, etc.; a nitrile such as aceto- nitrile or propionitrile, etc.; a halogenated aliphatic hydrocarbon such as dichloromethane, chloroform or 1,2- dichloroethane, etc.; water and a mixed solvent of the above with water, or a mixed solvent of an optional combination of the above, etc., preferably a mixed solvent of tetrahydrofuran-water. As the halogenating agent to be used, there may be mentioned, for example, a chlorinating agent such as chlorine, sulfuryl chloride or N-chlorosuccineimide, etc.; a brominating agent such as bromine, benzyltrimethyl- ammonium tribromide, trimethylphenylammonium tribromide, tetramethylammonium tribromide, tetraethylammonium tribromide, tetrabutylammonium tribromide, pyridinium hydrobromide perbromide or N-bromosuccineimide, etc., and the like, preferably N-chlorosuccineimide or N-bromo- succineimide. An amount of the halogenating agent to be used is generally 1 to 10-fold mol amount, preferably 1 to 3-fold mol amount based on 1 mol of Compound (106). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s). etc., and is generally in the range of -10°C to 100°C, preferably 0°C to 50°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 48 hours, preferably 1 hour to 24 hours. [429] Step 44B is a step for preparing a halohydrin compound by treating a haloacetyl derivative (112) with a reducing agent in an inert solvent. As the reducing agent to be used, there may be men¬tioned, for example, sodium borohydride, lithium boro- hydride, sodium cyanoborohydride, sodium trimethoxyboro- hydride and lithium aluminum hydride, etc., preferably sodium borohydride. An amount of the reducing agent to be used is generally 1 to 5-fold mol amount, preferably 1 to 2.5-fold mol amount based on 1 mol of Compound (112) . The solvent to be used may be mentioned, for example, an alcohol such as methanol, ethanol, propanol or butanol, etc.; an ether such as tetrahydrofuran, 1,4-dioxane or 1,2- dimethoxyethane, etc.; a nitrile such as acetonitrile or propionitrile, etc.; an amide such as N,N-dimethylform- amide, N,N-dimethylacetamide or N-methylpyrrolidone, etc.; water or a mixed solvent of the above solvents, preferably tetrahydrofuran or a mixed solvent with tetrahydrofuran. A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of -lOtto 100°C, preferably 0 to 50°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 10 hours, preferably 3 0 minutes to 6 hours. [430] Step 44C is a step for preparing an epoxide derivative (114) by treating a halohydrin compound (113) with a base in an inert solvent. As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an ether such as diethyl ether, tetrahydrofuran, 1,2-dimethoxyethane or 1,4- dioxane, etc.; an amide such as N,N-dimethylformamide, N,N- dimethylacetamide or N-methylpyrrolidone, etc.; or a mixed solvent of the above solvents, etc., preferably tetrahydro¬furan . As the base to be used, there may be mentioned an alkali metal such as lithium, sodium or potassium, etc.; an alkali metal hydride such as sodium hydride or potassium hydride, etc.; or an alkali metal alkoxide such as sodium methoxide, sodium ethoxide, sodium butoxide, sodium tert- butoxide or potassium tert-butoxide, etc., and the like, preferably potassium tert-butoxide. An amount of the base to be used is generally 1 to 5-fold mol amount, preferably 1 to 2-fold mol amount based on 1 mol of Compound (113). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of -10°C to 100°C, preferably 0°C to 60°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 24 hours, preferably 1 hour to 12 hours. [431] Step 44D is a step for preparing Compound (115) by treating an epoxide derivative (114) with methanol. A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of -lOtto 100°C, preferably 0°C to 60°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 10 minutes to 48 hours, preferably 1 hour to 24 hours. [432] Step 44E is a step for preparing Compound (116) by reducing Compound (115) under hydrogen atmosphere using a catalyst in an inert solvent. As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an alcohol such as methanol, ethanol, propanol or isopropanol, etc.; an ether such as tetrahydrofuran, 1,4-dioxane or 1,2-dimethoxy- ethane, etc.; a halogenated aliphatic hydrocarbon such as dichloromethane, chloroform or 1,2-dichloroethane, etc.; an ester such as methyl formate, ethyl formate, methyl acetate or ethyl acetate, etc.; an organic acid such as formic acid, acetic acid, propionic acid or trifluoroacetic acid, etc.; an aromatic hydrocarbon such as benzene or toluene, etc.; water; or a mixed solvent of an optional combination of the above, etc., preferably acetic acid. The catalyst to be used may be mentioned, for example, palladium-active carbon, platinum-active carbon, platinum black, rhodium-active carbon or Raney nickel, etc., pre¬ferably palladium-active carbon. An amount of the catalyst to be used is generally 0.0005 to 1-fold mol amount, preferably 0.01 to 0.1-fold mol amount based on 1 mol of Compound (115). A hydrogen partial pressure in the reaction is generally 1 atm to 10 atm, preferably 1 atm to 5 atm. A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of 0°C to 100°C, pre¬ferably 15°C to 80°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 15 minutes to 24 hours, preferably 3 0 minutes to 12 hours. [0433] Step 44F is a step for preparing an alkoxyethyl derivative (118) by reacting Compound (116) with an alkylating agent (117) in an organic solvent in the presence of a base. As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, an aprotic polar solvent such as N,N-dimethylformamide, N-methylpyrrolidone, dimethylsulfoxide, N,N-dimethylacetamide or hexamethylphos- phoric triamide, etc.; a halogenated hydrocarbon such as dichloromethane, chloroform or 1,2-dichloroethane, etc.; a ketone such as acetone, methyl ethyl ketone or methyl isobutyl ketone, etc.; a nitrile such as acetonitrile or propionitrile, etc.; an ester such as methyl formate, ethyl formate, methyl acetate or ethyl acetate, etc.; an ether such as diethyl ether, diisopropyl ether, tetrahydrofuran or 1,4-dioxane, etc.; or a mixed solvent of the above solvents, preferably an aprotic polar solvent, an ether or a mixed solvent thereof. As the base to be used, there may be mentioned, for example, an alkali metal hydroxide such as sodium hydroxide or lithium hydroxide, etc.; an alkali metal hydride such as sodium hydride, etc.; an alkali metal amide such as sodium amide, etc.; an amine such as triethylamine, tributylamine, N,N-diisopropylethylamine, pyridine, picoline, lutidine or 4-dimethylaminopyridine, etc.; an alkali metal carbonate such as sodium carbonate, potassium carbonate or sodium hydrogencarbonate, etc.; or an alkali metal alkoxide such as sodium methoxide, sodium ethoxide, sodium butoxide, sodium tert-butoxide or potassium tert-butoxide, etc., and the like, preferably sodium tert-butoxide or potassium tert-butoxide. An amount of the base to be used is generally 1 to 10-fold mol amount, preferably 1 to 3-fold mol amount based on 1 mol of Compound (116). Compound (117) is a compound which is conventionally known, or can be prepared from a conventionally known compound by a conventionally known method. An amount of Compound (117) to be used is generally 1 to 10-fold mol amount, preferably 1 to 5-fold mol amount based on 1 mol of Compound (116). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of -50*cto 150°C, preferably -lO'cto 10 0°C. A reaction time may vary depending on a reaction temperature, etc., and is generally for 5 minutes to 10 hours, preferably 3 0 minutes to 5 hours. [434] Step 44G is a step for preparing a halogen compound (119) by reacting Compound (118) with a halogenating agent (21) . This step is carried out in the same manner as in the above-mentioned "Step 6A" except for using Compound (118) in place of Compound (2e). [Preparation method 45] Ph , ,10 ptph _ O OHC rI ■O-'V^R .3R (26b) (2n) (120) [436] wherein R', R', R', R% R®, R" and X have the same meanings as defined above. Preparation method 4 5 is a method for preparing Compound (2n) wherein R^ of the above-mentioned compound (3) is an ethyl group substituted by . [437] Step 45A is a step for preparing an olefin compound (121) by reacting Compound (26b) with Compound (120) in an inert solvent in the presence of a base. This step is a reaction which has been known as the so-called Wittig Reaction, and can be carried out by optinally selecting known conditions. Compound (26b) can be prepared by the above-mentioned "Step 12A2". As the inert solvent to be used, it is not specific¬ally limited so long as it does not inhibit the reaction and dissolves the starting materials with a certain extent, and there may be mentioned, for example, a halogenated hydrocarbon such as dichloromethane, chloroform, 1,2- dichloroethane, etc.; an ether such as diethyl ether, tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, etc.; an aromatic hydrocarbon such as benzene, toluene, xylene, etc.; an ester such as methyl acetate, ethyl acetate, etc.; a nitrile such as acetonitrile or propionitrile, etc.; an amide such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, etc.; dimethylsulfoxide; or a mixed solvent of the above. The base to be used may be mentioned, for example, an alkali metal hydroxide such as lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.; an alkali metal carbonate such as sodium carbonate, potassium carbonate, etc.; an alkali metal alkoxide such as sodium methoxide, sodium ethoxide, sodium tert-butoxide, potassium tert- butoxide, etc.; an alkali metal hydride such as sodium hydride, potassium hydride, etc.; an alkyl lithium such as methyl lithium, butyl lithium, etc.; a metal amide such as sodium amide, lithium diisopropyl amide, etc.; or an organic amine such as triethylamine, N,N-diisopropylethyl- amine, tripropylamine, 1,5-diazabicyclo[4.3.0]-5-nonene, etc. An amount of the base to be used is generally 1 to 5- fold mol amount, preferably 1 to 2-fold mol amount based on 1 mol of Compound (26b). Compound (12 0) is a compound which is conventionally known, or can be prepared from a conventionally known compound by a conventionally known method. An amount of Compound (12 0) to be used is generally 1 to 10-fold mol amount, preferably 1 to 1.5-fold mol amount based on 1 mol of Compound (26b). A reaction temperature may vary depending on a kind, an amount to be used of starting materials, solvent(s), etc., and is generally in the range of 0°C to 150°C, preferably 15 to 80°C. A reaction time may vary depending on a reaction tem¬perature, etc., and is generally for 1 hour to 24 hours, preferably 1 hour to 6 hours. [438] Step 45B is a step for preparing Compound (2n) wherein R^ of Compound (2) is an ethyl group substituted by R" group by subjecting Compound (121) to hydrogenation reduction in the presence of a catalyst. Step 45B is carried out in the same manner as in the above-mentioned "Step 9C1" except for using Compound (121) in place of Compound (5k). [Preparation method 46] (Step 46) R Vq^N^ (122) [440] wherein R^, R^ and R^ have the same meanings as defined above, R^^ represents a Cj-Cg alkynyl group having the same meaning as defined above, and R^® represents a Cj-Cg alkenyl group having the same meaning as defined above. [441] Preparation method 4 6 is a step for preparing Compound (123) wherein R^ of the above-mentioned compound (1) is a Cj-Cg alkenyl group by subjecting Compound (122) wherein R^ is a C2-Cs alkynyl group to hydrogenation reduction in the presence of a catalyst. This step is carried out in the same manner as in the above-mentioned "Step 9B1" except for using Compound (122) in place of Compound (6j). [Preparation method 47] [0442] —IJ- n-R Deprotecfon ho' f Reduction (step47A) jV-N-J^^ . 3SEM 1' -1 -H II (2q') [443] wherein rS R® and R" have the same meanings as defined above. Preparation method 47 is a method for preparing Compound (5a) wherein R^ of Compound (5) described in the above-mentioned "Preparation method 1" is a group -CH(OH)R^^, and Compound (5b) wherein R" of the same is a group - CH2R^^ . Step 4 7A is a step for removing the SEM group as a protective group. Compound (2q') is a compound wherein R^ of Compound (2) is a group -CH(OH)R^^ and R® of the same is a SEM group, and can be prepared, for example, by the above-mentioned "Step 12B". This step is carried out in the same manner as in the above-mentioned (Treatment 1) of "Step IBll" except for using Compound (2q') in place of Compound (2'). [445] Step 4 7B is a step for preparing Compound (5b) by- reducing Compound (5a) having a hydroxy group using an organosilane compound or organotin compound in an inert solvent in the presence of an acid or a Lewis acid. This step is carried out in the same manner as in the above- mentioned "Step 12C1" except for using Compound (5a) in place of Compound (6q). [446] After completion of the above-mentioned respective reactions, the desired compound may be isolated from the reaction mixture according to the conventional manner. For example, it can be obtained by neutralizing the reaction mixture as needed, removing insoluble materials by filtration, if any one present, adding organic solvents which are not miscible with water such as ethyl acetate, washing with water, separating the organic layer containing the desired compound, drying it over anhydrous magnesium sulfate, etc., and then distillating off the solvent. The obtained desired compound can be separated and purified, if necessary, by a conventional manner, for example, recrystallization; reprecipitation; or a method conventionally used for separation and purification of an organic compound in an optional combination by eluting with an appropriate eluent (for example, an adsorption column chromatography method using a carrier such as silica gel, alumina, etc.; ion exchange chromatography method; or a normal phase•reverse phase column chromatography method using silica gel or alkylated silica gel (suitably it is high performance liquid chromatography.)). [0447] Compound (1) of the present invention can be converted into a pharmaceutically acceptable addition salt according to the conventional manner, if necessary, and it can be directly separated as an addition salt from the reaction mixture. As the pharmaceutically acceptable addition salt, when Compound (1) of the present invention has a substi¬tuted amino group, there may be mentioned, for example, an inorganic acid addition salt such as hydrochloride, hydro- bromide, hydroiodide, nitrate, sulfate or phosphate, etc.; or an organic acid addition salt such as acetate, benzoate, oxalate, malonate, succinate, maleate, fumarate, tartarate, citrate, methanesulfonate, ethanesulfonate, trifluoro- methanesulfonate, benzenesulfonate, p-tSlu.enesixLfo'^ste, glutamate or aspartate, etc. Also, when Compound (1) of the present invention has a carboxy group, there may be mentioned, for example, a metal salt such as a sodium salt, potassium salt, calcium salt or magnesium salt, etc.: or a salt with an organic base such as an ammonium salt, triethylamine salt or guanidine salt, etc., and the like. [448] When Compound (1) of the present invention or an addition salt thereof is used as a medicine, it can be administered as such (as a resulting powder as such), or as a preparation such as a tablet, capsule, granule, powder or syrup, etc., which are prepared by mixing with an optional pharmaceutically acceptable excipient, diluent, etc., orally, or non-orally (preferably orally) as a preparation such as an injection or suppository, etc., prepared in the same manner. These preparations are prepared by the conventionally known method by using an additive such as an excipient, a lubricant, a binder, a disintegrator, an emulsifier, a stabilizer, a corrigent or a diluent, etc. [449] The excipient may be mentioned, for example, an organic excipient or an inorganic excipient. The organic excipient may be mentioned, for example, a sugar derivative such as lactose, sucrose, glucose, mannitol or sorbitol, etc.; a starch derivative such as corn starch, potato starch, a-starch or dextrin, etc.; a cellulose derivative such as crystalline cellulose, etc.; Gum Arabic; dextran; or pullulan, etc. The inorganic excipient may be mention¬ed, for example, light silicic acid anhydride; or a sulfate such as calcium sulfate, etc., and the like. [450] The lubricant may be mentioned, for example, stearic acid; a stearic acid metal salt such as calcium stearate or magnesium stearate, etc.; talc; colloidal silica; a wax such as beeds wax or spermaceti, etc.; boric acid; adipic acid; a sulfate such as sodium sulfate, etc.; glycol; fumaric acid; sodium benzoate; D,L-leucine; sodium lauryl sulfate; a silicic acid such as silicic anhydride or silicic acid hydrate, etc.; or the starch derivative in the above-mentioned excipient, etc. [451] The binder may be mentioned, for example, hydroxy- propyl cellulose, hydroxypropylmethyl cellulose, polyvinyl¬pyrrolidone, Macrogol or compounds shown in the above- mentioned excipient, etc. [452] The disintegrator may be mentioned, for example, a cellulose derivative such as low-substitution degree hydroxypropyl cellulose, carboxymethyl cellulose, calcium carboxymethyl cellulose or internally cross-linked calcium carboxymethyl cellulose, etc.; cross-linked polyvinyl¬pyrrolidone; or chemically-modified starch or cellulose derivatives such as carboxymethyl starch or sodium carboxymethyl starch, etc. [453] The emulsifier may be mentioned, for example, a colloidal clay such as bentonite or bee gum, etc.; an anionic surfactant such as sodium lauryl sulfate, etc.; a cationic surfactant such as benzalkonium hydrochloride, etc.; or a nonionic surfactant such as polyoxyethylene alkyl ether, polyoxyethylene sorbitan aliphatic acid ester or sucrose aliphatic acid ester, etc., and the like. [454] The stabilizer may be mentioned, for example, a parahydroxybenzoic acid ester such as methylparaben or propylparaben, etc.; an alcohol such as chlorobutanol, benzylalcohol or phenylethylalcohol, etc.; benzalkonium hydrochloride; a phenol such as phenol or cresol, etc.; thimerosal; acetic anhydride; or sorbic acid. The corrigent may be mentioned, for example, a sweetening agent such as sodium saccharin or Aspartame, etc.; a souring agent such as citric acid, malic acid or tartaric acid, etc.; or a flavoring agent such as menthol, lemon extract or orange extract, etc., and the like. [456] The diluent is a compound which is usually used as a diluent, and there may be mentioned, for example, lactose, mannitol, glucose, sucrose, calcium sulfate, hydroxypropyl cellulose, microcrystalline cellulose, water, ethanol, polyethylene glycol, propylene glycol, glycerol, starch, polyvinylpyrrolidone or a mixture thereof, etc. [457] A dose of the desired Compound (1) or an addition salt thereof of the present invention may vary depending on symptom, an age, a body weight, etc., of a patient, and in the case of an oral administration, each can be admini¬stered in a lower limit of 0.005 mg/Kg (preferably 0.02 mg/Kg) and an upper limit of 2 0 mg/Kg (preferably 10 mg/Kg) per one time, and in the case of a non-oral administration, each can be administered in a lower limit of 0.0005 mg/Kg (preferably 0.002 mg/Kg) and an upper limit of 20 mg/Kg (preferably 10 mg/Kg), with 1 to 6 times per day per an adult depending on symptom. EXAMPLES [458] In the following, the present invention is explained in more detail by referring to Examples, Reference examples and Test examples, but the scope of the present invention is not limited by these. Example 1 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-1) [459] 1-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-1-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one To a mixture of 1.01 g (2.93 mmol) of 2-bromo-l-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in the following Reference example 15-(g) and 1.15 g (3.53 mmol) of 2-(3-cyclopropoxy-4-di- fluoromethoxyphenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaboro- lane obtained in the following Reference example 1-(a) were added 3 6 ml of toluene, 24 ml of ethanol and 6 ml of 2M aqueous sodium carbonate solution, and the mixture was degassed under reduced pressure and replaced with argon. Then, 702 rag (0.607 mmol) of tetrakis(triphenylphosphine)- palladium was added to the mixture, and the mixture was refluxed for 26 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water, and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=:l: 1->1: 4 (V/V) ) , and the fractions containing the desired compound were concentrated under reduced pressure to obtain 750 mg of the title compound as a yellowish solid. (Yield: 55%) Mass Spectrum (CI, m/z) : 464 (MVl) . 'H-NMR Spectrum (CDCI3, 8 ppm) : -0.03 (s, 9H), 0.82-0.95 (m, 6H), 3.54-3.56 (m, 2H), 3.77-3.85 (m, IH), 5.46 (s, 2H), 6.58 (t, J=74.7 Hz, IH) , 6.97 (d, J=0 . 7 Hz, IH) , 7.16 (dd, J=8.3, 2.0 Hz, IH), 7.26 (d, J=8.3 Hz, IH), 7.55 (d, J=2.0 Hz, IH) , 8.24 (d, J=0.7 Hz, IH) , 10.14 (brs, IH) . IR Spectrum (KBr, cm'^) : 1661. [0460] 1-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-1,5-di¬hydropyrrolo [2,3-d]pyridazin-4-one To 750 mg (1.62 mmol) of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 1- (a) were added 2.5 ml of tetrahydrofuran, 0.22 ml of ethylenediamine and 16.5 ml of tetrahydrofuran solution containing IM tetrabutylammonium fluoride, and the mixture was refluxed for 48 hours. After completion of the reaction, water and hexane were added to the reaction mixture, precipitated solid was collected by filtration, and dried under reduced pressure. The obtained dried material was dissolved in ethanol, poured into water, and precipitated solid was collected by filtration. The obtained solid was washed with water, and dried under reduced pressure to obtain 459 mg of the title compound as a white solid. (Yield: 85%) Melting point: 287-292°C. Mass Spectrum (CI, m/z) : 334 (MVl) . 'H-NMR Spectrum (DMSO-dg, 8 ppm): 0.72-0.79 (m, 2H), 0.85- 0.94 (m, 2H), 4.03-4.11 (m, IH), 7.07 (t, J=74.3 Hz, IH), 7.19 (s, IH), 7.27 (d, J=8.4 Hz, IH), 7.49 (dd, J=8.4, 2.1 Hz, IH), 7.88 (d, J=2.1 Hz, IH), 8.17 (s, IH), 12.28 (brs, IH) , 12.54 (brs, IH) . IR Spectrum (KBr, cm'): 1648. [461] Example 2 3-Chloro-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-2) [462] 2-(a) 3-Chloro-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 0.25 g (0.66 mol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 315 mg of the title compound was obtained as a pale yellowish foam. (Yield: 96%) Mass Spectrum (CI, m/z) : 498 (MVl) . ^H-NMR Spectrum (CDCI3, 5 ppm) : -0.03 (s, 9H) , 0.82-0.90 (m, 6H), 3.44-3.52 (m, 2H), 3.77-3.84 (m, IH), 5.38 (s, 2H), 6.61 (t, J-74.6 Hz, IH), 7.10 (dd, J=8.3, 2.1 Hz, IH), 7.30 (d, J=8.3 Hz, IH) , 7.52 (d, J=2 . 1 Hz, IH) , 8.21 (s, IH) , 10.02 (brs, IH). [0463] 2-(b) 3-Chloro-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 311 mg (0.624 mmol) of 3-chloro-2-(3-cyclopropoxy- 4-difluoromethoxyphenyl)-1-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 2-(a) was added 15 ml of 1,4-dioxane solution containing 4N hydrogen chloride, and the mixture was stirred at 40°C for 28 hours. After completion of the reaction, the reaction suspension was cooled by allowing to stand, and precipitated solid was collected by filtration and washed with diisopropyl ether. To the obtained solid were added 22 ml of methanol and 1.5 ml of 28% aqueous ammonia, and the mixture was stirred under room temperature for 3 hours. Then, the solution was concentrated under reduced pressure, diisopropyl ether and hexane were added to the obtained solid, a treatment with ultrasonic wave was carried out, and precipitated solid was collected by filtration. The obtained solid was washed with diisopropyl ether and dried under reduced pressure to obtain 177 mg of the title compound as a white solid. (Yield: 77%) Melting point: 281-283°C. Mass Spectrum (CI, m/z) : 368 (MVl) . ^H-NMR Spectrum (DMSO-dg, 8 ppm): 0.74-0.91 (m, 4H), 3.96- 4.03 (m, IH), 7.12 (t, J=74.2 Hz, IH), 7.35 (d, J=8.4 Hz, IH) , 7.43 (dd, J=8.4, 2.1 Hz, IH) , 7.89 (d, J=2 . 1 Hz, IH) , 8.15 (s, IH), 12.37 (brs, IH), 12.79 (brs, IH). IR Spectrum (KBr, cm'): 1639. [464] Example 3 3-Bromo-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-3) [465] 3- (a) l-Benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(a) except for using 9.50 g (28.4 mmol) of 1- benzyloxymethyl-2-bromo-l,5-dihydropyrrolo [2,3-d]pyridazin- 4- one obtained in the following Reference example 17-(d) in place of 2-bromo-l-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained crude solid was recrystallized from toluene to obtain 8.95 g of the title compound as a beige solid. (Yield: 69%) Mass Spectrum (CI, m/z) : 454 (M'^+l) . 'H-NMR Spectrum (CDCI3, 5 ppm): 0.67-0.83 (m, 4H), 3.69-3.75 (m, IH), 4.55 (s, 2H), 5.52 (s, 2H), 6.58 (t, J-74.7 Hz, IH) , 6.97 (d, J=0.7 Hz, IH) , 7.14 (dd, J=8.2, 2.2 Hz, IH) , 7.20-7.36 (m, 6H), 7.56 (d, J=2.2 Hz, IH), 8.12 (d, J=0.7 Hz, IH), 9.99 (brs, IH). IR Spectrum (KBr, cm"'): 1644. 3-(b) l-Benzyloxymethyl-3-bromo-2-(3-cyclopropoxy-4-di- fluoromethoxyphenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one To 460 mg (1.02 mmol) of l-benzyloxymethyl-2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-1,5-dihydropyrrolo[2, 3-d] - pyridazin-4-one obtained in Example 3-(a) were added 10 ml of acetonitrile and 4 ml of dichloromethane, followed by- addition of 214 mg (1.22 mmol) of N-bromosuccineimide, and the mixture was stirred under room temperature for 2.5 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, ethyl acetate and 5% aqueous sodium thiosulfate solution were added to the obtained solid, and the mixture was stirred under room temperature for 3 0 minutes. The organic layer after separation was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; toluene:ethyl acetate^l:0->l:l->0:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 4 73 mg of the title compound as a beige solid. (Yield: 87%) Mass Spectrum (CI, m/z) : 532 (M^l) . 'H-NMR Spectrum (CDCI3, 6 ppm): 0.70-0.85 (m, 4H), 3.70-3.77 (m, IH), 4.48 (s, 2H), 5.43 (s, 2H), 6.61 (t, J=74.6 Hz, IH), 7.08 (dd, J=8.2, 2.1 Hz, IH), 7.14-7.36 (m, 6H), 7.51 (d, J=2.1 Hz, IH), 8.11 (s, IH), 10.03 (brs, IH). IR Spectrum (KBr, cm"^) : 1650. [0467] 3-(c) 3-Bromo-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one In an autoclave made of a glass were charged 463 mg (0.870 mmol) of l-benzyloxymethyl-3-bromo-2-(3-cycloprop- oxy-4-difluoromethoxyphenyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Example 3-(b), 25 ml of ethanol and 25 ml of conc. hydrochloric acid, and the mixture was stirred at 12 0°C for 12 hours. After completion of the reaction, 50 ml of water was added to the reaction mixture, and precipitated solid was collected by filtration and washed with water. The obtained solid was purified by high performance liquid chromatography (column; Kromacil™ 100- 5-CI8 {2 0mmx250mm (manufactured by EKA CHEMICALS), Eluent; acetonitrile.-water: trifluoroacetic acid=600 : 400 :1 (V/V/V) , Flow rate; 10 ml/min) to obtain 92 mg of the title compound as a white solid. (Yield: 26%) Melting point: 267-270°C (decomposed). Mass Spectrum (CI, m/z): 412 (M^+1). 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.73-0.91 (m, 4H), 3.95- 4.02 (m, IH) , 7.12 (t, J=74.2 Hz, IH) , 7.34 (d, J=8.4 Hz, IH), 7.41 (dd, J=8.4, 2.0 Hz, IH), 7.91 (d, J=2.0 Hz, IH), 8.16 (s, IH), 12.35 (brs, IH). IR Spectrum (KBr, cm''): 1634. [468] Example 4 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-4) [469] 4-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one To a mixture of 1.46 g (3.00 mmol) of 2-bromo-3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 18-(d) and 1.47 g (4.50 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane obtained in the following Reference example 1 -(a) were added 7 mg of palladium acetate, 22 mg of butyl-di-1-adamantylphosphine, 2 0 ml of toluene, 2.5 9 g of potassium phosphate and 1.2 ml of water, and the mixture was degassed under reduced pressure and replaced with argon. The reaction mixture was refluxed for 6 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:0->2:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.54 g of the title compound as a slightly yellowish oil. (Yield: 84%) Mass Spectrum (CI, m/z) : 608 (M%1) . "•H-NMR Spectrum (CDCI3, 5 ppm) : -0.04 (s, 9H) , 0.00 (s, 9H) , 0.79-0.90 (m, 6H), 0.96-1.04 (m, 2H), 2.45 (s, 3H), 3.41- 3.49 (m, 2H), 3.70-3.77 (m, 2H), 3.76-3.83 (m, IH), 5.32 (s, 2H), 5.60 (s, 2H), 6.59 (t, J=74.7 Hz, IH), 7.00 (dd, J=8.2, 2.1 Hz, IH), 7.27 (d, J=8.2 Hz, IH), 7.38 (d, J=2.0 Hz, IH), 8.17 (s, IH). [0470] 4- (b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl- 5- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 1.54 g (2.53 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 4-(a) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane:ethyl acetate=19:l-> 1:1 (V/V)), and the fractions containing the desired compound were concen¬trated under reduced pressure to obtain 1.11 g of the title compound as a white solid. (Yield: 92%) Mass Spectrum (CI, m/z): 478 (M^+1). 'H-NMR Spectrum (CDCI3, 5 ppm): -0.02 (s, 9H), 0.83-0.88 (m, 4H), 0.94-1.00 (m, 2H), 2.62 (s, 3H), 3.68-3.77 (m, 2H), 3.79-3.87 (m, IH), 5.58 (s, 2H), 6.56 (t, J=74.7 Hz, IH), 7.08 (dd, J=8.3, 2.1 Hz, IH), 7.24 (d, J=8.3 Hz, IH), 7.48 (d, J=2.1 Hz, IH), 8.08 (s, IH), 8.96 (brs, IH). [471] 4-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 1.10 g (2.30 mmol) of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 4-(b) were added 3 0 ml of dichloromethane and 6 ml of trifluoroacetic acid, and the mixture was stirred under room temperature for 2.5 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, 2 0 ml of methanol and 2 ml of 28% aqueous ammonia were added to the obtained solid, and the mixture was stirred under room temperature for 12 hours. Then, water was added to the solution, precipitated solid was collected by filtration, washed with water, and then, dried under reduced pressure. To the obtained dried material was added ethyl acetate to dissolve therein, diisopropyl ether was added to the solution and precipitated solid was collected by filtration. The obtained solid was dried under reduced pressure to obtain 0.54 g of the title compound as a white solid. (Yield: 67%) Melting point: 245-246°C. Mass Spectrum (CI, m/z) : 348 (MVl) . ^H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.73-0.90 (m, 4H) , 2.56 (s, 3H), 3.97-4.05 (m, IH), 7.09 (t, J-74.3 Hz, IH), 7.24 (dd, J=8.4, 2.1 Hz, IH), 7.31 (d, J-8.4 Hz, IH), 7.64 (d, J=2.1 Hz, IH), 8.09 (s, IH), 12.14 (brs, IH). IR Spectrum (KBr, cm"'): 1634. [472] Example 5 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-ethyl-l,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-5) [473] 5-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-ethyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 7.05 g (14.0 mmol) of 2-bromo-3-ethyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 19-(d) in place of 2-bromo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one , whereby 9.36 g of the title compound was obtained as a pale yellowish oil substantially quantitatively. Mass Spectrum (CI, m/z): 622 (M"+l). 'H-NMR Spectrum (CDCI3, 5 ppm) : -0.04 (s, 9H) , 0.00 (s, 9H) , 0.79-0.88 (m, 6H), 0.97-1.03 (m, 2H), 1.25 (t, J=7.4 Hz, 3H), 2.80 (q, J=7.4 Hz, 2H), 3.41-3.48 (m, 2H), 3.71-3.82 (m, 3H), 5.30 (s, 2H), 5.61 (s, 2H), 6.60 (t, J=74.7 Hz, IH) , 6.99 (dd, J=8.2, 2.0 Hz, IH) , 7.26 (d, J=8.2 Hz, IH) , 7.37 (d, J=2.0 Hz, IH), 8.18 (s, IH). [474] 5-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-ethyl-5- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 9.35 g (containing an amount corresponding to 14.0 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-ethyl-l,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one obtained in Example 5-(a) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one, whereby 5.84 g of the title compound was obtained as a white solid. (Yield: 79%) Mass Spectrum (CI, m/z) : 492 (MVl) . 'H-NMR Spectrum (CDCI3, 5 ppm): -0.01 (s, 9H), 0.84-0.90 (m, 4H), 0.95-1.03 (ra, 2H), 1.37 (t, J=7.4 Hz, 3H), 3.01 (q, J=7.4 Hz, 2H), 3.70-3.78 (m, 2H), 3.80-3.87 (m, IH), 5.60 (s, 2H), 6.57 (t, J=74.8 Hz, IH), 7.05 (dd, J=8.3, 2.1 Hz, IH) , 7.26 (d, J=8.3 Hz, IH) , 7.48 (d, J=2 . 1 Hz, IH) , 8.08 (s, IH), 8.52 (brs, IH). IR Spectrum (KBr, cm"^) : 1636. [475] 5-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-ethyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(c) except for using 5.84 g (11.9 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-ethyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 5-(b) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- methyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3-d] pyridazin-4-one, whereby 4.41 g of the title compound was obtained as a white solid substantially quant itatively. Melting point: 223-225°C. Mass Spectrum (CI, m/z) : 362 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.73-0.89 (m, 4H) , 1.27 (t, J=7.3 Hz, 3H), 2.91 (q, J=7.3 Hz, 2H), 3.96-4.04 (m, IH) , 7.09 (t, J=74.3 Hz, IH) , 7.18 (dd, J=8.3, 2.0 Hz, IH) , 7.32 (d, J=8.3 Hz, IH), 7.58 (d, J=2.0 Hz, IH), 8.08 (s, IH), 12.14 (brs, IH) , 12.16 (brs, IH) . IR Spectrum (KBr, cm'): 1628. [476] Example 6 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-propyl-l,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-6) 6-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-propyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 900 mg (1.74 mmol) of 2-bromo-3-propyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 20-(c) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilylethoxymethyl) - 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 596 mg of the title compound was obtained as a pale yellowish oil. (Yield: 54%) Mass Spectrum (CI, m/z): 636 (MVl). 'H-NMR Spectrum (CDCI3, 8 ppm) : -0.05 (s, 9H), 0.00 (s, 9H) , 0.79-0.88 (m, 6H), 0.89 (t, J=7.8 Hz, 3H), 0.96-1.05 (m, 2H), 1.61-1.74 (m, 2H), 2.69-2.78 (m, 2H), 3.38-3.47 (m, 2H), 3.69-3.82 (m, 3H), 5.29 (s, 2H), 5.60 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 6.97 (dd, J=8.3, 2.0 Hz, IH), 7.26 (d, J=8.3 Hz, IH) , 7.35 (d, J=2 . 0 Hz, IH) , 8.17 (s, IH) . 6-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-propyl- 5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 595 mg (0.936 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-propyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 6-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one , whereby 3 77 mg of the title compound was obtained as a white solid. (Yield: 80%) Mass Spectrum (CI, m/z) : 506 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): -0.04 (s, 9H), 0.74-0.90 (m, 6H), 0.92 (t, J=7.2 Hz, 3H), 1.60-1.74 (m, 2H), 2.84- 2.94 (m, 2H), 3.64 (t, J=8.1 Hz, 2H), 3.93-4.06 (m, IH), 5.42 (s, 2H), 7.10 (t, J=74.3 Hz, IH), 7.18 (dd, J=8.4, 2.1 Hz, IH) , 7.33 (d, J-8.4 Hz, IH) , 7.58 (d, J=2 . 1 Hz, IH) , 8.14 (s, IH), 12.25 (brs, IH). IR Spectrum (KBr, cm"^) : 1630. [479] 6-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-propyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 431 mg (0.853 ramol) of 2-(3-cyclopropoxy-4-di- fluoromethoxyphenyl)-3-propyl-5-(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 6-(b) was added 6.7 ml of 1,4-dioxane solution containing 4N hydrogen chloride, and the mixture was stirred under room temperature for 24 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, 10 ml of methanol and 5 ml of 2 8% aqueous ammonia were added to the obtained solid, and the mixture was stirred under room temperature for 3 hours. Then, the solution was concentrated under reduced pressure, water was added to the obtained concen¬trate, and precipitated solid was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 3 07 mg of the title compound as a white solid. (Yield: 96%) Melting point: 208-210°C. Mass Spectrum (CI, m/z): 376 (M"+l). 'H-NMR Spectrum (DMSO-dg, 8 ppm): 0.73-0.86 (m, 4H), 0.91 (t, J=7.3 Hz, 3H), 1.61-1.74 (m, 2H), 2.84-2.93 (m, 2H), 3.96-4.03 (m, IH), 7.10 (t, J=74.3 Hz, IH), 7.18 (dd, J-8.3, 2.0 Hz, IH), 7.32 (d, J=8.3 Hz, IH), 7.58 (d, J=2.0 Hz, IH), 8.07 (s, IH), 12.12 (brs, IH), 12.16 (brs, IH). IR Spectrum (KBr, cm"^) : 1637. [480] Example 7 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-isopropyl-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1- 7) [481] 7-(a) l-Benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-isopropyl-5-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 414 mg (0.818 mmol) of l-benzyloxymethyl-2-bromo-3-isopropyl-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one obtained in the following Reference example 21- (g) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 3 69 mg of the title compound was obtained as a white solid. (Yield: 72%) Mass Spectrum (CI, m/z) : 626 (M'^+l) . 'H-NMR Spectrum (CDCI3, 5 ppm): 0.00 (s, 9H), 0.69-0.77 (m, 2H) , 0.77-0.83 (m, 2H) , 0.96-1.05 (m, 2H) , 1.37 (d, J=7.1 Hz, 6H), 3.05-3.18 (m, IH), 3.65-3.79 (m, 3H), 4.46 (s, 2H), 5.30 (s, 2H), 5.63 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 6.96 (dd, J=8.2, 2.1 Hz, IH), 7.16-7.36 (m, 7H), 8.09 (s, IH) . [482] 7-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- propyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one To 313 mg (0.500 mmol) of l-benzyloxymethyl-2-(3- cyclopropoxy-4 -dif luoromethoxyphenyl ) -3-isopropyl-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one obtained in Example 7-(a) were added 15 ml of ethanol, 1.6 ml of 28% aqueous ammonia and 3 9 mg of 5% palladium-active carbon, and the mixture was stirred under 1 atm hydrogen atmosphere at 3 0°C for 7 days. After completion of the reaction, the reaction suspension was filtered, and the filtrate was concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; toluene:ethyl acetate=9:l-> 4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 152 mg of the title compound as a white foam. (Yield: 60%) Mass Spectrum (CI, m/z): 506 (M^+1). ^H-NMR Spectrum (CDCI3, 5 ppm): -0.02 (s, 9H), 0.81-0.90 (m, 4H), 0.94-1.03 (m, 2H), 1.46 (d, J=6.8 Hz, 6H), 3.26-3.40 (m, IH), 3.69-3.77 (m, 2H), 3.77-3.85 (m, IH), 5.61 (s, 2H) , 6.58 (t, J=74.8 Hz, IH) , 7.02 (dd, J=8.3, 2.1 Hz, IH) , 7.25 (d, J=8.3 Hz, IH), 7.42 (d, J=2.1 Hz, IH), 8.06 (s, IH), 8.57 (brs, IH). [483] 7-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- propyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(c) except for using 152 rag (0.300 mmol) of 2-(3-eyelopropoxy-4-difluoromethoxyphenyl)- 3-isopropyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 7-(b) in place of 2-(3-eyelopropoxy-4-difluoromethoxyphenyl)-3- methyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 70 mg of the title compound was obtained as a white solid. (Yield: 62%) Melting point: 265-267°C. Mass Spectrum (CI, m/z) : 376 (M"'+l) . 'H-NMR Spectrum (DMSO-dg, S ppm) : 0.73-0.88 (m, 4H) , 1.40 (d, J=6.8 Hz, 6H), 3.16-3.27 (m, IH), 3.95-4.03 (m, IH), 7.10 (t, J=74.3 Hz, IH), 7.10 (dd, J=8.3, 2.1 Hz, IH), 7.32 (d, J=8.3 Hz, IH) , 7.50 (d, J=2 . 1 Hz, IH) , 8.07 (s, IH) , 12.15 (brs, 2H). IR Spectrum (KBr, em"^) : 1646. [484] Example 8 3-Butyl-2-(3-eyelopropoxy-4-difluoromethoxyphenyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1- 8) [485] 8-(a) 3-Butyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 4.86 g (9.15 mmol) of 2-bromo-3-butyl-l,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 22-(b) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 5.57 g of the title compound was obtained as a pale yellowish oil. (Yield: 94%) Mass Spectrum (CI, m/z): 650 (M^+1). 'H-NMR Spectrum (CDCI3, 5 ppm) : -0.05 (s, 9H) , 0.00 (s, 9H), 0.79-0.88 (m, 9H) , 0.96-1.04 (m, 2H) , 1.23-1.36 (m, 2H) , 1.56-1.68 (m, 2H), 2.73-2.81 (m, 2H), 3.38-3.47 (m, 2H), 3.70-3.81 (m, 3H), 5.29 (s, 2H), 5.61 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 6.97 (dd, J=8.3, 2.0 Hz, IH), 7.26 (d, J-8.3 Hz, IH) , 7.35 (d, J=2.0 Hz, IH) , 8.17 (s, IH) . IR Spectrum (neat, cm"^) : 1666. [0486] 8-(b) 3-Butyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-5- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 5.57 g (8.57 mmol) of 3-butyl-2-(3-eyelopropoxy-4-difluoromethoxy¬phenyl) -1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 8-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 3.95 g of the title compound was obtained as a white solid. (Yield: 89%) Mass Spectrum (CI, m/z): 520 (M^+l). 'H-NMR Spectrum (CDCI3, 5 ppm) : -0.02 (s, 9H), 0.82-0.87 (m, 4H), 0.88 (t, J=7.3 Hz, 3H), 0.93-1.02 (m, 2H), 1.32-1.46 (m, 2H), 1.64-1.77 (m, 2H), 2.92-3.01 (m, 2H), 3.68-3.76 (m, 2H), 3.78-3.85 (m, IH), 5.59 (s, 2H), 6.57 (t, J=74.7 Hz, IH) , 7.05 (dd, J=8.3, 2.1 Hz, IH) , 7.24 (d, J=8.3 Hz, IH), 7.47 (d, J=2.1 Hz, IH), 8.07 (s, IH), 8.75 (brs, IH). IR Spectrum (KBr, cm"^) : 1630. [487] 8- (c) 3-Butyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 6-(c) except for using 3.94 g (7.58 mmol) of 3- butyl-2-(3-eyelopropoxy-4-difluoromethoxyphenyl)-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Example 8-(b) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-propyl-5-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one, and post treatment was carried out except for using ethanol in place of methanol, whereby 2.81 g of the title compound was obtained as a white solid. (Yield: 95%) Melting point: 192-194°C. Mass Spectrum (CI, m/z) : 390 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.75-0.86 (m, 4H), 0.86 (t, J=7.3 Hz, 3H), 1.26-1.39 (m, 2H), 1.57-1.69 (m, 2H), 2.87-2.95 (m, 2H), 3.95-4.02 (m, IH), 7.10 (t, J=74.3 Hz, IH), 7.18 (dd, J-8.4, 2.1 Hz, IH), 7.32 (d, J=8.4 Hz, IH), 7.58 (d, J=2.1 Hz, IH), 8.07 (s, IH), 12.10 (brs, IH), 12.15 (brs, IH). IR Spectrum (KBr, cm"'): 1641. Example 9 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-isobutyl-l,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-9) [489] 9- (a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- butyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 4.77 g (9.00 mmol) of 2-bromo-3-isobutyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 23-(b) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 6.23 g of the title compound was obtained as a pale yellowish oil substantially quantitatively. Mass Spectrum (CI, m/z): 650 (MVl). ^H-NMR Spectrum (CDCI3, 5 ppm): -0.06 (s, 9H), -0.01 (s, 9H), 0.76-0.86 (m, 6H), 0.79 (d, J=6.8 Hz, 6H), 0.96-1.04 (m, 2H), 2.01-2.13 (m, IH), 2.67 (d, J=7.1 Hz, 2H), 3.35- 3.44 (m, 2H), 3.69-3.82 (m, 3H), 5.28 (s, 2H), 5.60 (s, 2H), 6.61 (t, J=74.7 Hz, IH), 6.95 (dd, J=8.1, 2.0 Hz, IH), 7.25 (d, J=8.1 Hz, IH), 7.32 (d, J=2.0 Hz, IH), 8.18 (s, IH) . [0490] 9-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- butyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 6.14 g (containing an amount corresponding to 9.00 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-isobutyl-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] pyrid- azin-4-one obtained in Example 9-(a) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-l,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one, whereby 5.74 g the title compound was obtained as a white foam substantially quantitatively. Mass Spectrum (CI, m/z): 520 (M^+1). 'H-NMR Spectrum (CDCI3, 8 ppm): -0.02 (s, 9H), 0.82-0.88 (m, 4H), 0.85 (d, J-6.6 Hz, 6H), 0.94-1.03 (m, 2H), 2.03-2.19 (m, IH), 2.90 (d, J=7.3 Hz, 2H), 3.69-3.77 (m, 2H), 3.80- 3.87 (m, IH), 5.59 (s, 2H), 6.57 (t, J=74.7 Hz, IH), 7.05 (dd, J=8.2, 2.1 Hz, IH), 7.24 (d, J=8.3 Hz, IH), 7.49 (d, J=2.0 Hz, IH), 8.07 (s, IH), 8.60 (brs, IH). [491] 9- (c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- butyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 5.74 g (containing an amount corresponding to 9.00 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-isobutyl-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 9-(b) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-5-(2-trimethylsilyl- ethoxymethyl)-3-propyl-1,5-dihydropyrrolo[2,3-d]pyridazin- 4-one, whereby 2.81 g of the title compound was obtained as a white solid. (Yield: 80%) Melting point: 239-241°C. Mass Spectrum (CI, m/z) : 390 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.73-0.88 (m, 4H), 0.80 (d, J=6.8 Hz, 6H), 1.92-2.06 (m, IH), 2.89 (d, J=7.1 Hz, 2H), 3.96-4.03 (m, IH), 7.10 (t, J=74.3 Hz, IH), 7.20 (dd, J=8.3, 2.0 Hz, IH), 7.30 (d, J=8.3 Hz, IH), 7.61 (d, J=2.0 Hz, IH), 8.07 (s, IH), 12.08 (brs, IH), 12.15 (brs, IH). IR Spectrum (KBr, cm"^) : 1648. [492] Example 10 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-hydroxymethyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-32) [493] 10- (a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-formyl- 1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 993 mg (2.66 mmol) of 2-bromo-3-formyl-l-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 24-(g) in place of 2- bromo-1- (2-trimethylsilylethoxyTnethyl) -1, 5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 966 mg of the title compound was obtained as a yellowish foam. (Yield: 74%) Mass Spectrum (CI, m/z): 492 (M"+l). ^H-NMR Spectrum (CDCI3, S ppm) : -0.03 (s, 9H) , 0.76-0.90 (m, 6H) , 3.42-3.50 (m, 2H) , 3.76-3.83 (m, IH) , 5.37 (s, 2H) , 6.62 (t, J=74.5 Hz, IH), 7.06 (dd, J=8.3, 2.1 Hz, IH), 7.28 (d, J=8.3 Hz, IH), 7.48 (d, J=2.1 Hz, IH), 8.29 (s, IH), 10.50 (brs, IH), 10.67 (s, IH). [0494] 10-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- hydroxymethyl-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one To 3 ml of tetrahydrofuran solution containing 221 mg (0.450 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-formyl-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 10-(a) was added 58 mg (1.53 mmol) of sodium borohydride under ice-cooling, and the reaction mixture was raised to room temperature. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydmis magnesijumsulfate J and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 155 mg of the title compound as a pale yellowish foam. (Yield: 70%) Mass Spectrum (EI, m/z): 493 (M"+l). 'H-NMR Spectrum (CDCI3, 8 ppm) : -0.03 (s, 9H) , 0.77-0.91 (m, 6H) , 3.42-3.52 (m, 2H) , 3.76-3.83 (m, IH) , 4.73 (s, 2H) , 5.37 (s, 2H), 6.60 (t, J=74.6 Hz, IH), 6.98 (dd, J=8.1, 2.0 Hz, IH) , 7.28 (d, J=8.1 Hz, IH) , 7.39 (d, J=2 . 0 Hz, IH) , 8.28 (s, IH), 10.45 (brs, IH). IR Spectrum (KBr, cm"^) : 1645. [495] 10- (c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- hydroxymethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 80 mg (0.16 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-hydroxymethyl-l-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 10-(b) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethylsilyl- ethoxymethyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, water was added to the reaction mixture and the precipitated solid was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 50 mg of the title compound as a white solid. (Yield: 85%) Melting point: 190-191°C. Mass Spectrum (EI, m/z) : 363 (MVl) . "-H-NMR Spectrum (DMSO-dg, 8 ppm) : 0.70-0.91 (m, 4H) , 3.93- 4.01 (m, IH) , 4.78 (d, J=5.2 Hz, 2H) , 5.60 (t, J=5.2 Hz, IH), 7.09 (t, J=74.3 Hz, IH), 7.28 (dd, J=8.3, 1.6 Hz, IH), 7.32 (d, J=8.3 Hz, IH) , 7.79 (d, J=1.6 Hz, IH) , 8.19 (s, IH), 12.46 (brs, IH). IR Spectrum (KBr, cm'^) : 1626. Example 11 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-methoxymethyl- l, 5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-50) [497] 11- (a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- methoxymethyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 219 mg (0.422 mmol) of 2-bromo-3-methoxymethyl-l,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in the following Reference example 25- (b) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 224 mg of the title compound was obtained as a yellowish oil (Yield: 83%) . Mass Spectrum (CI, m/z): 638 (M^+l). 'H-NMR Spectrum (CDCI3, 5 ppm) : -0.03 (s, 9H) , 0.00 (s, 9H) , 0.79-0.92 (m, 6H), 0.95-1.04 (m, 2H), 3.45-3.55 (m, 2H), 3.47 (s, 3H), 3.70-3.83 (m, 3H), 4.63 (s, 2H), 5.37 (s, 2H) , 5.61 (s, 2H) , 6.61 (t, J=74.7 Hz, IH) , 7.15 (dd, J=8.3, 2.0 Hz, IH), 7.27 (d, J=8.3 Hz, IH), 7.66 (d, J=2.0 Hz, IH), 8.21 (s, IH). IR Spectrum (neat, cm"^) : 1667. [0498] 11-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- methoxymethyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d] pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 239 mg (0.375 mmol) of 2-(3-eyelopropoxy-4-difluoromethoxyphenyl)- 3-methoxymethyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 11-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxy¬phenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 174 mg of the title compound was obtained as a white solid. (Yield: 91%) Mass Spectrum (CI, m/z) : 508 (MVl) . 'H-NMR Spectrum (acetone-dg, 5 ppm) : -0.02 (s, 9H) , 0.76- 0.83 (m, 2H), 0.84-0.95 (m, 4H), 3.43 (s, 3H), 3.70-3.77 (m, 2H), 3.93-4.00 (m, IH), 4.85 (s, 2H), 5.50 (s, 2H), 6.89 (t, J=75.1 Hz, IH), 7.30 (d, J=8.4 Hz, IH), 7.42 (dd, J=8.4, 2.1 Hz, IH) , 8.05 (d, J=2.1 Hz, IH) , 8.13 (s, IH) , 11.51 (brs, IH). IR Spectrum (KBr, cm'^) : 1633. [499] 11- (c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- methoxymethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 8 ml of methanol was added 1.3 ml (18.3 mmol) of acetyl chloride, and the mixture was stirred at 50°C for 15 minutes, and then, cooled to room temperature. To the solution was added 14 0 mg (0.276 mmol) of 2-(3-cycloprop- oxy-4-dif luoromethoxyphenyl) -3-methoxymethyl-5-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 11-(b), and the resulting mixture was stirred at room temperature for 3 hours. After completion of the reaction, to the reaction mixture were successively added 18.4 ml of methanol solution containing IM sodium methoxide and then water, and the mixture was extracted with a mixed solvent (chloroform:methanol=9:1 (V/V)). The organic layer after separation of liquids was washed with water, dried over arifi^drous-Kia^ntsLuwiaalfettand then concentrated under reduced pressure. Water was added to the obtained concentrate, and precipitated solid was collected by filtration and dried under reduced pressure to obtain 58 mg of the title compound as a white solid. (Yield: 56%) Melting point: 104-107°C. Mass Spectrum (CI, m/z) : 378 (M^l). ^H-NMR Spectrum (acetone-dg, 8 ppm): 0.76-0.92 (m, 4H), 3.42 (s, 3H), 3.92-4.00 (m, IH), 4.84 (s, 2H), 6.89 (t, J=75.2 Hz, IH), 7.30 (d, J=8.4 Hz, IH), 7.42 (dd, J=8.4, 2.0 Hz, IH) , 8.05 (d, J=2.0 Hz, IH) , 8.11 (s, IH) , 11.41 (brs, IH) , 11.50 (brs, IE). IR Spectrum (KBr, cm"^) : 1639. [500] Example 12 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-ethoxymethyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-60) 12-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-ethoxy- methyl-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1- (a) except for using 245 mg (0.609 mmol) of 2-bromo-3-ethoxymethyl-l-(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 26 in place of 2-bromo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 185 mg of the title compound was obtained as a yellowish foam. (Yield: 58%) Mass Spectrum (CI, m/z): 522 (M"+l). ^H-NMR Spectrum (DMSO-dg, 5 ppm): -0.11 (s, 9H), 0.70-0.85 (m, 6H), 1.05 (t, J=7.0 Hz, 3H), 3.38-3.45 (m, 2H), 3.48 (q, J=7.0 Hz, 2H), 3.88-3.95 (m, IH), 4.57 (s, 2H), 5.52 (s, 2H), 7.14 (t, J=74.2 Hz, IH), 7.24 (dd, J=8.3, 2.0 Hz, IH) , 7.34 (d, J=8.3 Hz, IH) , 7.69 (d, J=2.0 Hz, IH) , 8.50 (s, IH), 12.41 (brs, IH). [502] 12-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- ethoxymethyl-l,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 184 mg (0.353 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-ethoxymethyl-l-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 12-(a) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. To the obtained concentrate was added a small amount of tetrahydrofuran to dissolve the concentrate, hexane was then added thereto, and the mixture was subjected to ultrasonic wave treatment whereby the precipitated solid was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 52 mg of the title compound as a white solid. (Yield: 38%) Melting point: 141-143°C. Mass Spectrum (CI, m/z) : 392 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.73-0.90 (m, 4H) , 1.12 (t, J=7.0 Hz, 3H), 3.58 (q, J=7.0 Hz, 2H), 3.90-3.99 (m, IH), 4.78 (s, 2H), 7.10 (t, J=74.5 Hz, IH), 7.34 (d, J=8.4 Hz, IH), 7.39 (dd, J=8.4, 1.9 Hz, IH), 7.92 (d, J=1.9 Hz, IH), 8.15 (s, IH), 12.24 (brs, IH), 12.46 (brs, IH). IR Spectrum (KBr, cm"^) : 1643. [503] Example 13 3 -Cyclobutoxymethyl-2 -(3 -eyelopropoxy-4 -di fluoromethoxy- phenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-102) [504] 13-(a) 3-Cyclobutoxymethyl-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 50 0 mg (0.8 95 mmol) of 2-bromo-3-cyclobutoxymethyl-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one obtained in the following Reference example 27 in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo [2,3-d]pyridazin-4-one, whereby 502 mg of the title compound was obtained as a slightly yellowish oil. (Yield: 83%) 'H-NMR Spectrum (CDCI3, 5 ppm) : -0.03 (s, 9H) , 0.00 (s, 9H) , 0.78-0.92 (m, 6H), 0.95-1.03 (m, 2H), 1.41-1.58 (m, IH), 1.60-1.74 (m, IH), 1.88-2.04 (m, 2H), 2.12-2.25 (m, 2H), 3.47-3.55 (m, 2H), 3.68-3.76 (m, 2H), 3.77-3.84 (m, IH), 4.11-4.23 (m, IH), 4.58 (s, 2H), 5.35 (s, 2H), 5.61 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 7.17 (dd, J=8.3, 2.0 Hz, IH), 7.27 (d, J=8.3 Hz, IH), 7.69 (d, J=2.0 Hz, IH), 8.19 (s, IH) . [505] 13-(b) 3-Cyclobutoxymethyl-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 479 mg (0.696 mmol) of 3-cyclobutoxymethyl-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 13-(a) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-methyl-l,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 3 69 mg of the title compound was obtained as a white foam. (Yield: 97%) Mass Spectrum (CI, m/z): 548 (M^+1). 'H-NMR Spectrum (DMSO-dg, 5 ppm): -0.05 (s, 9H), 0.71-0.91 (m, 6H), 1.35-1.51 (m, IH), 1.53-1.69 (m, IH), 1.79-1.95 (m, 2H), 2.04-2.17 (m, 2H), 3.60-3.69 (m, 2H), 3.90-3.98 (m, 2H), 4.08-4.20 (m, 2H), 4.69 (s, IH), 5.43 (s, IH), 7.10 (t, J=74.3 Hz, IH), 7.34 (d, J=8.2 Hz, IH), 7.38 (dd, J=8.2, 1.7 Hz, IH) , 7.93 (d, J=1.7 Hz, IH) , 8.20 (s, IH) , 12.57 (brs, IH). [506] 13-(c) 3-Cyclobutoxymethyl-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 1 ml of N,N-dimethylformamide containing 193 mg (0.352 mmol) of 3-cyclobutoxymethyl-2-(3-cyclopropoxy-4- dif luoromethoxyphenyl) -5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 13-(b) were added 3 8.2 mg (0.44 0 mmol) of lithium bromide, 10 ]il of ethylenediamine and 3 ml of tetrahydro- furan solution containing IM tetrabutylammonium fluoride. and the mixture was stirred at 100°C for 8 hours while removing tetrahydrofuran. After completion of the reaction, water was added to the reaction mixture, and the precipitated solid was collected by filtration. The obtained crude solid was applied to silica gel column chromatography (Eluent; chloroform:ethyl acetate = l:0->0:1 (V/V)), the fractions containing the desired compound were concentrated under reduced pressure, and recrystallized from a mixed solvent of ethanol and water to obtain 7 0 mg of the title compound as a white solid. (Yield: 47%) Melting point: 95-100°C. Mass Spectrum (CI, m/z): 418 (M^+l). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.72-0.90 (m, 4H) , 1.34- 1.52 (m, IH), 1.53-1.67 (m, IH), 1.77-1.94 (m, 2H), 2.04- 2.17 (m, 2H), 3.89-3.98 (m, IH), 4.08-4.19 (m, IH), 4.69 (s, 2H) , 7.09 (t, J=74.3 Hz, IH) , 7.32 (d, J=8.3 Hz, IH) , 7.38 (dd, J=8.3, 1.8 Hz, IH), 7.93 (d, J=2.0 Hz, IH), 8.13 (s, IH), 12.21 (brs, IH). IR Spectrum (KBr, cm'^) : 1646. Example 14 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclopropyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-207) [508] 14-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 2.00 g (3.88 mmol) of 2-bromo-3-cyclopropyl-1,5-bis(2-trimethyl- silylethoxymethyl)-1, 5-dihydropyrrolo[2,3-d] pyridazin-4-one obtained in the following Reference example 28-(b) in place of 2-bromo-l-(2-trimethylsilylethoxyraethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 2.72 g of the title compound was obtained as a pale yellowish oil substantially quantitatively. Mass Spectrum (CI, m/z) : 634 (MVl) . 'H-NMR Spectrum (CDCI3, 5 ppm) : -0.04 (s, 9H), 0.00 (s, 9H), 0.68-0.89 (m, lOH) , 0.96-1.03 (m, 2H) , 1.96-2.03 (m, IH) , 3.41-3.48 (m, 2H), 3.70-3.82 (m, 3H), 5.27 (s, 2H), 5.60 (s, 2H) , 6.61 (t, J=74.7 Hz, IH) , 7.04 (dd, J=8.1, 2.0 Hz, IH) , 7.25 (d, J=8.1 Hz, IH) , 7.44 (d, J=2.0 Hz, IH) , 8.16 (s, IH). [509] 14-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 2.72 g (containing an amount corresponding to 3.88 mmol) of 2-(3- cyclopropoxy-4 -difluoromethoxyphenyl)-3 -cyclopropyl-1,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Example 14-(a) in place of 2- (3 -eyelopropoxy-4 -di fluoromethoxyphenyl)-3-methyl-1,5-bis- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one, whereby 3.95 g of the title compound was obtained as a white solid. (Yield: 93%) Mass Spectrum (CI, m/z) : 504 (MVl) . 'H-NMR Spectrum (CDCI3, 8 ppm) : -0.02 (s, 9H), 0.66-0.73 (m, 2H), 0.81-0.89 (m, 4H), 0.91-1.01 (m, 4H), 1.99-2.11 (m, IH), 3.69-3.76 (m, 2H), 3.80-3.87 (m, IH), 5.59 (s, 2H), 6.57 (t, J=74.8 Hz, IH), 7.14 (dd, J=8.3, 2.1 Hz, IH), 7.23 (d, J=8.3 Hz, IH) , 7.64 (d, J=2 . 1 Hz, IH) , 8.06 (s, IH) , 8.78 (brs, IH). IR Spectrum (KBr, cm"M : 1630. [510] 14-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(c) except for using 1.80 g (3.57 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-cyclopropyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 14-(b) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- methyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , whereby 1.21 g of the title compound was obtained as a white solid. (Yield: 91%) Melting point: 248-249°C. Mass Spectrum (CI, m/z) : 374 (M-'+l) . ^H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.72-0.92 (m, 8H) , 1.95- 2.07 (m, IH), 3.96-4.04 (m, IH), 7.10 (t, J=74.3 Hz, IH), 7.26-7.33 (m, 2H), 7.76 (s, IH), 8.05 (s, IH), 12.08 (brs, IH), 12.17 (brs, IH). IR Spectrum (KBr, cm"^) : 1642. [511] Example 15 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclopropyl- methyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-2 08) [512] 15-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-formyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 7.82 g (15.6 mmol) of 2-bromo-3-formyl-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 2 9 in place of 2-bromo-3-methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 5.57 g of the title compound was obtained as a brown solid substantially quantitatively. Mass Spectrum (CI, m/z): 622 (M^+1). 'H-NMR Spectrum (CDCI3, 5 ppm): -0.03 (s, 9H), 0.01 (s, 9H), 0.75-0.92 (m, 6H), 0.96-1.05 (m, 2H), 3.41-3.51 (m, 2H), 3.71-3.84 (m, 3H), 5.36 (s, 2H), 5.65 (s, 2H), 6.61 (t, J=74.5 Hz, IH), 7.05 (dd, J=8.3, 2.1 Hz, IH), 7.27 (d. J=8.3 Hz, IH) , 7.47 (d, J=2.1 Hz, IH) , 8.28 (s, IH) , 10.72 (s, IH). IR Spectrum (KBr, cm"^) : 1693. [513] 15-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propylhydroxymethyl-1,5-bls(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 50 ml of tetrahydrofuran solution containing 10.3 g (116 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-4- formyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 15-(a) was added 47 ml of tetrahydrofuran solution containing 0.5M cyclopropyl magnesium bromide by dividing it into 5 times, then, the mixture was stirred at room temperature for 2 hours. After completion of the reaction, the reaction mixture was poured into a saturated aqueous solution of ammonium chloride, water was added thereto and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure to obtain 11.6 g of the title compound as a yellowish oil substantially quantitatively. Mass Spectrum (CI, m/z) : 664 (M%1) . 'H-NMR Spectrum (CDCI3, S ppm) : -0.04 (s, 9H) , 0.00 (s, 9H) , 0.25-0.36 (m, IH), 0.37-0.47 (m, IH), 0.47-0.58 (m, IH), 0.75-0.89 (m, 7H), 0.97-1.04 (m, 2H), 1.29-1.41 (m, IH), 3.34-3.50 (m, 2H), 3.71-3.81 (m, 3H), 3.96 (dd, J=11.6, 7.9 Hz, IH), 5.25 (d, J=10.7 Hz, IH), 5.31 (d, J=10.7 Hz, IH), 5.64 (d, J=9.8 Hz, IH), 5.68 (d, J=9.8 Hz, IH), 6.05 (d, J=11.7 Hz, IH), 6.60 (t, J=74.5 Hz, IH), 6.99 (dd, J=8.1, 2.0 Hz, IH), 7.26 (d, J=8.1 Hz, IH), 7.37 (d, J=2.0 Hz, IH) , 8 .28 (s, IH) . IR Spectrum (neat, cm'^) : 1638. [514] 15-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propylmethyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 200 ml of dichloromethane solution containing 11.6 g (containing an amount corresponding to 16.6 mmol) of 2- (3 -eyelopropoxy-4 -difluoromethoxypheny1)-3 -eyelopropy1- hydroxymethyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 15-(b) was added 3.35 ml (21.0 mmol) of triethylsilane at -15°C. Then, 5 ml of trifluoroacetie acid was gradually added dropwise to the mixture at the same temperature, and after completion of dropwise addition, a temperature of the mixture was gradually raised to room temperature, and the mixture was stirred at room temperature for further 1 hour. After completion of the reaction, the reaction mixture was poured into a saturated aqueous solution of sodium hydro- gencarbonate, the organic layer after separating the liquids was dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:1 (V/V)), and the fractions contain¬ing the desired compound were concentrated under reduced pressure to obtain 6.14 g of the title compound as a yellowish oil. (Yield: 57%) Mass Spectrum (CI, m/z) : 648 (MVl) . 'H-NMR Spectrum (CDCI3, 5 ppm): -0.05 (s, 9H), 0.00 (s, 9H), 0.05-0.11 (m, 2H), 0.27-0.35 (m, 2H), 0.78-0.88 (m, 6H), 0.96-1.04 (m, 2H), 1.05-1.16 (m, IH), 2.74 (d, J=6.8 Hz, 2H), 3.38-3.46 (m, 2H), 3.70-3.82 (m, 3H), 5.27 (s, 2H), 5.61 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 6.98 (dd, J=8.2, 2.0 Hz, IH) , 7.25 (d, J=8.2 Hz, IH) , 7.35 (d, J=2 . 0 Hz, IH) , 8 . 19 (s, IH) . IR Spectrum (neat, cm'^) : 1665. [0515] 15-(d) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propylmethyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 6.14 g (9.48 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-cyclopropylmethyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 15-(c) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 3.41 g of the title compound was obtained as a white solid. (Yield: 70%) Mass Spectrum (CI, m/z): 518 (M"+l). 'H-NMR Spectrum (CDCI3, 6 ppm) : -0.02 (s, 9H), 0.18-0.25 (m, 2H), 0.31-0.39 (m, 2H), 0.83-0.87 (m, 4H), 0.92-1.00 (m, 2H) , 1.10-1.21 (m, IH) , 2.99 (d, J=6.6 Hz, 2H) , 3.68-3.76 (m, 2H), 3.79-3.86 (m, IH), 5.59 (s, 2H), 6.56 (t, J=74.8 Hz, IH), 7.09 (dd, J=8.3, 2.1 Hz, IH), 7.23 (d, J=8.3 Hz, IH), 7.55 (d, J=2.1 Hz, IH), 8.09 (s, IH), 9.04 (brs, IH). IR Spectrum (KBr, cm"^) : 1634. [0516] 15-(e) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propylmethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 3.40 g (3.13 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-cyclopropylmethyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 15-(d) in place of 2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-3-propyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 2.50 g of the title compound was obtained as a white solid. (Yield: 93%) Melting point: 204-206°C. Mass Spectrum (CI, m/z) : 387 (M%1) . ^H-NMR Spectrum (DMSO-dg, 6 ppm) : 0.16-0.35 (m, 4H) , 0.73- 0.90 (m, 4H), 1.05-1.16 (m, IH), 2.95 (d, J=6.3 Hz, 2H), 3.96-4.04 (m, IH), 7.10 (t, J=74.3 Hz, IH), 7.24 (dd, J=8.4, 2.0 Hz, IH), 7.32 (d, J=8.4 Hz, IH), 7.67 (d, J=2.0 Hz, IH), 8.09 (s, IH), 12.13 (brs, IH), 12.18 (brs, IH). IR Spectrum (KBr, : 1634. [517] Example 16 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-ethynyl-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-231) [518] 16-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-tri- ethylsilylethynyl-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 42 mg (0.095 mmol) of 2-chloro-3-triethylsilylethynyl-l-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in the following Reference example 30- (c) in place of 2-bromo-1-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 36 mg of the title compound was obtained as a yellow solid. (Yield: 64%) Mass Spectrum (CI, m/z): 602 (M^+1). 'H-NMR Spectrum (CDCI3, 6 ppm): -0.03 (s, 9H), 0.61 (q, J=7.8 Hz, 6H), 0.79-0.91 (m, 6H), 0.97 (t, J-7.8 Hz, 9H), 3.44-3.52 (m, 2H), 3.77-3.84 (m, IH), 5.40 (s, 2H), 6.58 (t, J=74.7 Hz, IH), 7.23 (dd, J=8.3, 1.7 Hz, IH), 7.27 (d, J=8.3 Hz, IH), 7.61 (d, J=1.7 Hz, IH), 8.16 (s, IH), 9.79 (brs, IH). IR Spectrum (KBr, cm"'): 1663. [519] 16-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- ethynyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 4-(b) except for using 32 mg (0.053 mmol) of 2-(3- cyclopropoxy-4 -di fluoromethoxyphenyl)-3 -1riethyls ilyl- ethynyl-1-(2-trimethylsilylethoxymethyl)-1,5"dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 16-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- methyl-1,5-bis(2-triraethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then concentrated under reduced pressure. To the obtained concentrate were added methanol and water, and the mixture was subjected to ultrasonic wave treatment and the precipitated solid was collected by filtration. The obtained solid was washed successively with water and then with diethyl ether and dried under reduced pressure to obtain 10 mg of the title compound as a beige solid. (Yield: 51%) Melting point: >300°C. Mass Spectrum (CI, m/z): 358 (M"+l). 'H-NMR Spectrum (DMSO-dg, S ppm): 0.72-0.81 (m, 2H), 0.82- 0.93 (m, 2H), 3.90-3.98 (m, IH), 4.35 (s, IH), 7.11 (t, J=74.2 Hz, IH), 7.33 (d, J=8.4 Hz, IH), 7.57 (dd, J=8.4, 2.0 Hz, IH), 8.13 (s, IH), 8.30 (d, J=2.0 Hz, IH), 12.31 (brs, IH), 12.73 (brs, IH). [520] Example 17 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-phenyl-l,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-245) [521] 17-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-phenyl- 1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 144 mg (0.383 mmol) of 2-chloro-3-phenyl-l-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 31 in place of 2-bromo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 91 mg of the title compound was obtained as a yellowish oil. (Yield: 44%) Mass Spectrum (CI, m/z): 540 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.53-0.57 (m, 4H), 0.87-0.94 (m, 2H), 3.41-3.49 (m, IH), 3.50-3.57 (m, 2H), 5.43 (s, 2H), 6.55 (t, J=74.7 Hz, IH), 7.01 (dd, J=8.3, 2.1 Hz, IH), 7.12 (d, J=2.1 Hz, IH), 7.19 (d, J=8.3 Hz, IH) , 7.21-7.34 (m, 5H) , 8.25 (s, IH) , 9.81 (brs, IH) . [522] 17-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-phenyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b)•except for using 86 mg (0.16 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-phenyl-1-(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 17-(a) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethylsilyl¬ethoxymethyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, water was added to the reaction mixture, and the precipitated solid was collected by filtration. The obtained solid was applied to silica gel column chromatography (Eluent; ethyl acetate), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 14 mg of the title compound as a pale beige solid. (Yield: 21%) Melting point: 138-143°C. Mass Spectrum (CI, m/z): 410 (M^+1). ^H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.45-0.53 (m, 4H) , 3.44- 3.52 (m, IH), 7.05 (t, J=74.2 Hz, IH), 7.10 (dd, J=8.4, 2.1 Hz, IH), 7.21 (d, J=2.1 Hz, IH), 7.21 (d, J-8.4 Hz, IH), 7.27-7.37 (m, 5H), 8.16 (s, IH), 12.19 (brs, IH), 12.53 (brs, IH). IR Spectrum (KBr, cm"^) : 1641. [523] Example 18 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(4-pyrazolyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-334) [524] 18-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-1,5-bis- (2-trimethylsilylethoxymethyl)-3-[1-(2-trimethylsilyl- ethoxymethyl)-4-pyrazolyl]-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 185 mg (0.276 mmol) of 2-bromo-1,5-bis(2-trimethylsilylethoxy- methyl)-3-[1-(2-trimethylsilylethoxymethyl)-4-pyrazolyl]- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 32-(c) in place of 2-bromo-3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1, 5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 173 mg of the title compound was obtained as a yellowish oil. (Yield: 83%) ^H-NMR Spectrum (cdci3, 5 ppm): -0.04 (s, 9H), -0.03 (s, 9H) , 0.01 (s, 9H) , 0.69-0.94 (m, 8H) , 0.96-1.06 (m, 2H) , 3.42-3.50 (m, 2H), 3.53-3.61 (m, 2H), 3.64-3.73 (m, IH), 3.70-3.78 (m, 2H), 5.31 (s, 2H), 5.37 (s, 2H), 5.61 (s, 2H), 6.60 (t, J=74.6 Hz, IH), 7.00 (dd, J=8.1, 2.0 Hz, IH), 7.10 (d, J=0.5 Hz, IH), 7.26 (d, J=8.1 Hz, IH), 7.34 (d, J=2.0 Hz, IH) , 8.22 (s, IH) , 8.42 (d, J=0.5 Hz, IH) . IR Spectrum (neat,cm"^): 1662. [525] 18-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(4- pyrazolyl)-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 190 mg (0.241 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1,5-bis(2-trimethylsilylethoxymethyl)-3-[1-(2-trimethyl¬silylethoxymethyl) -lH-pyrazol-4-yl]-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Example 18-(a) in place of 2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-l,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one, whereby 101 mg of the title compound was obtained as a white solid. (Yield: 79%) Mass Spectrum (CI, m/z): 530 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.01 (s, 9H), 0.66-0.75 (m, 4H), 0.94-1.01 (m, 2H), 3.59-3.66 (m, IH), 3.68-3.76 (m, 2H), 5.58 (s, 2H), 6.56 (t, J=74.7 Hz, IH), 7.06 (dd, J=8.3, 2.0 Hz, IH), 7.20 (d, J=8.3 Hz, IH), 7.41 (d, J=2.0 Hz, IH), 7.86 (s, 2H), 8.11 (s, IH), 9.08 (brs, IH). IR Spectrum (KBr, cm"'): 1639. [526] 18-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(4- pyrazolyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 100 mg (0.189 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(4-pyrazolyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 18-(b) in place of 2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-3-propyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 76 mg of the title compound was obtained as a pale yellowish solid substantially quantitatively. Melting point: 294-297°C Mass Spectrum (CI, m/z): 400 (M^+1). 'H-NMR Spectrum (DMSO-dg, 8 ppm): 0.60-0.70 (m, 4H), 3.69- 3.78 (m, IH), 7.09 (t, J=74.3 Hz, IH), 7.16 (dd, J=8.3, 2.0 Hz, IH) , 7.26 (d, J=8.3 Hz, IH) , 7.42 (brs, IH) , 7.50 (d, J=2.0 Hz, IH), 7.92 (brs, IH), 8.11 (s, IH), 12.16 (brs, IH), 12.39 (brs, IH), 12.73 (brs, IH). IR Spectrum (KBr, cm"'): 1642. [527] Example 19 3-Benzyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-378) [528] 19-(a) 3-Benzyl-l-benzyloxymethyl-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 2 78 mg (0.501 mmol) of 3-benzyl-l-benzyloxymethyl-2-bromo-5-(2- trimethylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in the following Reference example 33- (h) in place of 2-bromo-3-methyl-1,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 278 mg of the title compound was obtained as a colorless oil. (Yield: 83%) Mass Spectrum (CI, m/z): 674 (M^+l). 'H-NMR Spectrum (cdci3, 5 ppm) : 0.00 (s, 9H) , 0.47-0.55 (m, 2H), 0.62-0.69 (m, 2H), 0.96-1.03 (m, 2H), 3.40-3.48 (m, IH), 3.70-3.77 (m, 2H), 4.26 (s, 2H), 4.47 (s, 2H), 5.36 (s, 2H) , 5.60 (s, 2H) , 6.57 (t, J=74 .7 Hz, IH) , 6.93 (dd, J=8.2, 2.1Hz, IH), 7.05-7.34 (m, 12H), 8.13 (s, IH). [529] 19-(b) 3-Benzyl-l-benzyloxymethyl-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin- 4-one To 2 78 mg (0.413 mmol) of 3-benzyl-1-benzyloxymethyl- 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-5-(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 19-(a) was added 3.3 ml of 1,4-dioxane solution containing 4N hydrogen chloride, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, the reaction mixture was con¬centrated under reduced pressure, to the obtained solid were added 8.6 ml of methanol and 4.3 ml of 2 8% aqueous ammonia, and the mixture was stirred at room temperature for 1 hour. Then, the solution was concentrated under reduced pressure, water was added to the obtained concen¬trate, and the precipitated solid was collected by filtra¬tion. The obtained solid was washed with water and dried under reduced pressure to obtain 198 mg of the title compound as a white solid. (Yield: 88%) Mass Spectrum (CI, m/z) : 544 (MVl) . 'H-NMR Spectrum (cdci3, S ppm) : 0.49-0.57 (m, 2H) , 0.64-0.71 (m, 2H), 3.43-3.50 (m, IH), 4.24 (s, 2H), 4.46 (s, 2H), 5.37 (s, 2H), 6.58 (t, J=74.7 Hz, IH), 6.93 (dd, J=8.3, 2.0 Hz, IH), 7.06-7.34 (m, 12H), 8.10 (s, IH), 9.79 (brs, IH). [0530] 19-(c) 3-Benzyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 20 ml of ethanol solution containing 198 mg (0.364 mmol) of 3-benzyl-l-benzyloxymethyl-2-(3-cyclopropoxy-4- dif luoromethoxyphenyl) -1,5-dihydropyrrolo[2,3-d] pyridazin- 4-one obtained in Example 19-(b), then, 28 mg of 5% palladium-active carbon and 0.36 ml of IN hydrochloric acid were added thereto, and the mixture was stirred under 1 atm hydrogen atmosphere at 50°C for 3.8 hours. After comple¬tion of the reaction, the reaction mixture was filtered, the filtrate was concentrated under reduced pressure, 8.6 ml of methanol and 4.3 ml of 2 8% aqueous ammonia were added to the obtained solid and the mixture was stirred at room temperature for 1 hour. Then, the solution was concentrat¬ed under reduced pressure, water was added to the obtained concentrate, and the precipitated solid was collected by filtration. The obtained solid was washed successively with water and then with diisopropyl ether and dried under reduced pressure to obtain 12 8 mg of the title compound as a white solid. (Yield: 84%) Melting point: 215-217°C. Mass Spectrum (CI, m/z) : 424 (M%1) . ^H-NMR Spectrum (DMSO-dg, 5 ppm): 0.43-0.61 (m, 4H), 3.60- 3.67 (m, IH), 4.40 (s, 2H), 7.05 (t, J=74.3 Hz, IH), 7.09- 7.30 (m, 7H) , 7.38 (d, J=2 .2 Hz, IH) , 8.15 (s, IH) , 12.18 (brs, IH), 12.34 (brs, IH). IR Spectrum (KBr, cra'^) : 1637. [531] Example 2 0 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-hydroxypheny1- methyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-4 76) 20-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- hydroxyphenylmethyl-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 79 mg (0.18 mmol) of 2-bromo-3-hydroxyphenylmethyl-l-(2-tri¬methylsilylethoxymethyl ) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in the following Reference example 34 in place of 2-bromo-l-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 51 mg of the title compound was obtained as a pale yellowish oil. (Yield: 50%) Mass Spectrum (EI, m/z) : 569 (M") . [533] 20-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- hydroxyphenylmethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one Reaction was carried out in the same manner as in Example 1-(b) except for using 51 mg (0.0 90 mmol) of 2-(3- cyclopropoxy-4 -di fluoromethoxyphenyl)-3 -hydroxyphenyl- methyl-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4-one obtained in Example 20-(a) in place of 2-(3-eyelopropoxy-4-difluoromethoxyphenyl)-1-(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with a mixed solvent (chloroform:methanol=9:1 (V/V)). The organic layer after separating the liquids was dried over anhydrous magnesium sulfate and then concentrat¬ed under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 17 mg of the title compound as a white solid. (Yield: 42%) Melting point: >300°C. Mass Spectrum (EI, m/z) : 439 (M^) . ^H-NMR Spectrum (DMSO-dg, 8 ppm) : 0.26-0.73 (m, 4H) , 3.61- 3.69 (m, IH), 5.90 (d, J=11.0 Hz, IH), 7.07 (t, J=73.7 Hz, IH) , 7.12 (d, J=11.0 Hz, IH) , 7.14 (dd, J=8.3, 2.0 Hz, IH) , 7.17-7.34 (m, 7H) , 8.31 (s, IH) , 12.75 (brs, IH) . [534] Example 21 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-phenethyl-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-460) [535] 21-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- phenethyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 602 mg (1.04 mmol) of 2-bromo-3-phenethyl-1,5-bis(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 35-(b) in place of 2-bromo-3-methyl-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 5 09 mg of the title compound was obtained as an orange oil. (Yield: 73%) Mass Spectrum (CI, m/z): 698 (M'^+l) . ^H-NMR Spectrum (cdci3, 5 ppm) : -0.05 (s, 9H), 0.01 (s, 9H), 0.75-0.86 (m, 6H) , 0.98-1.06 (m, 2H) , 2.95-3.10 (m, 4H) , 3.34-3.42 (m, 2H), 3.69-3.81 (m, 3H), 5.24 (s, 2H), 5.65 (s, 2H), 6.56 (dd, J=8.2, 2.1 Hz, IH), 6.58 (t, J=75.1 Hz, IH), 6.99-7.03 (m, 2H), 7.08-7.20 (m, 5H), 8.20 (s, IH). 21-(b) 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- phenethyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 509 mg (0.729 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3- phenethyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 21-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-3-methyl-l,5-bis(2-triraethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 365 mg of the title compound was obtained as a pale yellowish foam. (Yield: 88%) Mass Spectrum (CI, m/z) : 568 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm) : 0.00 (s, 9H), 0.76-0.84 (m, 4H), 0.97-1.04 (m, 2H), 3.06 (dd, J=9.4, 6.4 Hz, 2H), 3.27 (dd, J=9.4, 6.4 Hz, 2H), 3.67-3.80 (m, 3H), 5.63 (s, 2H), 6.54 (t, J=74.8 Hz, IH), 6.80 (dd, J=8.1, 2.2 Hz, IH), 7.07-7.22 (m, 6H) , 7.28 (d, J=2 .2 Hz, IH) , 8.09 (s, IH) , 8.55 (brs, IH). [537] 21-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- phenethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 6-(c) except for using 3 64 mg (0.641 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-phenethyl-5 -(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 21-(b) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-5-(2-trimethylsilyl¬ethoxymethyl) -3-propyl-l,5-dihydropyrrolo[2,3-d]pyridazin- 4- one. After completion of the reaction, the solid was collected by filtration from the reaction suspension and washed with 1,4-dioxane. To the obtained solid were added methanol and 2 8% aqueous ammonia, and the mixture was stirred at room temperature for 16 hours. Then, water was added to the solution, and the precipitated solid was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 224 mg of the title compound as a white solid. (Yield: 80%) Melting point: 199-201°C. Mass Spectrum (CI, m/z) : 438 (M^l) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.70-0.79 (m, 4H), 2.99 (dd, J=10.2, 5.9 Hz, 2H), 3.18 (dd, J=10.2, 5.9 Hz, 2H), 3.91-3.98 (m, IH), 7.05-7.30 (m, 7H), 7.08 (t, J=74.3 Hz, IH), 7.49 (d, J=2.0 Hz, IH), 8.11 (s, IH), 12.18 (brs, IH), 12.19 (brs, IH). IR Spectrum (KBr, cm"^) : 1641. [538] Example 22 2- (3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2-fluoro- benzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-379) [539] 22-(a) l-Benzyloxymethyl-2-(3-eyelopropoxy-4-difluoro¬methoxyphenyl) -3-(2-fluorobenzyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one To 46 ml of ethylene glycol solution containing 5.01 g (8.44 mmol) of ethyl l-benzyloxymethyl-5-(3-eyelopropoxy-4- difluoromethoxyphenyl)-4-(2-fluorobenzyl)-2-formyl-IH- pyrrol-3-earboxylate obtained in the following Reference example 36-(f) was added 2.13 ml (42.5 mmol) of hydrazine monohydrate at 60°C, and then the mixture was stirred at 130°C for 8.5 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:1->1:2 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 4.2 8 g of the title compound as a white solid. (Yield: 90%) Mass Spectrum (EI, m/z) : 561 (M") . ^H-NMR Spectrum (cdci3, 5 ppm): 0.48-0.56 (m, 2H), 0.64-0.70 (m, 2H), 3.43-3.49 (m, IH), 4.26 (s, 2H), 4.46 (s, 2H), 5.38 (s, 2H) , 6.55 (t, J-74.7 Hz, IH) , 6.85-7.34 (m, 12H) , 8.12 (s, IH), 9.80 (brs, IH) . IR Spectrum (KBr, cm"'): 1651. [540] 22-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 330 ml of ethanol solution containing 4.28 g (7.62 mmol) of l-benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-(2-fluorobenzyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Example 22-(a) were added 1.50 g of 5% palladium-active carbon and 3.8 ml of 2N hydrochloric acid, and then the mixture was stirred under 1 atm hydrogen atmosphere at 50°C for 1 hour. After comple¬tion of the reaction, the reaction mixture was filtered, the filtrate was concentrated under reduced pressure, methanol and 2 8% aqueous ammonia were added to the obtained solid, and the mixture was stirred for 1 hour. Then, the solution was concentrated under reduced pressure, water was added to the obtained concentrate, and the precipitated solid was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 2.99 g of the title compound as a white solid. (Yield: 89%) Melting point: 202-204°C. Mass Spectrum (EI, m/z) : 441 (M^) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.42-0.63 (m, 4H), 3.54- 3.63 (m, IH), 4.37 (s, 2H), 6.87-7.40 (m, 7H), 7.04 (t, J=74.3 Hz, IH), 8.16 (s, IH), 12.17 (brs, IH). IR Spectrum (KBr, cm"'): 1628. [541] Example 23 2- (3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(3-fluoro- benzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-380) [542] 23-(a) l-Benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl ) -3-(3-fluorobenzyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 300 mg (0.67 8 mmol) of 1-benzyloxymethyl-2-bromo-3-(3-fluoro¬benzyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 37-(c) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 298 mg of the title compound was obtained as a brownish oil. (Yield: 78%) Mass Spectrum (EI, m/z) : 561 (M^) . ^H-NMR Spectrum (cdci3, 8 ppm) : 0.51-0.60 (m, 2H) , 0.65-0.72 (m, 2H), 3.45-3.53 (m, IH), 4.23 (s, 2H), 4.47 (s, 2H), 5.37 (s, 2H), 6.58 (t, J=74.6 Hz, IH), 6.74-7.35 (m, 12H), 8.13 (brs, IH), 9.90 (brs, IH). [543] 23-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(3- fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 22-(b) except for using 298 mg (0.531 mmol) of l-benzyloxymethyl-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-3-(3-fluorobenzyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 23-(a) in place of l-benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-(2-fluorobenzyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one, whereby 69 mg of the title compound was obtained as a white solid. (Yield: 56%) Melting point: 208-210°C. Mass Spectrum (FAB, m/z) : 442 (M^l) . ^H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.49-0.57 (m, 2H) , 0.58- 0.65 (m, 2H), 3.67-3.75 (m, IH), 4.41 (s, 2H), 6.91-7.01 (m, 3H) , 7.06 (t, J=74.3 Hz, IH) , 7.16 (dd, J=8.4, 1.9 Hz, IH), 7.23-7.29 (m, 2H), 7.40 (d, J=1.9 Hz, IH), 8.14 (s, IH) , 12.13 (brs, IH) , 12.40 (brs, IH) . IR Spectrum (KBr, cm"^) : 1626. Example 24 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(4-fluoro- benzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-381) [545] 24-(a) 1-Benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-(4-fluorobenzyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 300 mg (0.678 mmol) of l-benzyloxymethyl-2-bromo-3-(4-fluoro¬benzyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 38-(c) in place of 2- bromo-1-(2 -trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 185 mg of the title compound was obtained as a brownish oil. (Yield: 4 9%) Mass Spectrum (EI, m/z) : 561 (M^) . 'H-NMR Spectrum (cdci3, 5 ppm): 0.54-0.62 (m, 2H), 0.66-0.73 (m, 2H), 3.48-3.56 (m, IH), 4.19 (s, 2H), 4.46 (s, 2H), 5.36 (s, 2H) , 6.59 (t, J=74.6 Hz, IH) , 6.81-7.35 (m, 12H) , 8.12 (brs, IH), 9.85 (brs, IH). [546] 24-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(4- fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 22-(b) except for using 184 mg (0.531 mmol) of l-benzyloxymethyl-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-3-(4-fluorobenzyl)-1,5-dihydro- pyrrolo [2, 3-d]pyridazin-4-one obtained in Example 24-(a) in place of l-benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-(2-fluorobenzyl)-1,5-dihydropyrrolo[2,3- d] pyridaz in.-4-ons, whsireby 69 ing' of the title cornpound was obtained as a white solid. (Yield: 24%) Melting point: 193-195°C. Mass Spectrum (CI, m/z): 442 (M^+l). ^H-NMR Spectrum (DMSO-d^, 6 ppm): 0.49-0.66 (m, 4H), 3.67- 3.76 (m, IH), 4.37 (s, 2H), 7.01-7.19 (m, 5H), 7.06 (t, J=74.2 Hz, IH), 7.28 (d, J=8.3 Hz, IH), 7.39 (d, J=2.0 Hz, IH), 8.15 (s, IH), 12.21 (brs, IH), 12.37 (brs, IH). IR Spectrum (KBr, cm"'): 1638. [547] Example 2 5 3-(2-Cyanobenzyl)-2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-389) [548] 25-(a) l-Benzyloxymethyl-3-(2-cyanobenzyl)-2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 22-(a) except for using 900 mg (1.50 mmol) of ethyl l-benzyloxyTnethyl-4-(2-cyanobenzyl)-5- (3 -eyelopropoxy-4-difluoromethoxyphenyl)-2 -formy1-IH- pyrrol-3-carboxylate obtained in the following Reference example 39-(c) in place of ethyl l-benzyloxymethyl-5-(3- cyclopropoxy-4-dif luoromethoxyphenyl) -4-(2-fluorobenzyl)-2- formyl-lH-pyrrol-3-carboxylate, whereby 549 mg of the title compound was obtained as a yellowish foam. (Yield: 64%) Mass Spectrum (CI, m/z) : 569 (M''+l) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.43-0.59 (m, 4H) , 3.56- 3.63 (m, IH), 4.33 (s, 2H), 4.47 (s, 2H), 5.57 (s, 2H), 6.97 (dd, J=8.2, 1.8 Hz, IH), 7.05 (t, J=74.1 Hz, IH), 7.08 (d, J=8.2 Hz, IH), 7.12-7.17 (m, 2H), 7.20-7.36 (m, 6H), 7.52 (td, J=7.7, 1.4 Hz, IH) , 7.72 (dd, J=7.7, 1.4 Hz, IH) , 8.54 (s, IH) , 12.42 (brs, IH) . IR Spectrum (KBr, cm"'): 1655. 25- (b) 3-(2-Cyanobenzyl)-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl ) -1, 5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 22-(b) except for using 548 mg (0.964 mmol) of l-benzyloxymethyl-3-(2-cyanobenzyl)-2 -(3- cyclopropoxy-4-difluoromethoxyphenyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one obtained in Example 25-(a) in place of l-benzyloxymethyl-2-(3-cyclopropoxy-4-difluoromethoxy¬phenyl) -3-(2-fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one, whereby 3 74 mg of the title compound was obtained as a white solid. (Yield: 87%) Melting point: >300°C. Mass Spectrum (CI, m/z): 449 (M^+1). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.43-0.64 (m, 4H) , 3.59- 3.67 (m, IH), 4.55 (s, 2H), 7.04 (t, J=74.2 Hz, IH), 7.05 (d, J=7.8 Hz, IH), 7.10 (dd, J=8.3, 2.0 Hz, IH), 7.27 (d, J-8.3 HZ, IH) , 7.32 (d, J=2.0 Hz, IH) , 7.38 (t, J=7.8 Hz, IH) , 7.55 (td, J=7.7, 1.4 Hz, IH) , 7.83 (dd, J=7.7, 1.4 Hz, IH), 8.18 (s, IH), 12.18 (brs, IH). IR Spectrum (KBr, cm"^) : 1624. [550] Example 2 6 3-(3-Cyanobenzyl)-2-(3-cyclopropoxy-4-difluoromethoxy¬phenyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-390) [551] 26- (a) l-Benzyloxymethyl-3-(3-cyanobenzyl)-2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 22-(a) except for using 258 mg (0.430 mmol) of ethyl l-benzyloxymethyl-4-(3-cyanobenzyl)- 5-(3-cyclopropoxy-4-difluoromethoxyphenyl)-2-formyl-lH- pyrrol-3-carboxylate obtained in the following Reference example 40-(c) in place of ethyl l-benzyloxymethyl-5-(3- cyclopropoxy-4-difluoromethoxyphenyl)-4-(2-fluorobenzyl)-2- formyl-lH-pyrrol-3-carboxylate, whereby 111 mg of the title compound was obtained as a white foam. (Yield: 45%) Mass Spectrum (CI, m/z) : 569 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm) : 0.55-0.76 (m, 4H) , 3.50-3.58 (m, IH), 4.26 (s, 2H), 4.49 (s, 2H), 5.37 (s, 2H), 6.60 (t, J=74.5 Hz, IH), 6.90 (dd, J=8.3, 2.0 Hz, IH), 7.16-7.45 (m, IIH), 8.12 (s, IH), 9.90 (brs, IH). [0552] 26-(b) 3-(3-Cyanobenzyl)-2-(3-eyelopropoxy-4 -difluoro¬methoxyphenyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 22-(b) except for using 110 mg (0.193 mmol) of 1- benzyloxymethyl-3-(3-cyanobenzyl)-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin- 4-one obtained in Example 26-(a) in place of 1-benzyloxy- methyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, the reaction suspension was filtered, the filtrate was concentrated under reduced pressure, methanol and 28% aqueous ammonia were added to the obtained solid, and the mixture was stirred for 1 hour. Then, the solution was concentrated under reduced pressure and the obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:1->0:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 18 mg of the title compound as a white solid. (Yield: 20%) Melting point: 130-135°C. Mass Spectrum (CI, m/z) : 449 (M"'+l) . 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 0.49-0.68 (m, 4H) , 3.73- 3.80 (m, IH), 4.43 (s, 2H), 7.06 (t, J=74.2 Hz, IH), 7.14 (dd, J=8.3, 2.0 Hz, IH) , 7.30 (d, J=8.3 Hz, IH) , 7.36 (d, J=2.0 Hz, IH), 7.42-7.51 (m, 2H), 7.59 (s, IH), 7.61-7.65 (m, IH), 8.17 (s, IH), 12.24 (brs, IH), 12.33 (brs, IH). IR Spectrum (KBr, cm"^) : 1642. [553] Example 27 3-(3-Carboxybenzyl)-2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-3 93) 27-(a) l-Benzyloxymethyl-3-(3-carboxybenzyl)-2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 22-(a) except for using 1.21 g (1.95 mmol) of ethyl 1-benzyloxymethyl-4-(3-carboxybenzyl)- 5-(3-cyclopropoxy-4-difluoromethoxyphenyl)-2-formyl-lH- pyrrol-3-carboxylate obtained in the following Reference example 41-(d) in place of ethyl l-benzyloxymethyl-5-(3- cyclopropoxy-4-difluoromethoxyphenyl)-4-(2-fluorobenzyl)-2- formyl-lH-pyrrol-3-carboxylate at the time of the reaction, and adjusting a pH of the aqueous layer to 2 at the time of extraction with ethyl acetate in the post treatment, whereby 1.05 g of the title compound as a pale yellowish solid. (Yield: 92%) Mass Spectrum (CI, m/z) : 588 (MVl) . 'H-NMR Spectrum (cdci3, 8 ppm) : 0.68-0.76 (m, 2H) , 0.76-0.84 (m, 2H), 3.66-3.74 (m, IH), 4.24 (s, 2H), 4.41 (s, 2H), 5.33 (s, 2H) , 6.65 (t, J=74 . 6 Hz, IH) , 6.89-6.93 (m, IH) , 7.05 (dd, J=8.2, 2.0 Hz, IH), 7.11-7.16 (m, 2H), 7.20 (t, J=7.7 Hz, IH), 7.27-7.30 (m, 4H), 7.33 (d, J=8.2 Hz, IH), 7.38 (d, J=2.0 Hz, IH), 7.91 (dt, J=7.6, 1.3 Hz, IH), 8.14 (s, IH), 8.76 (brs, IH), 12.58 (brs, IH). [555] 27-(b) 3-(3-Carboxybenzyl)-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 22-(b) except for using 1.05 g (1.79 mmol) of 1- benzyloxymethyl-3-(3-carboxybenzyl)-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-1,5-dihydropyrrolo[2,3-d] pyridazin- 4-one obtained in Example 27-(a) in place of 1-benzyloxy- methyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, the reaction mixture was extracted with an alkaline aqueous solution with a pH 10, washed with diethyl ether, and after adjusting a pH of the aqueous layer to 2, the precipitated solid was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 0.68 g of the title compound as a beige solid. (Yield: 82%) Melting point: 155-163°C. Mass Spectrum (CI, m/z): 468 (M^+1). 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.41-0.50 (m, 2H), 0.53- 0.62 (m, 2H), 3.62-3.70 (m, IH), 4.46 (s, 2H), 7.05 (t, J=74.3 Hz, IH), 7.16 (dd, J=8.2, 2.0 Hz, IH), 7.28 (d, J=8.2 Hz, IH), 7.33-7.43 (m, 3H), 7.69-7.76 (m, 2H), 8.17 (s, IH), 12.23 (brs, IH), 12.43 (brs, IH). IR Spectrum (KBr, cm"^) : 1638. [556] Example 2 8 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(6-methoxy-2- pyridylmethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-43 9) [557] 28-(a) l-Benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-(6-methoxy-2-pyridylmethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 22-(a) except for using 1.11 g (1.82 mmol) of ethyl l-benzyloxymethyl-5-(3-cyclopropoxy-4- difluoromethoxyphenyl)-2-formyl-4-(6-methoxy-2-pyridyl¬methyl ) -IH-pyrrol- 3 -carboxylate obtained in the following Reference example 42-(c) in place of ethyl 1-benzyloxy- methyl-5-(3-cyclopropoxy-4-difluoromethoxyphenyl)-4-(2- fluorobenzyl)-2-formyl-lH-pyrrol-3-carboxylate, whereby 712 mg of the title compound was obtained as a white foam. (Yield: 68%) Mass Spectrum (EI, m/z) : 574 (M^) . 'H-NMR Spectrum (cdci3, 5 ppm): 0.49-0.57 (m, 2H), 0.65-0.72 (m, 2H), 3.51-3.59 (m, IH), 3.75 (s, 3H), 4.30 (s, 2H), 4.47 (s, 2H), 5.43 (s, 2H), 6.50 (d, J=8.1 Hz, IH), 6.56 (t, J=74.7 Hz, IH), 6.90 (d, J=7.3 Hz, IH), 7.15-7.22 (m, 4H), 7.28-7.37 (m, 3H), 7.41-7.49 (m, 2H), 8.11 (s, IH), 9.84 (brs, IH). [0558] 28-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(6- methoxy-2-pyridylmethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one Reaction was carried out in the same manner as in Example 22-(b) except for using 227 mg (0.396 mmol) of 1- benzyloxymethyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(6-methoxy-2-pyridylmethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one obtained in Example 28-(a) in place of 1- benzyloxymethyl-2-(3-eyelopropoxy-4-difluoromethoxyphenyl)- 3-(2-fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one. After completion of the reaction, the reaction suspension was filtered, the filtrate was concentrated under reduced pressure, methanol and 28% aqueous ammonia were added to the obtained solid, and the mixture was stirred for 1 hour. Then, the solution was concentrated under reduced pressure and the obtained residue was applied to silica gel column chromatography (Eluent; chloroform: ethyl acetate=l:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 3 9 mg of the title compound as a white solid. (Yield: 22%) Melting point: 224-226°C. Mass Spectrum (EI, m/z) : 454 (M^) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.50-0.69 (m, 4H) , 3.70- 3.80 (m, IH), 3.75 (s, 3H), 4.40 (s, 2H), 6.59 (d, J=7.7 Hz, IH), 6.81 (d, J=7.7 Hz, IH), 7.06 (t, J=74.3 Hz, IH), 7.28 (d, J=8.4 Hz, IH), 7.46 (dd, J=8.4, 2.0 Hz, IH), 7.56 (t, J=7.7 Hz, IH) , 7.57 (d, J=2.0 Hz, IH) , 8.14 (s, IH) , 12.14 (brs, IH). IR Spectrum (KBr, cm'^) : 1634. [559] Example 2 9 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(6-methoxy-3- pyridylmethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-445) [560] 29-(a) l-Benzyloxymethyl-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-(6-methoxy-3-pyridylmethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 22-(a) except for using 380 mg (0.626 mmol) of ethyl l-benzyloxymethyl-5-(3-cyclopropoxy- 4-difluoromethoxyphenyl)-2-formyl-4-(6-methoxy-3-pyridyl- methyl)-lH-pyrrol-3-carboxylate obtained in the following Reference example 43-(c) in place of ethyl l-benzyloxy¬methyl-5- (3-cyclopropoxy-4-difluoromethoxyphenyl)-4-(2- fluorobenzyl)-2-formyl-lH-pyrrol-3-carboxylate, whereby 267 mg of the title compound was obtained as a slightly yellowish oil. (Yield: 74%) Mass Spectrum (CI, m/z): 575 (M^+1). ^H-NMR Spectrum (cdci3, 8 ppm): 0.56-0.77 (m, 4H), 3.54-3.62 (m, IH), 3.85 (S, 3H), 4.13 (s, 2H), 4.45 (s, 2H), 5.35 (s, 2H), 6.59 (dd, J=8.4, 0.6 Hz, IH), 6.60 (t, J=74.6 Hz, IH), 6.92 (dd, J=8.2, 2.1 Hz, IH), 7.14-7.33 (m, 7H), 7.52 (dd, J=8.4, 2.5 Hz, IH), 7.78 (dd, J=2.5, 0.6 Hz, IH), 8.09 (s, IH), 9.80 (brs, IH). [561] 29-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(6- methoxy-3-pyridylmethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction was carried out in the same manner as in Example 22-(b) except for using 265 mg (1.79 mmol) of 1- benzyloxymethyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(6-methoxy-3-pyridylmethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Example 29-(a) in place of 1- benzyloxyraethyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3 -(2-fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one. After completion of the reaction, the reaction suspension was filtered, the filtrate was concentrated under reduced pressure, methanol and 2 8% aqueous ammonia were added to the obtained solid, and the mixture was stirred for 1 hour. Then, the solution was concentrated under reduced pressure and the obtained residue was applied to silica gel column chromatography (Eluent; ethyl acetate), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 14 6 mg of the title compound as a white solid. (Yield: 69%) Melting point: 220-221°C. Mass Spectrum (CI, m/z): 455 (M"+l). 'H-NMR Spectrum (DMSO-dg, 8 ppm): 0.58-0.67 (m, 4H), 3.76 (s, 3H), 3.77-3.84 (m, IH), 4.30 (s, 2H), 6.68 (d, J=8.5 Hz, IH), 7.07 (t, J=74.3 Hz, IH), 7.16 (dd, J=8.4, 2.1 Hz, IH) , 7.30 (d, J=8.4 Hz, IH) , 7.43 (d, J=2 .1 Hz, IH) , 7.47 (dd, J=8.5, 2.2 Hz, IH) , 7.93 (d, J=2 .2 Hz, IH) , 8.14 (s, IH), 12.20 (brs, IH). IR Spectrum (KBr, cm'^) : 1625. [562] Example 3 0 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-dimethylamino- methyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-197) [563] 30-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- dimethylaminomethyl-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 133 mg (0.270 mmol) of 2-(3-cyclopropoxy-4-di- fluoromethoxyphenyl)-3-formyl-l-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 10-(a) and 112 mg of Molecular sieve (3A) was added 5 ml of tetrahydrofuran solution containing 2M dimethylamine at room temperature, and the mixture was stirred for 10 minutes. Then, 156 mg (0.740 mmol) of sodium triacetoxyborohydride was added to the mixture, and the mixture was stirred for further 17 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; ethyl acetate->chloroform:methanol=4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 74 mg of the title compound as a pale yellowish solid. (Yield: 53%) Mass Spectrum (CI, m/z): 521 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.04 (s, 9H), 0.76-0.90 (m, 6H), 2.24 (s, 6H), 3.41-3.49 (m, 2H), 3.68 (s, 2H), 3.77- 3.85 (m, IH), 5.37 (s, 2H), 6.61 (t, J=74.7 Hz, IH), 7.16 (dd, J=8.2, 2.0 Hz, IH), 7.26 (d, J=8.2 Hz, IH), 7.75 (d, J=2.0 Hz, IH), 8.19 (s, IH), 9.94 (brs, IH). IR Spectrum (KBr, cm'^ : 1646. [0564] 30-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-di- methylaminomethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 7 0 mg (0.14 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-dimethylamino- methyl-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one obtained in Example 30-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one. After completion of the reaction, water was added to the reaction mixture to precipitate a solid. and the precipitated solid was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 3 6 mg of the title compound as a gray solid. (Yield: 68%) Melting point: 154-157°C. 'H-NMR Spectrum (DMSO-dg, 8 ppm): 0.72-0.88 (m, 4H), 2.23 (s, 6H), 3.73 (s, 2H), 3.93-4.00 (m, IH), 7.08 (t, J=74.5 Hz, IH), 7.30 (d, J=8.5 Hz, IH), 7.49 (dd, J=8.5, 2.0 Hz, IH), 8.12 (s, IH), 8.27 (d, J=2.0 Hz, IH), 12.16 (brs, IH), 12.36 (brs, IH). IR Spectrum (KBr, cm''): 1639. [565] Example 31 2-(3-Cyclobutoxy-4-difluoromethoxyphenyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1- 850) 31-(a) 2-(3-Cyclobutoxy-4-difluoromethoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] pyrid- azin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 0.50 g (1.5 mmol) of 2-(3-cyclobutoxy-4-difluoromethoxyphenyl)- 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(b) in place of 2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane, whereby 0.4 6 g of the title compound was obtained as a pale yellowish foam. (Yield: 80%) Mass Spectrum (CI, m/z): 478 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , 0.88-0.97 (m, 2H), 1.64-1.78 (m, IH), 1.84-1.97 (m, IH), 2.16-2.32 (m, 2H), 2.42-2.55 (m, 2H), 3.51-3.60 (m, 2H), 4.63-4.76 (m, IH), 5.43 (s, 2H), 6.66 (t, J=75.1 Hz, IH), 6.93 (s, IH), 7.06 (d, J=2.0 Hz, IH), 7.12 (dd, J=8.3, 2.0 Hz, IH), 7.26 (d, J=8.3 Hz, IH), 8.24 (s, IH), 10.61 (brs, IH). [567] 31-(b) 2-(3-Cyclobutoxy-4-difluoromethoxyphenyl)-1,5-di- hydropyrrolo [2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 2-(b) except for using 0.46 g (0.96 mmol) of 2-(3- cyclobutoxy-4-difluoromethoxyphenyl)-1-(2-triraethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 31-(a) in place of 3-chloro-2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-1-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, to the reaction mixture was added a saturated aqueous solution of sodium hydrogen- carbonate to neutralize the mixture, and the mixture was extracted with a mixed solvent (chloroform/methanol=9/l (V/V)). The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. To the obtained solid were added methanol and 2 8% aqueous ammonia, and the mixture was stirred under room temperature for 3 hours. Then, the solution was concentrated under reduced pressure and the obtained solid was washed with chloroform and dried under reduced pressure to obtain 199 mg of the title compound as a white solid. (Yield: 60%) Melting point: 289-291°C. Mass Spectrum (CI, m/z) : 348 (M^'+l) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 1.58-1.75 (m, IH), 1.76- 1.90 (m, IH), 2.02-2.18 (m, 2H), 2.45-2.60 (m, 2H), 4.84- 4.97 (m, IH) , 7.11 (t, J=74.5 Hz, IH) , 7.20 (d, J=0.6 Hz, IH), 7.27 (d, J=8.3 Hz, IH), 7.42 (d, J=2.1 Hz, IH), 7.45 (dd, J=8.3, 2.1 Hz, IH), 8.16 (d, J=0.6 Hz, IH), 12.26 (brs, IH), 12.45 (brs, IH). [0568] Example 32 3-Chloro-2-(3-cyclobutoxy-4-difluoromethoxyphenyl)-1,5-di- hydropyrrolo [2 , 3 -d] pyridazin-4 -one (Exemplary compound No. 1-851) 32-(a) 3-Chloro-2-(3-cyclobutoxy-4-difluoromethoxyphenyl)- 1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 31-(a) except for using 0.40 g (1.1 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 263 mg of the title compound was obtained as a white solid. (Yield: 48%) Mass Spectrum (CI, m/z): 512 (M"+l). ^H-NMR Spectrum (cdci3, S ppm) : -0.03 (s, 9H), 0.82-0.93 (m, 2H), 1.61-1.78 (m, IH), 1.84-1.98 (m, IH), 2.16-2.32 (m, 2H), 2.42-2.54 (m, 2H), 3.42-3.52 (m, 2H), 4.63-4.74 (m, IH) , 5.35 (s, 2H) , 6.68 (t, J=74 . 8 Hz, IH) , 7.00 (d, J=2 .2 Hz, IH), 7.06 (dd, J=8.2, 2.2 Hz, IH), 7.30 (d, J=8.2 Hz, IH), 8.19 (s, IH), 10.08 (brs, IH). [570] 32-(b) 3-Chloro-2-(3-cyclobutoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 2-(b) except for using 0.26 g (0.51 mmol) of 3- chloro-2-(3-cyclobutoxy-4-difluoromethoxyphenyl)-1-(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 32-(a) in place of 3-chloro- 2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one. After completion of the reaction, to the reaction mixture were added diisopropyl ether and cyclohexane, and the precipitated solid was collected by filtration and washed with cyclohexane. To the obtained solid were added methanol and 2 8% aqueous ammonia, and the mixture was stirred at room temperature for 3 hours. Then, the solution was concentrated under reduced pressure, and the obtained solid was washed with chloroform and dried under reduced pressure to obtain 12 0 mg of the title compound as a white solid. (Yield: 62%) Melting point: 273-275°C. Mass Spectrum (CI, m/z): 382 (M^+1). 'H-NMR Spectrum (DMSO-dg, S ppm): 1.59-1.90 (m, 2H), 2.06- 2.22 (m, 2H), 2.43-2.57 (m, 2H), 4.77-4.88 (m, IH), 7.16 (t, J=74.2 Hz, IH), 7.35 (d, J-8.5 Hz, IH), 7.38-7.43 (m, 2H), 8.15 (s, IH), 12.35 (brs, IH). IR Spectrum (KBr, cm"'): 1635. [571] Example 3 3 3-Bromo-2-(3-cyclobutoxy-4-difluoromethoxyphenyl)-1,5-di- hydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-852) [572] 33-(a) 3-Bromo-2-(3-cyclobutoxy-4-difluoromethoxyphenyl)-1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 31-(a) except for using 51 mg (0.12 mmol) of 2,3-dibromo-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 44 in place of 2-brorao- 1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one, whereby 57 mg of the title compound was obtained as a pale yellowish solid. (Yield: 84%) 'H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), 0.82-0.91 (m, 2H), 1.63-1.78 (m, IH), 1.84-1.98 (m, IH), 2.16-2.33 (m, 2H), 2.42-2.55 (m, 2H), 3.41-3.50 (m, 2H), 4.63-4.74 (m, IH) , 5.34 (s, 2H) , 6.68 (t, J=74 .8 Hz, IH) , 6.98 (d, J=2.1 Hz, IH), 7.04 (dd, J=8.2, 2.1 Hz, IH), 7.30 (d, J=8.1 Hz, IH) , 8.20 (s, IH) , 9.89 (brs, IH) . [573] 33-(b) 3-Brorao-2-(3-cyclobutoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 32-(b) except for using 54 mg (0.097 mmol) of 3-bromo-2-(3-cyclobutoxy-4-difluoromethoxy- phenyl)-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 33-(a) in place of 3-chloro-2-(3-cyclobutoxy-4-difluoromethoxy- phenyl)-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 27 mg of the title compound was obtained as a beige solid. (65%) Melting point: 234-238°C. Mass Spectrum (CI, m/z): 426 (MVl). 'H-NMR Spectrum (DMSO-dg, 5 ppm): 1.58-1.94 (m, 2H), 2.06- 2.23 (m, 2H), 2.43-2.59 (m, 2H), 4.75-4.90 (m, IH), 7.17 (t, J=74.2 Hz, IH), 7.31-7.45 (m, 3H), 8.15 (s, IH), 12.33 (brs, IH). IR Spectrum (KBr, cm"^) : 1652. [574] Example 34 2-(3-Cyclobutoxy-4-difluoromethoxyphenyl)-3-phenyl-l,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-870) [575] 34-(a) 2-(3-Cyclobutoxy-4-difluoromethoxyphenyl)-3-iodo-l- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one To 283 mg (0.593 mmol) of 2-(3-cyclobutoxy-4-difluoro- methoxyphenyl)-1-(2-trimethylsilylethoxymethyl)-1,5-di¬hydropyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 31- (a) were added 1.6 ml of dichloromethane and 5 ml of acetonitrile, then, 167 mg of sodium hydrogencarbonate and 3 67 mg of anhydrous magnesium sulfate were added to the mixture, and the resulting mixture was stirred at room temperature for 30 minutes. Then, 3 ml of dichloromethane solution containing 267 mg of iodine■monochlDYude. was added to the same, and the resulting mixture was further stirred at room temperature for 4 hours. After completion of the reaction, a filtrate obtained by removing insoluble material in the reaction suspension by filtration and a washed solution obtained by washing the filtered solid with ethyl acetate were combined and the combined solution was washed successively with 5% aqueous sodium thiosulfate solution and then with a saturated aqueous solution of sodium chloride. The organic layer after washing was dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l->0:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 314 mg of the title compound as a pale yellowish foam. (Yield: 88%) Mass Spectrum (CI, m/z) : 604 (M'"+l) . ^H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), 0.80-0.90 (m, 2H), 1.62-1.78 (m, IH), 1.84-1.98 (m, IH), 2.17-2.34 (m, 2H), 2.43-2.56 (m, 2H), 3.38-3.47 (m, 2H), 4.64-4.74 (m, IH) , 5.34 (s, 2H) , 6.69 (t, J=74 . 7 Hz, IH) , 6.93 (d, J=2 . 0 Hz, IH), 6.99 (dd, J=8.3, 2.0 Hz, IH), 7.29 (d, J=8.3 Hz, IH) , 8.22 (s, IH) , 9.95 (brs, IH) . IR Spectrum (KBr, cm"'): 1659. [0576] 34-(b) 2-(3-Cyclobutoxy-4-difluoromethoxyphenyl)-3-phenyl- 1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 299 mg (0.495 mmol) of 2-(3-cyclobutoxy-4-difluoromethoxyphenyl)- 3-iodo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one obtained in Example 34-(a) in place of 2-bromo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, and using 95 mg (0.779 mmol) of phenylboronic acid in place of 2-(3-cyclopropoxy-4- dif luoromethoxyphenyl ) -4,4,5,5-tetramethyl-[1,3,2]dioxa- borolane obtained in the following Reference example 1-(a), whereby 151 mg of the title compound was obtained as a pale beige solid. (Yield: 89%) Mass Spectrum (CI, m/z) : 554 (M%1) . 'H-NMR Spectrum (cdci3, 8 ppm): -0.02 (s, 9H), 0.86-0.95 (m, 2H) , 1.46-1.63 (m, IH) , 1.71-1.85 (m, IH) , 1.91-2.07 (m, 2H) , 2.07-2.20 (m, 2H) , 3.47-3.56 (m, 2H) , 4.25-4.37 (m, IH) , 5.39 (s, 2H) , 6.62 (d, J=2 . 1 Hz, IH) , 6.62 (t, J=75.0 Hz, IH), 6.95 (dd, J=8.3, 2.1 Hz, IH), 7.18 (d, J=8.3 Hz, IH) , 7.20-7.32 (m, 5H) , 8.24 (s, IH) , 9.87 (brs, IH) . IR Spectrum (KBr, cm"^) : 1654. [0577] 34-(c) 2-(3-Cyclobutoxy-4-difluoromethoxyphenyl)-3-phenyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 145 mg (0.261 mmol) of 2-(3- cyclobutoxy-4-difluoromethoxyphenyl)-3-phenyl-l-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 34-(b) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, water was added to the obtained concentrate, and the mixture was extracted with ethyl acetate. The organic layer after separation was dried over anhydrous magnesium sulfate and then concen¬trated under reduced pressure. The obtained solid was dissolved by adding ethyl acetate, followed by addition of diisopropyl ether and hexane, and the precipitated solid was collected by filtration. The obtained solid was dried under reduced pressure to obtain 93 mg of the title compound as a beige solid. (Yield: 84%) Melting point: 280-284°C. Mass Spectrum (CI, m/z) : 424 (M"'+l) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 1.37-1.55 (m, IH), 1.62- 1.76 (m, IH), 1.81-2.10 (m, 4H), 4.18-4.29 (m, IH), 6.73 (d, J=2.1 Hz, IH), 7.07 (dd, J=8.4, 2.1 Hz, IH), 7.08 (t. J-73.4 Hz, IH), 7.21 (d, J=8.4 Hz, IH), 7.28-7.40 (m, 5H), 8.15 (s, IH), 12.17 (brs, IH), 12.47 (brs, IH). IR Spectrum (KBr, cm"^) : 1624. [578] Example 3 5 2-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-1,5-di- hydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-482) Reaction was carried out in the same manner as in Example 22-(a) except for using 114 rag (0.30 mmol) of ethyl 5-(3-cyclopropylmethoxy-4-difluoromethoxyphenyl)-2-formyl- lH-pyrrol-3-carboxylate obtained in the following Reference example 45-(d) in place of ethyl l-benzyloxyraethyl-5-(3- cyclopropoxy-4-difluoromethoxyphenyl)-4-(2-fluorobenzyl)-2- formyl-lH-pyrrol-3-carboxylate. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with a mixed solvent (chloroform: methanol=9:l (V/V)). The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; chloroform:methanol=9:1 (V/V)), and the fractions contain¬ing the desired compound were concentrated under reduced pressure to obtain 4 9 rag of the title compound as a white solid. (Yield: 47%) Melting point: 294-295°C. Mass Spectrum (CI, m/z) : 348 (MVl) . 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 0.34-0.40 (m, 2H) , 0.58- 0.64 (m, 2H), 1.23-1.34 (m, IH), 4.01 (d, J=6.8 Hz, 2H), 7.12 (t, J=74.7 Hz, IH), 7.21 (d, J=0.7 Hz, IH), 7.26 (d, J=8.3 Hz, IH) , 7.45 (dd, J=8.3, 2.0 Hz, IH) , 7.62 (d, J=2 . 0 Hz, IH), 8.16 (d, J=0.7 Hz, IH), 12.21 (s, IH), 12.46 (brs, IH) . [579] Example 3 6 3-Chloro-2-(3-cyclopropylmethoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-4 83) [580] 36-(a) 3-Chloro-2-(3-cyclopropylmethoxy-4-difluoromethoxy¬phenyl) -1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 0.40 g (1.1 mmol) of 2-bromo-3-chloro-1-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4-one, and using 0.55 g (2.1 mmol) of 3- cyclopropylmethoxy-4-difluoromethoxyphenylboronic acid obtained in the following Reference example 3-(b) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane, whereby 254 mg of the title compound was obtained as a white solid. (Yield: 46%) Mass Spectrum (CI, m/z): 512 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), 0.33-0.40 (m, 2H) , 0.63-0.71 (m, 2H) , 0.82-0.91 (m, 2H) , 1.24-1.39 (m, IH) , 3.42-3.50 (m, 2H) , 3.90 (d, J=6.8 Hz, 2H) , 5.34 (s, 2H), 6.73 (t, J-75.1 Hz, IH), 7.08 (dd, J=8.1, 2.0 Hz, IH), 7.13 (d, J=2.0 Hz, IH), 7.31 (d, J=8.1 Hz, IH), 8.19 (s, IH), 10.11 (brs, IH). [581] 36-(b) 3-Chloro-2-(3-cyclopropylmethoxy-4-difluoromethoxy- phenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 2-(b) except for using 254 mg (0.496 mmol) of 3- chloro-2-(3-cyclopropylmethoxy-4-difluoromethoxyphenyl)-1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Example 36-(a) in place of 3- chloro-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-1-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] pyrid- azin-4-one. After completion of the reaction, diisopropyl ether and cyclohexane were added to the reaction mixture, and the precipitated solid was collected by filtration. The obtained crude solid was applied to silica gel column chromatography (Eluent; chloroform: methanol:=9 :1 (V/V) ) , the fractions containing the desired compound were concen¬trated, methanol and 2 8% aqueous ammonia were added to the obtained solid, and the mixture was stirred at room temperature for 3 hours. Then, the solution was concen¬trated under reduced pressure, and the obtained solid was washed with diisopropyl ether and dried under reduced pressure to obtain 10 0 mg of the title compound as a white solid. (Yield: 58%) Melting point: 258-260°C. Mass Spectrum (CI, m/z): 382 (M"+l). 'H-NMR Spectrum (DMSO-d^, 6 ppm): 0.34-0.41 (m, 2H), 0.56- 0.65 (m, 2H), 1.23-1.38 (m, IH), 3.99 (d, J=7.1 Hz, 2H), 7.17 (t, J=74.5 Hz, IH), 7.35 (d, J=8.4 Hz, IH), 7.44 (dd, J=8.4, 2.1 Hz, IH) , 7.51 (d, J=2 . 1 Hz, IH) , 8.14 (s, IH) , 12.35 (brs, IH). [582] Example 3 7 2-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-3-ethyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one HCl adduct (Exemplary compound No. 1-486) [583] 37-(a) 2-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-3- ethyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 36-(a) except for using 105 mg (0.19 mmol) of 3-ethyl-2-iodo-1,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 4 6 in place of 2-bromo-3-chloro-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 91 mg of the title compound was obtained as a yellowish oil. (Yield: 75%) ^H-NMR Spectrum (cdci3, 6 ppm) : -0.04 (s, 9H), 0.00 (s, 9H) , 0.32-0.39 (m, 2H) , 0.61-0.70 (m, 2H) , 0.81-0.88 (m, 2H) , 0.97-1.04 (m, 2H), 1.22 (t, J-7.4 Hz, 3H), 1.23-1.34 (m, IH), 2.77 (q, J=7.4 Hz, 2H), 3.39-3.46 (m, 2H), 3.71-3.78 (m, 2H), 3.88 (d, J=7.1 Hz, 2H), 5.26 (s, 2H), 5.61 (s, 2H) , 6.34 (dd, J=8.5, 2.8 Hz, IH) , 6.46 (d, J=2.8 Hz, IH) , 6.51 (t, J=76.0 Hz, IH), 7.02 (d, J=8.5 Hz, IH), 8.16 (s, IH) . IR Spectrum (neat, cm'^) : 1643. [584] 37-(b) 2-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-3- ethyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 615 mg (0.967 mmol) of 2-(3-cyclopropylmethoxy-4-difluoromethoxy- phenyl) -3-ethyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 37-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxy- phenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 44 0 mg of the title compound was obtained as a white solid. (Yield: 90%) Mass Spectrum (CI, m/z) : 506 (M^l) . ^H-NMR Spectrum (cdci3, 5 ppm) : -0.01 (s, 9H) , 0.34-0.41 (m, 2H), 0.64-0.71 (m, 2H), 0.94-1.02 (m, 2H), 1.24-1.37 (m, IH) , 1.33 (t, J=7.4 Hz, 3H) , 2.96 (q, J=7.4 Hz, 2H) , 3.69- 3.77 (m, 2H) , 3.92 (d, J=:7.1 Hz, 2H) , 5.59 (s, 2H) , 6.69 (t, J=75.2 Hz, IH) , 7.04 (dd, J=8.2, 2.1 Hz, IH) , 7.07 (d, J=2.1 Hz, IH), 7.27 (d, J=8.2 Hz, IH), 8.06 (s, IH), 8.56 (brs, IH). IR Spectrum (KBr, cm^^) : 1630. [585] 37-(c) 2-(3-Cyclopropylmethoxy-4 -di fluoromethoxyphenyl)-3 - ethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one HCl adduct Reaction was carried out in the same manner as in Example 6-(c) except for using 476 mg (0.941 mmol) of 2-(3- cyclopropylmethoxy-4-difluoromethoxyphenyl) -3-eth.yl-5- (2- trimethylsilylethoxymethyl) -1, 5-dihydropyrrolo [2, 3-d]pyrid- azin-4-one obtained in Example 37-(b) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-propyl-5-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one. After completion of the reaction, the solid obtained by filtrating the reaction suspension was washed with diisopropyl ether and dried under reduced pressure to obtain 352 mg of the title compound as a white solid. (Yield: 91%) Melting point: 224-227°C. Mass Spectrum (CI, m/z) : 376 (M'^+l) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.33-0.40 (m, 2H) , 0.56- 0.64 (m, 2H) , 1.19-1.37 (m, IH) , 1.23 (t, J=7.4 Hz, 3H) , 2.88 (q, J=7.4 Hz, 2H), 3.98 (d, J=6.8 Hz, 2H), 7.14 (dd, J=8.3, 2.0 Hz, IH), 7.16 (t, J=74.5 Hz, IH), 7.27 (d, J=2.0 Hz, IH) , 7.32 (d, J=8.3 Hz, IH) , 8.08 (s, IH) , 12.12 (brs, IH), 12.14 (brs, IH). IR Spectrum (KBr, cm"^) : 1502. [586] Example 3 8 2-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-3-phenyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-545) 38-(a) 2-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 500 mg (1.47 mmol) of 2-(3-cyclopropylmethoxy-4-difluoromethoxy¬phenyl) -4,4,5,5-tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(c) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane, whereby 44 8 mg of the title compound was obtained as a yellowish oil. (Yield: 76%) Mass Spectrum (CI, m/z): 478 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.33-0.40 (m, 2H), 0.64-0.71 (m, 2H), 0.86-0.95 (m, 2H), 1.23-1.39 (m, IH), 3.50-3.58 (m, 2H), 3.91 (d, J=6.8 Hz, 2H), 5.43 (s, 2H) , 6.71 (t, J=75.1 Hz, IH) , 6.93 (d, J=0.5 Hz, IH) , 7.13 (dd, J=8.3, 2.1 Hz, IH), 7.20 (d, J=2.1 Hz, IH), 7.28 (d, J=8.3 Hz, IH), 8.22 (d, J=0.5 Hz, IH), 10.18 (brs, IH). IR Spectrum (KBr, cm"^) : 1660. [588] 38-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iodo-l- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 34-(a) except for using 403 mg (0.845 mmol) of 2-(3-cyclopropylmethoxy-4-difluoromethoxy- phenyl)-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 38-(a) in place of 2-(3-cyclobutoxy-4-difluoromethoxyphenyl)-1-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one, whereby 4 64 mg of the title compound was obtained as a pale yellowish foam. (Yield: 91%) Mass Spectrum (CI, m/z): 604 (M^+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.04 (s, 9H), 0.34-0.40 (m, 2H), 0.63-0.71 (m, 2H), 0.80-0.88 (m, 2H), 1.23-1.39 (m, IH), 3.39-3.46 (m, 2H), 3.91 (d, J=6.8 Hz, 2H), 5.34 (s, 2H), 6.74 (t, J=75.0 Hz, IH), 7.01 (dd, J=8.2, 2.0 Hz, IH), 7.06 (d, J=2.0 Hz, IH) , 7.31 (d, J=8.2 Hz, IH), 8.22 (s, IH), 9.99 (brs, IH). IR Spectrum (KBr, cm"^) : 1658. [589] 38-(c) 5-Benzyl-2-(3-cyclopropylmethoxy-4-difluoromethoxy¬phenyl) -3-iodo-l-(2-trimethylsilylethoxymethyl)-1, 5-di- hydropyrrolo [2,3-d]pyridazin-4-one To 452 mg (0.749 mmol) of 2-(3-cyclopropylmethoxy-4- difluoromethoxyphenyl)-3-iodo-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 38-(b) and 126 mg of potassium carbonate was added 4 ml of dehydrated N,N-dimethylformamide, then 0.1 ml of benzyl bromide was added to the mixture, and the resulting mixture was stirred at room temperature for 16 hours. Moreover, 36 mg of sodium hydride (55% dispersed material in mineral oil) and 0.1 ml of benzyl bromide were further added to the mixture, and the resulting mixture was stirred for 2 hours. After completion of the reaction, a saturated aqueous solution of ammonium chloride was added to the reaction mixture, and the mixture was extracted with toluene. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane:ethyl acetate=19:1->1:1 (V/V)), and the fractions containing the desired compound were concen¬trated under reduced pressure to obtain 389 mg of the title compound as a pale yellowish foam. (Yield: 75%) Mass Spectrum (CI, m/z): 694 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.05 (s, 9H), 0.33-0.40 (m, 2H), 0.62-0.70 (m, 2H), 0.79-0.86 (m, 2H), 1.24-1.39 (m, IH), 3.37-3.44 (m, 2H), 3.90 (d, J=7.1 Hz, 2H), 5.30 (s, 2H), 5.42 (s, 2H), 6.73 (t, J=75.0 Hz, IH), 6.99 (dd, J=8.2, 2.1 Hz, IH), 7.05 (d, J=2.1 Hz, IH), 7.21-7.38 (m, 4H), 7.45-7.50 (m, 2H), 8.19 (s, IH). IR Spectrum (KBr, cm"^) : 1662. [0590] 38-(d) 5-Benzyl-2-(3-eyelopropylmethoxy-4-difluoromethoxy¬phenyl) -3-phenyl-1-(2-trimethylsilylethoxymethyl)-1,5-di¬hydropyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 3 83 mg (0.552 mmol) of 5-benzyl-2-(3-cyclopropylmethoxy-4-di- fluoromethoxyphenyl)-3-iodo-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 38-(c) in place of 2-bromo-l-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, using 84 mg (0.69 mmol) of phenylboronic acid in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetra- methyl-[1, 3 , 2] dioxaborolane, and using 55 lal of tetra- hydrofuran solution containing 10 0 mM palladium complex prepared previously from 231 mg (1.03 mmol) of palladium acetate and 846 mg of 2-dicyclohexylphosphino-2',6'- dimethoxybiphenyl in place of tetrakis(triphenylphosphine)- palladium, whereby 33 0 mg of the title compound was obtained as a pale brownish foam. (Yield: 93%) 'H-NMR Spectrum (cdci3, S ppm): -0.03 (s, 9H), 0.19-0.25 (m, 2H), 0.50-0.58 (m, 2H), 0.85-0.92 (m, 2H), 0.93-1.05 (m, IH), 3.46-3.54 (m, 2H), 3.58 (d, J-7.1 Hz, 2H), 5.37 (s, 2H) , 5.43 (s, 2H) , 6.65 (t, J=75 . 1 Hz, IH) , 6.77 (d, J=2 . 0 Hz, IH) , 6.93 (dd, J=8.3, 2.0 Hz, IH) , 7.14-7.50 (m, lOH) , 7.16 (d, J=8.3 Hz, IH) , 8.23 (s, IH) . [0591] 38-(e) 5-Benzyl-2-(3-cyclopropylmethoxy-4-difluoromethoxy¬phenyl) -3-phenyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 328 mg (0.501 mmol) of 5-benzyl-2-(3-cyclopropylmethoxy-4-di- f luoromethoxyphenyl) -3-phenyl-1-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 38-(d) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl ) -3-methyl-l,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 207 mg of the title compound was obtained as a white solid. (81%) Mass Spectrum (CI, m/z): 514 (M^+1). 'H-NMR Spectrum (cdci3, 8 ppm): 0.10-0.18 (m, 2H), 0.46-0.55 (m, 2H), 0.85-1.04 (m, IH), 3.36 (d, J=6.8 Hz, 2H), 5.40 (s, 2H) , 6.59 (t, J=75.3 Hz, IH) , 6.66 (d, J=2 .1 Hz, IH) , 6.81 (dd, J=8.3, 2.1 Hz, IH), 7.02 (d, J=8.3 Hz, IH), 7.09- 7.41 (m, lOH), 7.99 (s, IH), 9.37 (brs, IH). IR Spectrum (KBr, cm"^) : 1622. [592] 38- (f) 2-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-3- phenyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 15 ml of acetic acid solution containing 2 05 mg (0.3 99 mmol) of 5-benzyl-2-(3-cyclopropylmethoxy-4-di- f luoromethoxyphenyl) -3-phenyl-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one obtained in Example 38-(e) was added 103 mg of 10% palladium-active carbon, and under 1 atm hydrogen atmosphere, the mixture was stirred at 95°C for 31.5 hours. After completion of the reaction, insoluble material was removed from the reaction suspension by filtration, and the filtrate was concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane:ethyl acetate=4:l->0:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure. The obtained crude solid was purified by high performance liquid chromato¬graphy (column; Kromacil™ 100-5-C18 (20x250 mm (manufac¬tured by EKA CHEMICALS), Eluent; acetonitrile:water:tri- fluoroacetic acid-1500:1000:2.5 (V/V/V), Flow rate; 10 ml/min) to obtain 3 0 mg of the title compound as a white solid. (Yield: 18%) Melting point: 249-2510C. Mass Spectrum (CI, m/z) : 424 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.18-0.27 (m, 2H), 0.46- 0.56 (m, 2H), 0.97-1.10 (m, IH), 3.58 (d, J=6.8 Hz, 2H), 6.92-7.00 (m, 2H), 7.09 (t, J=73.6 Hz, IH), 7.16 (d, J=8.8 Hz, IH) , 7.23-7.40 (m, 5H) , 8.15 (s, IH) , 12.15 (brs, IH) , 12.48 (brs, IH). IR Spectrum (KBr, cm"M : 1618. [593] Example 3 9 2-(4-Difluoromethoxy-3-isopropoxyphenyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1- 666) [594] 39-(a) 2-{4-Difluoromethoxy-3-isopropoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 125 mg (0.382 mmol) of 2-(4-difluoromethoxy-3-isopropoxyphenyl)- 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(d) in place of 2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane, whereby 108 mg of the title compound was obtained as a pale yellowish solid substantially quantitatively. 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.88-0.94 (m, 2H), 1.40 (d, J=6.1 Hz, 6H), 3.52-3.58 (m, 2H), 4.55-4.64 (m, IH), 5.44 (s, 2H), 6.64 (t, J=75.0 Hz, IH), 6.94 (d, J=0.5 Hz, IH), 7.12 (dd, J=8.1, 2.1 Hz, IH), 7.22 (d, J=2.1 Hz, IH), 7.27 (d, J=8.1 Hz, IH), 8.22 (d, J=0.5 Hz, IH), 10.11 (brs, IH). [595] 3 9-(b) 2-(4-Difluoromethoxy-3-isopropoxyphenyl)-1,5-di- hydropyrrolo[2,3-d]pyridazin-4-one To 2 ml of dichloromethane solution containing 99 mg (0.21 mmol) of 2-(4-difluoromethoxy-3-isopropoxyphenyl)-l- (2 - trimethylsilylethoxymethyl) - 1 , 5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Example 39-(a) was added 0.1 ml of boron trifluoride diethyl ether complex under ice- cooling, and the mixture was reacted at room temperature for 3 hours. After completion of the reaction, methanol and 2 8% aqueous ammonia were added to the solid obtained by filtrating the reaction suspension, and the mixture was stirred at room temperature for 12 hours. Then, the solution was concentrated under reduced pressure, and the obtained solid was washed with chloroform and dried under reduced pressure to obtain 2 9 tng of the title compound as a white solid. (Yield: 42%) Melting point: 269-273°C. Mass Spectrum (CI, m/z): 336 (MVl). 'H-NMR Spectrum (DMSO-dg, 8 ppm): 1.33 (d, J=5.9 Hz, 6H), 4.77-4.85 (m, IH), 7.07 (t, J=74.7 Hz, IH), 7.20 (d, J-0.6 Hz, IH), 7.25 (d, J=8.4 Hz, H=l), 7.45 (dd, J=8.4, 2.1 Hz, IH) , 7.64 (d, J=2.1 Hz, IH) , 8.16 (d, J=0.6 Hz, IH) , 12.23 (brs, IH), 12.45 (brs, IH). IR Spectrum (KBr, cm"'): 1645. [596] Example 4 0 3-Chloro-2-(4-difluoromethoxy-3-isopropoxyphenyl)-1,5-di- hydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-667) [597] 40-(a) 3-Chloro-2-(4-difluoromethoxy-3-isopropoxyphenyl)-1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 3 9-(a) except for using 4 05 mg (1.09 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 249 mg of the title compound was obtained as a white solid. (Yield: 46%) Mass Spectrum (CI, m/z): 500 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), 0.83-0.91 (m, 2H), 1.40 (d, J=6.1 Hz, 6H), 3.42-3.51 (m, 2H), 4.51-4.63 (m, IH), 5.36 (s, 2H), 6.66 (t, J=75.1 Hz, IH), 7.06 (dd, J=8.3, 2.1 Hz, IH), 7.15 (d, J=2.1 Hz, IH), 7.30 (d, J=8.3 Hz, IH), 8.19 (s, IH), 10.00 (brs, IH). [598] 40-(b) 3-Chloro-2-(4-difluoromethoxy-3-isopropoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 247 mg (0.495 mmol) of 3- chloro-2-(4-difluoromethoxy-3-isopropoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 40-(a) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one. After completion of the reaction, active carbon was added to the reaction suspension, and the mixture was stirred at room temperature for further 2 hours, and insoluble material was removed by filtration. The filtrate was concentrated under reduced pressure, the obtained solid was dissolved by adding a small amount of tetrahydrofuran, followed by addition of water, and the solid precipitated by ultrasonic wave treatment was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 175 mg of the title compound as a white solid. (Yield: 96%) Melting point: 248-262°C. Mass Spectrum (CI, m/z) : 370 (M^'+l) . 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 1.35 (d, J=6.1 Hz, 6H) , 4.63-4.77 (m, IH), 7.11 (t, J=74.5 Hz, IH), 7.32 (d, J=8.4 Hz, IH), 7.44 (dd, J=8.4, 2.1 Hz, IH), 7.56 (d, J=2.1 Hz, IH) , 8.12 (s, IH) , 12.24 (brs, IH) . IR Spectrum (KBr, cm''): 1635. [599] Example 41 3-Bromo-2-(4-difluoromethoxy-3-isopropoxyphenyl)-1,5-di- hydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-668) [600] 41-(a) 3-Bromo-2-(4-difluoromethoxy-3-isopropoxyphenyl)-1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 39-(a) except for using 30 mg (0.070 mmol) of 2,3-dibromo-1-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 44 in place of 2-bromo- 1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one, whereby 24 mg of the title compound was obtained as a pale yellowish solid. (Yield: 64%) 'H-NMR Spectrum (CDCI3, 6 ppm): -0.03 (s, 9H), 0.82-0.90 (m, 2H), 1.40 (d, J=6.1 Hz, 6H), 3.41-3.49 (m, 2H), 4.52-4.64 (m, IH), 5.35 (s, 2H), 6.67 (t, J=75.0 Hz, IH), 7.03 (dd, J=8.3, 2.1 Hz, IH), 7.13 (d, J=2.1 Hz, IH), 7.30 (d, J=8.3 Hz, IH) , 8.20 (s, IH) , 9.90 (brs, IH) . [0601] (b) 3-Bromo-2-(4-difluoromethoxy-3-isopropoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 32-(b) except for using 22 mg (0.040 mmol) of 3-bromo-2-(4-difluoromethoxy-3-isopropoxy¬phenyl) -1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 41-(a) in place of 3-chloro-2-(3-cyclobutoxy-4-difluoromethoxy- phenyl)-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 7 mg of the title compound was obtained as a white solid. (Yield: 40%) Melting point: 250-256°C (decomposed). 'H-NMR Spectrum (DMSO-dg, 5 ppm): 1.35 (d, J=5.9 Hz, 6H) , 4.64-4.78 (m, IH), 7.13 (t, J=74.3 Hz, IH), 7.34 (d, J=8.3 Hz, IH) , 7.38 (dd, J=8.3, 2.0 Hz, IH) , 7.53 (d, J=2.0 Hz, IH), 8.16 (s, IH), 12.35 (brs, IH), 12.79 (brs, IH). [0602] Example 42 3-Chloro-2-(3-cyclopropoxy-4-methoxyphenyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1- 917) [0603] (a) 3-Chloro-2-(3-cyclopropoxy-4-methoxyphenyl)-1-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 400 mg (1.07 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3-d] pyridazin-4-one, and using 468 mg (1.61 mmol) of 2- (3-cyclopropoxy-4-methoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane obtained in the following Reference example 1-(e) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane, whereby 322 mg of the title compound was obtained as a pale yellowish solid. (Yield: 65%) Mass Spectrum (CI, m/z): 462 (M^+1). 'H-NMR Spectrum (CDCI3, 6 ppm) : -0.04 (s, 9H) , 0.77-0.93 (m, 6H) , 3.41-3.49 (m, 2H) , 3.72-3.80 (m, IH) , 3.93 (s, 3H) , 5.39 (s, 2H), 7.00 (d, J=8.3 Hz, IH), 7.09 (dd, J=8.3, 2.1 Hz, IH), 7.41 (d, J=2.1 Hz, IH), 8.19 (s, IH), 9.84 (brs, IH) . IR Spectrum (KBr, cm'^) : 1663. [0604] 42-(b) 3-Chloro-2-(3-cyclopropoxy-4-methoxyphenyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 313 mg (0.677 mmol) of 3- chloro-2-(3-cyclopropoxy-4-methoxyphenyl)-1-(2-trimethyl¬silylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 42-(a) in place of 2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-1-(2-trimethylsilylethoxymethyl) - 1, 5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, water was added to the reaction mixture, and the precipitated solid was collected by filtration. The obtained crude solid was dissolved by adding small amounts of tetrahydrofuran and methanol, followed by addition of water, and the solid precipitated by ultrasonic wave treatment was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 13 6 mg of the title compound as a white solid. (Yield: 61%) Melting point: 293-294°C. Mass Spectrum (CI, m/z): 332 (M^+1). ^H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.66-0.77 (m, 2H) , 0.77- 0.86 (m, 2H), 3.80 (s, 3H), 3.84-3.92 (m, IH), 7.12 (d, J=8.5 Hz, IH), 7.40 (dd, J=8.5, 2.2 Hz, IH), 7.75 (d, J=2.2 Hz, IH), 8.10 (s, IH), 12.23 (brs, IH). IR Spectrum (KBr, cm"^) : 1628. [605] Example 4 3 3-Bromo-2-(3-cyclopropoxy-4-methoxyphenyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1- 918) [606] 43-(a) 3-Bromo-2-(3-cyclopropoxy-4-methoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one Reaction and post treatment were carried out in the same manner as in Example 42-(a) except for using 227 mg (0.536 mmol) of 2,3-dibromo-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 44 in place of 2-bromo- 3-chloro-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 241 mg of the title compound was obtained as a pale yellowish solid. (Yield: 90%) ^H-NMR Spectrum (CDCI3, 8 ppm): -0.04 (s, 9H), 0.77-0.95 (m, 6H), 3.39-3.47 (m, 2H), 3.72-3.80 (m, IH), 3.93 (s, 3H), 5.39 (s, 2H), 6.99 (d, J=8.3 Hz, IH), 7.07 (dd, J=8.3, 2.0 Hz, IH), 7.39 (d, J=2.0 Hz, IH), 8.21 (s, IH), 9.97 (brs, IH) . [0607] 43-(b) 3-Bromo-2-(3-cyclopropoxy-4-methoxyphenyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 1 ml of dichloromethane solution containing 186 mg (0.367 mraol) of 3-brorao-2-(3-cyclopropoxy-4-methoxyphenyl)- 1- (2-tritnethylsilylethoxymethyl) -1, 5-dihydropyrrolo [2 , 3-d] - pyridazin-4-one obtained in Example 43-(a) was added 6 ml of 1,4-dioxane solution containing 4N hydrogen chloride, and the mixture was stirred at room temperature for 8 hours. After completion of the reaction, the solid obtained from the reaction suspension by filtration was washed with diisopropyl ether. To the obtained crude solid were added methanol and 28% aqueous ammonia, and the mixture was stirred at room temperature for 5 hours. Then, the solution was concentrated under reduced pressure and the obtained solid was washed with ethyl acetate and dried under reduced pressure to obtain 85 mg of the title compound as a white solid. (Yield: 62%) Melting point: 293-296°C (decomposed). Mass Spectrum (CI, m/z) : 376 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.68-0.87 (m, 4H), 3.81 (s, 3H), 3.85-3.92 (m, IH), 7.13 (d, J=8.5 Hz, IH), 7.38 (dd, J=8.5, 2.2 Hz, IH) , 7.76 (d, J=2 .2 Hz, IH) , 8.14 (s, IH), 12.32 (brs, IH), 12.78 (brs, IH). IR Spectrum (KBr, cm'^) : 1634. [0608] Example 44 3-Butyl-2-(3-cyclopropoxy-4-methoxyphenyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one (Exemplary compound No. 1- 923) [0609] 44-(a) 3-Butyl-2-(3-cyclopropoxy-4-methoxyphenyl)-1,5-bis- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 53 0 mg (0.999 mmol) of 2-bromo-3-butyl-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 22-(b) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1, 5-d.ihydropyrrolo [2, 3-d]pyrid.azin-4-one, and using 435 mg (1.50 mmol) of 2-(3-cyclopropoxy-4-methoxyphenyl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(e) in place of 2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxa¬borolane, whereby 53 7 mg of the title compound was obtained as a brownish oil. (Yield: 88%) Mass Spectrum (CI, m/z) : 614 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.05 (s, 9H), 0.00 (s, 9H), 0.76-0.92 (m, 6H), 0.83 (t, J=7.3 Hz, 3H), 0.95-1.04 (m, 2H), 1.22-1.35 (m, 2H), 1.56-1.68 (m, 2H), 2.73-2.81 (m, 2H), 3.36-3.43 (m, 2H), 3.69-3.79 (m, 3H), 3.93 (s, 3H), 5.30 (s, 2H), 5.61 (s, 2H), 6.93-6.99 (m, 2H), 7.25-7.27 (m, IH) , 8 . 17 (s, IH) . [0610] 44-(b) 3-Butyl-2-(3-cyclopropoxy-4-methoxyphenyl)-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 53 6 mg (0.8 73 mmol) of 3-butyl-2-(3-cyclopropoxy-4-methoxyphenyl)- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one obtained in Example 44-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-l,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one, whereby 329 mg of the title compound was obtained as a white solid. (Yield: 78%) Mass Spectrum (CI, m/z): 484 (M^+l). 'H-NMR Spectrum (CDCI3, 8 ppm) : -0.01 (s, 9H) , 0.78-0.94 (m, 4H), 0.89 (t, J=7.3 Hz, 3H), 0.95-1.03 (m, 2H), 1.33-1.47 (m, 2H), 1.66-1.78 (m, 2H), 2.93-3.02 (m, 2H), 3.68-3.81 (m, 3H), 3.91 (s, 3H), 5.60 (s, 2H), 6.96 (d, J=8.3 Hz, IH) , 7.05 (dd, J=8.3, 2.1 Hz, IH) , 7.41 (d, J=2.1 Hz, IH) , 8.06 (s, IH), 8.53 (brs, IH). IR Spectrum (KBr, cm"^) : 1628. [0611] 44- (c) 3-Butyl-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 6- (c) except for using 328 mg (0.678 mmol) of 3-butyl-2-(3-cyclopropoxy-4-methoxyphenyl)- 5-(2 -trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Example 44-(b) in place of 2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-3-propyl-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one, whereby 222 mg of the title compound was obtained as a white solid. (Yield: 93%) Melting point: 198-200°C. Mass Spectrum (CI, m/z): 354 (M^+l). ^H-NMR Spectrum (DMSO-dg, 8 ppm): 0.69-0.82 (m, 4H), 0.86 (t, J=7.3 Hz, 3H) , 1.25-1.38 (m, 2H) , 1.56-1.69 (m, 2H) , 2.85-2.94 (m, 2H), 3.79 (s, 3H), 3.82-3.91 (m, IH), 7.07- 7.16 (m, 2H), 7.43 (d, J=1.2 Hz, IH), 8.04 (s, IH), 12.01 (brs, IH), 12.05 (brs, IH). IR Spectrum (KBr, cm'^) : 1641. [0612] Example 45 3-Chloro-2-(3-cyclobutoxy-4-methoxyphenyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1- 1224) [0613] 45- (a) 3-Chloro-2-(3-cyclobutoxy-4-methoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 0.40 g (1.1 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, and using 0.49 g (1.6 mmol) of 2- (3-cyclobutoxy-4-methoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane obtained in the following Reference example l-(f) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane, whereby 339 mg of the title compound was obtained as a pale yellowish solid. (Yield: 67%) Mass Spectrum (CI, m/z) : 476 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.04 (s, 9H) , 0.81-0.90 (m, 2H), 1.55-1.75 (m, IH), 1.81-1.95 (m, IH), 2.21-2.36 (m, 2H), 2.42-2.54 (m, 2H), 3.40-3.47 (m, 2H), 3.94 (s, 3H), 4.61-4.72 (m, IH), 5.36 (s, 2H), 6.89 (d, J=2.0 Hz, IH), 6.99 (d, J=8.3 Hz, IH), 7.05 (dd, J=8.3, 2.0 Hz, IH), 8.19 (s, IH), 10.16 (brs, IH). [614] 45-(b) 3-Chloro-2-(3-cyclobutoxy-4-methoxyphenyl)-1,5- dihydropyrrolo[2,3-d] pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 32-(b) except for using 335 mg (0.70 mmol) of 3-chloro-2-(3-cyclobutoxy-4-methoxyphenyl)- 1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Example 45-(a) in place of 3- chloro-2-(3-cyclobutoxy-4-difluoromethoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one, whereby 2 04 mg of the title compound was obtained as a white solid. (Yield: 84%) Melting point: 285-287°C. Mass Spectrum (CI, m/z) : 346 (M'^+l) . 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 1.57-1.74 (m, IH) , 1.74- 1.88 (m, IH), 2.03-2.18 (m, 2H), 2.40-2.49 (m, 2H), 3.83 (s, 3H), 4.66-4.78 (m, IH), 7.13 (d, J=8.5 Hz, IH), 7.25 (d, J-2.1 Hz, IH), 7.37 (dd, J=8.5, 2.1 Hz, IH), 8.11 (s, IH), 12.31 (brs, IH). [615] Example 4 6 2- (3-Cyclopentoxy-4-methoxyphenyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one (Exemplary compound No. 1-1256) Reaction was carried out in the same manner as in Example 22-(a) except for using 107 mg (0.30 mmol) of ethyl 5-(3-cyclopentoxy-4-methoxyphenyl)-2-formyl-lH-pyrrol-3- carboxylate obtained in the following Reference example 47- (e) in place of ethyl l-benzyloxymethyl-5-(3-cyclopropoxy- 4-dif luoromethoxyphenyl) -4-(2-fluorobenzyl)-2-formyl-lH- pyrrol-3-carboxylate. After completion of the reaction, the solid obtained from the reaction suspension by filtra¬tion was washed successively with ethanol, water and then with diisopropyl ether, and dried under reduced pressure to obtain 44 mg of the title compound as a white solid. (Yield: 45%) Melting point: 290°C (decomposed). Mass Spectrum (CI, m./z) : 326 (M^+1) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 1.52-1.66 (m, 2H), 1.66- 1.79 (m, 4H), 1.86-2.01 (m, 2H), 3.78 (s, 3H), 4.90-4.96 (m, IH) , 7.03 (S, IH) , 7.03 (d, J=8.3 Hz, IH) , 7.37-7.43 (m, 2H), 8.12 (s, IH), 12.17 (brs, IH), 12.37 (brs, IH). IR Spectrum (KBr, cm"'): 1644. [0616] Example 4 7 3-Chloro-2-(3-cyclopropylmethoxy-4-methoxyphenyl)-1,5-di- hydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-1101) [0617] 47-(a) 3-Chloro-2-(3-cyclopropylmethoxy-4-methoxyphenyl) -1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 0.40 g (1.1 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , and using 0.57 g (1.9 mmol) of 2- (3-cyclopropylmethoxy-4-methoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane obtained in the following Reference example 2-(a) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl) -4,4,5,5-tetramethyl-[1,3,2]dioxaborolane, whereby 0.34 g of the title compound was obtained as a pale yellowish solid. (Yield: 67%) Mass Spectrum (CI, m/z) : 476 (M'^+l) . 'H-NMR Spectrum (cdci3, 5 ppm) -. -0.04 (s, 9H) , 0.33-0.40 (m, 2H), 0.62-0.70 (m, 2H), 0.80-0.88 (m, 2H), 1.29-1.41 (m, IH), 3.39-3.47 (m, 2H), 3.88 (d, J=6.8 Hz, 2H), 3.95 (s, 3H), 5.35 (s, 2H), 7.01 (d, J-8.2 Hz, IH), 7.02 (d, J=1.9 Hz, IH), 7.07 (dd, J=8.2, 1.9 Hz, IH), 8.18 (s, IH), 10.10 (brs, IH). [0618] 47-(b) 3-Chloro-2-(3-cyclopropylmethoxy-4-methoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 32-(b) except for using 340 mg (0.71 mmol) of 3-chloro-2-(3-cyclopropylmethoxy-4-methoxy- phenyl)-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 47-(a) in place of 3-chloro-2-(3-cyclobutoxy-4-difluoromethoxy- phenyl)-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 134 mg of the title compound was obtained as a white solid. (Yield: 55%) Melting point: 256-258°C. Mass Spectrum (CI, m/z): 346 (MVl). 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 0.30-0.38 (m, 2H) , 0.55- 0.64 (m, 2H), 1.20-1.35 (m, IH), 3.84 (s, 3H), 3.88 (d, J=6.8 Hz, 2H) , 7.13 (d, J=8.5 Hz, IH) , 7.34 (d, J=2.1 Hz, IH), 7.42 (dd, J=8.5, 2.1 Hz, IH), 8.11 (s, IH), 12.30 (brs, IH). [0619] Example 4 8 3-Chloro-2-(3-isopropoxy-4-methoxyphenyl)-1,5-dihydro- pyrrolo [2,3-d]pyridazin-4-one (Exemplary compound No. 1- 1191) [0620] 48-(a) 3-Chloro-2-(3-isopropoxy-4-raethoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 409 mg (1.10 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3-d] pyridazin-4-one, and using 714 mg (2.44 mmol) of 2- (3-isopropoxy-4-methoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane obtained in the following Reference example 1-(g) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane, whereby 315 mg of the title compound was obtained as a white solid. (Yield: 62%) Mass Spectrum (CI, m/z): 464 (M"+l). ^H-NMR Spectrum (cdci3, 5 ppm) : -0.04 (s, 9H) , 0.81-0.88 (m, 2H), 1.40 (d, J=6.1 Hz, 6H), 3.39-3.47 (m, 2H), 3.93 (s, 3H) , 4.50-4.59 (m, IH) , 5.37 (s, 2H) , 7.01 (d, J=8.5 Hz, IH) , 7.03-7.08 (m, 2H) , 8.18 (s, IH) , 9.94 (brs, IH) . [0621] 48-(b) 3-Chloro-2-(3-isopropoxy-4-methoxyphenyl)-1,5-di¬hydropyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 40-(b) except for using 305 mg (0.657 mmol) of 3-chloro-2-(3-isopropoxy-4-methoxyphenyl)- 1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one obtained in Example 48-(a) in place of 3- chloro-2-(4-difluoromethoxy-3-isopropoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] pyrid- azin-4-one, whereby 164 mg of the title compound was obtained as a white solid. (Yield: 75%) Melting point: 291-299°C. Mass Spectrum (CI, m/z): 334 (M^+l). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 1.31 (d, J=5.9 Hz, 6H) , 3.82 (s, 3H) , 4.54-4.67 (m, IH) , 7.14 (d, J=8.3 Hz, IH) , 7.37-7.44 (m, 2H), 8.11 (s, IH), 12.30 (brs, IH), 12.56 (brs, IH). IR Spectrum (KBr, cm"'): 1633. [0622] Example 4 9 2- (7-Difluoromethoxy-2,3-dihydrobenzofuran-2-spiro-1'- cyclopentan-4-yl)-1,5-dihydropyrrolo[2,3-d] pyridazin-4-one (Exemplary compound No. 5-67) To 1 ml of ethylene glycol solution containing 41 mg (0.1 mmol) of ethyl 5-(7-difluoromethoxy-2,3-dihydro- benzofuran-2-spiro-l'-cyclopentan-4-yl)-2-formyl-lH-pyrrol- 3- carboxylate obtained in the following Reference example 48-(e) was added 24 ]xl (0.5 mmol) of hydrazine monohydrate, and the mixture was stirred at 130°C for 16 hours. After completion of the reaction, the reaction mixture was poured into water, and the precipitated solid was collected by filtration. The obtained crude solid was applied to silica gel column chromatography (Eluent; chloroform:methanol= 20:1->10:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 22 mg of the title compound as a pale yellowish solid. (Yield: 59%) Melting point: 290-295°C. Mass Spectrum (CI, m/z) : 374 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 1.70-1.89 (m, 6H), 1.99- 2.08 (m, 2H), 3.52 (s, 2H), 6.85 (s, IH), 7.14 (d, J=8.8 Hz, IH), 7.15 (t, J=74.2 Hz, IH), 7.25 (d, J=8.8 Hz, IH), 8.15 (s, IH), 12.22 (brs, IH), 12.35 (brs, IH). IR Spectrum (KBr, cm"'): 1634. [0623] Example 50 2-(2,3-Dihydro-7-methoxybenzofuran-2-spiro-l'-cyclopentan- 4- yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 5-166) To 3 ml of ethylene glycol solution containing 111 mg (0.3 mmol) of ethyl 2-formyl-5-(2,3-dihydro-7-methoxy- benzofuran-2-spiro-l'-cyclopentan-4-yl)-lH-pyrrol-3- carboxylate obtained in the following Reference example 49- (e) was added 73 lal (1.5 mmol) of hydrazine monohydrate, and the mixture was stirred at 13 0°C for 5 hours. After completion of the reaction, the reaction mixture was poured into water, and the mixture was extracted with a mixed solvent (chloroform:methanol=5:1 (V/V)). The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; chloroform:methanol=20:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 82 mg of the title compound as a white solid. (Yield: 81%) Melting point: 265°C (decomposed). Mass Spectrum (CI, m/z) : 338 (M"+l) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 1.68-1.88 (m, 6H) , 1.91- 2.06 (m, 2H), 3.45 (s, 2H), 3.81 (s, 3H), 6.74 (d, J=0.6 Hz, IH) , 6.97 (d, J=8.5 Hz, IH) , 7.21 (d, J=8.5 Hz, IH) , 8.14 (d, J=0.6 Hz, IH), 12.22 (brs, 2H). IR Spectrum (KBr, cm'^) : 1645. [624] Example 51 3-Chloro-2-(2,3-dihydro-7-methoxybenzofuran-2-spiro-1'- cyclopentan-4-yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 5-167) [625] 51-(a) 3-Chloro-2-(2,3-dihydro-7-methoxybenzofuran-2-spiro- 1'-cyclopentan-4-yl)-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 201 mg (pure content: 84.6%, 0.450 mmol) of 2-bromo-3-chloro-l-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in the following Reference example 16- (d) in place of 2-bromo-l-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, and using 22 0 mg (0.665 mmol) of 2-(2,3-dihydro-7-methoxybenzofuran-2-spiro- 1'-cyclopentan-4-yl)-4,4,5,5-tetramethyl-[1,3,2]dioxa- borolane obtained in the following Reference example 1-(h) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane, whereby 253 mg of the title compound was obtained as pale yellowish foam substantially quantitatively. ^H-NMR Spectrum (cdci3, 5 ppm): -0.05 (s, 9H), 0.77-0.85 (m, 2H), 1.61-1.84 (m, 4H), 1.86-2.00 (m, 2H), 2.11-2.25 (m, 2H), 2.86 (d, J=15.9 Hz, IH), 3.25 (d, J=15.9 Hz, IH), 3.30-3.37 (m, 2H), 3.94 (s, 3H), 5.26 (d, J=10.7 Hz, IH), 5.35 (d, J=10.7 Hz, IH), 6.76 (d, J=8.3 Hz, IH), 6.87 (d, J=8.3 Hz, IH) , 8.20 (s, IH) , 10.11 (brs, IH) . [0626] 51-(b) 3-Chloro-2-(2,3-dihydro-7-methoxybenzofuran-2-spiro- 1'-cyclopentan-4-yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one Reaction and post treatment were carried out in the same manner as in Example 32-(b) except for using 233 mg (containing an amount corresponding to 0.450 mmol) of 3- chloro-2-(2,3-dihydro-7-methoxybenzofuran-2-spiro-1'-cyclo- pentan-4-yl)-1-(2-trimethylsilylethoxymethyl)-1,5 -dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 51-(a) in place of 3-chloro-2-(3-cyclobutoxy-4-difluoromethoxy¬phenyl) -1-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 127 mg of the title compound was obtained as a white solid. (Yield: 74%) Melting point: >300°C. Mass Spectrum (CI, m/z): 372 (M"+l). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 1.64-1.86 (m, 6H) , 1.90- 2.05 (m, 2H), 3.29 (s, 2H), 3.82 (s, 3H), 6.97 (d, J=8.5 Hz, IH), 7.00 (d, J=8.5 Hz, IH), 8.11 (s, IH), 12.32 (brs, IH) . IR Spectrum (KBr, cm"'): 1625. [627] Example 52 3 -Chloro-2 -(8 -di fluoromethoxy-2,2-dimethyl-2H-chromen-5- yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 2 -2) [628] 52-(a) 3-Chloro-2-(8-difluoromethoxy-2,2-dimethyl-2H- chromen-5-yl)-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 189 mg (0.500 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4-one , and using 352 mg (1.00 mmol) of 2- (8-difluoromethoxy-2,2 -dimethyl-2H-chromen-5-yl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(i) in place of 2-(3-cyclopropoxy-4- dif luoromethoxyphenyl) -4,4,5,5-tetramethyl-[1,3,2]dioxa¬borolane, whereby 183 mg of the title compound was obtained as a pale yellowish foam. (Yield: 70%) Mass Spectrum (CI, m/z): 524 (M'+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.07 (s, 9H), 0.75-0.82 (m, 2H), 1.50 (s, 3H), 1.51 (s, 3H), 3.25-3.32 (m, 2H), 5.23 (d, J=11.0 Hz, IH), 5.30 (d, J=11.0 Hz, IH), 5.72 (d, J=10.0 Hz, IH), 5.96 (d, J=10.0 Hz, IH), 6.68 (t, J=74.7 Hz, IH) , 6.81 (d, J-8.3 Hz, IH) , 7.15 (d, J=8.3 Hz, IH) , 8 .21 (s, IH) , 9.87 (brs, IH) . [0629] 52-(b) 3-Chloro-2-(8-difluoromethoxy-2,2-dimethyl-2H- chromen-5-yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 180 mg (0.34 mmol) of 3- chloro-2-(8-difluororaethoxy-2,2-dimethyl-2H-chromen-5-yl)- 1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Example 52-(a) in place of 2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethyl¬silylethoxymethyl) -1,5-dihydropyrrolo [2,3-d]pyridazin-4- one. After completion of the reaction, water was added to the reaction mixture and the precipitated solid was collected by filtration. The obtained solid was dissolved by adding a small amount of isopropanol, followed by addition of water, and the precipitated solid was collected by filtration. The obtained solid was washed with water and dried under reduced pressure to obtain 98 mg of the title compound as a white solid. (Yield: 73%) Melting point: 226-234°C. Mass Spectrum (FAB, m/z) : 394 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 1.45 (s, 6H) , 5.89 (d, J=9.9 Hz, IH), 6.19 (d, J=9.9 Hz, IH), 7.00 (d, J=8.4 Hz, IH) , 7.15 (t, J=74.2 Hz, IH) , 7.19 (d, J-8.4 Hz, IH) , 8.10 (s, IH), 12.27 (brs, IH). IR Spectrum (KBr, cm"'): 1649. [630] Example 53 2- (8-Difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)-3- methyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one HCl adduct (Exemplary compound No. 2-4) [631] 53-(a) 2-(8-Difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)- 3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 525 mg (1.49 mmol) of 2-(8-difluoromethoxy-2,2-dimethyl-2H- chromen-5-yl)-4,4,5,5 -tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(i) in place of 2-(3-eyelopropoxy-4-difluoromethoxyphenyl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane, whereby 574 mg of the title compound was obtained as a brownish oil substantially quantitatively. Mass Spectrum (CI, m/z) : 634 (M%1) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.08 (s, 9H) , 0.01 (s, 9H) , 0.73-0.80 (m, 2H), 0.97-1.04 (m, 2H), 1.49 (s, 3H), 1.50 (s, 3H), 2.27 (s, 3H), 3.22-3.30 (m, 2H), 3.71-3.79 (m, 2H), 5.17 (d, J=10.9 Hz, IH), 5.26 (d, J=10.9 Hz, IH), 5.59 (s, 2H) , 5.68 (d, J=10.0 Hz, IH) , 5.92 (d, J^IO.O Hz, IH) , 6.67 (t, J=75.0 Hz, IH), 6.77 (d, J=8.3 Hz, IH), 7.12 (d, J=8 .3 Hz, IH) , 8.18 (s, IH) . [632] 53-(b) 2-(8-Difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)- 3-methyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 574 mg (containing an amount corresponding to 0.754 mmol) of 2-(8- difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)-3-methyl-l,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Example 53-(a) in place of 2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-3-methyl-l,5-bis- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one, whereby 163 mg of the title compound was obtained as a white solid. (Yield: 43%) Mass Spectrum (CI, m/z): 5 04 (MVl) . 'H-NMR Spectrum (DMSO-dg, 8 ppm): -0.02 (s, 9H), 0.82-0.91 (m, 2H), 1.45 (s, 6H), 2.21 (s, 3H), 3.60-3.69 (m, 2H), 5.41 (s, 2H), 5.90 (d, J=10.2 Hz, IH), 6.11 (d, J=10.2 Hz, IH) , 6.95 (d, J=8.4 Hz, IH) , 7.14 (t, J=74.3 Hz, IH) , 7.19 (d, J=8.4 Hz, IH), 8.12 (s, IH), 12.19 (brs, IH). IR Spectrum (KBr, cm'^) : 1631. [633] 53-(c) 2-(8-Difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)- 3-methyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one HCl adduct Reaction was carried out in the same manner as in Example 6-(c) except for using 163 mg (0.323 mmol) of 2-(8- difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)-3-methyl-5- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Example 53-(b) in place of 3- chloro-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one. After completion of the reaction, the solid obtained from the reaction suspension by filtration was washed with diisopropyl ether and dried under reduced pressure to obtain 112 mg of the title compound as a white solid. (Yield: 84.6%) Melting point: >300°C. Mass Spectrum (CI, m/z) : 374 (M%1) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 1.45 (s, 6H) , 2.20 (s, 3H), 5.89 (d, J=10.0 Hz, IH), 6.11 (d, J=10.0 Hz, IH), 6.94 (d, J-8.4 Hz, IH), 7.14 (t, J=74.5 Hz, IH), 7.18 (d, J=8.4 Hz, IH), 8.06 (s, IH), 12.09 (brs, IH), 12.14 (brs, IH). IR Spectrum (KBr, cm"^) : 1505. [634] Example 54 2- (8-Difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)-3-ethyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one HCl adduct (Exemplary compound No. 2-5) [635] 54-(a) 2-(8-Difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)- 3- ethyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 794 mg (1.57 mmol) of 2-bromo-3-ethyl-1,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 19-(d) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, using 1.08 g (3-06 mmol) of 2-(8-difluoromethoxy-2,2-dimethyl-2H- chromen-5-yl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(i) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane, and using 57 mg of tricyclohexylphosphine in place of butyl-di-l-adamantyl- phosphine, whereby 1.03 g of the title compound was obtained as a brownish oil substantially quantitatively. Mass Spectrum (CI, m/z): 648 (M^+1). ^H-NMR Spectrum (cdci3, 5 ppm) : -0.08 (s, 9H) , 0.00 (s, 9H) , 0.73-0.80 (m, 2H), 0.97-1.05 (m, 2H), 1.12 (t, J=7.4 Hz, 3H), 1.49 (s, 6H), 2.56 (dq, J=13.7, 7.4 Hz, IH), 2.76 (dq, J=13.7, 7.4 Hz, IH) , 3.22-3.30 (m, 2H) , 3.72-3.80 (m, 2H) , 5.10 (d, J=10.9 Hz, IH), 5.23 (d, J=10.9 Hz, IH), 5.61 (s, 2H), 5.66 (d, J=10.0 Hz, IH), 5.90 (d, J=10.G Hz, IH), 6.68 (t, J=75.0 Hz, IH), 6.77 (d, J=8.3 Hz, IH), 7.11 (d, J=8.3 Hz, IH) , 8.19 (s, IH) . [0636] 54-(b) 2-(8-Difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)- 3-ethyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 1.02 g (containing an amount corresponding to 1.57 mmol) of 2-(8- difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)-3-ethyl-l,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Example 54-(a) in place of 2- (3 -eyelopropoxy-4 -di fluoromethoxyphenyl)-3-methyl-1,5-bis- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one, whereby 626 mg of the title compound was obtained as a yellowish white solid. (Yield: 77%) Mass Spectrum (CI, m/z): 518 (M"+l). 'H-NMR Spectrum (cdci3, 8 ppm) : 0.00 (s, 9H) , 0.96-1.04 (m, 2H), 1.18 (t, J=7.4 Hz, 3H), 1.50 (s, 6H), 2.75 (q, J=7.4 Hz, 2H), 3.71-3.79 (m, 2H), 5.60 (s, 2H), 5.70 (d, J=10.0 Hz, IH), 6.13 (d, J=10.G Hz, IH), 6.66 (t, J=75.0 Hz, IH), 6.85 (d, J=8.3 Hz, IH), 7.10 (d, J=8.3 Hz, IH), 8.05 (s. IH), 8.38 (brs, IH). IR Spectrum (KBr, cm'^) : 1633. [637] 54- (c) 2-(8-Difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)- 3-ethyl-l,5-dihydropyrrolo[2,3-d]pyridazin-4-one HCl adduct Reaction was carried out in the same manner as in Example 6-(c) except for using 613 mg (1.18 mmol) of 2-(8- difluoromethoxy-2,2-dimethyl-2H-chromen-5-yl)-3-ethyl-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 54-(b) in place of 3-chloro- 2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-1-(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one. After completion of the reaction, the solid obtained from the reaction suspension by filtration was washed with hexane and dried under reduced pressure to obtain 467 mg of the title compound as a white solid. (Yield: 93%) Melting point: >300°C. Mass Spectrum (CI, m/z): 388 (M"+l). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 1.08 (t, J=7.4 Hz, 3H) , 1.45 (s, 6H), 2.58 (q, J=7.4 Hz, 2H), 5.87 (d, J=10.0 Hz, IH), 6.07 (d, J=10.0 Hz, IH), 6.92 (d, J=8.3 Hz, IH), 7.15 (t, J=74.3 Hz, IH), 7.17 (d, J=8.3 Hz, IH), 8.05 (s, IH), 12.06 (brs, IH), 12.15 (brs, IH). IR Spectrum (KBr, cm'^) : 1498. [638] Example 55 3- Cyclopropyl-2-(8-difluoromethoxy-2,2-dimethyl-2H-chromen- 5-yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one HCl adduct (Exemplary compound No. 2-38) [639] 55- (a) 3-Cyclopropyl-2-(8-difluoromethoxy-2,2-dimethyl-2H- chromen-5-yl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 1.03 g (2.0 mmol) of 2-bromo-3-cyclopropyl-l,5-bis(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 28-(b) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, and using 1.40 g (3.97 mmol) of 2-(8-difluororaethoxy-2,2-dimethyl-2H- chromen-5-yl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(i) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane, whereby 1.3 5 g of the title compound was obtained as a yellowish oil substantial¬ly quantitatively. Mass Spectrum (CI, m/z): 660 (M^+1). 'H-NMR Spectrum (CDCl^, 5 ppm) : -0.07 (s, 9H) , 0.01 (s, 9H) , 0.60-0.84 (m, 6H), 0.97-1.04 (m, 2H), 1.48 (s, 3H), 1.50 (s, 3H), 1.86-1.96 (m, IH), 3.22-3.30 (m, 2H), 3.71-3.79 (m, 2H) , 5.12 (d, J=10.7 Hz, IH) , 5.21 (d, J=10.7 Hz, IH) , 5.60 (s, 2H), 5.68 (d, J=10.0 Hz, IH), 5.99 (d, J=10.0 Hz, IH), 6.69 (t, J=75.0 Hz, IH), 6.79 (d, J=8.3 Hz, IH), 7.11 (d, J=8.3 Hz, IH), 8.17 (s, IH). [0640] 55-(b) 3-Cyclopropyl-2-(8-difluoromethoxy-2,2-dimethyl-2H- chromen-5-yl)-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 1.35 g (containing an amount corresponding to 2.00 mmol) of 3- cyclopropyl-2-(8-difluoromethoxy-2,2-dimethyl-2H-chromen-5- yl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 55-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one , whereby 907 mg of the title compound was obtained as a pale yellowish solid. (Yield: 84%) Mass Spectrum (CI, m/z): 530 (M"+l) . 'H-NMR Spectrum (cdci3, 6 ppm) : -0.01 (s, 9H) , 0.62-0.69 (m. 2H), 0.71-0.80 (m, 2H), 0.93-1.02 (m, 2H), 1.50 (s, 6H), 1.84-1.95 (m, IH), 3.69-3.77 (m, 2H), 5.58 (s, 2H), 5.71 (d, J=10.0 Hz, IH) , 6.25 (d, J=10.0 Hz, IH) , 6.66 (t, J=75.1 Hz, IH) , 6.87 (d, J=8.3 Hz, IH) , 7.08 (d, J=8.3 Hz, IH) , 8.04 (s, IH) , 8.61 (brs, IH) . IR Spectrum (KBr, cm^') : 1647. [641] 55-(c) 3-Cyclopropyl-2-(8-difluoromethoxy-2,2-dimethyl-2H- chromen-5-yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one HCl adduct Reaction was carried out in the same manner as in Example 6-(c) except for using 900 mg (1.70 mmol) of 3- cyclopropyl-2-(8-difluoromethoxy-2,2-dimethyl-2H-chromen-5- yl)-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one obtained in Example 55-(b) in place of 3-chloro-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one. After completion of the reaction, the solid obtained from the reaction suspension by filtration was washed with 1,4-dioxane and dried under reduced pressure to obtain 73 9 mg of the title compound as a white solid substantially quantitatively. Melting point: >300°C. Mass Spectrum (CI, m/z) : 400 (M^l) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.64-0.71 (m, 2H), 0.76- 0.83 (m, 2H) , 1.44 (s, 6H) , 1.68-1.80 (m, IH) , 5.88 (d, J=10.2 Hz, IH) , 6.16 (d, J=10.2 Hz, IH) , 6.96 (d, J=8.3 Hz, IH) , 7.15 (t, J=74.5 Hz, IH) , 7.17 (d, J=8 .3 Hz, IH) , 8.02 (s, IH), 12.11 (brs, 2H). IR Spectrum (KBr, cm"'): 14 99. [642] Example 56 3-Chloro-2-(8-difluoromethoxy-2H-chromen-2-spiro-l'-cyclo- butan-5-yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 4-35) Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 0.34 g (0.90 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , and using 0.49 g (1.3 mmol) of 2- (8-difluoromethoxy-2H-chromen-2-spiro-l'-cyclobutan-5-yl)- 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example l-(j) in place of 2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-4,4,5,5 -tetramethyl- [1,3,2]dioxaborolane, whereby 249 mg of a pale yellowish foam was obtained. Then, the reaction was carried out in the same manner as in Example 1-(b) except for using the above-mentioned pale yellowish foam in place of 2-(3-cyclopropoxy-4- dif luoromethoxyphenyl ) -1-(2-trimethylsilylethoxymethyl)- 1, 5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, water was added to the reaction mixture and the precipitated solid was collected by filtration. The obtained crude solid was purified by high performance liquid chromatography (column; Kromacil™ 100-5-C18 (20x250 mm (manufactured by EKA CHEMICALS), Eluent; acetonitrile: water:trifluoroacetic acid=600:400:1 (V/V/V), Flow rate; 10 ml/min) to obtain 90 mg of the title compound as a white solid. (Yield: 24%) Melting point: 289-291°C. Mass Spectrum (CI, m/z) : 406 (M%1) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 1.68-1.92 (m, 2H) , 2.19- 2.29 (m, 2H), 2.38-2.51 (m, 2H), 6.18 (d, J=10.2 Hz, IH), 6.30 (d, J=10.2 Hz, IH), 7.01 (d, J=8.5 Hz, IH), 7.21 (d, J=8.5 Hz, IH), 7.21 (t, J=74.2 Hz, IH), 8.12 (s, IH), 12.36 (brs, IH), 12.68 (brs, IH). [0643] Example 57 3-Chloro-2-(8-difluoromethoxy-2H-chromen-2-spiro-l'-cyclo- pentan-5-yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 4-68) [644] 57-(a) 3-Chloro-2-(8-difluoromethoxy-2H-chromen-2-spire-1'- cyclopentan-5-yl)-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 0.34 g (0.90 mmol) of 2-bromo-3-chloro-l-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the following Reference example 16-(d) in place of 2- bromo-1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3-d] pyridazin-4-one, and using 0.51 g (1.34 mmol) of 2- (8-difluoromethoxy-2H-chromen-2-spiro-l'-cyclopentan-5-yl)- 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(k) in place of 2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane, whereby 290 mg of the title compound was obtained as a pale yellowish foam. (Yield: 59%) 'H-NMR Spectrum (cdci3, 5 ppm): -0.07 (s, 9H), 0.74-0.82 (m, 2H), 1.56-1.83 (m, 4H), 1.88-2.06 (m, 2H), 2.12-2.34 (m, 2H), 3.25-3.32 (m, 2H), 5.22 (d, J=10.9 Hz, IH), 5.30 (d, J=10.9 Hz, IH), 5.76 (d, J=10.0 Hz, IH), 5.99 (d, J=10.0 Hz, IH) , 6.64 (t, J=74.7 Hz, IH) , 6.80 (d, J=8.4 Hz, IH) , 7.13 (d, J=8.4 Hz, IH) , 8.21 (s, IH) , 9.88 (brs, IH) . [645] 57-(b) 3-Chloro-2-(8-difluoromethoxy-2H-chromen-2-spiro-l'- cyclopentan-5-yl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 1-(b) except for using 0.2 9 g (0.53 mmol) of 3- chloro-2-(8-difluoromethoxy-2H-chromen-2-spiro-l'-cyclo- pentan-5-yl)-1-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 57-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-1-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one. After completion of the reaction, water was added to the reaction mixture and the precipitated solid was collected by filtration. The obtained solid was washed with a mixed solvent (acetonitrile:water=l:1 (V/V)) and dried under reduced pressure to obtain 66 mg of the title compound as a white solid. (Yield: 3 0%) Melting point: >300°C. Mass Spectrum (CI, m/z): 420 (MVl). 'H-NMR Spectrum (DMSO-dg, 5 ppm): 1.62-1.77 (m, 4H), 1.78- 1.92 (m, 2H), 2.04-2.16 (m, 2H), 5.97 (d, J=10.0 Hz, IH), 6.20 (d, J=10.0 Hz, IH), 6.99 (d, J=8.3 Hz, IH), 7.10 (t, J-74.1 Hz, IH), 7.19 (d, J=8.3 Hz, IH), 8.12 (s, IH), 12.36 (brs, IH), 12.70 (brs, IH). [646] Example 5 8 2-(2-Cyclopropyl-8-difluoromethoxy-2H-chromen-5-yl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 3-1) [647] 58-(a) 2-(2-Cyclopropyl-8-difluoromethoxy-2H-chromen-5-yl)- 1-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 0.30 g (0.82 mmol) of 2-(2-cyclopropyl-8-difluoromethoxy-2H- chromen-5-yl)-4,4,5,5 -tetramethyl-[1,3,2]dioxaborolane obtained in the following Reference example 1-(1) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane, whereby 2 06 mg of the title compound was obtained as a slightly yellowish oil. (Yield: 60%) Mass Spectrum (CI, m/z): 502 (M^+l). 'h-NMR Spectrum (cdci3, 8 ppm) : -0.08 (s, 9H), 0.33-0.42 (m, IH), 0.48-0.57 (m, IH), 0.58-0.69 (m, 2H), 0.75-0.84 (m, 2H), 1.19-1.34 (m, IH), 3.24-3.34 (m, 2H), 4.30-4.37 (m, IH) , 5.31 (s, 2H) , 5.83 (dd, J=10.1, 3.7 Hz, IH) , 6.22 (dd, J=10.1, 1.6 Hz, IH), 6.73 (t, J=75.1 Hz, IH), 6.83 (d, J=0.7 Hz, IH), 6.86 (d, J=8.3 Hz, IH), 7.12 (d, J=8.3 Hz, IH), 8.26 (d, J-0.7 Hz, IH), 10.43 (brs, IH). [648] 58-(b) 2-(2-Cyclopropyl-8-difluoromethoxy-2H-chromen-5-yl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Example 31-(b) except for using 194 mg (0.387 mmol) of 2- (2-cyclopropyl-8-difluoromethoxy-2H-chromen-5-yl)-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Example 58-(a) in place of 2-(3- cyclobutoxy-4-difluoromethoxyphenyl)-1-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, the reaction mixture was neutralized with a saturated aqueous solution of sodium hydrogencarbonate and the mixture was extracted with a mixed solvent (chloroform/methanol=9/l (V/V)). The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. To the obtained solid were added methanol and 28% aqueous ammonia, and the mixture was stirred under room temperature for 3 hours. Then, the solution was concentrated under reduced pressure and the obtained residue was applied to silica gel column chromatography (Eluent; chloroform: methanol=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 81 mg of the title compound as a white solid. (Yield: 56%) Melting point: 232-242°C. Mass Spectrum (CI, m/z): 372 (M^+1). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.37-0.63 (m, 4H) , 1.22- 1.33 (m, IH), 4.44 (ddd, J=8.1, 3.7, 1.5 Hz, IH), 6.04 (dd, J=10.0, 3.7 Hz, IH), 6.65 (d, J=0.6 Hz, IH), 6.68 (dd, J=10.0, 1.5 Hz, IH), 7.09 (d, J=8.4 Hz, IH), 7.14 (t, J=74.5 Hz, IH), 7.20 (d, J=8.4 Hz, IH), 8.16 (d, J=0.6 Hz, IH), 12.31 (brs, IH), 12.40 (brs, IH). [649] Example 59 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclopropyl- methoxymethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-112) [650] 59-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propylmethoxymethyl-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 1-(a) except for using 610 mg (1.42 mmol) of 2-bromo-3-cyclopropylmethoxymethyl-l-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in the following Reference example 50 in place of 2-bromo-l-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 590 mg of the title compound was obtained as a pale yellowish foam. (Yield: 76%) Mass Spectrum (CI, m/z): 548 (M'+l). ^H-NMR Spectrum (DMSO-dg, 8 ppm) : -0.12 (s, 9H) , 0.03-0.10 (m, 2H), 0.33-0.41 (m, 2H), 0.67-0.86 (m, 6H), 0.86-0.98 (m, IH), 3.26 (d, J=6.8 Hz, 2H), 3.36-3.45 (m, 2H), 3.88- 3.96 (m, IH), 4.58 (s, 2H), 5.52 (s, 2H), 7.14 (t, J=74.2 Hz, IH) , 7.25 (dd, J=8.3, 2.0 Hz, IH) , 7.33 (d, J=8.3 Hz, IH), 7.69 (d, J=2.0 Hz, IH), 8.50 (s, IH), 12.41 (brs, IH). [651] 59-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propylmethoxymethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one Reaction was carried out in the same manner as in Example 1-(b) except for using 581 mg (1.06 mmol) of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclopropylmethoxy- methyl-1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one obtained in Example 59-(a) in place of 2-(3-eyelopropoxy-4-difluoromethoxyphenyl)-1-(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, water was added to the obtained concentrate, and precipitated solid was collected by filtration and washed with water. The obtained crude solid was applied to silica gel column chromatography (Eluent; ethyl acetate), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 287 mg of the title compound as a white solid. (Yield: 65%) Melting point: 170-172°C. Mass Spectrum (CI, m/z): 418 (M^+1). 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 0.10-0.16 (m, 2H) , 0.38- 0.46 (m, 2H), 0.73-0.82 (m, 2H), 0.83-0.91 (m, 2H), 0.96- 1.07 (m, IH), 3.37 (d, J=6.8 Hz, 2H), 3.93-4.00 (m, IH), 4.80 (s, 2H), 7.11 (t, J=74.3 Hz, IH), 7.34 (d, J=8.4 Hz, IH) , 7.43 (dd, J-8.4, 2.0 Hz, IH) , 7.94 (d, J=2 . 0 Hz, IH) , 8.15 (s, IH), 12.24 (brs, IH), 12.48 (brs, IH). IR Spectrum (KBr, cm'^) : 1645. [652] Example 60 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-isopropoxy- methyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-86) 60-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- propoxymethyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 171 mg (0.314 mmol) of 2-bromo-3-isopropoxymethyl-1,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in the following Reference example 51 in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 196 mg of the title compound was obtained as a slightly yellowish oil. (Yield: 94%) Mass Spectrum (CI, m/z) : 666 (M^'+l) . 'H-NMR Spectrum (cdci3, 8 ppm) : -0.02 (s, 9H) , 0.00 (s, 9H), 0.79-1.03 (m, 8H), 1.18 (d, J=6.1 Hz, 6H), 3.47-3.56 (m, 2H) , 3.68-3.77 (m, 2H) , 3.78-3.90 (m, 2H) , 4.68 (s, 2H) , 5.34 (s, 2H), 5.60 (s, 2H), 6.60 (t, J=74.8 Hz, IH), 7.19 (dd, J-8.3, 1.9 Hz, IH), 7.26 (d, J=8.3 Hz, IH), 7.64 (d, J=1.9 Hz, IH), 8.19 (s, IH). IR Spectrum (neat, cm"^) : 1667. [654] 60-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- propoxymethyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 191 mg (0.287 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-isopropoxymethyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 60-(a) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-methyl-l,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 135 mg of the title compound was obtained as a white solid. (Yield: 88%) Mass Spectrum (CI, m/z): 536 (M^+1). ^H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , 0.80-0.90 (m, 4H), 0.91-1.00 (m, 2H), 1.22 (d, J=6.1Hz, 6H), 3.66-3.75 (m, 2H), 3.84-3.99 (m, 2H), 4.85 (s, 2H), 5.59 (s, 2H), 6.56 (t, J=74.8 Hz, IH), 7.20-7.25 (m, IH), 7.26 (d, J=8.3 Hz, IH) , 7.83 (d, J=1.2 Hz, IH) , 8.09 (s, IH) , 9.11 (brs, IH) . IR Spectrum (KBr, cm"'): 1627. [655] 60-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso¬propoxymethyl-l, 5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 1.22 g (2.28 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-isopropoxymethyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the same manner as in Example 60-(b) in place of 3-cyclobutoxy- methyl-2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one, whereby 619 mg of the title compound was obtained as a white solid. (Yield: 67%) Melting point: 196-197°C. Mass Spectrum (CI, m/z): 406 (M^+1). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.75-0.80 (m, 2H) , 0.83- 0.88 (m, 2H) , 1.13 (d, J=6.1 Hz, 6H) , 3.76-3.84 (m, IH) , 3.93-3.98 (m, IH), 4.79 (s, 2H), 7.10 (t, J=74.3 Hz, IH), 7.33 (d, J=8.4 Hz, IH), 7.43 (dd, J=8.4, 2.0 Hz, IH), 7.93 (d, J=2.0 Hz, IH) , 8.15 (s, IH) , 12.23 (brs, IH) . IR Spectrum (KBr, cm'^) : 1657. [656] Example 61 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2-fluoro- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-90) [657] 61-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- fluoroethoxymethyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 4 00 mg (0.726 mmol) of 2-bromo-3-(2-fluoroethoxymethyl)-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in the following Reference example 52 in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilyl¬ethoxymethyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 43 6 mg of the title compound was obtained as a colorless oil. (Yield: 90%) ^H-NMR Spectrum (cdci3, 5 ppm) : -0.03 (s, 9H) , -0.01 (s, 9H) , 0.76-0.85 (m, 4H) , 0.85-0.93 (m, 2H) , 0.95-1.03 (m, 2H) , 3.47-3.57 (m, 2H) , 3.68-3.77 (m, 2H) , 3.80-3.88 (m, 2H) , 3.92-3.98 (m, IH) , 4.44-4.49 (m, IH) , 4.60-4.65 (m. IH), 4.76 (s, 2H), 5.37 (s, 2H), 5.60 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 7.16 (dd, J=8.3, 2.0 Hz, IH), 7.27 (d, J=8.3 Hz, IH) , 7.70 (d, J=2 . 0 Hz, IH) , 8.22 (s, IH) . [658] 61-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- fluoroethoxymethyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 4 06 mg (0.606 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-fluoroethoxymethyl)-1,5-bis(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 61-(a) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 280 mg of the title compound was obtained as a white solid. (Yield: 86%) Mass Spectrum (CI, m/z) : 540 (MVl) . 'H-NMR Spectrum (DMSO-dg, 8 ppm) : -0.05 (s, 9H) , 0.71-0.80 (m, 2H), 0.80-0.90 (m, 4H), 3.60-3.68 (m, 2H), 3.70-3.75 (m, IH), 3.80-3.86 (m, IH), 3.91-3.99 (m, IH), 4.43-4.48 (m, IH), 4.59-4.64 (m, IH), 4.84 (s, 2H), 5.43 (s, 2H), 7.10 (t, J=74.2 Hz, IH) , 7.33 (d, J=8.3 Hz, IH) , 7.38 (dd, J=8.3, 1.9 Hz, IH) , 7.92 (d, J=1. 9 Hz, IH) , 8.22 (s, IH) , 12.62 (brs, IH). [659] 61-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- fluoroethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 248 mg (0.460 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-fluoroethoxymethyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 61-(b) in place of 3-cyclobutoxymethyl-2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-5-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 60 mg of the title compound was obtained as a gray solid. (Yield: 32%) Melting point: 139-140°C. 'H-NMR Spectrum (DMSO-dg, 8 ppm): 0.67-0.90 (m, 4H), 3.67- 3.76 (m, IH), 3.78-3.87 (m, IH), 3.90-3.99 (m, IH), 4.42- 4.51 (m, IH), 4.56-4.67 (m, IH), 4.84 (s, 2H), 7.09 (t, J=74.1 Hz, IH), 7.32 (d, J=8.5 Hz, IH), 7.39 (d, J=8.8 Hz, IH), 7.92 (s, IH), 8.15 (s, IH), 12.27 (brs, IH). IR Spectrum (KBr, cm''): 1639. [0660] Example 62 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-isobutoxy- methyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-1289) [0661] 62-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- butoxymethyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 1.22 g (2.18 mmol) of 2-bromo-3-isobutoxymethyl-1,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one obtained in the same manner as in the following Reference example 53 in place of 2-bromo-3-methyl-1,5-bis- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one, whereby 1.3 5 g of the title compound was obtained as a slightly yellowish oil. (Yield: 91%) Mass Spectrum (CI, m/z) : 680 (M%1) . 'H-NMR Spectrum (cdci3, 8 ppm): -0.03 (s, 9H), -0.01 (s, 9H), 0.79-0.85 (m, 4H), 0.85-0.90 (m, 2H), 0.85 (d, J=6.7 Hz, 6H), 0.96-1.01 (m, 2H), 1.80-1.89 (m, IH), 3.35 (d, J=6.7 Hz, 2H), 3.48-3.53 (m, 2H), 3.71-3.75 (m, 2H), 3.79- 3.84 (m, IH), 4.69 (s, 2H), 5.36 (s, 2H), 5.61 (s, 2H), 6.59 (t, J=74.7 Hz, IH), 7.19 (dd, J=8.3, 1.9 Hz, IH), 7.26 (d, J=8.3 Hz, IH) , 7.62 (d, J=1.9 Hz, IH) , 8.20 (s, IH) . 62-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-iso- butoxymethyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 1.35 g (1.99 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-isobutoxymethyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 62-(a) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0. 84 g of the title compound was obtained as a white foam. (Yield: 77%) Mass Spectrum (CI, m/z) : 550 (M^l) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H), 0.83-0.87 (m, 4H), 0.87 (d, J=6.7 Hz, 6H), 0.93-0.99 (m, 2H), 1.82-1.91 (m, IH), 3.41 (d, J=6.7 Hz, 2H), 3.70-3.74 (m, 2H), 3.85- 3.89 (m, IH), 4.86 (s, 2H), 5.59 (s, 2H), 6.56 (t, J=74.8 Hz, IH), 7.23 (d, J=8.3 Hz, IH), 7.26 (dd, J=8.3, 1.9 Hz, IH) , 7.83 (d, J=1.9 Hz, IH) , 8.11 (s, IH) , 9.03 (brs, IH) . [0663] 62-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3- isobutoxymethyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 0.83 g (1.51 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-isobutoxymethyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 62-(b) in place of 3-cyclobutoxymethyl-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-5-(2-trimethylsilylethoxymethyl)- 1, 5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 402 mg of the title compound was obtained as a white solid. (Yield: 64%) Melting point: 162-164°C. Mass Spectrum (CI, m/z): 420 (M^+1). 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 0.73-0.89 (m, 4H) , 0.82 (d, J=6.7 Hz, 6H), 1.71-1.86 (m, IH), 3.30 (d, J=6.7 Hz, 2H), 3.91-4.00 (m, IH), 4.80 (s, 2H), 7.10 (t, J=74.3 Hz, IH) , 7.32 (d, J=8.4 Hz, IH) , 7.43 (dd, J=8.4, 2.0 Hz, IH) , 7.91 (d, J=2.0 Hz, IH) , 8.15 (s, IH) , 12.21 (brs, IH) . IR Spectrum (KBr, cm"^) : 1645. [0564] Example 63 3-(sec-Butoxymethyl)-2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-12 99) [665] 63-(a) 3-(sec-Butoxymethyl)-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-1,5-bis(2 -trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d] pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 0.81 g (1.44 mmol) of 2-bromo-3-(sec-butoxymethyl)-1,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one obtained in the same manner as in the following Reference example 54 in place of 2-bromo-3-methyl-1,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one, whereby 0.8 8 g of the title compound was obtained as a pale yellowish solid. (Yield: 90%) Mass Spectrum (CI, m/z) : 680 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.03 (s, 9H) , -0.01 (s, 9H), 0.78-0.91 (m, 6H), 0.83 (t, J=7.2 Hz, 3H), 0.94-1.03 (m, 2H), 1.16 (d, J=6.1 Hz, 3H), 1.34-1.49 (m, IH), 1.50- 1.65 (m, IH), 3.47-3.55 (m, 2H), 3.53-3.64 (m, IH), 3.69- 3.76 (m, 2H), 3.78-3.85 (m, IH), 4.67 (d, J=10.3 Hz, IH), 4.73 (d, J=10.3 Hz, IH), 5.34 (s, 2H), 5.59 (d, J=9.8 Hz, IH) , 5.62 (d, J=9.8 Hz, IH) , 6.59 (t, J=74.7 Hz, IH) , 7.20 (dd, J=8.3, 1.9 Hz, IH) , 7.26 (d, J=8.3 Hz, IH) , 7.62 (d, J=1.9 Hz, IH), 8.19 (s, IH). 63-(b) 3-(sec-Butoxymethyl)-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-5-(2 -trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.88 g (1.30 mmol) of 3-(sec-butoxymethyl)-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 63-(a) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.64 g of the title compound was obtained as a white foam. (Yield: 90%) Mass Spectrum (CI, m/z) : 550 (MVl) . ^H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , 0.81-0.89 (m, 4H), 0.85 (t, J=7.4 Hz, 3H), 0.92-1.01 (m, 2H), 1.21 (d, J-6.1 Hz, 3H), 1.38-1.54 (m, IH), 1.54-1.71 (m, IH), 3.63- 3.75 (m, 3H), 3.84-3.91 (m, IH), 4.85 (d, J=10.7 Hz, IH), 4.89 (d, J=10.7 Hz, IH), 5.60 (s, 2H), 6.57 (t, J=74.8 Hz, IH) , 7.23 (d, J=8.3 Hz, IH) , 7.29 (dd, J=8.3, 2.0 Hz, IH) , 7.82 (d, J=2.0 Hz, IH), 8.10 (s, IH), 8.93 (brs, IH). [0667] 63-(c) 3-(sec-Butoxymethyl)-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 0.64 g (1.16 mmol) of 3-(sec-butoxymethyl)-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 63-(b) in place of 3-cyclobutoxymethyl-2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-5-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 3 03 mg of the title compound was obtained as a white solid. (Yield: 61%) Melting point: 103-106°C. Mass Spectrum (CI, m/z): 420 (M^+l). 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.72-0.90 (m, 4H) , 0.77 (t, J-7.4 Hz, 3H), 1.11 (d, J=6.1 Hz, 3H), 1.31-1.56 (m, 2H) , 3.53-3.65 (m, IH) , 3.91-3.99 (m, IH) , 4.78 (d, J=ll.l Hz, IH), 4.83 (d, J=ll.l Hz, IH), 7.10 (t, J=74.5 Hz, IH), 7.32 (d, J=8.4 Hz, IH), 7.46 (dd, J=8.4, 2.1 Hz, IH), 7.94 (d, J=2.1 Hz, IH), 8.14 (s, IH), 12.20 (brs, IH). IR Spectrum (KBr, cm"'): 1643. [0668] Example 64 3-(tert-Butoxyraethyl)-2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-13 09) [669] 64-(a) 3-(tert-Butoxymethyl)-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 0.83 g (1.48 mmol) of 2-bromo-3-(tert-butoxymethyl)-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in the same manner as in the following Reference example 55 in place of 2-bromo-3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 0.90 g of the title compound was obtained as a slightly yellowish oil. (Yield: 89%) Mass Spectrum (CI, m/z): 680 (M^+1). 'H-NMR Spectrum (cdci3, 8 ppm): -0.02 (s, 9H), 0.00 (s, 9H), 0.78-0.92 (m, 6H), 0.95-1.03 (m, 2H), 1.35 (s, 9H), 3.48- 3.57 (m, 2H), 3.68-3.76 (m, 2H), 3.80-3.87 (m, IH), 4.64 (s, 2H), 5.31 (s, 2H), 5.60 (s, 2H), 6.59 (t, J=74.7 Hz, IH) , 7.22 (dd, J=8.3, 1.7 Hz, IH) , 7.26 (d, J=8.3 Hz, IH) , 7.61 (d, J=1.7 Hz, IH) , 8.17 (s, IH) . [670] 64-(b) 3-(tert-Butoxymethyl)-2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.90 g (1.33 mmol) of 3-(tert-butoxymethyl)-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 64-(a) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxy- methyl) -1, 5-dihydropyrrolo [2 , 3-d] pyrida2;in-4-one, whereby 0.51 g of the title compound was obtained as a white solid. (Yield: 70%) Mass Spectrum (CI, m/z) : 550 (M''+l) . ^H-NMR Spectrum (cdci3, 5 ppm): -0.01 (s, 9H), 0.81-0.87 (m, 4H), 0.93-1.00 (m, 2H), 1.35 (s, 9H), 3.66-3.74 (m, 2H), 3.87-3.94 (m, IH), 4.80 (s, 2H), 5.59 (s, 2H), 6.56 (t, J=74.7 Hz, IH), 7.24 (d, J=8.3 Hz, IH), 7.33 (dd, J=8.3, 2.1 Hz, IH), 7.73 (d, J=2.1 Hz, IH), 8.07 (s, IH), 8.83 (brs, IH) . [0671] 64-(c) 3-(tert-Butoxymethyl)-2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 0.48 g (0.87 mmol) of 3-(tert-butoxymethyl)-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 64-(b) in place of 3-cyclobutoxymethyl-2-(3-cyclo- propoxy-4 -dif luoromethoxyphenyl) -5-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 183 mg of the title compound was obtained as a white solid. (Yield: 50%) Melting point: >300°C. Mass Spectrum (CI, m/z): 420 (MVl). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.73-0.90 (m, 4H) , 1.26 (s, 9H), 3.95-4.03 (m, IH), 4.71 (s, 2H), 7.10 (t, J=74.2 Hz, IH), 7.33 (d, J=8.4 Hz, IH), 7.49 (dd, J=8.4, 2.1 Hz, IH), 7.83 (d, J=2.1 Hz, IH), 8.13 (s, IH), 12.17 (brs, IH). IR Spectrum (KBr, cm"^) : 1656. [672] Example 65 2- (3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1-ethyl- propoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-1319) [673] 65-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- ethylpropoxymethyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 0.65 g (1.13 mmol) of 2-bromo-3-(1-ethylpropoxymethyl)-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one obtained in the following Reference example 56 in place of 2-bromo-3-methyl-1,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.7 0 g of the title compound was obtained as a slightly yellowish oil. (Yield: 89%) Mass Spectrum (CI, m/z) : 694 (M^+1) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), -0.01 (s, 9H), 0.81-1.00 (m, 8H), 0.82 (t, J=7.4 Hz, 6H), 1.47-1.54 (m, 4H), 3.34-3.40 (m, IH), 3.47-3.51 (m, 2H), 3.70-3.75 (m, 2H), 3.78-3.83 (m, IH), 4.71 (s, 2H), 5.34 (s, 2H), 5.61 (s, 2H), 6.59 (t, J=74.7 Hz, IH), 7.20 (dd, J=8.2, 2.0 Hz, IH) , 7.25 (d, J=8.2 Hz, IH) , 7.61 (d, J=2 . 0 Hz, IH) , 8.20 (s, IH). [674] 65-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- ethylpropoxymethyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.70 g (1.01 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3- (1-ethylpropoxymethyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 65-(a) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-methyl-1,5-bis(2-trimethylsilylethoxy- methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.2 7 g of the title compound was obtained as a white solid. (Yield: 47%) Mass Spectrum (CI, m/z) : 564 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : -0.06 (s, 9H) , 0.74 (t, J=7.4 Hz, 6H), 0.75-0.87 (m, 6H), 1.40-1.49 (m, 4H), 3.40- 3.45 (m, IH), 3.61-3.66 (m, 2H), 3.91-3.96 (m, IH), 4.81 (s, 2H), 5.43 (S, 2H), 7.09 (t, J=74.4 Hz, IH), 7.31 (d, J=8.4 Hz, IH) , 7.46 (dd, J=8.4, 2.0 Hz, IH) , 7.94 (d, J=2 .0 Hz, IH), 8.20 (s, IH), 12.56 (brs, IH). [675] 65-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- ethylpropoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4- one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 0.26 g (0.46 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(1-ethylpropoxymethyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 65-(b) in place of 3-cyclobutoxymethyl-2-(3-cyclo¬propoxy-4 -dif luoromethoxyphenyl) -5-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 6 9 mg of the title compound was obtained as a white solid. (Yield: 35%) Melting point: 133-162°C. Mass Spectrum (CI, m/z): 434 (M"+l). 'H-NMR Spectrum (DMSO-dg, 8 ppm): 0.72-0.81 (m, 2H), 0.75 (t, J=7.3 Hz, 6H), 0.82-0.90 (m, 2H), 1.38-1.53 (m, 4H), 3.39-3.48 (m, IH), 3.91-3.99 (m, IH), 4.82 (s, 2H), 7.10 (t, J=74.3 Hz, IH) , 7.32 (d, J=8 .3 Hz, IH) , 7.47 (dd, J=8.3, 2.0 Hz, IH), 7.95 (d, J=2.0 Hz, IH), 8.15 (s, IH), 12.22 (brs, IH). IR Spectrum (KBr, cm"^) : 1643. [676] Example 66 (3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2-methoxy- ethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-51) [677] 66-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- methoxyethyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 1.12 g (2.10 mmol) of 2-bromo-3-(2-methoxyethyl)-1,5-bis(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one obtained in the following Reference example 57- (g) in place of 2-bromo-3-methyl-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 1.35 g of the title compound was obtained as a pale brownish oil. (Yield: 99%) Mass Spectrum (CI, m/z): 652 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm) : -0.04 (s, 9H) , 0.00 (s, 9H) , 0.75-0.90 (m, 6H), 0.95-1.05 (m, 2H), 3.03 (t, J=6.3 Hz, 2H), 3.25 (s, 3H), 3.40-3.48 (m, 2H), 3.69-3.85 (m, 3H), 3.77 (t, J=6.3 Hz, 2H), 5.30 (s, 2H), 5.60 (s, 2H), 6.59 (t, J=74.8 Hz, IH) , 7.07 (dd, J=8 .4, 2.0 Hz, IH) , 7.25 (d, J=8.4 Hz, IH) , 7.58 (d, J=2 . 0 Hz, IH) , 8.18 (s, IH) . [678] 66-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- methoxyethyl)-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 1.34 g (2.06 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3- (2-methoxyethyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 66-(a) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.90 g of the title compound was obtained as a white solid. (Yield: 84%) Mass Spectrum (CI, m/z) : 522 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.80-0.87 (m, 4H), 0.93-1.01 (m, 2H), 3.19 (t, J=6.2 Hz, 2H), 3.29 (s, 3H), 3.68-3.76 (m, 2H), 3.80-3.89 (m, IH), 3.86 (t, J=6.2 Hz, 2H), 5.58 (s, 2H), 6.55 (t, J=74.8 Hz, IH), 7.12 (dd, J=8.3, 2.1 Hz, IH) , 7.21 (d, J=8.3 Hz, IH) , 7.82 (d, J=2 .1 Hz, IH), 8.07 (s, IH), 8.98 (brs, IH). [679] 66-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- methoxyethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 0.90 g (1.73 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-methoxyethyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 66-(b) in place of 3-cyclobutoxymethyl-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 412 mg of the title compound was obtained as a white solid. (Yield: 61%) Melting point: 215-217°C. Mass Spectrum (CI, m/z) : 392 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.73-0.80 (m, 2H), 0.81- 0.89 (m, 2H), 3.10 (t, J=6.7 Hz, 2H), 3.21 (s, 3H), 3.70 (t, J=6.7 Hz, 2H), 3.93-4.00 (m, IH), 7.10 (t, J=74.3 Hz, IH) , 7.25 (dd, J=8.4, 1.9 Hz, IH) , 7.32 (d, J=8.4 Hz, IH) , 7.78 (d, J=1.9 Hz, IH), 8.10 (s, IH), 12.19 (brs, IH). IR Spectrum (KBr, cm"'): 1642. [680] Example 67 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2-ethoxy- ethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-61) [0681] 61- {a.) 2- (3-Cyclopropoxy-4-dif luoromethoxyphenyl) - 3- (2- ethoxyethyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(a) except for using 85 0 mg (1.55 mmol) of 2-bromo-3-(2-ethoxyethyl)-1,5-bis(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one obtained in the following Reference example 58- (b) in place of 2-bromo-3-methyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.91 g of the title compound was obtained as a pale brownish oil. (Yield: 88%) Mass Spectrum (CI, m/z): 666 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.05 (s, 9H), 0.00 (s, 9H), 0.77-0.88 (m, 6H), 0.96-1.04 (m, 2H), 1.09 (t, J=7.0 Hz, 3H), 3.03 (t, J=6.6 Hz, 2H), 3.39-3.47 (m, 2H), 3.42 (q, J=7.0 Hz, 2H), 3.70-3.85 (m, 2H), 3.78 (t, J=6.6 Hz, 2H), 5.31 (s, 2H), 5.60 (s, 2H), 6.59 (t, J=74.7 Hz, IH), 7.09 (dd, J=8.3, 2.1 Hz, IH), 7.25 (d, J=8.3 Hz, IH), 7.50 (d, J=2 . 1 Hz, IH) , 8 . 19 (s, IH) . [0682] 67-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- ethoxyethyl)-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.90 g (1.35 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-ethoxyethyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 67-(a) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.65 g of the title compound was obtained as a white solid. (Yield: 90%) Mass Spectrum (CI, m/z): 536 (M^+1). ^H-NMR Spectrum (cdci3, 8 ppm): -0.01 (s, 9H), 0.80-0.87 (m. 4H), 0.94-1.01 (m, 2H), 1.08 (t, J=7.0 Hz, 3H), 3.20 (t, J=6.4 Hz, 2H), 3.44 (q, J=7.0 Hz, 2H), 3.68-3.76 (m, 2H), 3.82-3.91 (m, IH), 3.87 (t, J=6.4 Hz, 2H), 5.58 (s, 2H), 6.56 (t, J=74.8 Hz, IH), 7.17 (dd, J=8.3, 2.0 Hz, IH), 7.22 (d, J=8.3 Hz, IH) , 7.74 (d, J=2.0 Hz, IH) , 8.08 (s, IH) , 8 . 84 (s, IH) . [683] 67-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- ethoxyethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 0.65 g (1.20 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-ethoxyethyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 67- (b) in place of 3-cyclobutoxymethyl-2-(3-cyclopropoxy-4- difluoromethoxyphenyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 279 mg of the title compound was obtained as a white solid. (Yield: 57%) Melting point: 201-203°C. Mass Spectrum (CI, m/z) : 4 06 (MVl) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.73-0.90 (m, 4H), 1.04 (t, J=7.0 Hz, 3H), 3.11 (t, J=7.0 Hz, 2H), 3.39 (q, J=7.0 Hz, 2H), 3.72 (t, J=7.0 Hz, 2H), 3.94-4.02 (m, IH), 7.10 (t, J=74.3 Hz, IH), 7.28 (dd, J=8.5, 1.9 Hz, IH), 7.32 (d, J=8.5 Hz, IH), 7.74 (d, J=1.9 Hz, IH), 8.10 (s, IH), 12.19 (brs, IH). IR Spectrum (KBr, cm'M : 1643. [684] Example 68 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-pentyl-l,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-10) [685] (a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- pentenyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 10 ml of tetrahydrofuran solution containing 1.2 0 g (3.00 mmol) of butyltriphenylphosphonium bromide was added 0.3 8 g (3.40 mmol) of potassium tert-butoxide under room temperature, and the mixture was stirred at the same temperature for 3 0 minutes. Then, to the mixture was added 0.62 g (1.00 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-3-formyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the same method as in Example 15-(a), and the mixture was stirred for further 4 hours. After completion of the reaction, the reaction suspension was filtered, and the filtrate was concentrated under reduced pressure. The residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:3 (V/V)), and the fractions con¬taining the desired compound were concentrated under reduced pressure to obtain 0.35 g of the title compound as a slightly yellowish oil. (Yield: 53%). Mass Spectrum (CI, m/z) : 662 (MVl) . 'H-NMR Spectrum (cdci3, 8 ppm) : -0.05 (s, 9H), 0.00 (s, 9H) , 0.78-0.89 (m, 9H), 0.95-1.05 (m, 2H), 1.30-1.45 (m, 2H), 2.02-2.12 (m, 2H), 3.38-3.46 (m, 2H), 3.69-3.80 (m, 3H), 5.28 (s, 2H), 5.61 (s, 2H), 6.51 (dd, J=16.2, 3.3 Hz, IH), 6.58 (dt, J=16.2, 5.1 Hz, IH), 6.60 (t, J=74.7 Hz, IH), 7.00 (dd, J=8.1, 2.0 Hz, IH), 7.27 (d, J=8.1 Hz, IH), 7.38 (d, J=2.0 Hz, IH) , 8.17 (s, IH) . [0686] 68-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-pentyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one To 2 6 ml of ethanol solution containing 1.0 8 g (1.60 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- pentenyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the same manner as in Example 68-(a) was added 43.8 mg of platinum oxide, and the mixture was stirred under 1 atm hydrogen atmosphere at room temperature for 3 hours. After comple¬tion of the reaction, the insoluble material was filtered off from the reaction mixture, and the filtrate was concen¬trated under reduced pressure. The residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.66 g of the title compound as a colorless oil. (Yield: 62%). Mass Spectrum (CI, m/z): 664 (M^+1), 'H-NMR Spectrum (cdci3, S ppm): -0.05 (s, 9H), -0.01 (s, 9H), 0.76-0.89 (m, 9H), 0.95-1.04 (m, 2H), 1.16-1.31 (m, 4H), 1.57-1.69 (m, 2H), 2.70-2.82 (m, 2H), 3.38-3.46 (m, 2H), 3.69-3.81 (m, 3H), 5.29 (s, 2H), 5.60 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 6.97 (dd, J-8.2, 2.1 Hz, IH), 7.26 (d, J=8.2 Hz, IH) , 7.35 (d, J=:2.1 Hz, IH) , 8.17 (s, IH) . [0687] 68-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-pentyl- 5-(2-trimethylsilylethoxyraethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.65 g (0.98 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-pentyl-l,5-bis(2 -trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3-d] pyridazin-4-one obtained in Example 68-(b) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 0.33 g of the title compound was obtained as a white solid. (Yield: 62%) Mass Spectrum (CI, m/z) : 534 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.04 (s, 9H) , 0.77-0.87 (m, 4H), 0.81 (t, J=7.2 Hz, 3H), 0.90-0.98 (m, 2H), 1.19-1.37 (m, 4H), 1.62-1.79 (m, 2H), 2.88-2.98 (m, 2H), 3.66-3.75 (m, 2H), 3.76-3.84 (m, IH), 5.58 (s, 2H), 6.55 (t, J=74.8 Hz, IH), 7.06 (dd, J=8.3, 2.0 Hz, IH), 7.21 (d, J=8.3 Hz, IH) , 7.47 (d, J=2.0 Hz, IH) , 8.07 (s, IH) , 9.25 (brs, IH) . 68- (d) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-pentyl- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 0.32 g (0.60 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-pentyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 68-(c) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- propyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , whereby 99 mg of the title compound was obtained as a white solid. (Yield: 41%) Melting point: 191-193°C. Mass Spectrum (CI, m/z): 404 (M^+1). 'H-NMR Spectrum (DMSO-dg, 8 ppm): 0.73-0.88 (m, 7H), 1.19- 1.35 (m, 4H), 1.57-1.73 (m, 2H), 2.85-2.96 (m, 2H), 3.95- 4.03 (m, IH) , 7.10 (t, J=74.3 Hz, IH) , 7.17 (dd, J=8.3, 2.0 Hz, IH) , 7.32 (d, J=8.3 Hz, IH) , 7.58 (d, J=2 . 0 Hz, IH) , 8.07 (s, IH), 12.10 (brs, IH). IR Spectrum (KBr, cm"'): 1641. [689] Example 69 2- (3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-hexyl-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-12) [690] 69- (a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- hexenyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 68-(a) except for using 2.00 g (3.22 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3- formyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in the same manner as in Example 15-(a), and using 4.00 g (9.68 mmol) of pentyltriphenylphosphonium bromide in place of butyl- triphenylphosphonium bromide, whereby 1.07 g of the title compound was obtained as a slightly yellowish oil. (Yield: 49%) Mass Spectrum (CI, m/z) : 676 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.05 (s, 9H), 0.00 (s, 9H), 0.76-0.88 (m, 9H), 0.96-1.04 (m, 2H), 1.20-1.39 (m, 6H), 2.02-2.15 (m, 2H), 3.38-3.46 (m, 2H), 3.60-3.80 (m, 5H), 5.28 (s, 2H), 5.61 (s, 2H), 6.51 (dd, J=15.8, 2.7 Hz, IH), 6.58 (dt, J=15.8, 5.1 Hz, IH), 6.61 (t, J=74.7 Hz, IH), 7.00 (dd, J=8.2, 2.0 Hz, IH), 7.27 (d, J=8.2 Hz, IH), 7.38 (d, J=2.0 Hz, IH), 8.17 (s, IH). [691] 69-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-hexyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 68-(b) except for using 1.05 g (1.55 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(1-hexenyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 69-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxy¬phenyl) -3-(1-pentenyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.62 g of the title compound was obtained as a colorless oil. (Yield: 59%) Mass Spectrum (CI, m/z) : 678 (MVl) . ^H-NMR Spectrum (cdci3, 8 ppm): -0.05 (s, 9H), 0.00 (s, 9H), 0.77-0.90 (m, 9H) , 0.96-1.03 (m, 2H) , 1.15-1.32 (m, 6H) , 1.56-1.69 (m, 2H) , 2.72-2.81 (m, 2H) , 3.39-3.46 (m, 2H) , 3.70-3.81 (m, 3H), 5.29 (s, 2H), 5.60 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 6.97 (dd, J=8.3, 2.0 Hz, IH), 7.26 (d, J=8.3 Hz, IH) , 7.35 (d, J=2 . 0 Hz, IH) , 8.17 (s, IH) . [692] 69-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-hexyl- 5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.61 g (0.90 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-hexyl-l,5-bis(2-trimethylsilylethoxyraethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Example 69-(b) in place of 2-(3-eyelopropoxy-4-difluoromethoxyphenyl)-3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 0.43 g of the title compound was obtained as a white solid. (Yield: 87%) Mass Spectrum (CI, m/z): 548 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), 0.78-0.87 (m, 7H), 0.92-0.99 (m, 2H), 1.16-1.27 (m, 6H), 1.27-1.39 (m, 2H), 1.64-1.77 (m, 2H), 2.88-3.00 (m, 2H), 3.67-3.76 (m, 2H), 3.77-3.85 (m, IH), 5.58 (s, 2H), 6.56 (t, J=74.8 Hz, IH) , 7.05 (dd, J=8.3, 2.0 Hz, IH) , 7.22 (d, J=8.3 Hz, IH) , 7.47 (d, J=2.0 Hz, IH), 8.07 (s, IH), 9.01 (brs, IH). [0693] 69-(d) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-hexyl- 1, 5-dihydropyrrolo [2 , 3-d] pyridazin-'4-one Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 0.41 g (0.75 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-hexyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Example 69-(c) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3- propyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , whereby 210 mg of the title compound was obtained as a white solid. (Yield: 67%) Melting point: 186-188°C. Mass Spectrum (CI, m/z) : 418 {W+1) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.72-0.88 (m, 7H) , 1.15- 1.36 (m, 6H), 1.56-1.71 (m, 2H), 2.85-2.97 (m, 2H), 3.95- 4.02 (m, IH), 7.09 (t, J=74.3 Hz, IH), 7.17 (dd, J=8.4, 2.2 Hz, IH) , 7.32 (d, J=8.4 Hz, IH) , 7.57 (d, J-2.2 Hz, IH) , 8.07 (s, IH), 12.10 (brs, IH). IR Spectrum (KBr, cm"^) : 1640. [694] Example 70 (3-cyclopropoxy-4-difluoromethoxyphenyl)-3-(2-cyclo- propylethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-216) [695] 70-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- cyclopropylvinyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1, 5-dih.ydropyrrolo [2 , 3-d] pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 68-(a) except for using 0.62 g (1.00 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3- formyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in the same manner as in Example 15-(a), and using 1.19 g (3.00 mmol) of cyclopropylmethyltriphenylphosphonium bromide in place of butyltriphenylphosphonium bromide, whereby 0.4 7 g of the title compound was obtained as a colorless oil. (Yield: 71%) Mass Spectrum (CI, m/z) : 660 (M"'+l) . 'H-NMR Spectrum (cdci3, S ppm) : -0.05 (s, 9H) , 0.00 (s, 9H) , 0.38-0.45 (m, 2H), 0.67-0.75 (m, 2H), 0.78-0.88 (m, 6H), 0. 96-1.04 (m, 2H) , 1.36-1.49 (m, IH) , 3.38-3.45 (m, 2H) , 3.68-3.82 (m, 3H), 5.28 (s, 2H), 5.60 (s, 2H), 6.29 (dd, J=15.9, 9.0 Hz, IH), 6.55 (d, J=15.9 Hz, IH), 6.61 (t, J=74.7 Hz, IH), 7.01 (dd, J=8.2, 2.0 Hz, IH), 7.27 (d, J=8.2 Hz, IH) , 7.38 (d, J=2 . 0 Hz, IH) , 8.16 (s, IH) . [696] 70-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- cyclopropylethyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1, 5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 68-(b) except for using 0.47 g (0.71 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-cyclopropylvinyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 70-(a) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-(1-pentenyl)-1,5-bis(2 -trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.44 g of the title compound was obtained as a colorless oil. (Yield: 94%) Mass Spectrum (CI, m/z) : 662 (M'"+l) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.05 (s, 9H) , 0.00 (s, 9H) , 0.25-0.33 (m, 2H), 0.55-0.69 (m, IH), 0.77-0.89 (m, 7H), 0.95-1.04 (m, 2H), 1.50-1.61 (m, 3H), 2.84-2.93 (m, 2H), 3.38-3.47 (m, 2H), 3.69-3.82 (m, 3H), 5.29 (s, 2H), 5.60 (s, 2H) , 6.60 (t, J=74.7 Hz, IH) , 6.98 (dd, J-8.0, 2.0 Hz, IH), 7.26 (d, J=8.0 Hz, IH), 7.36 (d, J=2.0 Hz, IH), 8.17 (s, IH) . [697] 70-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- cyclopropylethyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.44 g (0.66 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-cyclopropylethyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 70-(b) in place of 2-(3-eyelopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.29 g of the title compound was obtained as a white foam. (Yield: 83%) Mass Spectrum (CI, m/z): 532 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.01 (s, 9H), 0.00-0.06 (m, 2H), 0.30-0.37 (m, 2H), 0.63-0.76 (m, IH), 0.80-0.91 (m, 4H), 0.94-1.02 (m, 2H), 1.58-1.69 (m, 2H), 3.03-3.12 (m, 2H), 3.68-3.77 (m, 2H), 3.79-3.88 (m, IH), 5.58 (s, 2H), 6.57 (t, J=74.8 Hz, IH), 7.07 (dd, J=8.3, 2.0 Hz, IH), 7.25 (d, J=8.3 Hz, IH) , 7.47 (d, J=2. 0 Hz, IH) , 8.06 (s, IH) , 8 . 64 (brs, IH) . [698] 70- (d) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- cyclopropylethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 0.29 g (0.54 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-cyclopropylethyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 70-(c) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-propyl-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 209 mg of the title compound was obtained as a white solid. (Yield: 96%) Melting point: 194-197°C. Mass Spectrum (CI, m/z) : 402 (MVl). 'H-NMR Spectrum (DMSO-dg, 8 ppm): -0.05-0.07 (m, 2H), 0.29- 0.39 (m, 2H), 0.62-0.91 (m, 5H), 1.49-1.64 (m, 2H), 2.95- 3.04 (m, 2H), 3.96-4.04 (m, IH), 7.10 (t, J=74.3 Hz, IH), 7.19 (dd, J=8.3, 2.0 Hz, IH), 7.32 (d, J=8.3 Hz, IH), 7.59 (d, J=2.0 Hz, IH), 8.07 (s, IH), 12.09 (brs, IH). IR Spectrum (KBr, cm"^) : 1643. [699] Example 71 (3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2-propynyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-232) [700] 71- (a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- hydroxy-2-propynyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 25 ml of tetrahydrofuran solution containing 1.01 g (1.62 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3- formyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in the same manner as in Example 15-(a) was added dropwise 3.6 ml of tetra¬hydrofuran solution containing 0.5M ethynyl magnesium bromide at 60°C, and the mixture was stirred at the same temperature for 3 0 minutes. After completion of the reaction, the reaction mixture was poured into a saturated ammonium chloride solution, and extracted with toluene. The organic layer after separation was washed successively with water, and then, with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.11 g of the title compound as a yellowish oil. (Yield: 96%) Mass Spectrum (CI, m/z): 647 (M^+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), 0.00 (s, 9H), 0.75-0.94 (m, 6H), 0.95-1.05 (m, 2H), 2.58 (d, J=2.3 Hz, IH), 3.43-3.57 (m, 2H), 3.71-3.84 (m, 3H), 5.26 (dd, J=11.6, 2.3 Hz, IH), 5.34 (d, J=ll.0 Hz, IH), 5.38 (d, J=11.0 Hz, IH), 5.56 (d, J=9.9 Hz, IH), 5.79 (d, J=9.9 Hz, IH), 6.61 (t, J=74.5 Hz, IH), 6.96 (d, J=11.6 Hz, IH), 7.09 (dd, J=8.3, 2.1 Hz, IH), 7.29 (d, J=8.3 Hz, IH), 7.50 (d, J=2.1 Hz, IH), 8.29 (S, IH). [0701] 71-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- hydroxy-2-propynyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.73 g (1.13 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(1-hydroxy-2-propynyl)-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 71-(a) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.4 8 g of the title compound was obtained as a beige solid. (Yield: 81%) Mass Spectrum (CI, m/z): 518 (M"+l). 'H-NMR Spectrum (cdci3, 8 ppm): -0.01 (s, 9H), 0.78-0.94 (m, 4H), 0.94-1.02 (m, 2H), 2.62 (d, J=2.4Hz, IH), 3.71-3.78 (m, 2H), 3.80-3.87 (m, IH), 5.51 (dd, J=11.7, 2.4 Hz, IH), 5.56 (d, J=9.9 Hz, IH), 5.74 (d, J=9.9 Hz, IH), 6.58 (t, J-74.6 Hz, IH), 7.07 (dd, J=8.3, 2.1 Hz, IH), 7.26 (d, J=8.3 Hz, IH), 7.29 (d, J-11.7 Hz, IH), 7.55 (d, J=2.1 Hz, IH), 8.19 (s, IH), 9.13 (brs, IH). [702] 71-(c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- propynyl)-5-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 15-(c) except for using 0.41 g (0.79 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(1-hydroxy-2-propynyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 71-(b) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-cyclopropylhydroxymethyl-l,5-bis(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one, whereby 0.14 g of the title compound was obtained as a pale yellowish solid. (Yield: 35%) Mass Spectrum (CI, m/z) : 502 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.81-0.92 (m, 4H) , 0.92-1.00 (m, 2H) , 2.05 (t, J=2.7 Hz, IH) , 3.67-3.76 (m, 2H), 3.83-3.91 (m, IH), 3.95 (d, J=2.7 Hz, 2H), 5.58 (s, 2H) , 6.57 (t, J=74.8 Hz, IH) , 7.16 (dd, J=8.3, 2.0 Hz, IH) , 7.25 (d, J=8.3 Hz, IH) , 7.76 (d, J=2.0 Hz, IH) , 8.10 (s, IH), 9.14 (brs, IH). [703] 71-(d) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- propynyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 151 mg (0.30 mmol) of 2-(3-eyelopropoxy-4-difluoromethoxyphenyl)- 3-(2-propynyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 71- (c) in place of 2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-3-propyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 56 mg of the title compound was obtained as a pale brownish solid. (Yield: 50%) Melting point: 245-246°C. Mass Spectrum (CI, m/z): 372 (M^+1). 'H-NMR Spectrum (DMSO-dg, 6 ppm): 0.74-0.83 (m, 2H), 0.84- 0.93 (m, 2H) , 2.92 (t, J=2 .5 Hz, IH) , 3.93 (d, J=2 .5 Hz, 2H), 3.93-4.02 (m, IH), 7.11 (t, J=74.3 Hz, IH), 7.32 (dd, J=8.5, 1.6 Hz, IH) , 7.35 (d, J=8.5 Hz, IH) , 7.84 (d, J=1.6 Hz, IH), 8.13 (s, IH), 12.25 (brs, IH). IR Spectrum (KBr, cm"'): 1634. [704] Example 72 3-(2-Butynyl)-2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-233) [705] 72- (a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- hydroxy-2-butynyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 71-(a) except for using 1.01 g (1.62 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-formyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in the same manner as in Example 15-(a), and using 3.6 ml of tetrahydrofuran solution containing 0.5M propynyl magnesium bromide in place of tetrahydrofuran solution containing ethynyl magnesium bromide, whereby 1.07 g of the title compound was obtained as a pale brownish foam substantially quantita¬tively . Mass Spectrum (CI, m/z) : 662 (M'"+l) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.03 (s, 9H) , 0.00 (s, 9H) , 0.76-0.95 (m, 6H), 0.96-1.05 (m, 2H), 1.80 (d, J=2.2 Hz, 3H), 3.42-3.57 (m, 2H), 3.71-3.85 (m, 3H), 5.24 (dq, J=11.5, 2.2 Hz, IH), 5.36 (s, 2H), 5.59 (d, J=9.8 Hz, IH), 5.75 (d, J=9.8 Hz, IH) , 6.60 (t, J=74.6 Hz, IH) , 6.85 (d, J=11.5 Hz, IH), 7.10 (dd, J=8.2, 2.0 Hz, IH), 7.29 (d, J=8.2 Hz, IH) , 7.52 (d, J-2.0 Hz, IH) , 8.28 (s, IH) . 72-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2- butynyl)-1,5-bis(2 -trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 15-(c) except for using 1.57 g (2.37 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(1-hydroxy-2-butynyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the same manner as in Example 71-(b) in place of 2-(3- cyclopropoxy-4-difluoromethoxyphenyl)-3-eyelopropy1hydroxy- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 1.04 g of the title compound was obtained as a yellowish oil. (Yield: 68%) Mass Spectrum (CI, m/z): 646 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm) : -0.03 (s, 9H) , 0.00 (s, 9H) , 0.77-0.92 (m, 6H), 0.95-1.05 (m, 2H), 1.68 (t, J=2.4 Hz, 3H), 3.45-3.54 (m, 2H), 3.70-3.79 (m, 4H), 3.80-3.88 (m, IH), 5.33 (s, 2H), 5.61 (s, 2H), 6.60 (t, J=74.7 Hz, IH), 7.13 (dd, J=8.3, 2.0 Hz, IH), 7.28 (d, J=8.3 Hz, IH), 7.61 (d, J=2.0 Hz, IH) , 8.18 (s, IH) . [707] 72-(c) 3-(2-Butynyl)-2-(3-cyclopropoxy-4-difluoromethoxy¬phenyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-233) Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 1.02 g (1.58 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(2-butynyl)-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 72-(b) in place of 2-(3-cyclopropoxy-4-difluoromethoxy- phenyl)-3-propyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 2 05 mg of the title compound was obtained as a pale yellowish solid. (Yield: 34%) Melting point: 231-236°C. Mass Spectrum (CI, m/z) : 386 (M%1) . 'H-NMR Spectrum (DMSO-dg, 5 ppm): 0.74-0.92 (m, 4H), 1.69 (t, J=2.4 Hz, 3H), 3.86 (q, J=2.4 Hz, 2H), 3.95-4.02 (m, IH), 7.11 (t, J=74.3 Hz, IH), 7.30-7.37 (m, 2H), 7.84-7.87 (m, IH), 8.11 (s, IH), 12.22 (brs, IH). IR Spectrum (KBr, cm"'): 1642. [708] Example 73 2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-3-(4-methyl-2- pentynyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-23 6) [709] 73-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- hydroxy-4-methyl-2-pentynyl)-1,5-bis(2-trimethylsilyl¬ethoxymethyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 71-(a) except for using 1.74 g (2.80 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3- formyl-l,5-bis(2 -trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3-d] pyridazin-4-one obtained in the same manner as in Example 15-(a), and using 6 ml of toluene solution containing 2 7wh^ 3-methyl-l-butynyl magnesium bromide prepared from ethyl magnesium bromide and 3-methyl-1-butyne in place of tetrahydrofuran solution containing ethynyl magnesium bromide, whereby 1.30 g of the title compound was obtained as a white foam. (Yield: 67%) Mass Spectrum (CI, m/z): 690 (MVl). ^H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), 0.00 (s, 9H), 0.76-0.93 (m, 6H), 0.96-1.04 (m, 2H), 1.08 (d, J=6.8 Hz, 3H), 1.11 (d, J=6.8 Hz, 3H), 2.47-2.59 (m, IH), 3.41-3.56 (m, 2H), 3.70-3.87 (m, 3H), 5.26 (dd, J=11.5, 2.0 Hz, IH), 5.36 (s, 2H), 5.62 (d, J=9.9 Hz, IH), 5.71 (d, J=9.9 Hz, IH) , 6.60 (t, J=74.5 Hz, IH) , 6.82 (d, J=11.5 Hz, IH), 7.10 (dd, J=8.3, 2.0 Hz, IH), 7.28 (d, J=8.3 Hz, IH), 7.49 (d, J=2 . 0 Hz, IH) , 8 .28 (s, IH) . [710] 73-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(4- methyl-2-pentynyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 15-(c) except for using 1.72 g (2.49 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(l-hydroxy-4-methyl-2-pentynyl)-1,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in the same manner as in Example 73-(a) in place of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3-cyclo- propylhydroxymethyl-1,5-bis(2-triraethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 1.43 g of the title compound was obtained as a slightly yellowish oil. (Yield: 85%) Mass Spectrum (CI, m/z): 674 (M^+1). 'H-NMR Spectrum (cdci3, 8 ppm): -0.03 (s, 9H), 0.00 (s, 9H), 0.81-0.90 (m, 6H), 0.95-1.04 (m, 2H), 0.99 (d, J=6.8 Hz, 6H), 2.31-2.43 (m, IH), 3.43-3.52 (m, 2H), 3.70-3.78 (m, 2H), 3.81-3.88 (m, IH), 3.84 (d, J-2.2 Hz, 2H), 5.34 (s, 2H), 5.60 (s, 2H), 6.60 (t, J=74.8 Hz, IH), 7.15 (dd, J=8.2, 1.9 Hz, IH), 7.27 (d, J=8.2 Hz, IH), 7.53 (d, J=1.9 Hz, IH), 8.18 (s, IH). [711] 73- (c) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(4- methyl-2-pentynyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 1.43 g (2.12 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(4-methyl-2-pentynyl)-1,5-bis(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 73-(b) in place of 2-(3-cyclopropoxy-4-difluoro- methoxyphenyl)-3-methyl-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.99 g of the title compound was obtained as a pale beige foam. (Yield: 86%) Mass Spectrum (CI, m/z) : 544 (M^+1) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , 0.83-0.92 (m, 4H), 0.92-1.01 (m, 2H), 0.98 (d, J=6.8 Hz, 6H), 2.31-2.46 (m, IH), 3.68-3.76 (m, 2H), 3.86-3.94 (m, IH), 3.99 (d, J=2.2 Hz, 2H), 5.57 (s, 2H), 6.56 (t, J=74.8 Hz, IH), 7.20 (dd, J=8.4, 1.9 Hz, IH) , 7.24 (d, J=8.4 Hz, IH) , 7.73 (d, J=1.9 Hz, IH), 8.09 (s, IH), 9.05 (brs, IH). [712] 73-(d) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(4- methyl-2-pentynyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 6-(c) except for using 0.99 g (1.82 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(4-methyl-2-pentynyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 73-(c) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-propyl-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 544 mg of the title compound was obtained as a white solid. (Yield: 72%) Melting point: 139-143°C. Mass Spectrum (CI, m/z) : 414 (MVl) . ^H-NMR Spectrum (DMSO-dg, 5 ppm): 0.73-0.84 (m, 2H), 0.85- 0.98 (m, 2H) , 0.94 (d, J=6.8 Hz, 6H) , 2.35-2.47 (m, IH) , 3.93-4.02 (m, IH), 3.95 (d, J=2.0 Hz, 2H), 7.10 (t, J=74.3 Hz, IH) , 7.33 (d, J=8.3 Hz, IH) , 7.37 (dd, J=8.3, 1.9 Hz, IH) , 7.77 (d, J=1.9 Hz, IH) , 8.12 (s, IH) , 12.22 (brs, IH) . IR Spectrum (KBr, cm"^) : 1641. [713] Example 74 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(2-propenyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-22 0) To 5 ml of mixed solvent (ethyl acetate:tetrahydro- furan=4:1 (V/V)) solution containing 63.2 mg (0.17 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)-3-(2-propynyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 73-(c) was added 32.2 mg of 5% Lindlar catalyst, and the mixture was stirred under 1 atm hydrogen atmosphere at room temperature for 2 hours. After completion of the reaction, the insoluble material was removed from the reaction mixture by filtration, and the filtrate was concentrated under reduced pressure. The residue was purified by high performance liquid chromatography (column; Sunfire Prep C18 OBD™ (19mmx250mm (manufactured by Waters Co.), Eluent; acetonitrile:water:trifluoroacetic acid= 600:400:1 (V/V/V), Flow rate; 10 ml/min) to obtain 17.6 mg of the title compound as a white solid. (Yield: 28%) Melting point: 176-179°C. Mass Spectrum (CI, m/z) : 374 (M^+l) . 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 0.71-0.88 (m, 4H) , 3.72 (d, J=5.4 Hz, 2H), 3.91-3.98 (m, IH), 4.92 (dd, J=17.1, 2.0 Hz, IH), 5.01 (dd, J=10.0, 2.0 Hz, IH), 6.13 (ddt, J=17.1, 10.3, 5.5 Hz, IH), 7.08 (t, J=74.3 Hz, IH), 7.21 (dd, J=8.5, 2.2 Hz, IH) , 7.31 (d, J=8.5 Hz, IH) , 7.61 (d, J=2 .2 Hz, IH), 8.10 (s, IH), 12.13 (brs, IH). IR Spectrum (KBr, cm''): 1633. [714] Example 75 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(l-hydroxy-2- propenyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one (Exemplary compound No. 1-23 7) [715] 75-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- hydroxy-2-propenyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 71-(a) except for using 1.02 g (1.64 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-formyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in the same manner as in Example 15-(a), and using 4 ml of tetrahydrofuran solution containing IM ethynyl magnesium bromide in place of tetrahydrofuran solution containing ethynyl magnesium bromide, whereby 1.01 g of the title compound was obtained as a yellowish oil substantially quantitatively. Mass Spectrum (EI, m/z) : 649 (M") . 'H-NMR Spectrum (CDCI3, 5 ppm) : -0.04 (s, 9H), 0.00 (s, 9H) , 0.76-0.89 (m, 6H), 0.95-1.04 (m, 2H), 3.41-3.49 (m, 2H), 3.69-3.79 (m, 3H), 5.00-5.08 (m, IH), 5.01 (dt, J=17.3, 1.5 Hz, IH), 5.09 (dt, J=10.3, 1.5 Hz, IH), 5.34 (s, 2H), 5.57 (d, J=9.8 Hz, IH), 5.71 (d, J=9.8 Hz, IH), 6.24 (ddd, J=17.3, 10.3, 5.1 Hz, IH), 6.31 (d, J=11.7 Hz, IH), 6.60 (t, J=74.6 Hz, IH), 6.99 (dd, J=8.2, 1.9 Hz, IH), 7.26 (d, J=8.2 Hz, IH) , 7.38 (d, J=1.9 Hz, IH) , 8.28 (s, IH) . [0716] 75-(b) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-3-(1- hydroxy-2-propenyl)-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 4-(b) except for using 0.31 g (0.48 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(1-hydroxy-2-propenyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 75-(a) in place of 2-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -3-methyl-l,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 0.20 g of the title compound was obtained as a pale yellowish solid. (Yield: 81%) ^H-NMR Spectrum (CDCI3, 8 ppm): -0.02 (s, 9H), 0.74-0.89 (m, 4H), 0.92-1.01 (m, 2H), 3.68-3.79 (m, 3H), 5.06 (dt, J=17.2, 1.4 Hz, IH), 5.16 (dt, J=10.3, 1.4 Hz, IH), 5.32 (ddt, J=11.5, 5.1, 1.4 Hz, IH), 5.57 (d, J=9.8 Hz, IH), 5.67 (d, J=9.8 Hz, IH), 6.33 (ddd, J=17.2, 10.3, 5.1 Hz, IH) , 6.56 (t, J=74.6 Hz, IH) , 6.65 (d, J=11.5 Hz, IH) , 6.99 (dd, J=8.3, 2.0 Hz, IH), 7.20 (d, J=8.3 Hz, IH), 7.39 (d, J=2.0 Hz, IH), 8.15 (s, IH), 9.33 (brs, IH). [717] 75-(c) 2-(3-Cyclopropoxy-4 -di fluoromethoxyphenyl)-3 -(1- hydroxy-2-propenyl)-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Example 13-(c) except for using 0.18 g (0.35 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 3-(1-hydroxy-2-propenyl)-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Example 75-(b) in place of 3-cyclobutoxymethyl-2-(3-cyclo- propoxy-4-difluoromethoxyphenyl)-5-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 6 8 mg of the title compound was obtained as a white solid. (Yield: 50%) Melting point: 202-203°C. Mass Spectrum (CI, m/z): 390 (M"+l). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : 0.67-0.90 (m, 4H) , 3.92- 4.00 (m, IH), 5.01 (dt, J=17.1, 1.5 Hz, IH), 5.07 (dt, J=10.3, 1.5 Hz, IH), 5.24-5.32 (m, IH), 6.23 (ddd, J=17.1, 10.3, 5.1 Hz, IH), 6.58 (dd, J=10.7, 2.9 Hz, IH), 7.11 (t, J=74.2 Hz, IH), 7.18 (dd, J=8.3, 2.0 Hz, IH), 7.34 (d, J=8.3 Hz, IH) , 7.57 (d, J=2 . 0 Hz, IH) , 8.26 (s, IH) , 12.73 (brs, IH). IR Spectrum (KBr, cm"'): 1617. [718] The substituted catechol boronic acid derivative used in Examples was synthesized as follows. [719] Reference example 1-(a) 2-(3-Cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetra- methyl-[1,3,2]dioxaborolane 2L of dehydrated 1,4-dioxane solution containing 12 8 g (457 mmol) of 4-bromo-2-cyclopropoxy-l-difluoromethoxy- benzene was degassed by blowing argon into the mixture to make argon atmosphere. Then, to the solution were added 174 g (685 mmol) of bis(pinacolato)diboron, 37.3 g (45.7 mmol) of 1,1'-bis(diphenylphosphino)ferrocene palladium chloride dichloromethane complex and 13 5 g (1.38 mol) of potassium acetate, and the mixture was stirred at 80°C for 12 hours. After completion of the reaction, to the reaction mixture were added IL of ethyl acetate and 1.2L of a saturated aqueous solution of ammonium chloride, then, the insoluble material was removed by filtration using 70 g of Celite (trade name), and the resulting solid was washed with 1.5L of ethyl acetate. The organic layer after separation was washed successively with water, and then, with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. To the obtained solid were added 1.2L of cyclohexane and 22 g of activated carbon, the mixture was stirred at 50°C, then cooled to room tempera¬ture, and the insoluble material was removed by filtration. The obtained filtrate and the washing solution obtained by washing the filtered material with cyclohexane were combined and the solution was concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=50:1- >9:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 150 g of the title compound as a white solid substantially quantitatively. Mass Spectrum (CI, m/z): 327 (M"+l). 'H-NMR Spectrum (CDCI3, 8 ppm): 0.80-0.85 (m, 4H), 1.35 (s, 12H), 3.84-3.91 (m, IH), 6.53 (t, J=75.1 Hz, IH), 7.12 (d, J=8.0 Hz, IH), 7.41 (dd, J=8.0, 1.4 Hz, IH), 7.69 (d, J=1.4 Hz, IH). [0720] In the following, the following substituted catechol boronic acids were synthesized in the same manner by using various bromo-substituted catechols. Reference example 1-(b) 2-(3-Cyclobutoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetra- methyl-[1,3,2]dioxaborolane Characteristics: pale yellowish oil (Yield: 73%). 'H-NMR Spectrum (CDCI3, 5 ppm) : 1.33 (s, 12H), 1.60-1.77 (m, IH), 1.80-1.94 (m, IH), 2.12-2.29 (m, 2H), 2.42-2.56 (m, 2H), 4.67-4.83 (m, IH), 6.61 (t, J=75.4 Hz, IH), 7.13 (d, J=8.0 Hz, IH) , 7.23 (d, J=1.3 Hz, IH) , 7.37 (dd, J-8.0, 1.3 Hz, IH). [722] Reference example 1-(c) 2-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane Characteristics: pale yellowish oil (Yield: 73%). 'H-NMR Spectrum (CDCI3, 8 ppm) : 0.31-0.38 (m, 2H) , 0.60-0.67 (m, 2H) , 1.23-1.32 (m, IH) , 1.34 (s, 12H) , 3.91 (d, J=7.1 Hz, 2H) , 6.67 (t, J=75.7 Hz, IH) , 7.14 (d, J=7.9 Hz, IH) , 7.35 (d, J=1.3 Hz, IH), 7.39 (dd, J=7.9, 1.3 Hz, IH). [723] Reference example 1-(d) 2 -(4-Difluoromethoxy-3-isopropoxyphenyl)-4,4,5,5-tetra- methyl-[1,3,2]dioxaborolane Characteristics: yellowish brown oil (Yield: 71%). Mass Spectrum (CI, m/z): 329 (M"+l). 'H-NMR Spectrum (CDCI3, 5 ppm) : 1.34 (s, 12H), 1.36 (d, J=6.1 Hz, 6H), 4.57-4.71 (m, IH), 6.60 (t, J=75.6 Hz, IH), 7.14 (dd, J=7.4, 0.6 Hz, IH), 7.36-7.41 (m, 2H). [724] Reference example 1-(e) 2-(3-Cyclopropoxy-4-methoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane Characteristics: white solid (Yield: 62%). Mass Spectrum (CI, m/z): 291 (M"+l). 'H-NMR Spectrum (CDCI3, 5 ppm): 0.79-0.87 (m, 4H), 1.34 (s, 12H) , 3.80-3.91 (m, IH) , 3.87 (s, 3H) , 6.87 (d, J=:8.0 Hz, IH) , 7.44 (dd, J=8.0, 1.6 Hz, IH) , 7.62 (d, J=1.6 Hz, IB). [725] Reference example 1-(f) 2-(3-Cyclobutoxy-4-methoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane Characteristics: colorless oil (Yield: 81%). 'H-NMR Spectrum (CDCI3, 5 ppm): 1.33 (s, 12H), 1.59-1.76 (m, IH), 1.78-1.91 (m, IH), 2.19-2.32 (m, 2H), 2.44-2.57 (m, 2H), 3.89 (s, 3H), 4.69-4.81 (m, IH), 6.87 (d, J=7.9 Hz, IH) , 7.15 (d, J=1.4 Hz, IH) , 7.40 (dd, J=7.9, 1.4 Hz, IH) . [726] Reference example 1- (g) 2-(3-Isopropoxy-4-methoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane Characteristics: white solid (Yield: 76%). Mass Spectrum (EI, m/z) : 292 (M"") . 'H-NMR Spectrum (CDCI3, 5 ppm) : 1.33 (s, 12H) , 1.36 (d, J=6.1 Hz, 6H), 3.87 (s, 3H), 4.53-4.67 (m, IH), 6.88 (d, J=8.1 Hz, IH) , 7.33 (d, J=1.5 Hz, IH) , 7.41 (dd, J=8.1, 1.5 Hz, IH). [727] Reference example 1- (h) 2-(2,3-Dihydro-7-methoxybenzofuran-2-spiro-l'-cyclopentan- 4-yl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane Characteristics: white solid (Yield: 69%). Mass Spectrum (EI, m/z) : 330 (M") . 'H-NMR Spectrum (CDCI3, 8 ppm): 1.32 (s, 12H), 1.69-1.82 (m, 4H), 1.86-1.99 (m, 2H), 2.08-2.21 (m, 2H), 3.35 (s, 2H), 3.87 (s, 3H) , 6.73 (d, J=8 .3 Hz, IH) , 7.26 (d, J=8.3 Hz, IH) . [728] Reference example 1-(i) 2-(8-Difluoromethoxy-2,2 -dimethyl-2H-chromen-5-yl)-4,4,5,5- tetramethyl-[1,3,2]dioxaborolane Characteristics: yellowish oil (Yield: 90%). Mass Spectrum (CI, m/z): 353 (M"+l). ^H-NMR Spectrum (CDCI3, 8 ppm) : 1.34 (s, 12H) , 1.45 (s, 6H) , 5.69 (d, J=10.2 Hz, IH), 6.61 (t, J=75.6 Hz, IH), 6.97 (d, J=8.1 Hz, IH), 7.17 (d, J=10.2 Hz, IH), 7.31 (d, J-8.1 Hz, IH) . [729] Reference example l-(j) 2-(8-difluoromethoxy-2H-chromen-2-spiro-l'-cyclobutan-5- yl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane Characteristics: slightly yellowish oil (Yield: 77%). Mass Spectrum (CI, m/z): 365 (M"+l). ^H-NMR Spectrum (CDCI3, 5 ppm): 1.33 (s, 12H), 1.60-1.77 (m, IH), 1.80-1.96 (m, IH), 2.18-2.29 (m, 2H), 2.42-2.55 (m, 2H), 6.05 (d, J=10.2 Hz, IH), 6.64 (t, J=75.4 Hz, IH), 6.96 (d, J=8.2 Hz, IH), 7.19 (d, J=10.2 Hz, IH), 7.31 (d, J=8.2 Hz, IH). [730] Reference example 1-(k) 2-(8-Difluoromethoxy-2H-chromen-2-spiro-l'-cyclopentan-5- yl)-4,4,5,5-tetramethyl-[1,3,2]dioxaborolane Characteristics: pale yellowish oil (Yield: 80%). Mass Spectrum (EI, m/z): 378 (M^) . 'H-NMR Spectrum (CDCI3, 5 ppm): 1.34 (s, 12H), 1.52-1.79 (m, 4H), 1.85-2.01 (m, 2H), 2.09-2.23 (m, 2H), 5.73 (d, J=10.2 Hz, IH) , 6.57 (t, J=75.4 Hz, IH) , 6.96 (d, J=8.2 Hz, IH) , 7.20 (d, J=10.2 Hz, IH), 7.30 (d, J=8.2 Hz, IH). Reference example 1- (1) 2-(2-cyclopropyl-8-difluoromethoxy-2H-chromen-5-yl)- 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane Characteristics: pale yellowish solid (Yield: 56%). Mass Spectrum (EI, m/z) : 364 (M^) . 'H-NMR Spectrum (CDCI3, 8 ppm) : 0.31-0.39 (m, IH) , 0.45-0.53 (m, IH), 0.53-0.64 (m, 2H), 1.20-1.37 (m, IH), 1.34 (s, 12H), 4.24 (ddd, J=8.1, 3.6, 1.7 Hz, IH), 5.84 (dd, J=10.2, 3.5 Hz, IH), 6.68 (dd, J=76.4, 74.7 Hz, IH), 6.98 (d, J=8.2 Hz, IH) , 7.27 (dd, J=10.2, 1.7 Hz, IH) , 7.32 (d, J=8.2 Hz, IH) . [732] Reference example 2-(a) 2-(3-Cyclopropylmethoxy-4-methoxyphenyl)-4,4,5,5-tetra- methyl-[1,3,2]dioxaborolane To 60 ml of dehydrated tetrahydrofuran solution containing 3.64 g (14.2 mmol) of 4-bromo-2-cyclopropyl- methoxy-l-methoxybenzene was added dropwise 18.0 ml of tetrahydrofuran solution containing 0.97M sec-butyl lithium at -70°C under argon atmosphere, and the mixture was stirred at the same temperature for 50 minutes. Then, 3.70 ml (19.2 mmol) of 2-isopropoxy-4,4,5,5-tetramethyl-[1,3,2]- dioxaborolane was added to the mixture, and the resulting mixture was raised to room temperature. After completion of the reaction, a saturated aqueous solution of ammonium chloride was added to the reaction mixture, and after adjusting a pH thereof to 2 with IN hydrochloric acid, the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure to obtain 4.78 g (purity: 84.7%) of the title compound as a slightly yellowish oil. (Yield: 94%) Mass Spectrum (EI, m/z): 304 (M"") . 'H-NMR Spectrum (CDCI3, 5 ppm): 0.30-0.42 (m, 2H), 0.58-0.67 (m, 2H) , 1.22-1.44 (m, IH) , 1.33 (s, 12H) , 3.89 (d, J=7. 1 Hz, 2H), 3.89 (s, 3H), 6.88 (d, J=8.1 Hz, IH), 7.27 (d, J=1.5 Hz, IH), 7.41 (dd, J-8.1, 1.5 Hz, IH). [733] Reference example 2-(b) 2-(3-Cyclopentoxy-4-methoxyphenyl)-4,4,5,5-tetramethyl- [1,3,2]dioxaborolane Reaction and post treatment were carried out in the same manner as in Reference example 2-(a) except for using 2.6 6 g (9.81 mmol) of 4-bromo-2-cyclopentoxy-1-methoxy- benzene in place of 4-bromo-2-cyclopropylmethoxy-l-methoxy- benzene, whereby 3.35 g (purity: 85%) of the title compound was obtained as a pale yellowish oil. (Yield: 91%) Mass Spectrum (EI, m/z) : 318 (M") . ^H-NMR Spectrum (CDCI3, 8 ppm): 1.33 (s, 12H), 1.54-1.65 (m, 2H) , 1.80-1.98 (m, 6H) , 3.86 (s, 3H) , 4.82-4.88 (m, IH) , 6.87 (d, J=8.1 Hz, IH), 7.30 (d, J-1.5 Hz, IH), 7.39 (dd, J=8.1, 1.5 Hz, IH). [734] Reference example 3 3 -Cyclopropylmethoxy-4 -difluoromethoxyphenylboronic acid [735] 3-(a) 2-(3-cyclopropylmethoxy-4-difluoromethoxyphenyl)- [1,3,6,2]dioxoazaborocane To 90 ml of isopropanol solution containing 32.0 g (purity: 53.5%, 50.3 mmol) of 2-(3-cyclopropylmethoxy-4- difluoromethoxyphenyl)-4,4,5,5-tetramethyl-[1,3,2]dioxa- borolane obtained in Reference example 1-(c) was added 32.8 g of diethanolamine, and the mixture was stirred at room temperature for 63 hours. After completion of the reac¬tion, 150 ml of hexane was added to the reaction mixture, and the precipitated solid was collected by filtration. The obtained solid was washed with hexane and then with isopropanol, and dried under reduced pressure to obtain 14.2 g of the title compound as a white solid. (Yield: 86%) Mass Spectrum (CI, m/z): 328 (M"+l). 'H-NMR Spectrum (CDCI3, 5 ppm): 0.29-0.36 (m, 2H), 0.57-0.65 (m, 2H), 1.19-1.35 (m, IH), 2.76-2.93 (m, 2H), 3.17-3.36 (m, 2H), 3.88 (d, J=6.8 Hz, 2H), 3.92-4.16 (m, 4H), 4.38- 4.50 (m, IH), 6.61 (t, J=76.2 Hz, IH), 7.06 (d, J=7.9 Hz, IH) , 7.10 (dd, J=7.9, 1.0 Hz, IH) , 7.21 (d, J=1.0 Hz, IH) . [736] 3-(b) 3-Cyclopropylmethoxy-4-difluoromethoxyphenylboronic acid To 20 ml of tetrahydrofuran solution containing 2.56 g (7.81 mmol) of 2-(3-cyclopropylmethoxy-4-difluoromethoxy- phenyl)-[1,3,6,2]dioxoazaborocane obtained in Reference example 3-(a) was added 40 ml of 2N hydrochloric acid, and the mixture was reacted at room temperature for 2 hours. After completion of the reaction, the reaction mixture was extracted with ethyl acetate, and the organic layer after separating the liquids was extracted with IN aqueous solution of sodium hydroxide. The aqueous layer was adjusted a pH to 1.6 by conc. hydrochloric acid and extracted with ethyl acetate. The obtained organic layer was dried over anhydrous magnesium sulfate, and concen¬trated under reduced pressure to obtain 1.63 g of the title compound as a white solid. (Yield: 81%) ^H-NMR Spectrum (CDCI3+CD3OD, 8 ppm): 0.34-0.40 (m, 2H), 0.60-0.68 (m, 2H), 1.23-1.36 (m, IH), 3.92 (d, J=6.8 Hz, 2H), 6.70 (t, J=75.6 Hz, IH), 7.05-7.46 (m, 3H). [737] The substituted bromobenzene derivatives used in Reference examples 1 and 2 are known compounds or can be synthesized according to the following Reference examples. As the known compounds, 4-bromo-2-cyclopropylmethoxy-l- difluoromethoxybenzene (Reference example 1-(c) starting material: see WO 2004/033430), 4-bromo-2-cyclopropyl- methoxy-l-methoxybenzene (Reference example 2-(a) starting material: see WO 95/27692), 4-bromo-2-isopropoxy-l-methoxy- benzene (Reference example 1-(g) starting material: see Organic Letters, 17, 2881 (2002)), 4-bromo-2-cyclopentoxy- 1-methoxybenzene (Reference example 2-(b) starting mater¬ial: see Tetrahedron Letters, 41, 811 (2000)), and 4-bromo- 2,3-dihydro-7-methoxybenzofuran-2-spiro-l'-cyclopentane (Reference example 1-(h) starting material: see J. Med. Chem., 44, 2523 (2001)) were used. [738] Reference example 4 4 -Bromo-2 -eyelopropoxy-1-di fluoromethoxybenzene To 1.5L of toluene solution containing 116 g (508 mmol) of 4-bromo-2-cyclopropoxyphenol (see J.Org.Chem., 2005, 70, 3021-3030) were added 81.9 g (254 mmol) of tetrabutylammonium bromide, and 900 ml of 15% aqueous solution of sodium hydroxide previously degassed under argon atmosphere. Then, the mixture was heated to 8 0°C by blowing 86 g of chlorodifluoromethane therein, and the mixture was stirred at the same temperature for 3 0 minutes. After completion of the reaction, IL of water was added to the reaction mixture, and the resulting mixture was extracted with toluene. The organic layer after separation was washed successively with water, and then, with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained concentrate was applied to distillation under reduced pressure (93 to 98°C/60 to llOPa) to obtain 127.6 g of the title compound as a colorless oil. (Yield: 90%) Mass Spectrum (EI, m/z) : 278 (M^) . 'H-NMR Spectrum (CDCI3, 8 ppm) : 0.81-0.87 (m, 4H) , 3.74-3.81 (m, IH), 6.46 (t, J=74.7 Hz, IH), 7.01 (d, J=8.5 Hz, IH), 7.07 (dd, J-8.5, 2.2 Hz, IH), 7.44 (d, J=2.2 Hz, IH). [739] Reference example 5 4- Bromo-2-cyclopropoxy-l-difluoromethoxybenzene 5- (a) 5-Bromo-2-methoxymethoxybenzaldehyde To 600 ml of acetone solution containing 3 0.0 g (0.15 mol) of 5-bromo-2-hydroxybenzaldehyde was added 20.6 g (0.15 mol) of potassium carbonate, and then, 12.5 ml (0.17 mol) of chloromethylmethyl ether was added dropwise to the mixture over 30 minutes under ice-cooling. After stirring the mixture at the same temperature for 3 0 minutes, the mixture was further stirred at room temperature for 5 hours. After completion of the reaction, 600 ml of water was added to the reaction mixture. A pH of the mixture was adjusted to 7.6 with conc. hydrochloric acid, and extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chlor¬ide, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain 28.4 g of the title compound as a pale yellowish oil. (Yield: 77%) Mass Spectrum (EI, m/z) : 244 (M^) . 'H-NMR Spectrum (CDCI3, 8 ppm) : 3.52 (s, 3H) , 5.29 (s, 2H) , 7.14 (d, J=8.8 Hz, IH), 7.61 (dd, J=8.8, 2.6 Hz, IH), 7.94 (d, J=2.6 Hz, IH) , 10.42 (s, IH) . [0741] 5-(b) 5-Bromo-2-methoxymethoxyphenol To 660 ml of dichloromethane solution containing 27.9 g (0.11 mol) of 5-bromo-2-methoxymethoxybenzaldehyde obtained in Reference example 5-(a) was added 42.9 g (0.132 mol) of m-chloroperbenzoic acid (purity: 53%), and the mixture was stirred at room temperature for 3 days. After completion of the reaction, the precipitated solid was removed from the reaction suspension by filtration, 97 ml of 2M aqueous sodium thiosulfate solution was added to the filtrate, and the mixture was stirred at room temperature for 2 hours. The organic layer after separation was concentrated under reduced pressure and the obtained solid was dissolved in diethyl ether. The solution was washed successively with IM aqueous sodium thiosulfate solution, a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 20.3 g of the title compound as a colorless oil. (Yield: 79%) Mass Spectrum (EI, m/z) : 232 (M") . 'H-NMR Spectrum (CDCI3, 8 ppm) : 3.46 (s, 3H) , 5.16 (s, 2H) , 7.13 (d, J=8.8 Hz, IH) , 7.26 (d, J=2.2 Hz, IH) , 7.33 (dd, J=8.8, 2.2 Hz, IH) , 8.24 (s, IH) . [742] 5- (c) 4-Brorao-2-cyclobutoxy-l-methoxyniethoxybenzene To 10 ml of N,N-dimethylformamide solution containing 1.73 g (7.4 mmol) of 5-broTno-2-methoxymethoxyphenol obtained in Reference example 5-(b) were added 1.0 g (7.2 mmol) of potassium carbonate and 1.0 g (7.4 mmol) of cyclobutyl bromide, and the mixture was stirred at 100°C for 5 hours. After completion of the reaction, 10 ml of water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.4 g of the title compound as a colorless oil. (Yield: 66%) Mass Spectrum (EI, m/z) : 286 (M^) . 'H-NMR Spectrum (CDCI3, 5 ppm) : 1.60-1.76 (m, IH) , 1.80-1.93 (m, IH), 2.15-2.30 (m, 2H), 2.40-2.53 (m, 2H), 3.51 (s, 3H), 4.56-4.67 (m, IH), 5.16 (s, 2H), 6.86 (d, J=1.8 Hz, IH) , 6.97 (dd, J=8.6, 1.8 Hz, IH) , 7.00 (d, J=8.6 Hz, IH) . [743] 5-(d) 4-Bromo-2-cyclobutoxyphenol To 7.26 g (25.3 mmol) of 4-bromo-2-cyclobutoxy-l- methoxymethoxybenzene obtained in Reference example 5-(c) was added 3 0 ml of 1,4-dioxane solution containing 4N hydrogen chloride, and the mixture was stirred at room temperature for 24 hours. After completion of the reac¬tion, 100 ml of water was added to the reaction mixture, and the mixture was extracted with diethyl ether. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 3.07 g of the title compound as a pale yellowish oil. (Yield: 50%) 'H-NMR Spectrum (CDCI3, 8 ppm) : 1.62-1.79 (m, IH) , 1.82-1.95 (m, IH), 2.11-2.26 (ra, 2H), 2.42-2.54 (m, 2H), 4.60-4.70 (m, IH) , 5.56 (s, IH) , 6.79 (d, J=8.4 Hz, IH) , 6.82 (d, J=2.3 Hz, IH), 6.96 (dd, J=8.4, 2.3 Hz, IH). [744] 5- (e) 4-Bromo-2-cyclobutoxy-l-difluoromethoxybenzene Reaction and post treatment were carried out in the same manner as in Reference example 4 except for using 3.07 g (12.6 mmol) of 4-bromo-2-cyclobutoxyphenol obtained in Reference example 5-(d) in place of 4-bromo-2-cyclopropoxy- phenol, and the obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 4.11 g of the title compound as a colorless oil. (Yield: 78%) 'H-NMR Spectrum (CDCI3, 8 ppm) : 1.61-1.79 (m, IH) , 1.81-1.96 (m, IH), 2.12-2.28 (m, 2H), 2.40-2.54 (m, 2H), 4.56-4.70 (m, IH), 6.53 (t, J=75.1 Hz, IH), 6.92-6.94 (m, IH), 6.99- 7.06 (m, 2H). [745] Reference example 6 4-Bromo-l-difluoromethoxy-2-isopropoxybenzene [746] 6- (a) 4-Bromo-2-isopropoxyphenol To 200 ml of dichloromethane solution containing 27.2 g (0.179 mol) of 2-isopropoxyphenol was added dropwise 50 ml of dichloromethane solution containing 28.4 g (0.177 mol) of bromine at -70°C or lower. After completion of the dropwise addition, the mixture was stirred at the same temperature 1 hour, and gradually raised to -10°C. After completion of the reaction, the reaction mixture was poured into ice-water, the mixture was neutralized with a satur¬ated aqueous solution of sodium hydrogencarbonate, and then extracted with chloroform. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 3 8.8 g of the title compound as a colorless oil. (Yield: 94%) 'H-NMR Spectrum (cdci3, 5 ppm) : 1.37 (d, J=6.1 Hz, 6H) , 4.49-4.62 (m, IH), 5.62 (s, IH), 6.80 (d, J=8.8 Hz, IH), 6.94-6.99 (m, 2H). [0747] 6-(b) 4-Bromo-l-difluoromethoxy-2-isopropoxybenzene To 21.9 g (94.9 mmol) of 4-bromo-2-isopropoxyphenol obtained in Reference example 6-(a) were added 2.01 g (9.56 mmol) of tetraethylammonium bromide, 15 0 ml of 1,4-dioxane, 11.2 g (275 mmol) of sodium hydroxide and 10 ml of water, and the mixture was stirred at 80°C. Then, the mixture was stirred at the same temperature for 1 hour while blowing 40.4 g of chlorodifluoromethane therein. After completion of the reaction, water was added to the reaction mixture, a pH of the mixture was adjusted to 7 with conc. hydrochloric acid, and extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane:ethyl acetate=100:1->25:1 (V/V)), and the obtained crude oil containing the desired compound was applied to distillation under reduced pressure (105 to 110°C/7Pa) to obtain 8.27 g of the title compound as a colorless oil. (Yield: 31%) 'H-NMR Spectrum (CDCI3, 5 ppm) : 1.36 (d, J=6.1 Hz, 6H) , 4.46-4.60 (m, IH), 6.51 (t, J=75.2 Hz, IH), 7.00-7.07 (m, 2H), 7.09-7.11 (m, IH). [748] Reference example 7 4 -Bromo-2 -cyclopropoxy-1-methoxybenzene [749] 7-(a) 4-Bromo-2-(2-chloroethoxy)-1-methoxybenzene To 1.2L of N,N-dimethylformamide solution containing 159 g (0.79 mol) of 5-bromo-2-methoxyphenol (see WO 01019785) were added 340 g (2.37 mol) of l-bromo-2-chloro- ethane and 120 g (0.868 mol) of potassium carbonate, and the mixture was stirred at 70°C for 5 hours. Then, 220 g (1.53 mol) of l-brorao-2-chloroethane and 80 g (0.58 mol) of potassium carbonate were additionally added thereto twice by dividing them to two portions during the reaction, and the mixture was further stirred for 7 hours. After comple¬tion of the reaction, the reaction mixture was poured into water, and extracted with toluene. The organic layer after separation was washed with water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to obtain 217 g of the title compound as a dark brownish solid substantially quantitatively. Mass Spectrum (EI, m/z) : 264 (M^) . 'H-NMR Spectrum (CDCI3, 8 ppm): 3.83 (t, J=6.1 Hz, 2H) , 3.85 (s, 3H) , 4.25 (t, J=6.1 Hz, 2H) , 6.76 (d, J=8.5 Hz, IH) , 7.02 (d, J=:2.2 Hz, IH) , 7.08 (dd, J=8.5, 2.2 Hz, IH) . 7-(b) 4-Bromo-2-vinyloxy-1-methoxybenzene To 2L of toluene solution containing 217 g (containing an amount corresponding to 790 mmol) of 4-bromo-2-(2- chloroethoxy)-1-methoxybenzene obtained in Reference example 7-(a) were added 780 ml of 50% aqueous solution of sodium hydroxide and 268 g (789 mmol) of tetrabutylammonium hydrogensulfate under ice-cooling, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, the reaction mixture was poured into water, the organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained concentrate was applied to distillation under reduced pressure (79 to 83°C/100Pa) to obtain 122 g of the title compound as a colorless oil. (Yield Mass Spectrum (CI, m/z): 229 (M^l). 'H-NMR Spectrum (CDCI3, 8 ppm) : 3.86 (s, 3H) , 4.47 (dd, J=6.1, 2.1 Hz, IH), 4.76 (dd, J=13.7, 2.1 Hz, IH), 6.56 (dd, J=13.7, 6.1 Hz, IH), 6.81 (d, J=8.7 Hz, IH), 7.12 (d, J=2.4 Hz, IH), 7.17 (dd, J=8.7, 2.4 Hz, IH). [0751] 7-(c) 4-Bromo-2-cyclopropoxy-l-methoxybenzene To 60 ml of dehydrated toluene solution containing 30.0 g (131 mmol) of 4-bromo-2-vinyl-l-methoxybenzene obtained in Reference example 7-(a) was added dropwise 200 ml of toluene solution containing 1.IM diethyl zinc at -40°C, followed by addition of 46.2 g (262 mmol) of chloroiodomethane dropwisely at the same temperature. After stirring at the same temperature for 15 minutes, the mixture was raised to room temperature, and stirred for 2 8 hours. After completion of the reaction, the reaction mixture was poured into a saturated aqueous solution of ammonium chloride, and extracted with toluene. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, an4 concentrated under reduced pressure to obtain 33.7 g of the title compound as a white solid substantially quantitatively. Mass Spectrum (CI, m/z) : 243 (MVl) . 'H-NMR Spectrum (CDCI3, 5 ppm) : 0.79-0.88 (m, 4H), 3.69-3.77 (m, IH) , 3.83 (s, 3H) , 6.73 (d, J=8.7 Hz, IH) , 7.04 (dd, J=8.7, 2.2 Hz, IH), 7.35 (d, J=2.2 Hz, IH). [752] Reference example 8 4-Bromo-2 -eye1opropoxypheno1 To 3 00 ml of dehydrated dichloromethane solution containing 6 0.0 g (247 mmol) of 4-bromo-2-cyclopropoxy-l- methoxybenzene obtained in Reference example 7- (c) was added 3 00 ml of dichloromethane solution containing IM boron tribromide under argon atmosphere at -70°C. After completion of the addition, the mixture was gradually raised to 0°C, and stirred at the same temperature for 30 minutes. After completion of the reaction, the reaction mixture was poured into ice-water, and extracted with toluene. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to obtain 58.6 g of the title compound as a blue-greenish solid substantially quantitatively. Mass Spectrum (CI, m/z): 229 (MVl). 'H-NMR Spectrum (CDCI3, 8 ppm) : 0.80-0.86 (m, 4H) , 3.75-3.82 (m, IH), 5.37 (s, IH), 6.78 (d, J=8.4 Hz, IH), 7.00 (dd, J=8.4, 2.2 Hz, IH) , 7.29 (d, J=2 .2 Hz, IH) . [753] Reference example 9 4-Bromo-2 -cyclobutoxy-1-methoxybenzene To 60 ml of N,N-dimethylformamide solution containing 6.22 g (25.6 mmol) of 4-bromo-2-cyclobutoxyphenol obtained in Reference example 5-(d) were successively added 3.54 g of potassium carbonate and 3.2 ml of methyl iodide, and the mixture was stirred at room temperature for 6 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with toluene. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; toluene), and the obtained crude solid was recrystallized from hexane to obtain 3.90 g of the title compound as a colorless solid. (Yield: 59%) 'H-NMR Spectrum (CDCI3, 6 ppm) : 1.60-1.77 (m, IH) , 1.80-1.94 (m, IH), 2.17-2.32 (m, 2H), 2.42-2.54 (m, 2H), 3.84 (s, 3H), 4.57-4.68 (m, IH), 6.73 (d, J=8.6 Hz, IH), 6.83 (d, J=2.3 Hz, IH), 7.00 (dd, J=8.6, 2.3 Hz, IH). [754] Reference example 10 4 -Bromo-2 -i sopropoxy-1-methoxybenzene Reaction and post treatment were carried out in the same manner as in Reference example 7- (a) except for using 10.1 g (49.8 mraol) of 5-bromo-2-methoxyphenol, and using 15 ml of isopropyl iodide in place of 1-bromo-2-chloroethane, whereby 10.4 g of the title compound was obtained as a pale yellowish solid. (Yield: 86%) Mass Spectrum (EI, m/z) : 244 (M^) . 'H-NMR Spectrum (CDCI3, 8 ppm): 1.37 (d, J-6.1 Hz, 6H), 3.82 (s, 3H), 4.43-4.56 (m, IH), 6.71-6.76 (m, IH), 7.00-7.04 (m, 2H). [755] Reference example 11 5 -Bromo-8 -di fluoromethoxy-2,2-dimethyl-2H-chromene [756] 11-(a) 5-Bromo-2-difluoromethoxyphenol To 60 ml of methanol solution containing 5.80 g (19.7 mmol) of 4-bromo-2-cyclopropylmethoxy-l-difluoromethoxy- benzene (see WO 2004033430) was added 60 ml of conc. hydrochloric acid, and the mixture was refluxed for 5 hours. After completion of the reaction, 60 ml of water was added to the reaction mixture, and the mixture was extracted with diethyl ether. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 4.80 g of the title compound as a slightly yellowish oil substantially quantitatively. Mass Spectrum (EI, m/z) : 238 (M^) . 'H-NMR Spectrum (CDCI3, 5 ppm) : 5.70 (brs, IH), 6.51 (t, J=73.2 Hz, IH), 6.98 (dd, J=8.6, 0.6 Hz, IH), 7.02 (dd, J=8.6, 2.0 Hz, IH), 7.19 (dd, J=2.0, 0.6 Hz, IH). [0757] 11-(b) 4-Bromo-l-difluoromethoxy-2-(1,l-dimethyl-2- propynyloxy)benzene To 3 0 ml of acetonitrile solution containing 7.31 g (30.6 mmol) of 5-bromo-2-difluoromethoxyphenol obtained in Reference example 11-(a) were added 6.4 mg of cuprous chloride and 6.43 ml of 1,8-diazabicyclo[5.4,0]-7-undecene at -10°C, and the mixture was stirred at the same tempera¬ture for 3 0 minutes. To the reaction mixture was added dropwise 30 ml of acetonitrile solution containing 6.18 g (73.5 mmol) of 2-methyl-3-butyn-2-ol which further contains 7.34 ml of 1,8-diazabicyclo[5,4,0]-7-undecene and 5.05 ml of trifluoroacetic anhydride at -10°C. After completion of the dropwise addition, the mixture was stirred at the same temperature for 1.5 hours, and further at 0°C for 2 hours. After completion of the reaction, water was added to the reaction mixture, and extracted with toluene. The organic layer after separation was washed successively with 2N hydrochloric acid, a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 4.88 g of the title compound as a colorless oil. (Yield: 52%) 'H-NMR Spectrum (CDCI3, 8 ppm): 1.67 (s, 6H), 2.64 (s, IH), 6.48 (t, J=74.8 Hz, IH) , 7.04 (d, J=8.6 Hz, IH) , 7.18 (dd. J=8.6, 2.3 Hz, IH), 7.72 (d, J=2.3 Hz, IH). [758] 11- (c) 5-Bromo-8-difluoromethoxy-2,2-dimethyl-2H-chromene To 4.86 g (15.9 mmol) of 4-bromo-l-difluoromethoxy-2- (l , l-dimethyl-2-propynyloxy) benzene obtained in Reference example 11-(b) was added 47 ml of N,N-diethylaniline, and the mixture was stirred at 200°C for 2 hours. After com¬pletion of the reaction, the reaction mixture was concen¬trated under reduced pressure, and the obtained concentrate was washed successively with IN hydrochloric acid, a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 3.76 g of the title compound as a yellowish oil. (Yield: 78%) Mass Spectrum (EI, m/z) : 304 (M^) . ^H-NMR Spectrum (cdci3, 5 ppm) : 1.47 (s, 6H) , 5.76 (d, J=10.2 Hz, IH), 6.54 (t, J=75.1 Hz, IH), 6.63 (d, J=10.2 Hz, IH) , 6.88 (d, J=8.7 Hz, IH) , 7.04 (d, J=8 . 7 Hz, IH) . [759] Reference example 12 5-Bromo- 8 -di fluorome thoxy-2 H-chromen-2 -sp i ro-1'-eye1obut ane [760] 12- (a) l-Bromo-2-cyclopropylmethoxy-3-methoxymethoxybenzene To 200 ml of N,N-dimethylformamide solution containing 23.3 g (0.10 mol) of 2-bromo-6-methoxymethoxyphenol (see Synthesis, 2001, 741-744) were added 13.8 g (0.10 mol) of potassium carbonate and 19.5 ml (0.20 mol) of cyclo- propylmethyl bromide, and the mixture was stirred at 80°C for 2 hours. After completion of the reaction, water was added to the reaction mixture, and extracted with toluene. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 24.1 g of the title compound as a colorless oil. (Yield: 84%) 'H-NMR Spectrum (cdci3, 5 ppm) : 0.29-0.37 (m, 2H) , 0.56-0.64 (m, 2H), 1.27-1.40 (m, IH), 3.51 (s, 3H), 3.86 (d, J=7.1 Hz, 2H), 5.19 (s, 2H), 6.88 (t, J=8.1 Hz, IH), 7.07 (dd, J=8.1, 1.6 Hz, IH), 7.19 (dd, J=8.1, 1.6 Hz, IH). [0761] 12-(b) 2-Cyclopropylmethoxy-l-iodo-3-methoxymethoxybenzene To 76 ml of diethyl ether solution containing 24.1 g (84 mmol) of l-bromo-2-cyclopropylmethoxy-3-methoxymethoxy- benzene obtained in Reference example 12-(a) was added dropwise 53.4 ml (84 mmol) of 1.58M n-butyl lithium hexane solution at -60°C or lower under argon atmosphere. The mixture was stirred at the same temperature for further 3 0 minutes, raised to -30°C, and then, 50 ml of diethyl ether solution containing 21.3 g (84 mmol) of iodine was added dropwise to the mixture. After completion of the dropwise addition, the mixture was stirred at the same temperature for 3 0 minutes, and then, gradually raised to room temperature. After completion of the reaction, to the reaction mixture was added 95 ml of 2% aqueous sodium thiosulfate solution, and the mixture was stirred for 1 hour. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over dried over anhydrous sodium sulfate, and concentrated under reduced pressure to obtain 29.8 g of the title compound as a reddish oil substantially quantitatively. Mass Spectrum (EI, m/z) : 334 (M^) . 'H-NMR Spectrum (cdci3, 8 ppm) : 0.31-0.39 (m, 2H) , 0.58-0.66 (m, 2H), 1.29-1.42 (m, IH), 3.50 (s, 3H), 3.85 (d, J=7.1 Hz, 2H), 5.18 (s, 2H), 6.75 (t, J=8.1 Hz, IH), 7.09 (dd, J=8.1, 1.5 Hz, IH), 7.42 (dd, J=8.1, 1.5 Hz, IH). [762] 12-(c) 2-Cyclopropylmethoxy-3-iodophenol To 100 ml of 1,4-dioxane solution containing 33.9 g (0.10 mol) of 2-cyclopropylmethoxy-l-iodo-3-methoxymethoxy- benzene obtained in Reference example 12-(b) was added 150 ml of 1,4-dioxane solution containing 4N hydrogen chloride, and the mixture was stirred at room temperature for 6 hours. After completion of the reaction, 100 ml of water was added to the reaction mixture, and the resulting mixture was extracted with diethyl ether. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 22.3 g of the title compound as a colorless oil. (Yield: 77%) Mass Spectrum (EI, m/z): 290 (M"") . 'H-NMR Spectrum (cdci3, 5 ppm) : 0.33-0.40 (m, 2H) , 0.62-0.71 (m, 2H) , 1.24-1.37 (m, IH) , 3.88 (d, J=7.3 Hz, 2H) , 5.84 (s, IH) , 6.75 (t, J=8.0 Hz, IH) , 6.92 (dd, J=8.0, 1.6 Hz, IH), 7.27 (dd, J-8.0, 1.6 Hz, IH). [763] 12-(d) 4-Bromo-2-cyclopropylmethoxy-3-iodophenol To 15 ml of 1,4-dioxane solution containing 1.62 g (5.6 mmol) of 2-cyclopropylmethoxy-3-iodophenol obtained in Reference example 12-(c) was added dropwise 10 ml of 1,4- dioxane solution containing 1,4-dioxane-bromine complex adjusted to 0.56M at 10°C. After completion of the drop- wise addition, the mixture was stirred at the same tempera¬ture for 10 minutes. After completion of the reaction, 20 ml of ice-water was added to the reaction mixture, and after adjusting a pH thereof to 7 with sodium hydrogen- carbonate, then, the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 465 mg of the title compound as a colorless oil. (Yield: 15%) Mass Spectrum (CI, m/z) : 368 (M^) . 'H-NMR Spectrum (cdci3, 5 ppm): 0.33-0.41 (m, 2H), 0.63-0.72 (m, 2H), 1.23-1.37 (m, IH), 3.87 (d, J=7.3 Hz, 2H), 5.85 (s, IH), 6.86 (d, J=8.7 Hz, IH), 7.31 (d, J=8.7 Hz, IH). [0764] 12- (e) l-Bromo-3-cyclopropylmethoxy-4-difluoromethoxy-2- iodobenzene To 2 0 ml of toluene solution containing 1.84 g (5.0 mmol) of 4-bromo-2-cyclopropylmethoxy-3-iodophenol obtained in Reference example 12-(d) were added 0.8 g (2.5 mmol) of tetrabutylammonium bromide and 10 ml of 3 5% aqueous solution of sodium hydroxide, and then, 5.0 g (62 mmol) of chlorodifluoromethane was blown thereinto at 80°C over 30 minutes. After completion of the reaction, 2N hydrochloric acid was added to the reaction mixture to adjust a pH thereof to 5. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:1 (V/V)), and the fractions contain¬ing the desired compound were concentrated under reduced pressure to obtain 1.93 g of the title compound as a color¬less oil. (Yield: 92%) Mass Spectrum (EI, m/z) : 418 (M") . ^H-NMR Spectrum (cdci3, 5 ppm): 0.32-0.40 (m, 2H), 0.59-0.68 (m, 2H), 1.28-1.43 (m, IH), 3.86 (d, J=7.3 Hz, 2H), 6.52 (t, J=74.3 Hz, IH), 7.07 (dt, J=8.8, 0.7 Hz, IH), 7.40 (d, J=8.8 Hz, IH). [765] 12-(f) 3-Bromo-6-difluoromethoxy-2-iodophenol To 59.5 ml of methanol solution containing 8.1 g (22 mmol) of l-bromo-3-cyclopropylmethoxy-4-difluoromethoxy-2- iodobenzene obtained in Reference example 12-(e) was added 59.5 ml of conc. hydrochloric acid, and the mixture was refluxed for 4 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with diethyl ether. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 6.9 g of the title compound as a colorless solid. (Yield: 87%) Mass Spectrum (CI, m/z) : 3 64 (M") . 'H-NMR Spectrum (cdci3, 5 ppm): 6.13 (s, IH), 6.54 (t, J=73.1 Hz, IH), 7.06 (dt, J=8.9, 0.9 Hz, IH), 7.24 (d, J=8.9 Hz, IH). 12-(g) 5-Bromo-8-difluoromethoxy-2H-chromen-2-spiro-l'- cyclobutane To 48 ml of N,N-dimethylformamide solution containing 10.0 g (27.5 mmol) of 3-bromo-6-difluoromethoxy-2-iodo- phenol obtained in Reference example 12-(f) were added 0.62 g (2.8 mmol) of palladium acetate, 9.2 g (110 mmol) of sodium hydrogencarbonate and 3.23 g (32.9 mmol) of 1-vinyl- cyclobutanol (see J. Org. Chem., 1977, 42, 300-305) under argon atmosphere, and the mixture was stirred at 140°C for 4 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with toluene. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.61 g of the title compound as a pale yellowish oil. (Yield: 70%) Mass Spectrum (CI, m/z): 317 (M'+l). 'H-NMR Spectrum (cdci3, 5 ppm) : 1.65-1.78 (m, IH) , 1.83-1.97 (m, IH), 2.20-2.31 (m, 2H), 2.45-2.58 (m, 2H), 6.11 (d, J-10.0 Hz, IH), 6.57 (t, J=75.0 Hz, IH), 6.63 (d, J=10.0 Hz, IH) , 6.87 (d, J=8.7 Hz, IH) , 7.03 (d, J=8 . 7 Hz, IH) . [767] Reference example 13 5-Bromo-8-difluoromethoxy-2H-chromen-2-spiro-1'-cyclo- pentane Reaction and post treatment were carried out in the same manner as in Reference example 12-(g) except for using 5.10 g (45.5 mmol) of 1-vinylcyclopentanol (see J. Org. Chem., 1977, 42, 682-685) in place of 1-vinylcyclobutanol, whereby 1.60 g of the title compound was obtained as a yellowish oil. (Yield: 11%) 'H-NMR Spectrum (cdci3, 5 ppm) : 1.57-1.80 (m, 4H) , 1.86-1.98 (m, 2H), 2.11-2.23 (m, 2H), 5.80 (d, J=10.0Hz, IH), 6.50 (t, J=75.0 Hz, IH), 6.65 (d, J=10.0 Hz, IH), 6.86 (d, J=8.7 Hz, IH), 7.03 (d, J=8.7 Hz, IH). [768] Reference example 14 5 -Bromo-2 -eyelopropyl- 8 -di fluoromethoxy-2H-chromene [769] 14-(a) 4-Bromo-2-(l-cyclopropyl-3-trimethylsilyl-2- propynyloxy)-1-difluoromethoxybenzene To 23 ml of toluene solution containing 3.8 g (16 mmol) of 5-bromo-2-difluoromethoxy-phenol obtained in Reference example 11-(a) were added 4.14 g (15.8 mmol) of triphenylphosphine and 2.74 g (16.2 mmol) of 1-cyclopropyl- 3-trimethylsilyl-2-propyn-l-ol (see J. Org. Chem., 1999, 64, 5321-5324), and then, 2.3 ml of diethyl azodicarboxyl- ate (4 0% toluene solution) was gradually added dropwise to the mixture at 5°C under argon atmosphere. The mixture was stirred at the same temperature for 3 0 minutes, and further stirred at room temperature for 3 hours. After completion of the reaction, the reaction mixture was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 4.07 g of the title compound as pale yellowish liquid. (Yield: 66%) Mass Spectrum (CI, m/z): 389 (MVl). 'H-NMR Spectrum (cdci3, 5 ppm): 0.13-0.21 (m, IH), 0.15 (s, 9H), 0.48-0.57 (m, IH), 0.58-0.71 (m, 2H), 1.36-1.48 (m, IH) , 4.59 (d, J=6.3 Hz, IH) , 6.57 (dd, J=76.0, 74.3 Hz, IH) , 7.03 (d, J=8.5 Hz, IH) , 7.11 (dd, J-8.5, 2.2 Hz, IH) , 7.37 (d, J=2.2 Hz, IH). [0770] 14-(b) 4-Bromo-2-(l-cyclopropyl-2-propynyloxy)-1-difluoro- methoxybenzene To 34 ml of methanol solution containing 4.05 g (10.5 mmol) of 4-bromo-2-(l-cyclopropyl-3-trimethylsilyl-2- propynyloxy)-1-difluoromethoxybenzene obtained in Reference example 14-(a) was added 0.48 g (3.5 mmol) of potassium carbonate, and the mixture was stirred at room temperature for 5 hours. After completion of the reaction, 50 ml of water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 2.8 g of the title compound as colorless liquid. (Yield: 84%) Mass Spectrum (EI, m/z) : 316 (M"") 'H-NMR Spectrum (cdci3, 8 ppm): 0.51-0.73 (m, 4H), 1.40-1.51 (m, IH), 2.53 (d, J=2.0 Hz, IH), 4.59 (dd, J=6.6, 2.0 Hz, IH), 6.55 (dd, J=75.7, 74.2 Hz, IH), 7.04 (d, J=8.5 Hz, IH) , 7.12 (dd, J=8.5, 2.2 Hz, IH) , 7.30 (d, J=2 .2 Hz, IH) . [771] 14-(c) 5-Bromo-2-cyclopropyl-8-difluoromethoxy-2H-chromene To 545 mg (1.7 mmol) of 4-bromo-2-(l-cyclopropyl-2- propynyloxy)-1-difluoromethoxybenzene obtained in Reference example 14-(b) was added 5 ml of N,N-diethylaniline, and the mixture was stirred at 200°C for 2 hours. After com¬pletion of the reaction, water was added to the reaction mixture, and then, a pH of the mixture was adjusted to 1 with conc. hydrochloric acid, and the mixture was extracted with diethyl ether. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 33 9 mg of the title compound as yellowish liquid. (Yield: 63%) Mass Spectrum (EI, m/z) : 316 (M^) . 'H-NMR Spectrum (cdci3, 5 ppm): 0.32-0.40 (m, IH), 0.45-0.53 (m, IH), 0.54-0.67 (m, 2H), 1.18-1.31 (m, IH), 4.29 (ddd, J=8.3, 3.7, 1.6 Hz, IH), 5.90 (dd, J=10.0, 3.7 Hz, IH), 6.60 (dd, J=75.7, 74.5 Hz, IH), 6.73 (dd, J=10.1, 1.6 Hz, IH) , 6.89 (d, J=8.7 Hz, IH) , 7.05 (d, J-8.7 Hz, IH) . [772] Pyrrolopyridazinone compounds and ethyl 2-formyl-lH- pyrrol-3-carboxylate derivatives used in Examples as starting substances were synthesized as follows. [773] Reference example 15 2-Bromo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one [774] 15-(a) Potassium 4,4-diethoxy-2-ethoxycarbonylbutanoate To 15L of dehydrated ethanol solution containing 2.48 Kg (purity: 95.1%, 8.54 mol) of diethyl 2-(2,2-diethoxy- ethyl)malonate was added 564 g (purity: 85%, 8.54 mol) of potassium hydroxide under argon gas atmosphere, and the mixture was stirred at room temperature for 4 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, 2L of toluene was added to the obtained concentrate and the mixture was concentrated under reduced pressure. This operation of azeotropic dehydration with toluene was repeated three times to obtain 2.45 Kg of the title compound as a yellowish high-viscous oil substantially quantitatively. 'H-NMR Spectrum (D^O, 5 ppm) : 1.19 (t, J=7.1 Hz, 3H) , 1.19 (t, J=7.1 Hz, 3H), 1.28 (t, J=7.1 Hz, 3H), 2.00-2.25 (m, 2H), 3.36 (dd, J=8.5, 6.1 Hz, IH), 3.54-3.67 (m, 2H), 3.68- 3.81 (m, 2H), 4.20 (q, J-7.1 Hz, 2H), 4.63 (dd, J=6.2, 5.2 Hz, IH). [775] 15-(b) Ethyl 2-(2,2-diethoxyethyl)-4-methoxy-3-oxobutanoate To IIL of dehydrated ethyl acetate solution containing 2.45 Kg (8.54 mol) of potassium 4,4-diethoxy-2-ethoxy- carbonylbutanoate obtained in Reference example 15-(a) were added 1.63 Kg (17.1 mol) of anhydrous magnesium chloride and 3.12L (22.2 mol) of triethylamine under argon atmos¬phere, and the mixture was stirred at 75°C for 1 hour. Then, 974 g (8.97 mol) of methoxyacetyl chloride was added dropwise to the mixture at 15°C or lower under cooling in ice-bath, and the mixture was further stirred at room temperature for 6 hours. After completion of the reaction, the reaction mixture was poured into lOL of ice-water. neutralized with 2 0% aqueous potassium hydrogen sulfate solution and extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to obtain 1.68 kg (purity: 66.4%) of the title compound as a yellow¬ish oil. (Yield: 47.3%) Mass Spectrum (FAB, m/z) 231 (M''-45) . 'H-NMR Spectrum (cdci3, 8 ppm) : 1.17 (t, J=7.1 Hz, 3H) , 1.18 (t, J=7.1 Hz, 3H), 1.26 (t, J=7.1 Hz, 3H), 2.10-2.34 (m, 2H), 3.37-3.52 (m, 2H), 3.42 (s, 3H), 3.55-3.69 (m, 2H), 3.77 (dd, J=8.2, 5.7 Hz, IH), 4.17 (q, J=7.1 Hz, 2H), 4.19, 4.20 (each s, 2H in total), 4.51 (t, J=5.1 Hz, IH). [0776] 15-(c) Ethyl 2-methoxyraethyl-lH-pyrrol-3-carboxylate To 1.68 kg (purity: 66.4%, 4.04 mol) of ethyl 2-(2,2- diethoxyethyl)-4-methoxy-3-oxobutanoate obtained in Reference example 15-(b) was added 1.38L of cold water, then, added 1.38L of 85% phosphoric acid at 10°C or lower, and the mixture was stirred at the same temperature for 3 hours. After completion of the reaction, the reaction mixture was poured into ice-water, neutralized with 20% aqueous solution of sodium hydroxide, and extracted with chloroform. The obtained organic layer was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to obtain 1.31Kg of a deacetalated product as a reddish brown oil. To lOL of ethanol solution containing 1.31 Kg of the obtained deacetalated product was added 3.11 Kg (40.4 mol) of ammonium acetate, and the mixture was refluxed for 3 hours. After completion of the reaction, the reaction mixture was poured into ice-water, and extracted with toluene. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, 15 g of activated carbon was added to the mixture, and the mixture was stirred at room temperature for 1 hour. The insoluble material was filtered off, the filtrate was concentrated under reduced pressure, and the obtained crude solid was recrystallized from 800 ml of cyclohexane to obtain 384 g (purity: 95%) of the title compound as a pale brownish solid. (Yield: 52%) 'H-NMR Spectrum (cdci3, 5 ppm) : 1.34 (t, J=7.2 Hz, 3H), 3.46 (s, 3H), 4.27 (q, J=7.2 Hz, 2H), 4.82 (s, 2H), 6.59 (t, J=2.8 Hz, IH), 6.67 (t, J=2.8 Hz, IH), 8.79 (brs, IH). [0777] 15-(d) Ethyl 2-methoxymethyl-l-(2-trimethylsilylethoxy- methyl)-lH-pyrrol-3-carboxylate To 1250 ml of dehydrated N,N-dimethylformamide solution containing 63.1 g (1.45 mol) of sodium hydride (55% dispersed material in mineral oil) which had been washed three times with each 50 0 ml of dehydrated heptane was added dropwise 750 ml of dehydrated N,N-dimethyl- formamide solution containing 2 63 g (purity: 95%, 1.3 6 mol) of ethyl 2-methoxymethyl-lH-pyrrol-3-carboxylate obtained in Reference example 15-(c) at room temperature under argon atmosphere, and the mixture was stirred for 3 0 minutes. Then, 242 g (1.45 mol) of (2-trimethylsilylethoxy)methyl chloride was added dropwise to the mixture under ice- cooling, and the mixture was further stirred at room temperature for 3 hours. After completion of the reaction, the reaction mixture was poured into ice-water, neutralized with 3 0% aqueous potassium hydrogen sulfate solution, and extracted with toluene. The organic layer after separation was washed successively with water, and then, with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to obtain 420 g (purity: 98.6%) of the title compound as a yellowish oil. (Yield: 96%) Mass Spectrum (EI, m/z) : 313 (M") . ^H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , 0.86-0.94 (m, 2H), 1.35 (t, J=7.2 Hz, 3H), 3.34 (s, 3H), 3.44-3.52 (m. 2H), 4.28 (q, J=7.2 Hz, 2H), 4.90 (s, 2H), 5.31 (s, 2H), 6.57 (d, J=3.2 Hz, IH) , 6.71 (d, J=3.2 Hz, IH) . [778] 15-(e) Ethyl 5-bromo-2-methoxymethyl-l-(2-triinethylsilyl- ethoxymethyl)-lH-pyrrol-3-carboxylate To 2.5L of acetonitrile solution containing 420 g (purity: 98.6%, 1.32 mol) of ethyl 2-methoxymethyl-l-(2- trimethylsilylethoxymethyl) -IH-pyrrol-3-carboxylate obtained in Reference example 15-(d) was added 223 g (1.25 mol) of N-bromosuccineimide at -10°C or lower by dividing it into several portions, and the mixture was stirred for 2 hours. 12.5 g (0.07 mol) of N-bromosuccineimide was addi¬tionally added to the mixture, and the mixture was stirred at the same temperature for 1.5 hours. After completion of the reaction, the reaction mixture was poured into a saturated aqueous solution of sodium hydrogencarbonate, and extracted with toluene. The organic layer after separation was washed successively with 5% aqueous sodium thiosulfate solution and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane: ethyl acetate=:9:l (V/V) ) , and the fractions containing the desired compound were concentrated under reduced pressure to obtain 460 g of the title compound as a colorless oil. (Yield: 89%) 'H-NMR Spectrum (cdci3, 8 ppm) : -0.01 (s, 9H) , 0.86-0.95 (m, 2H), 1.34 (t, J=7.1 Hz, 3H), 3.35 (s, 3H), 3.51-3.60 (m, 2H), 4.27 (q, J=7.1 Hz, 2H), 4.91 (s, 2H), 5.42 (s, 2H), 6.61 (s, IH). [779] 15-(f) Ethyl 5-bromo-2-formyl-l-(2-trimethylsilylethoxy- methyl)-IH-pyrrol-3-carboxylate To 450 g (1.15 mol) of ethyl 5-bromo-2-methoxymethyl- 1-(2-trimethylsilylethoxymethyl)-IH-pyrrol-3-carboxylate obtained in Reference example 15-(e) were added 5.4L of dichloromethane and 540 ml of water, and then, 363 g (1.60 mol) of 2,3-dichloro-5,6-dicyano-l,4-benzoquinone was added to the mixture by dividing it into several portions at room temperature. The mixture was stirred at room temperature for 3 0 minutes, and then, refluxed for 6 hours. After completion of the reaction, 450 g of Celite and 2.5L of toluene were added to the reaction suspension, the mixture was stirred at room temperature for 3 0 minutes, and insoluble material was removed by filtration. The organic layer obtained by separating the filtrate was washed successively with a saturated aqueous solution of sodium hydrogencarbonate, and with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to obtain 43 0 g of the title compound as a pale brownish oil substantially quantitatively. 'H-NMR Spectrum (cdci3, 5 ppm) : -0.03 (s, 9H), 0.86-0.94 (m, 2H), 1.38 (t, J=7.2 Hz, 3H), 3.55-3.63 (m, 2H), 4.35 (q, J=7.2 Hz, 2H), 5.86 (s, 2H), 6.78 (s, IH), 10.32 (s, IH). [0780] 15-(g) 2-Bromo-l-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 2.IL of ethylene glycol solution containing 43 0 g (1.14 mol) of ethyl 5-bromo-2-formyl-l-(2-trimethyl- silylethoxymethyl)-lH-pyrrol-3-carboxylate obtained in Reference example 15-(f) was added 290 ml (5.98 mOL ) of hydrazine monohydrate at 6 0°C, and the mixture was stirred at 125°C for 2 hours. After completion of the reaction, the reaction mixture was poured into water, and precipi¬tated solid was collected by filtration and washed with water. The obtained crude solid was recrystallized from 3L of a mixed solvent (toluene/cyclohexane=l/l (V/V)) to obtain 289 g of the title compound as a beige solid.(:(ield:74%) ^H-NMR Spectrum (cdci3, S ppm) : -0.03 (s, 9H), 0.86-0.96 (m, 2H), 3.52-3.61 (m, 2H), 5.55 (s, 2H), 6.95 (d, J=0.6 Hz, IH) , 8.18 (d, J=0.6 Hz, IH) , 10.62 (brs, IH) . [781] Reference example 16 2-Bromo-3-chloro-l-(2-trimethylsilylethoxymethyl)-1, 5- dihydropyrrolo[2,3-d]pyridazin-4-one [782] 16-(a) Ethyl 2-formyl-l-(2-trimethylsilylethoxymethyl)-IH- pyrrol-3 -carboxylate Reaction was carried out in the same manner as in Reference example 15-(f) except for using 42.1 g (0.134 mol) of ethyl 2-methoxymethyl-l-(2-trimethylsilylethoxy¬methyl) -lH-pyrrol-3 -carboxylate obtained in Reference example 15-(d) in place of ethyl 5-bromo-2-methoxymethyl-l- (2 -trimethylsilylethoxymethyl)-IH-pyrrol-3 -carboxylate. After completion of the reaction, 45 g of Celite and 200 ml of toluene were added to the reaction suspension, the mixture was stirred at room temperature for 3 0 minutes, and insoluble material was removed by filtration. The organic layer obtained by separating the filtrate was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane:ethyl acetate=9:l->7:3 (V/V)), and the fractions containing the desired compound were concen¬trated under reduced pressure to obtain 37.7 g of the title compound as a colorless oil. (Yield: 95%) Mass Spectrum (CI, m/z): 298 (M"+l). ^H-NMR Spectrum (cdci3, 8 ppm): -0.02 (s, 9H), 0.86-0.96 (m, 2H), 1.38 (t, J=7.2 Hz, 3H), 3.50-3.60 (m, 2H), 4.35 (q, J=7.2 Hz, 2H) , 5.74 (s, 2H) , 6.72 (d, J=2.9 Hz, IH) , 7.08 (dd, J=2.9, 0.8 Hz, IH), 10.42 (d, J-0.8 Hz, IH). [783] 16-(b) 1-(2-Trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 15-(g) except for using 37.6 g (0.127 mol) of ethyl 2-formyl-l-(2-trimethylsilyl- ethoxymethyl)-lH-pyrrol-3-carboxylate obtained in Reference example 16-(a) in place of ethyl 5-bromo-2-formyl-l-(2- trimethylsilylethoxymethyl)-lH-pyrrol-3-carboxylate, whereby 28.7 g of the title compound was obtained as a pale yellowish solid. (Yield: 85%) Melting point: 147-148°C. 'H-NMR Spectrum (cdci3, 8 ppm): -0.04 (s, 9H), 0.85-0.95 (m, 2H), 3.43-3.54 (m, 2H), 5.47 (s, 2H), 6.90 (dd, J=3.2, 0.6 Hz, IH) , 7.15 (d, J=3.2 Hz, IH) , 8.22 (d, J-0.6 Hz, IH) , 10.67 (brs, IH). [0784] 16- (c) 3-Chloro-l-(2-triraethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 150 ml of acetonitrile solution containing 2.99 g (11.3 mmol) of 1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Reference example 16-(b) was added 1.42 g (10.6 mmol) of N-chloro- succineimide, the mixture was stirred at room temperature for 3.5 hours, 0.53 g (4.0 mmol) of N-chlorosuccineimide was further added to the mixture and the resulting mixture was stirred for 24 hours. After completion of the reaction, to the reaction mixture were added a saturated aqueous solution of sodium hydrogencarbonate, 5% sodium hydrogen sulfite and ethyl acetate, and the mixture was stirred for 1 hour. Then, a saturated aqueous solution of sodium chloride was added to the solution and the liquids were separated. The organic layer after separation was further washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; toluene:ethyl acetate=9:l->7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 2.20 g of the title compound as a white solid. (Yield: 65%) 'H-NMR Spectrum (cdci3, 8 ppm): -0.03 (s, 9H), 0.86-0.96 (m, 2H), 3.45-3.55 (m, 2H), 5.41 (s, 2H), 7.11 (s, IH), 8.16 (s, IH), 10.60 (brs, IH). [785] 16- (d) 2-Bromo-3-chloro-l-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 30 ml of acetonitrile solution containing 903 mg (3.00 mmol) of 3-chloro-l-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 16-(c) was added 703 mg (3.95 mmol) of N- bromosuccineimide at room temperature, and the mixture was stirred for 8.5 hours. After completion of the reaction, ethyl acetate was added to the reaction mixture, and the mixture was washed successively with a saturated aqueous solution of sodium hydrogencarbonate, 5% aqueous sodium hydrogen sulfite solution and then a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. To the obtained concentrate were added diisopropyl ether and cyclohexane, precipitated solid was collected by filtra¬tion. The obtained solid was washed with cyclohexane and then with hexane, and dried under reduced pressure to obtain 943 mg of the title compound as a pale yellowish solid. (yield-.sayo Mass Spectrum (EI, m/z) : 377 (M") . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.01 (s, 9H) , 0.88-0.97 (m, 2H), 3.53-3.61 (m, 2H), 5.56 (s, 2H), 8.14 (s, IH), 9.95 (brs, IH). [786] Reference example 17 l-Benzyloxymethyl-2-bromo-l,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one [787] (a) Ethyl l-benzyloxymethyl-2-methoxymethyl-lH-pyrrol-3- carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 15-(d) except for using 453 g (2.89 mol) of benzyloxymethyl chloride in place of (2-trimethylsilylethoxy)methyl chloride, whereby 880 g (purity: 93.5%) of the title compound was obtained as a brownish oil. (Yield: 99%) Mass Spectrum (EI, m/z) : 303 (M") . ^H-NMR Spectrum (cdci3, 5 ppm) : 1.36 (t, J=7.2 Hz, 3H), 3.33 (s, 3H), 4.29 (q, J=7.2 Hz, 2H), 4.44 (s, 2H), 4.89 (s, 2H) , 5.39 (s, 2H) , 6.60 (d, J=3 .1 Hz, IH) , 6.73 (d, J=3.1 Hz, IH), 7.25-7.39 (m, 5H). [788] 17-(b) Ethyl 1-benzyloxymethyl-5-bromo-2-methoxymethyl-lH- pyrrol- 3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 15-(e) except for using 880 g (purity: 93.5%, 2.71 mol) of ethyl 1-benzyloxymethyl- 2-methoxymethyl-lH-pyrrol-3-carboxylate obtained in Reference example 17-(a) in place of ethyl 2-methoxymethyl- 1-(2-triraethylsilylethoxymethyl)-IH-pyrrol-3-carboxylate, whereby 1.10 kg (purity: 85.1%) of the title compound was obtained as a brownish oil. (Yield: 90%) Mass Spectrum (EI, m/z) : 381 (M^) . 'H-NMR Spectrum (cdci3, 8 ppm): 1.34 (t, J=7.1 Hz, 3H) , 3.32 (s, 3H), 4.28 (q, J=7.1 Hz, 2H), 4.53 (s, 2H), 4.89 (s, 2H), 5.51 (s, 2H), 6.63 (s, IH), 7.25-7.39 (m, 5H). [789] 17-(c) Ethyl 1-benzyloxymethyl-5-bromo-2-formyl-IH-pyrrol- 3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 15-(f) except for using 8 95 g (purity: 85.1%, 1.99 mol) of ethyl 1-benzyloxymethyl- 5-bromo-2-methoxymethyl-lH-pyrrol-3-carboxylate obtained in Reference example 17-(b) in place of ethyl 5-bromo-2- methoxymethyl-1-(2-trimethylsilylethoxymethyl)-lH-pyrrol-3- carboxylate, whereby 805 g (purity: 86.3%) of the title compound was obtained as a brownish oil. (Yield: 95%) Mass Spectrum (CI, m/z) : 366 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): 1.38 (t, J=7.1 Hz, 3H), 4.35 (q, J=7.1 Hz, 2H), 4.60 (s, 2H), 5.98 (s, 2H), 6.78 (s, IH), 7.22-7.36 (m, 5H), 10.31 (s, IH). IR Spectrum (KBr, cm"'): 1665, 1713. [790] 17- (d) l-Benzyloxymethyl-2-bromo-l,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 15-(g) except for using 600 g (purity: 86.3%, 1.41 mol) of ethyl 1-benzyloxymethyl- 5-bromo-2-formyl-lH-pyrrol-3-carboxylate obtained in Reference example 17-(c) in place of ethyl 5-bromo-2- formyl-1-(2-trimethylsilylethoxymethyl)-lH-pyrrol-3- carboxylate, whereby 407 g (purity: 96.9%) of the title compound was obtained as a pale brownish solid. (Yield: 83%) Mass Spectrum (EI, m/z) : 333 (M^) . 'H-NMR Spectrum (cdci3, 5 ppm): 4.54 (s, 2H), 5.62 (s, 2H), 6.94 (d, J=0.6 Hz, IH), 7.25-7.38 (m, 5H), 8.11 (d, J=0.6 Hz, IH), 10.12 (brs, IH). IR Spectrum (KBr, cm"'): 1667. [791] Reference example 18 2-Bromo-3-methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one [792] 18- (a) 1,5-Bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one To 1.5L of dehydrated N,N-dimethylformamide solution containing 107 g (0.403 mol) of 1-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 16-(b) was added 22.2 g (0.509 mol) of sodium hydride (55% dispersed material in mineral oil) by dividing it into several portions under argon atmosphere and under ice-cooling, and the mixture was stirred at room temperature for 1 hour. Then, 85.9 g (0.515 mol) of (2- trimethylsilylethoxy)methyl chloride was added dropwise to the mixture under ice-cooling, and the mixture was stirred at room temperature for 5 hours. After completion of the reaction, the reaction mixture was poured into ice-water, neutralized with a saturated aqueous solution of ammonium chloride, and extracted with toluene. The organic layer after separation was washed successively with water and then a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained concentrate was recrystallized from 400 ml of cyclohexane to obtain 76.2 g of the title compound as a white solid. (Yield: 48%) Mass Spectrum (CI, m/z) : 3 96 (M"'+l) . 'H-NMR Spectrum (cdci3, 8 ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.86-0.94 (m, 2H), 0.94-1.02 (m, 2H), 3.44-3.53 (m, 2H), 3.68-3.77 (m, 2H), 5.45 (s, 2H), 5.61 (s, 2H), 6.89 (dd, J=3.0, 0.6 Hz, IH) , 7.12 (d, J=3 .0 Hz, IH) , 8.20 (d, J=0.6 Hz, IH). IR Spectrum (KBr, cm"^) : 1645. [0793] 18-(b) 3-Iodo-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 65 ml of acetonitrile solution containing 7.0 g (18 mmol) of 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 18-(a) were added 6.0 g (71 mmol) of sodium hydrogen- carbonate and 12.4 g (103 mmol) of anhydrous magnesium sulfate under argon atmosphere, and the mixture was stirred at room temperature for 1 hour. Then, 4.0 g (36 mmol) of 8-caprolactam and 35.5 ml (35.5 mmol) of dichloromethane solution containing IM iodine jnonochLoYiiic were added to the mixture, and the mixture was further stirred for 3 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with 5% aqueous sodium hydrogen sulfite solution and then a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=5:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 7.3 g of the title compound as a brownish solid. (Yield: 79%) Mass Spectrum (CI, m/z): 522 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , -0.01 (s, 9H) , 0.87-0.94 (m, 2H) , 0.94-1.02 (m, 2H) , 3.45-3.53 (m, 2H), 3.69-3.77 (m, 2H), 5.41 (s, 2H), 5.55 (s, 2H), 7.20 (s, IH) , 8 . 18 (s, IH) . IR Spectrum (KBr, cm"') : 1651. [0794] 18-(c) 3-Methyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one 1 ml of tetrahydrofuran was added to 34 mg (0.15 mmol) of palladium acetate and 126 mg (0.3 06 mmol) of 2-dicyclo- hexylphosphino-2',6'-dimethoxybiphenyl, the mixture was degassed under reduced pressure and replaced with argon. Then, the mixture was stirred at room temperature for 3 0 minutes. Thereafter, 1.5 9 g (3.04 mmol) of 3-iodo-l,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Reference example 18-(b), 551 mg (9.20 mmol) of methylboronic acid, 2.62 g (12.3 mmol) of potassium phosphate and 9 ml of toluene were added to the mixture, and after the resulting mixture was again degassed under reduced pressure and replaced with agron, the mixture was stirred at 100°C for 4 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane:ethyl acetate=19:l->3:2 (V/V)), and the fractions containing the desired compound were concen¬trated under reduced pressure to obtain 1.15 g of the title compound as a yellowish solid. (Yield: 92%) Mass Spectrum (CI, m/z): 410 (MVl). 'H-NMR Spectrum (cdci3, 5 ppm) : -0.03 (s, 9H) , -0.01 (s, 9H), 0.85-0.94 (m, 2H), 0.94-1.02 (m, 2H), 2.47 (d, J=1.0 Hz, 3H), 3.43-3.50 (m, 2H), 3.68-3.76 (m, 2H), 5.37 (s, 2H), 5.56 (s, 2H), 6.86 (d, J=1.0 Hz, IH), 8.11 (s, IH). IR Spectrum (KBr, cm"^) : 1648. [0795] 18-(d) 2-Bromo-3-methyl-l,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 25 ml of acetonitrile solution containing 1.13 g (2.76 mmol) of 3-methyl-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 18-(c) was added 516 mg (2.90 mmol) of N-bromosuccineimide, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, ethyl acetate was added to the reaction mixture, and the mixture was washed successively with 5% aqueous sodium hydrogen sulfite solution, a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate^l:0->7 : 3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.31 g of the title compound as a pale yellowish solid. (Yield: 97%) Mass Spectrum (CI, m/z): 488 (MVl). 'H-NMR Spectrum (cdci3, 8 ppm) : -0.03 (s, 9H), -0.01 (s, 9H) , 0.87-0.94 (m, 2H) , 0.95-1.02 (m, 2H) , 2.46 (s, 3H) , 3.51-3.58 (m, 2H), 3.67-3.75 (m, 2H), 5.51 (s, 2H), 5.55 (s, 2H), 8.11 (s, IH). IR Spectrum (KBr, cm"^) : 1669. [796] Reference example 19 2-Bromo-3-ethyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one [797] 19-(a) 1,5-Bis(2-trimethylsilylethoxymethyl)-3-trimethyl- silylethynyl-1 , 5-dihydropyrrolo[2,3-d]pyridazin-4-one To 50 ml of tetrahydrofuran solution containing 16.6 g (purity: 78.4%, 25.0 mmol) of 3-iodo-1,5-bis(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 18-(b) were added 880 mg (1.25 mmol) of bis(triphenylphosphine)palladium dichloride, 62 0 mg (3.25 mmol) of cuprous iodide, 1.31 g (5.00 mmol) of triphenylphosphine and 10.5 ml (75.3 mmol) of triethyl- amine, and the mixture was degassed under reduced pressure and replaced with argon. Then, 11 ml of trimethylsilyl- acetylene was added to the mixture, and the mixture was stirred at 60°C for 24 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with toluene. The organic layer after separation was washed successively with a saturated aqueous solution of ammonium chloride and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l-> 4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 10.8 g of the title compound as a yellowish solid. (Yield: 88%) Mass Spectrum (CI, m/z) : 492 (M^l) . ^H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), -0.01 (s, 9H) , 0.27 (s, 9H) , 0.85-0.94 (m, 2H) , 0.94-1.02 (m, 2H) , 3.42-3.50 (m, 2H), 3.67-3.75 (m, 2H), 5.40 (s, 2H), 5.57 (S, 2H) , 7.26 (S, IH) , 8.14 (s, IH) . IR Spectrum (KBr, cm"'): 1669. [798] 19-(b) 3-Ethynyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 150 ml of methanol solution containing 10.8 g (22.0 mmol) of 1,5-bis(2-trimethylsilylethoxymethyl)-3-trimethyl- silylethynyl-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 19-(a) was added 1.00 g (7.23 mmol) of potassium carbonate, and the mixture was stirred at room temperature for 3.5 hours. After completion of the reaction, water and a saturated aqueous solution of sodium chloride were added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane: ethyl acetate=:7:3 (V/V) ) , and the fractions containing the desired compound were concentrated under reduced pressure to obtain 8.58 g of the title compound as a pale yellowish solid. (Yield: 93%) Mass Spectrum (CI, m/z) : 420 (M''+l) . 'H-NMR Spectrum (cdci3, 8 ppm) : -0.03 (s, 9H) , -0.01 (s, 9H) , 0.86-1.01 (m, 4H) , 3.25 (s, IH) , 3.45-3.53 (m, 2H) , 3.69-3.77 (m, 2H), 5.42 (s, 2H), 5.58 (s, 2H), 7.32 (s, IH) , 8 . 17 (s, IH) . IR Spectrum (KBr, cm"'): 1658. [799] 19-(c) 3-Ethyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 8.56 g (20.4 mmol) of 3-ethynyl-1,5-bis(2-tri¬methylsilylethoxymethyl) -1, 5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 19-(b) were added 300 ml of ethanol and 200 ml of tetrahydrofuran, then, 2.0 g of 5% palladium-active carbon was added to the mixture, and the mixture was stirred under 1 atm hydrogen atmosphere at room temperature for 15 hours. After completion of the reaction, insoluble material was removed from the reaction suspension by filtration, and the filtrate was concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l->4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 8.00 g of the title compound as a pale yellowish solid. (Yield: 93%) Mass Spectrum (CI, m/z): 424 (M^+1). 'H-NMR Spectrum (cdci3, 6 ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.85-0.94 (m, 2H), 0.94-1.02 (m, 2H), 1.29 (t, J=7.5 Hz, 3H), 2.93 (qd, J=7.5, 1.0 Hz, 2H), 3.44-3.51 (m, 2H), 3.68-3.76 (m, 2H), 5.38 (s, 2H), 5.57 (s, 2H), 6.88 (t, J=l. 0 Hz, IH) , 8 . 12 (s, IH) . IR Spectrum (KBr, cm'^) : 1648. [0800] 19-(d) 2-Bromo-3-ethyl-l,5-bis(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 6.61 g (15.6 mmol) of 3-ethyl-l,5-bis-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 19-(c) in place of 3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5 -dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 7.91 g of the title compound was obtained as a white solid substantially quantitatively. Mass Spectrum (EI, m/z) : 501 (M"^) . 'H-NMR Spectrum (cdci3, 8 ppm): -0.03 (s, 9H), -0.02 (s, 9H), 0.86-1.02 (m, 4H), 1.23 (t, J-7.5 Hz, 3H), 2.89 (q, J=7.5 Hz, 2H), 3.51-3.59 (m, 2H), 3.68-3.76 (m, 2H), 5.52 (s, 2H), 5.56 (s, 2H), 8.11 (s, IH). IR Spectrum (KBr, cm'^) : 1649. [0801] Reference example 2 0 2-Bromo-3-propyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one [0802] 20- (a) 3-Bromo-l, 5-bis (2-trimeth.ylsilylethoxymethyl) -1, 5- dihydropyrrolo[2,3-d]pyridazin-4-one To IL of acetonitrile solution containing 109 g (0.274 mol) of 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 18-(a) was added 58.6 g (0.3^,9 mol) of N-bromosuccineimide by dividing it into several portions at room temperature, and the mixture was stirred at 35°C for 9 hours. After completion of the reaction, to the reaction mixture were added 5% aqueous sodium thiosulfate solution and a saturated aqueous solution of sodium hydrogencarbonate, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained crude solid was recrystallized from 600 ml of a mixed solvent (cyclohexane:hexane=l:2 (V/V)) to obtain 105 g of the title compound as a pale reddish solid. (Yield: 80%) Mass Spectrum (CI, m/z) : 474 (M'^+l) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , -0.01 (s, 9H) , 0.87-1.02 (m, 4H) , 3.45-3.54 (m, 2H) , 3.69-3.77 (m, 2H), 5.40 (s, 2H), 5.56 (s, 2H), 7.13 (s, IH), 8.16 (s, IH) . IR Spectrum (KBr, cm"^) : 1649. [0803] 20-(b) 3-Propyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 2.37 g (5.00 mmol) of 3-bromo-l,5-bis(2-trimethyl¬silylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 20-(a) were added 1.76 g (20 mmol) of propylboronic acid, 4.25 g (20 mmol) of potassium phosphate, 15.8 ml of toluene, 0.95 ml of water, 56 mg of palladium acetate and 179 mg of butyl-di-l-adamantyl- phosphine, and the mixture was degassed under reduced pressure, replaced with argon and stirred at 100°C for 5.5 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with toluene. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:l->5:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 834 mg of the title compound as a pale brownish solid. (Yield: 38%) Mass Spectrum (CI, m/z): 438 (M^+l). 'H-NMR Spectrum (cdci3, 8 ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.85-0.93 (m, 2H), 0.93-1.03 (m, 2H), 0.96 (t, J=7.5 Hz, 3H), 1.65-1.78 (m, 2H), 2.86 (td, J=7.5, 0.6 Hz, 2H), 3.43-3.51 (m, 2H), 3.68-3.75 (m, 2H), 5.38 (s, 2H), 5.57 (s, 2H) , 6.87 (t, J=0.6 Hz, IH) , 8.12 (s, IH) . [0804] 20-(c) 2-Bromo-3-propyl-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 833 mg (1.90 mmol) of 3-propyl-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 20-(b) in place of 3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , whereby 901 mg of the title compound was obtained as a white solid. (Yield: 92%) Mass Spectrum (CI, m/z): 516 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.86-1.01 (m, 4H), 0.95 (t, J=7.2 Hz, 3H), 1.62-1.76 (m, 2H), 2.80-2.88 (m, 2H), 3.50-3.58 (m, 2H), 3.67-3.76 (m, 2H), 5.52 (s, 2H), 5.56 (s, 2H), 8.11 (s, IH). IR Spectrum (KBr, cm"'): 1650. [805] Reference example 21 l-Benzyloxymethyl-2-bromo-3-isopropyl-5-(2-trimethylsilyl- ethoxymethyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one [806] 21-(a) 1-Benzyloxymethyl-l,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one To 33.4 g (100 mmol) of l-benzyloxymethyl-2-bromo-l,5- dihydropyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Reference example 17-(d) were added 4.5 g of 5% palladium-active carbon, 33 0 ml of toluene, 33 0 ml of tetrahydrofuran and 21 ml (121 mmol) of N,N-diisopropylethylamine, and the mixture was stirred under 1 atm hydrogen atmosphere at 60°C for 1 hour. After completion of the reaction, the insoluble material in the reaction suspension was removed by filtration, followed by washing with 300 ml of a mixed solution (chloroform/methanol=l/l (V/V)), and the filtrate and the washing solution were combined, then concentrated under reduced pressure. To the obtained concentrate was added 4 00 ml of water, and the mixture was extracted with a mixed solvent comprising 500 ml of chloroform and 3 0 ml of ethanol. The organic layer after separation was washed successively with water and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to obtain 24.3 g of the title compound as a yellowish brown solid. (Yield: 95%) Mass Spectrum (CI, m/z) : 3 76 (M^l) . 'H-NMR Spectrum (cdci3, 5 ppm): 4.46 (s, 2H), 5.52 (s, 2H), 6.91 (dd, J=3.0, 0.7 Hz, IH), 7.14 (d, J=3.0 Hz, IH), 7.23- 7.41 (m, 5H) , 8.16 (d, J=0.7 Hz, IH) , 10.10 (brs, IH) . [0807] 21-(b) l-Benzyloxymethyl-3-iodo-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(b) except for using 5.3 8 g (21.1 mmol) of 1-benzyloxymethyl-l,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one obtained in Reference example 21-(a) in place of 1,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 5.43 g of the title compound was obtained as a beige solid. (Yield: 68%) Mass Spectrum (CI, m/z): 382 (M"+l). 'H-NMR Spectrum (DMSO-dg, 8 ppm) : 4.50 (s, 2H) , 5.69 (s, 2H), 7.21-7.36 (m, 5H), 7.74 (s, IH), 8.41 (s, IH), 12.40 (brs, IH). [0808] 21-(c) 3-Acetyl-1-benzyloxymethyl-l,5-dihydropyrrolo[2,3- d]pyridazin-4-one To 43 ml of dehydrated N,N-dimethylformamide solution containing 6.48 g (17.0 mmol) of l-benzyloxymethyl-3-iodo- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 21-(b) were added 0.19 g (0.46 mmol) of 1,3-bis(diphenylphosphino)propane, 94 mg (0.42 mmol) of palladium acetate and 8.4 g (83.9 mmol) of butylvinyl ether, and after degassing under reduced pressure, 4.7 ml of triethylamine was further added to the mixture under nitrogen atmosphere, and the mixture was stirred at 100°C for 7.5 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, the obtained residue was applied to silica gel column chromatography (Eluent; toluene:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 2.02 g of the title compound as a pale yellowish solid. (Yield: 40%) Mass Spectrum (CI, m/z): 298 (M^+1). 'H-NMR Spectrum (DMSO-dg, 8 ppm): 2.77 (s, 3H) , 4.52 (s, 2H), 5.78 (s, 2H), 7.20-7.36 (m, 5H), 8.15 (s, IH), 8.45 (s, IH) , 12.63 (brs, IH) . [0809] 21-(d) l-Benzyloxymethyl-3-(1-hydroxy-1-methylethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 8 7 ml of tetrahydrofuran solution containing 1.6 9 g (5.7 mmol) of 3-acetyl-1-benzyloxymethyl-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one obtained in Reference example 21-(c) was added dropwise 7.5 ml of 3M methyl magnesium bromide in diethyl ether solution under ice-cooling, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, a saturated aqueous solution of ammonium chloride was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; toluene:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.66 g of the title compound as a white solid. (Yield: 93%) Mass Spectrum (CI, m/z): 314 (M^+l). 'H-NMR Spectrum (cdci3, 5 ppm) : 1.64 (s, 6H) , 4.47 (s, 2H) , 5.48 (s, 2H), 6.26 (brs, IH), 6.94 (s, IH), 7.21-7.42 (m, 5H), 8.17 (s, IH), 10.55 (brs, IH). [0810] 21-(e) l-Benzyloxymethyl-3-isopropyl-l,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4-one To 13 ml of dichloromethane solution containing 2.47 g of triethylsilane was added 1.31 ml of boron trifluoride diethyl ether complex under ice-cooling, then 30 ml of dichloromethane solution containing 1.65 g (5.3 mmol) of 1- benzyloxymethyl-3-(1-hydroxy-1-methylethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 21-(d) was added dropwise to the mixture, and the mixture was stirred at room temperature for 22 hours. After completion of the reaction, a saturated aqueous solution of sodium hydrogencarbonate was added to the reaction mixture, and the mixture was extracted with chloroform. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; toluene:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.98 g of the title compound as a white solid. (Yield: 62%) Mass Spectrum (CI, m/z) : 298 (MVl) . 'H-NMR Spectrum (CDCl,, 5 ppm) : 1.33 (d, J=6.8 Hz, 6H) , 3.41-3.55 (m, IH), 4.46 (s, 2H), 5.45 (s, 2H), 6.88 (d, J=0.7 Hz, IH), 7.22-7.41 (m, 5H), 8.07 (s, IH), 9.85 (brs, IH) . [0811] 21-(f) l-Benzyloxymethyl-3-isopropyl-5-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Reference example 18-(a) except for using 0.98 g (3.3 mmol) of l-benzyloxymethyl-3-isopropyl-l,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Reference example 21-(e) in place of 1-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2, 3-d] pyridazin-4 -one. After completion of the reaction, the reaction mixture was poured into ice-water, neutralized with a saturated aqueous solution of ammonium chloride and extracted with toluene. The organic layer after separation was washed successively with water and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=3:2 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.87 g of the title compound as a slightly yellowish oil. (Yield: 62%) Mass Spectrum (CI, m/z) : 428 (MVl) . 'H-NMR Spectrum (CDClj, S ppm): -0.01 (s, 9H), 0.93-1.04 (m. 2H), 1.32 (d, J=6.8 Hz, 6H), 3.45-3.59 (m, IH), 3.69-3.78 (m, 2H), 4.45 (s, 2H), 5.43 (s, 2H), 5.58 (s, 2H), 6.86 (d, J=0.7 Hz, IH), 7.23-7.40 (m, 5H), 8.07 (s, IH). [0812] 21- (g) l-Benzyloxymethyl-2-bromo-3-isopropyl-5-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 0.8 7 g (2.0 mmol) of l-benzyloxyraethyl-3-isopropyl-5-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 21-(f) in place of 3-methyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 932 mg of the title compound was obtained as a slightly yellowish oil. (Yield: 92%) Mass Spectrum (CI, m/z) : 506 (M"'+l) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.01 (s, 9H), 0.94-1.03 (m, 2H), 1.41 (d, J=7.1 Hz, 6H), 3.37-3.52 (m, IH), 3.69-3.76 (m, 2H), 4.55 (s, 2H), 5.57 (s, 2H), 5.59 (s, 2H), 7.15- 7.37 (m, 5H) , 8.05 (s, IH) . [813] Reference example 22 2-Bromo-3-butyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one [814] 22- (a) 3-Butyl-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 20-(b) except for using 430 mg (4.20 mmol) of butylboronic acid in place of propylboronic acid, whereby 550 mg of the title compound was obtained as a yellowish solid. (Yield: 58%) Mass Spectrum (CI, m/z): 452 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm) : -0.04 (s, 9H) , -0.02 (s, 9H), 0.85-0.93 (m, 2H), 0.93 (t, J=7.3 Hz, 3H), 0.94-1.02 (m, 2H), 1.32-1.46 (m, 2H), 1.59-1.73 (m, 2H), 2.89 (td, J=7.6, 0.6 Hz, 2H), 3.43-3.50 (m, 2H), 3.68-3.76 (m, 2H), 5.38 (s, 2H), 5.57 (s, 2H), 6.87 (t, J=0.6 Hz, IH), 8.12 (s, IH). IR Spectrum (KBr, cm"'): 1665. [815] 22- (b) 2-Bromo-3-butyl-l,5-bis(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 6.00 g (13.3 mmol) of 3-butyl-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 22-(a) in place of 3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 6.89 g of the title compound was obtained as a pale yellowish solid. (Yield: 98%) Mass Spectrum (CI, m/z) : 530 (M%1) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.86-1.02 (m, 4H), 0.92 (t, J=7.4 Hz, 3H), 1.30-1.44 (m, 2H), 1.58-1.69 (m, 2H), 2.87 (t, J=7.4 Hz, 2H), 3.50- 3.58 (m, 2H), 3.67-3.75 (m, 2H), 5.52 (s, 2H), 5.56 (s, 2H) , 8 . 11 (s, IH) . IR Spectrum (KBr, cm^^) : 1658. [816] Reference example 2 3 2-Bromo-3-isobutyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one [0817] 23- (a) 3-Isobutyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 20-(b) except for using 3.87 g (37.9 mmol) of isobutylboronic acid in place of propylboronic acid, using 423 mg (1.27 mmol) of 2-dicyclo- taexylphosphino-2 ' , 6 '-dimethoxybiphenyl in place of butyl- di-l-adamantylphosphine, and using toluene alone in place of toluene and water as a solvent, respectively, whereby 3.52 g of the title compound was obtained as a yellowish solid. (Yield: 67%) Mass Spectrum (CI, m/z) : 452 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.85-0.92 (m, 2H), 0.92 (d, J=6.6 Hz, 6H), 0.95-1.01 (m, 2H) , 1.96-2.10 (m, IH) , 2.74 (dd, J-7.1, 0.5 Hz, 2H) , 3.42-3.50 (m, 2H), 3.67-3.76 (m, 2H), 5.39 (s, 2H), 5.57 (s, 2H) , 6.86 (t, J=0.5 Hz, IH) , 8.13 (s, IH) . IR Spectrum (KBr, cm"^) : 1664. [0818] 23- (b) 2-Bromo-3-isobutyl-l,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 4.46 g (9.87 mmol) of 3-isobutyl-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 23-(a) in place of 3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 4.82 g of the title compound was obtained as a pale yellowish solid. (Yield: 92%) Mass Spectrum (CI, m/z): 530 (M^+l). 'H-NMR Spectrum (cdci3, 8 ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.85-0.93 (m, 2H), 0.93 (d, J=6.6 Hz, 6H), 0.93-1.01 (m, 2H), 2.05-2.17 (m, IH), 2.73 (d, J=7.3 Hz, 2H), 3.50- 3.58 (m, 2H), 3.66-3.75 (m, 2H), 5.54 (s, 2H), 5.56 (s, 2H) , 8 .12 (s, IH) . [819] Reference example 24 2-Bromo-3-formyl-l-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one [820] 24- (a) 5-Benzyloxymethyl-l-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Reference example 18-(a) except for using 9.26 g (51.2 mmol) of benzyloxymethyl chloride in place of (2-trimethyl- silylethoxy) methyl chloride. After completion of the reaction, the reaction mixture was poured into ice-water, neutralized with a saturated aqueous solution of ammonium chloride and extracted with toluene. The organic layer after separation was washed successively with water and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=3:2 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 10.5 g of the title compound as a pale yellowish solid. (Yield: 69%) 'H-NMR Spectrum (DMSO-d,, 5 ppm): -0.10 (s, 9H), 0.77-0.85 (m, 2H), 3.43-3.51 (m, 2H), 4.61 (s, 2H), 5.54 (s, 2H), 5.61 (s, 2H), 6.74 (dd, J=3.0, 0.7 Hz, IH), 7.21-7.35 (m, 5H) , 7.58 (d, J=3.0 Hz, IH) , 8.48 (d, J=0.7 Hz, IH) . [0821] 24-(b) 5-Benzyloxymethyl-3-bromo-1-(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 20-(a) except for using 27.2 g (71 mmol) of 5-benzyloxymethyl-l-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 24-(a) in place of l,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] pyrid¬azin-4-one, whereby 3 0.8 g of the title compound was obtained as a gray solid. (Yield: 93%) ^H-NMR Spectrum (DMSO-dg, 5 ppm): -0.08 (s, 9H), 0.78-0.87 (m, 2H), 3.44-3.54 (m, 2H), 4.62 (s, 2H), 5.50 (s, 2H), 5.57 (s, 2H), 7.21-7.35 (m, 5H), 7.78 (s, IH), 8.49 (s, IH) . [0822] 24-(c) 5-Benzyloxymethyl-3-methyl-l-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 20-(b) except for using 30.8 g (66.3 mmol) of 5-benzyloxymethyl-3-bromo-1-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 24-(b) in place of 3-bromo-l,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, and using 12.0 g (200 mmol) of methylboronic acid in place of propylboronic acid, respectively, whereby 25.3 g of the title compound was obtained as a brownish oil. (Yield: 96%) ^H-NMR Spectrum (DMSO-dg, 5 ppm): -0.09 (s, 9H), 0.76-0.86 (m, 2H), 2.34 (d, J=1.0 Hz, 3H), 3.41-3.51 (m, 2H), 4.61 (s, 2H), 5.50 (s, 2H), 5.52 (s, 2H), 7.21-7.35 (m, 6H), 8.40 (s, IH). [0823] 24-(d) 3-Methyl-l-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 3 80 ml of ethanol solution containing 25.3 g (65 mmol) of 5-benzyloxymethyl-3-methyl-l-(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 24-(c) was added 25 g of 5% palladium-active carbon, and the mixture was stirred under 1 atm hydrogen atmosphere at room temperature for 2.5 hours. After completion of the reaction, insoluble material was removed from the reaction suspension by filtration, 100 ml of 28% aqueous ammonia was added to the obtained filtrate, and the mixture was stirred at room temperature for 5 hours. Then, the solution was concen¬trated under reduced pressure, 500 ml of water was added to the obtained concentrate, and precipitated solid was collected by filtration. The obtained solid was washed with water, and dried under reduced pressure to obtain 14.3 g of the title compound as a pale yellowish solid. (Yield: 79%) Mass Spectrum (CI, m/z) : 2 80 (M"'+l) . ^H-NMR Spectrum (DMSO-dg, 8 ppm) : -0.09 (s, 9H) , 0.76-0.84 (m, 2H), 2.32 (d, J=1.0 Hz, 3H), 3.41-3.48 (m, 2H), 5.49 (s, 2H), 7.24 (d, J=1.0 Hz, IH), 8.30 (s, IH), 12.17 (brs, IH) . [824] 24- (e) 2-Bromo-3-methyl-1-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 14.3 g (51.2 mmol) of 3-methyl-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 24-(d) in place of 3-methyl-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one, whereby 16.7 g of the title compound was obtained as a white solid. (Yield: 91%) Mass Spectrum (CI, m/z) : 358 (M^l) . 'H-NMR Spectrum (DMSO-dg, 5 ppm) : -0.09 (s, 9H) , 0.77-0.86 (m, 2H), 2.30 (s, 3H), 3.46-3.55 (m, 2H), 5.58 (s, 2H), 8.40 (s, IH), 12.38 (brs, IH). [825] 24-(f) 2-Bromo-3-bromomethyl-1-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 4 ml of 1,2-dichloroethane solution containing 100 mg (0.28 mmol) of 2-bromo-3-methyl-1-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 24-(e) was added 50 mg (0.28 mmol) of N-bromosuccineimide, and the mixture was stirred at 4 0°C for 4 hours under irradiation with a mercury lamp (300WH). After completion of the reaction, a saturated aqueous solution of sodium hydrogencarbonate was added to the reaction mixture, and the mixture was extracted with chloroform. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 39.3 mg of the title compound as a pale yellowish solid. (Yield: 32%) 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.87-0.95 (m, 2H), 3.52-3.61 (m, 2H), 4.86 (s, 2H), 5.55 (s, 2H), 8.15 (s, IH), 10.14 (brs, IH). [0826] 24-(g) 2-Bromo-3-formyl-l-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 3 70 mg (4.2 mmol) of 2-nitropropane were added 10 ml of dehydrated ethanol and 1.43 g (4.2 mmol) of 2 0% sodium ethoxide ethanol solution, then, 500 mg (0.84 mmol) of 2-bromo-3-bromomethyl-l-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 24-(f) was added to the mixture at 5°C, and the mixture was stirred at the same temperature for 1 hour. After completion of the reaction, ice water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous sodium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 167 mg of the title compound as a white solid. (Yield: 32%) Mass Spectrum (CI, m/z) : 372 (M"+l) . 'H-NMR Spectrum (DMSO-dg, 8 ppm): -0.09 (s, 9H), 0.79-0.88 (m, 2H), 3.52-3.61 (m, 2H), 5.72 (s, 2H), 8.58 (s, IH), 10.48 (s, IH), 12.90 (brs, IH). [0827] Reference example 2 5 2-Bromo-3-methoxymethyl-1,5-bis(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one [0828] 25-(a) 2-Bromo-3-bromomethyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 250 ml of 1,2-dichloroethane solution containing 15.6 g (38.0 mmol) of 3-methyl-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 18-(c) was added 15.9 g (89.3 mmol) of N-bromosuccineimide, and the mixture was stirred at room temperature for 4 hours under irradiation with a mercury lamp (300WH). After completion of the reaction, water and a saturated aqueous solution of sodium hydrogen- carbonate were added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with a saturated aqueous solution of sodium hydrogencarbonate, water and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; toluene:ethyl acetate=4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 15.5 g of the title compound as a pale reddish solid. (Yield: 72%) Mass Spectrum (CI, m/z) : 566 (M''+l) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), -0.01 (s, 9H), 0.86-1.03 (m, 4H), 3.52-3.61 (m, 2H), 3.68-3.77 (m, 2H), 4.88 (s, 2H), 5.54 (s, 2H), 5.57 (s, 2H), 8.14 (s, IH) . IR Spectrum (KBr, cm"^) : 1658. [0829] 25-(b) 2-Bromo-3-methoxymethyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 4 ml of tetrahydrofuran solution containing 459 mg (0.81 mmol) of 2-bromo-3-bromomethyl-l,5-bis(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 25-(a) was added 4 ml of 28% sodium methoxide methanol solution, and the mixture was stirred at room temperature for 2 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 359 mg of the title compound as a colorless oil. (Yield: 86%) Mass Spectrum (CI, m/z): 518 (M"+l). 'H-NMR Spectrum (cdci3, 8 ppm): -0.03 (s, 9H), -0.02 (s, 9H), 0.85-1.02 (m, 4H), 3.44 (s, 3H), 3.53-3.61 (m, 2H), 3.67-3.75 (m, 2H), 4.76 (s, 2H), 5.55 (s, 2H), 5.57 (s, 2H), 8.15 (s, IH). IR Spectrum (KBr, cm'^) : 1668. [0830] Reference example 2 6 2-Bromo-3-ethoxymethyl-l-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 23 ml of ethanol solution containing 1.06 g (2.42 mmol) of 2-bromo-3-bromomethyl-l-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 24-(f) was added 3.33 g (9.78 mmol) of 2 0% sodium ethoxide ethanol solution, and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=2:1->1:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 54 9 mg of the title compound as a white solid. (Yield: 56%) ^H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , 0.88-0.95 (m, 2H), 1.23 (t, J=7.1 Hz, 3H), 3.54-3.61 (m, 2H), 3.64 (q, J=7.1 Hz, 2H), 4.80 (s, 2H), 5.56 (s, 2H), 8.14 (s, IH), 9.94 (brs, IH). [0831] Reference example 2 7 2-Bromo-3-cyclobutoxymethyl-1,5-bis(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 10 ml of dehydrated tetrahydrofuran solution containing 0.89 g (12 mmol) of cyclobutanol was added 0.25 g (6.2 mmol) of sodium hydride (60% dispersed material in mineral oil) under ice-cooling, and the mixture was stirred at room temperature for 3 0 minutes. To the mixture was further added 0.7 0 g (1.2 mmol) of 2-bromo-3-bromomethyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one obtained in Reference example 25- (a), and the mixture was stirred at 45°C for 1 hour. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 561 mg of the title compound as a pale yellowish oil. (Yield: 82%) ^H-NMR Spectrum (cdci3, 8 ppm) : -0.03 (s, 9H), -0.02 (s, 9H) , 0.86-1.02 (m, 4H) , 1.40-1.57 (m, IH) , 1.60-1.75 (m, IH), 1.90-2.06 (m, 2H), 2.13-2.27 (m, 2H), 3.52-3.60 (m, 2H) , 3.66-3.75 (m, 2H) , 4.08-4.19 (m, IH) , 4.71 (s, 2H) , 5.53 (s, 2H), 5.56 (s, 2H), 8.13 (s, IH). [832] Reference example 2 8 2-Bromo-3-cyclopropyl-1,5-bis(2-trimethylsilylethoxy- methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one [833] 28-(a) 3-Cyclopropyl-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in ReFtv-ence e>«9n^pVe 2.o-ti>)except for using 7.00 g (purity: 78.4%, 10.5 mmol) of 3-iodo-1,5-bis(2-trimethyl¬silylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 18-(b) in place of 3-bromo- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , and using 589 mg (2.10 mmol) of tricyclohexylphosphine in place of butyl-di-l-adamantyl- phosphine, respectively, whereby 3.60 g of the title compound was obtained as a white solid. (Yield: 79%) Mass Spectrum (CI, m/z): 436 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.04 (s, 9H), -0.01 (s, 9H), 0.59-0.65 (m, 2H), 0.84-0.92 (m, 2H), 0.95-1.03 (m, 4H), 2.41-2.52 (m, IH), 3.42-3.49 (m, 2H), 3.69-3.77 (m, 2H), 5.35 (s, 2H), 5.58 (s, 2H), 6.68 (d, J=0.7 Hz, IH), 8.11 (s, IH). IR Spectrum (KBr, cm"^) : 1648. [834] 28-(b) 2-Bromo-3-cyclopropyl-1,5-bis(2-trimethylsilyl¬ethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 3.6 0 g (8.26 mmol) of 3-cyclopropyl-1,5-bis(2-trimethyl¬silylethoxymethyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 28-(a) except for using 3- methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 4.11 g of the title compound was obtained as a pale yellowish solid. (Yield: 97%) Mass Spectrum (CI, m/z): 514 (M^+l). 'H-NMR Spectrum (cdci3, 8 ppm) : -0.03 (s, 9H), -0.01 (s, 9H) , 0.86-1.03 (m, 6H), 1.10-1.17 (m, 2H) , 2.00-2.11 (m, IH) , 3.51-3.59 (m, 2H) , 3.67-3.74 (m, 2H) , 5.51 (s, 2H), 5.55 (s, 2H), 8.10 (s, IH). IR Spectrum (KBr, cm"^) : 1651. [835] Reference example 29 2-Br0m0-3-f02rmyl-l, 5-bis (2-trimethylsilylethoxymethyl) -1,5- dihydropyrrolo [2 , 3 - d] pyridazin-4 - one Reaction and post treatment were carried out in the same manner as in Reference example 24-(g) except for using 5.70 g (10.0 mmol) of 2-bromo-3-bromomethyl-l,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one and using 2.0 g (23.3 mmol)of cyclopropylboronic acid in place of butylboronic acid obtained in Reference example 25-(a) in place of 2-bromo-3-bromomethyl-l-(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one, whereby 3.38 g of the title compound was obtained as a white solid. (Yield: 67%) Mass Spectrum (CI, m/z): 502 (MVI). 'H-NMR Spectrum (cdci3, 5 ppm) : -0.02 (s, 9H) , -0.01 (s, 9H) , 0.88-1.03 (m, 4H) , 3.53-3.64 (m, 2H) , 3.69-3.77 (m, 2H), 5.61 (s, 2H), 5.65 (s, 2H), 8.24 (s, IH), 10.70 (s, IH) . IR Spectrum (KBr, cm''): 1686, 1664. [836] Reference example 3 0 2-Chloro-3-triethylsilylethynyl-l-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one [837] 30-(a) 3-Iodo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(b) except for using 3.81 g (14.4 mmol) of 1-(2-trimethylsilylethoxymethyl-l,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 16-(b) in place of 1,5-bis(2-trimethylsilylethoxy methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 4.2 8 g of the title compound was obtained as a beige solid. (Yield: 76%) Mass Spectrum (CI, m/z) : 392 (M'^+l) . ^H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.87-0.95 (m, 2H), 3.46-3.54 (m, 2H), 5.42 (s, 2H), 7.21 (s, IH), 8.19 (s, IH) , 10 . 00 (brs, IH) . IR Spectrum (KBr, cm"^) : 1659. [838] 30-(b) 2-Chloro-3-iodo-l-(2-trimethylsilylethoxymethyl)- 1, 5-dihydropyrrolo[2,3-d]pyridazin-4-one To 40 ml of acetonitrile solution containing 3.00 g (7.66 mmol) of 3-iodo-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 30-(a) was added 4.04 g (30.3 mmol) of N-chloro- succineimide, and the mixture was stirred at 80°C for 12 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with 5% aqueous sodium hydrogen sulfite solution, a saturated aqueous solution of sodium hydrogen- carbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; chloroform:ethyl acetate=7:3->l:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.87 g of the title compound as a pale yellowish solid. (Yield: 57%) 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.87-0.96 (m, 2H), 3.53-3.60 (m, 2H), 5.58 (s, 2H), 8.16 (s, IH), 10.00 (brs, IH) . [839] 30-(c) 2-Chloro-3-triethylsilylethynyl-l-(2-trimethylsilyl¬ethoxymethyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 61 mg (0.14 mmol) of 2-chloro-3-iodo-l-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo [2,3- d]pyridazin-4-one obtained in Reference example 30-(b) were added 5 mg of bis(triphenylphosphine)palladium dichloride, 4 mg of cuprous iodide, 8 mg of triphenylphosphine, 1 ml of diisopropylamine, 0.04 ml of triethylsilylacetylene and 0.4 ml of N,N-dimethylformamide, the mixture was degassed under reduced pressure and replaced with argon, and the mixture was stirred at 80°C for 1.5 hours. After completion of the reaction, toluene was added to the reaction mixture, and the mixture was washed successively with 5% aqueous sodium hydrogen sulfite solution, a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride. The organic layer after separation was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate = 7:3->l: 1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 47 mg of the title compound as a yellowish solid. (Yield: 75%) Mass Spectrum (CI, m/z): 438 (M^+1). 'H-NMR Spectrum (cdci3, S ppm): -0.02 (s, 9H), 0.72 (q, J=7.8 Hz, 6H), 0.87-0.95 (m, 2H), 1.09 (t, J=7.8 Hz, 9H), 3.51-3.59 (m, 2H), 5.53 (s, 2H), 8.10 (s, IH), 9.89 (brs, IH) . [0840] Reference example 31 2-Chloro-3-phenyl-1-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 206 mg (0.484 mmol) of 2-chloro-3-iodo-l-(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 30-(b) were added 71 mg (0.58 mmol) of phenylboronic acid, 54 mg of tetrakis- triphenylphosphine palladium, 6 ml of toluene, 4 ml of ethanol and 1 ml of 2M aqueous sodium carbonate solution, the mixture was degassed under reduced pressure and replaced with argon, and the mixture was stirred at 80°C for 16 hours. After completion of the reaction, a saturated aqueous solution of sodium chloride was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was dried over anhydrous magnesium sulfate and then concen¬trated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; toluene:ethyl acetate=l:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 152 mg of the title compound as a pale yellowish solid. (Yield: 84%) Mass Spectrum (CI, m/z): 376 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm): -0.01 (s, 9H), 0.90-1.00 (m, 2H), 3.59-3.67 (m, 2H), 5.62 (s, 2H), 7.33-7.67 (m, 5H), 8.19 (s, IH), 9.91 (brs, IH). IR Spectrum (KBr, cm"') : 1661. [841] Reference example 32 2-Bromo-l,5-bis(2-trimethylsilylethoxymethyl)-3-[1-(2-tri- methylsilylethoxymethyl)-4-pyrazolyl]-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one 32-(a) 4-(4,4,5,5-Tetramethyl-[1,3,2]dioxaborolan-2-yl)-1- (2-trimethylsilylethoxymethyl)-IH-pyrazole Under argon atmosphere, to 2 0 ml of tetrahydrofuran solution containing 1.09 g (5.62 mmol) of 4-(4,4,5,5- tetramethyl-[1,3,2]dioxaborolan-2-yl)-IH-pyrazole was added 443 mg (11.1 mmol) of 60% sodium hydride under ice-cooling, and the mixture was stirred for 5 minutes. Then, 3 ml (17.0 mmol) of (2-trimethylsilylethoxy)methyl chloride was added dropwise to the mixture, and the mixture was reacted at room temperature for 2 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was separated, and the solutions were washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromato¬graphy (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 832 mg of the title compound as a colorless oil. (Yield ; Mass Spectrum (CI, m/z): 325 (M"+l). 'H-NMR Spectrum {cdci3, 5 ppm): -0.03 (s, 9H), 0.86-0.94 (m, 2H), 1.32 (s, 12H), 3.51-3.59 (m, 2H), 5.43 (s, 2H), 7.81 (d, J=0.5 Hz, IH), 7.86 (d, J=0.5 Hz, IH). [843] 32-(b) 1,5-Bis(2-trimethylsilylethoxymethyl)-3-[1-(2-tri- methylsilylethoxymethyl)-4-pyrazolyl]-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 31 except for using 289 mg (0.61 mmol) of 3-bromo-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 20-(a) in place of 2-chloro-3-iodo-1- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one, and using 619 mg (1.91 mmol) of 4- (4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-1-(2- trimethylsilylethoxymethyl)-IH-pyrazole obtained in Reference example 32-(a) in place of phenylboronic acid, respectively, whereby 166 mg of the title compound was obtained as a slightly yellowish oil. (Yield: 46%) Mass Spectrum (CI, m/z) : 592 (M"+l) . 'H-NMR Spectrum (cdci3, 8 ppm): -0.02 (s, 18H), -0.01 (s, 9H), 0.88-1.04 (m, 6H), 3.49-3.56 (m, 2H), 3.57-3.64 (m, 2H), 3.69-3.77 (m, 2H), 5.44 (s, 2H), 5.46 (s, 2H), 5.60 (s, 2H), 7.31 (s, IH), 7.87 (d, J=0.6 Hz, IH), 8.17 (s, IH) , 8.74 (d, J=0.6 Hz, IH) . IR Spectrum (neat, cm"^) : 1664. [844] 32- (c) 2-Bromo-l,5-bis(2-trimethylsilylethoxymethyl)-3-[1- (2-trimethylsilylethoxymethyl)-4-pyrazolyl] -1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 192 mg (0.369 mmol) of 1,5-bis(2-trimethylsilylethoxy¬methyl) -3-[1-(2-trimethylsilylethoxymethyl)-4-pyrazolyl]- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 32-(b) in place of 3-methyl-l,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one, whereby 198 mg of the title compound was obtained as a yellowish oil. (Yield: 80%) Mass Spectrum (CI, m/z): 670 (M^+1). 'H-NMR Spectrum (cdci3, 8 ppm): -0.02 (s, 9H), -0.01 (s, 9H), -0.01 (s, 9H), 0.89-1.03 (m, 6H), 3.55-3.76 (m, 6H), 5.48 (s, 2H), 5.57 (s, 2H), 5.61 (s, 2H), 8.17 (s, IH), 8.20 (d, J=0.6 Hz, IH), 8.47 (d, J=0.6 Hz, IH). IR Spectrum (neat, cm"^) : 1667. [845] Reference example 33 3-Benzyl-1-benzyloxymethyl-2-bromo-5 -(2 -trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d] pyridazin-4-one [846] 33- (a) 1-Benzyloxymethyl-2-bromo-5-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 300 ml of dichloromethane solution containing 33.4 g (0.100 mol) of l-benzyloxymethyl-2-bromo-l,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 17-(d) was added 25.8 g (0.200 mol) of N,N-diiso- propylethylamine, and 25.0 g (0.15 mol) of (2-trimethyl- silylethoxy)methyl chloride was added dropwise to the mix¬ture under ice-cooling. After completion of the dropwise addition, the mixture was stirred at 40°C for 3 hours. After completion of the reaction, the reaction mixture was washed successively with IN hydrochloric acid, a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. To the obtained concentrate was added 3 00 ml of cyclohexane, and precipitated solid was collected by filtration. The obtained solid was washed with cyclohexane, and dried under reduced pressure to obtain 33.1 g of the title compound as a beige solid. (Yield: 71%) Mass Spectrum (CI, m/z): 464 (M^+1). 'H-NMR Spectrum (DMSO-dg, 5 ppm) : -0.07 (s, 9H) , 0.79-0.88 (m, 2H), 3.57-3.66 (m, 2H), 4.54 (s, 2H), 5.40 (s, 2H), 5.75 (s, 2H) , 6.95 (d, J=0.6 Hz, IH) , 7.20-7.33 (m, 5H) , 8.52 (d, J=0.6 Hz, IH). [847] 33-(b) l-Benzyloxymethyl-5-(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 5.00 g (10.8 mmol) of l-benzyloxymethyl-2-bromo-5- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one obtained in Reference example 33-(a) were added 50 ml of methanol, 30 ml of toluene, 1.5 g of potas¬sium carbonate and 2.5 g of 5% palladium-active carbon, and the mixture was stirred under 1 atm hydrogen atmosphere at room temperature for 3 hours. After completion of the reaction, insoluble material of the reaction suspension was removed by filtration, and the filtrate was concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; toluene:ethyl acetate=l:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 8.15 g of the title compound as a pale yellowish solid. (Yield: 77%) 'H-NMR Spectrum (DMSO-dg, 8 ppm) : -0.07 (s, 9H) , 0.79-0.88 (m, 2H), 3.58-3.67 (m, 2H), 4.47 (s, 2H), 5.41 (s, 2H), 5.73 (S, 2H) , 6.73 (dd, J=2.9, 0.5 Hz, IH) , 7.12-7.34 (m, 5H) , 7.60 (d, J=2.9 Hz, IH) , 8.46 (d, J=0.5 Hz, IH) . [848] 33-(c) l-Benzyloxymethyl-3-iodo-5-(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(b) except for using 39.1 g (0.104 mmol) of l-benzyloxymethyl-5-(2-trimethyl- silylethoxyraethyl ) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 33-(b) in place of l,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one, whereby 45.3 g of the title compound was obtained as a brownish solid. (Yield: 89%) 'H-NMR Spectrum (DMSO-dg, 5 ppm): -0.05 (s, 9H), 0.81-0.89 (m, 2H), 3.58-3.65 (m, 2H), 4.49 (s, 2H), 5.37 (s, 2H), 5.69 (s, 2H), 7.19-7.33 (m, 5H), 7.76 (s, IH), 8.46 (s, IH) . [0849] 33-(d) l-Benzyloxymethyl-3-formyl-5-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one In 500 ml of an autoclave made of stainless were charged 4 5.3 g (86.8 mmol) of l-benzyloxymethyl-3-iodo-5- (2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Reference example 33-(c), 390 mg (1.74 mmol) of palladium acetate, 1.92 g (3.47 mmol) of 1,1'-bis(diphenylphosphino)ferrocene, 30.2 ml (220 mmol) of triethylamine, 27.7 ml (170 mmol) of triethylsilane and 300 ml of N,N-dimethylformamide, and the mixture was stirred at 8 0°C for 8 hours under carbon monoxide atmosphere of 15 atm. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with toluene. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 14.2 g of the title compound as a brownish solid. (Yield: 40%) Mass Spectrum (CI, m/z) : 414 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): 0.00 (s, 9H), 0.96-1.04 (m, 2H), 3.70-3.79 (m, 2H), 4.50 (s, 2H), 5.54 (s, 2H), 5.62 (s, 2H), 7.23-7.40 (m, 5H), 7.76 (s, IH), 8.21 (s, IH), 10.58 (s, IH) . IR Spectrum (KBr, cm''): 1682, 1667. [0850] 33-(e) l-Benzyloxymethyl-3-hydroxyphenylmethyl-5-(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one To 87 ml of dehydrated tetrahydrofuran solution containing 3.6 0 g (8.71 mmol) of l-benzyloxymethyl-3- formyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one obtained in Reference example 33-(d) were added 12.2 ml of IM phenyl magnesium bromide tetra¬hydrofuran solution under ice-cooling and under argon atmosphere, and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, to the reaction mixture were added a saturated aqueous solution of ammonium chloride and a saturated aqueous solution of sodium chloride, and the mixture was extracted with ethyl acetate. The organic layer after separation was dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:1- >1:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 3.12 g of the title compound as a yellowish oil. (Yield: 73%) 'H-NMR Spectrum (cdci3, 8 ppm): 0.00 (s, 9H), 0.95-1.04 (m, 2H), 3.70-3.78 (m, 2H), 4.38 (d, J=12.1 Hz, IH), 4.43 (d, J=12.1 Hz, IH), 5.37 (s, 2H), 5.60 (d, J=9.9 Hz, IH), 5.65 (d, J=9.9 Hz, IH) , 6.00 (d, J=5.5 Hz, IH) , 6.53 (d, J=0 . 7 Hz, IH), 6.54 (d, J=5.5 Hz, IH), 7.17-7.23 (m, 2H), 7.28- 7.41 (m, 6H), 7.45-7.52 (m, 2H), 8.17 (s, IH). 33- (f) 3-Benzyl-l-tienzyloxymethyl-5-hydroxymethyl-l, 5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 21-(e) except for using 3.0 8 g (6.26 mmol) of l-benzyloxymethyl-3-hydroxyphenyl- methyl-5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3-d] pyridazin-4-one obtained in Reference example 33-(e) in place of l-benzyloxymethyl-3-(1-hydroxy-l-methylethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 1.68 g of the title compound was obtained as a pale yellowish solid. (Yield: 71%) 'H-NMR Spectrum (cdci3, 6 ppm) : 4.02 (brs, IH) , 4.28 (d, J=0.8 Hz, 2H), 4.40 (s, 2H), 5.38 (s, 2H), 5.65 (s, 2H), 6.67 (t, J=0.8 Hz, IH), 7.18-7.25 (m, 3H), 7.28-7.38 (m, 7H) , 8 . 06 (s, IH) . IR Spectrum (KBr, cm"'): 1655. [852] 33-(g) 3-Benzyl-l-benzyloxymethyl-5-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction was carried out in the same manner as in Reference example 33-(a) except for using 1.66 g (4.82 mmol) of 3-benzyl-l-benzyloxymethyl-5-hydroxymethyl-l,5- dihydropyrrolo [2 , 3-d] pyridazin-4-one obtained in Reference example 33-(f) in place of l-benzyloxymethyl-2-bromo-l,5- dihydropyrrolo[2,3-d]pyridazin-4-one. After completion of the reaction, the reaction mixture was washed successively with IN hydrochloric acid, a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:1->1:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.66 g of the title compound as a yellowish oil. (Yield: 29%) Mass Spectrum (CI, ra/z) : 476 (M^+1) . 'H-NMR Spectrum (cdci3, 8 ppm): 0.01 (s, 9H), 0.96-1.03 (m, 2H), 3.71-3.77 (m, 2H), 4.30 (brs, 2H), 4.40 (s, 2H), 5.37 (s, 2H), 5.58 (s, 2H), 6.63 (t, J=0.6 Hz, IH), 7.18-7.37 (m, lOH) , 8.07 (s, IH) . [853] 33-(h) 3-Benzyl-l-benzyloxymethyl-2-bromo-5-(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 0.64 g (1.35 mmol) of 3-benzyl-l-benzyloxymethyl-5-(2-tri- methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 33-(g) in place of 3-methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 0.70 g of the title compound was obtained as a yellowish oil. (Yield: 94%) Mass Spectrum (CI, m/z) : 554 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.01 (s, 9H), 0.95-1.02 (m, 2H), 3.68-3.75 (m, 2H), 4.27 (s, 2H), 4.53 (s, 2H), 5.56 (s, 2H), 5.58 (s, 2H), 7.12-7.19 (m, IH), 7.21-7.35 (m, 7H) , 7.41-7.47 (m, 2H) , 8.05 (s, IH) . [854] Reference example 34 2-Bromo-3-hydroxyphenylmethyl-1-(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 33-(e) except for using 200 mg (0.54 mmol) of 2-bromo-3-formyl-l-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 24-(g) in place of 1-benzyl- oxymethyl-3-formyl-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 78.5 mg of the title compound was obtained as a pale yellowish solid. (Yield: 32%) Mass Spectrum (EI, m/z) : 449 (M'') . 'H-NMR Spectrum (DMSO-d^, 5 ppm): -0.13 (s, 9H), 0.74-0.82 (m, 2H), 3.48-3.56 (m, 2H), 5.62 (d, J=11.9Hz, IH), 5.66 (d, J=11.9 Hz, IH), 5.78 (d, J=10.9 Hz, IH), 7.07 (d, J=10.9 Hz, IH), 7.19 (tt, J=7.1, 1.8 Hz, IH), 7.24-7.31 (m, 2H), 7.33-7.40 (m, 2H), 8.61 (s, IH), 13.01 (brs, IH). [855] Reference example 3 5 2-Bromo-3-phenethyl-1,5-bis(2-trimethylsilylethoxymethyl)- 1, 5-dihydropyrrolo[2,3-d]pyridazin-4-one [856] 35-(a) 3-Phenethyl-1,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(c) except for using 855 mg (1.80 mmol) of 3-bromo-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 20-(a) in place of 3-iodo- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , and using 965 mg (6.43 mmol) of phenethylboronic acid in place of methylboronic acid, respectively, whereby 698 mg of the title compound was obtained as an orange oil. (Yield: 78%) Mass Spectrum (CI, m/z): 500 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), -0.01 (s, 9H), 0.84-0.91 (m, 2H), 0.96-1.04 (m, 2H), 3.02 (dd, J=8.8, 6.3 Hz, 2H), 3.20 (dd, J=8.8, 6.3 Hz, 2H), 3.37-3.45 (m, 2H), 3.70-3.78 (m, 2H), 5.33 (s, 2H), 5.60 (s, 2H), 6.71 (s, IH) , 7.12-7.39 (m, 5H) , 8.13 (s, IH) . [857] 35-(b) 2-Bromo-3-phenethyl-l,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 755 mg (1.51 mmol) of 3-phenethyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 35-(a) in place of 3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, wnereDy bUb mg of the title com¬pound was obtained as a yellowish oil. (Yield: 69%) Mass Spectrum (CI, m/z) : 578 (M"+l) . 'H-NMR Spectrum (cdci3, 8 ppm) : -0.03 (s, 9H) , -0.01 (s, 9H), 0.86-0.93 (m, 2H), 0.96-1.04 (m, 2H), 2.93-3.01 (m, 2H), 3.11-3.20 (m, 2H), 3.46-3.56 (m, 2H), 3.69-3.78 (m, 2H), 5.49 (s, 2H), 5.59 (s, 2H), 7.13-7.31 (m, 5H), 8.12 (s, IH) . [858] Reference example 3 6 Ethyll-benzyloxymethyl-5 - (3- cyclopropoxy-4-difluoromethoxy- phenyl)-4-(2-fluorobenzyl)-2-formyl-lH-pyrrol-3-carboxylate [859] 36-(a) Ethyl 1-benzyloxymethyl-2-formyl-IH-pyrrol-3- carboxylate To 43 ml of toluene solution containing 3.66 g (10.0 mmol) of ethyl l-benzyloxymethyl-5-bromo-2-formyl-lH- pyrrol-3-carboxylate obtained in Reference example 17-(c) were added 2.1 ml of N,N-diisopropylethylamine and 0.4 g of 5% palladium-active carbon, and the mixture was stirred under 1 atm hydrogen atmosphere at room temperature for 6 hours. After completion of the reaction, insoluble materi¬al was removed by filtration from the reaction mixture, ethyl acetate was added to the filtrate, and the filtrate was washed successively with water and a saturated aqueous solution of sodium chloride. The organic layer after separation was dried over anhydrous magnesium sulfate, and concentrated under reduced pressure to obtain 2.96 g the title compound as a pale yellowish solid substantially quantitatively. Mass Spectrum (CI, m/z): 288 (MVl). 'H-NMR Spectrum (cdci3, 5 ppm): 1.39 (t, J=7.1 Hz, 3H), 4.36 (q, J=7.1 Hz, 2H), 4.54 (s, 2H), 5.83 (s, 2H), 6.73 (d, J=2.8 Hz, IH), 7.07 (dd, J=2.8, 0.7 Hz, IH), 7.26-7.38 (m, 5H), 10.44 (d, J=0.7 Hz, IH). IR Spectrum (KBr, cm"'): 1713, 1660. 36-(b) Ethyl l-benzyloxymethyl-4-bromo-2-formyl-lH-pyrrol- 3 -carboxylate To 10 ml of acetonitrile solution containing 1.00 g (3.48 mmol) of ethyl l-benzyloxymethyl-2-formyl-lH-pyrrol- 3-carboxylate obtained in Reference example 36-(a) was added 0.62 g (3.48 mmol) of N-bromosuccineimide under ice- cooling, and the mixture was stirred at room temperature for 4.5 hours. After completion of the reaction, a satur¬ated aqueous solution of sodium hydrogencarbonate was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous-magiesLuw auLPa^t and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l->4 :1 (V/V)) , and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.00 g of the title compound as a pale yellowish solid. (Yield: 78%) Mass Spectrum (CI, m/z) : 366 (M'^+l) . 'H-NMR Spectrum (cdci3, 5 ppm): 1.42 (t, J=7.2 Hz, 3H), 4.41 (q, J=7.2 Hz, 2H), 4.56 (s, 2H), 5.79 (s, 2H), 7.15 (d, J=0.9 Hz, IH), 7.26-7.39 (m, 5H), 10.27 (d, J=0.9 Hz, IH). [0861] 36-(c) Ethyl l-benzyloxymethyl-2-formyl-4-(4,4,5,5-tetra- methyl-[1,3,2]dioxaborolan-2-yl)-IH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 1-(a) except for using 366 mg (1.00 mmol) of ethyl l-benzyloxymethyl-4-bromo-2- formyl-lH-pyrrol-3-carboxylate obtained in Reference example 36-(b) in place of 4-bromo-2-cyclopropoxy-1- difluoromethoxybenzene, whereby 43 9 mg (purity: 55%) of the title compound was obtained as a brownish oil. (Yield: 58%) 'H-NMR Spectrum (cdci3, 8 ppm) : 1.35 (s, 12H) , 1.40 (t, J=7.2 Hz, 3H), 4.38 (q, J=7.2 Hz, 2H), 4.53 (s, 2H), 5.79 (s, 2H) , 7.26-7.37 (m, 5H) , 7.34 (d, J=1.0 Hz, IH) , 10.27 (d, J=1. 0 Hz, IH) . [0862] 36-(d) Ethyl l-benzyloxymeth.yl-4-(2-fluorobenzyl)-2-formyl- lH-pyrrol-3 -ca^i»oxylate To 10 0 ml of 1,2-dimethoxyethane solution containing 4.3 8 g (10.6 mmol) of ethyl l-benzyloxymethyl-2-formyl-4- (4,4,5, 5-tetramethyl- [1,3,2] dioxaboro.lan-2-yl) -lH-pyrrol-3- carboxylate obtained in Reference example 36-(c) were added 2.60 ml (21.4 mmol) of 2-fluorobenzyl bromide and 100 ml of 2M sodium carbonate aqueous solution, the mixture was degassed under reduced pressure and replaced with argon. Further, 2.47 g (2.14 mmol) of tetrakistriphenylphosphine palladium was added to the mixture, and the resulting mixture was stirred at 50°C for 3 hours. After completion of the reaction, to the reaction mixture were added water and a saturated aqueous solution of sodium chloride, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l-> 4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 3.80 g of the title compound as a yellowish oil. (Yield: 91%) Mass Spectrum (CI, m/z) : 396 (M^+1) . 'H-NMR Spectrum (cdci3, 5 ppm): 1.33 (t, J=7.2 Hz, 3H) , 4.10 (brs, 2H) , 4.34 (q, J=7.2 Hz, 2H) , 4.49 (s, 5H) , 5.73 (s, 2H), 6.71 (brs, IH), 7.00-7.10 (m, 2H), 7.11-7.37 (m, 7H), 10.36 (d, J=0.7 Hz, IH). [0863] 36-(e) Ethyl l-benzyloxymethyl-5-bromo-4-(2-fluorobenzyl)- 2 -formyl-IH-pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 3.80 g (9.61 mmol) of ethyl l-benzyloxymethyl-4-(2-fluoro- benzyl)-2-formyl-lH-pyrrol-3-carboxylate obtained in Reference example 36-(d) in place of 3-methyl-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one, whereby 4.05 g of the title compound was obtained as a slightly yellowish oil. (Yield: 89%) Mass Spectrum (CI, m/z) : 474 (M^+l) . ^H-NMR Spectrum (cdci3, 8 ppm) : 1.18 (t, J=7.2 Hz, 3H) , 4.14 (s, 2H), 4.23 (q, J=7.2 Hz, 2H), 4.63 (s, 2H), 6.03 (s, 2H), 6.81-6.88 (m, IH), 6.95-7.06 (m, 2H), 7.12-7.22 (m, IH), 7.23-7.36 (m, 5H), 10.22 (s, IH). [0864] 36-(f) Ethyl l-benzyloxymethyl-5-(3-cyclopropoxy-4- difluoromethoxyphenyl)-4-(2-fluorobenzyl)-2-formyl-lH- pyrrol-3 -carboxylate To 4.04 g (8.52 mmol) of ethyl l-benzyloxymethyl-5- bromo-4-(2-fluorobenzyl)-2-formyl-lH-pyrrol-3-carboxylate obtained in Reference example 36-(e) were added 3.62 g (11.1 mmol) of 2-(3-cyclopropoxy-4-difluoromethoxyphenyl)- 4,4,5,5-tetramethyl-[1,3,2]dioxaborolane obtained in Reference example 1-(a), 7.23 g (34.0 mmol) of potassium phosphate, 60 ml of toluene and 3.6 ml of water, the mixture was degassed under reduced pressure and replaced with argon. Further, 4 0 mg (0.178 mmol) of palladium acetate and 128 mg (0.356 mmol) of butyl-di-l-adamantyl- phosphine were added to the mixture, and the mixture was stirred at 100°C for 2 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=19:l-> 9:1 (v/v)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 5.01 g of the title compound as a yellowish oil substantially quantitatively. Mass Spectrum (CI, m/z): 594 (M^+l). ^H-NMR Spectrum (cdci3, 5 ppm) : 0.36-0.45 (m, 2H) , 0.55-0.64 (m, 2H), 1.13 (t, J=7.2 Hz, 3H), 3.31-3.38 (m, IH), 4.01 (s, 2H), 4.21 (q, J=7.2 Hz, 2H), 4.62 (s, 2H), 5.71 (s, 2H), 6.52 (t, J=74.7 Hz, IH), 6.82-6.89 (m, IH), 6.90-7.00 (m, 2H) , 6.93 (dd, J=8.2, 2.1 Hz, IH) , 7.08-7.17 (m, IH) , 7.13 (d, J=8.1 Hz, IH) , 7.20-7.33 (m, 5H) , 7.22 (d, J=2 . 1 Hz, IH), 10.46 (s, IH). [865] Reference example 3 7 l-Benzyloxymethyl-2-bromo-3-(3-fluorobenzyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one [866] 37-(a) l-Benzyloxyraethyl-3-[(3-fluorophenyl)hydroxymethyl]- 5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d] - pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 33-(e) except for using 6.2 ml of IM 3-fluorophenyl magnesium bromide tetrahydro- furan solution in place of phenyl magnesium bromide, whereby 2.60 g of the title compound was obtained as a brownish oil. (Yield: 82%) Mass Spectrum (CI, m/z) 510 (M"'+l) . ^H-NMR Spectrum (cdci3, 5 ppm): 0.00 (s, 9H), 0.95-1.04 (m, 2H) , 3.69-3.78 (m, 2H) , 4.40 (d, J=12.0 Hz, IH) , 4.45 (d, J=12.0 Hz, IH), 5.40 (s, 2H), 5.60 (d, J=9.8 Hz, IH), 5.64 (d, J=9.8 Hz, IH), 5.97 (brs, IH), 6.57 (d, J=0.7 Hz, IH), 6.95-7.04 (m, IH), 7.17-7.39 (m, 8H), 8.17 (s, IH). [0867] 37-(b) l-Benzyloxymethyl-3-(3-fluorobenzyl)-1,5-dihydro¬pyrrolo [2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 21-(e) except for using 2.6 0 g (5.10 mmol) of l-benzyloxymethyl-3-[(3-fluoro- phenyDhydroxymethyl]-5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 37-(a) in place of l-benzyloxymethyl-3-(1-hydroxy- 1-methylethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 1.07 g of the title compound was obtained as a white solid. (Yield: 58%) Mass Spectrum (CI, m/z): 354 (M"+l). "-H-NMR Spectrum (CDClj, 8 ppm) : 4.27 (brs, 2H) , 4.43 (s, 2H), 5.41 (s, 2H), 6.71 (t, J=1.0 Hz, IH), 6.87-6.95 (m, IH), 6.99-7.05 (m, IH), 7.10-7.15 (m, IH), 7.18-7.39 (m, 6H), 8.10 (s, IH), 9.96 (brs, IH). IR Spectrum (KBr, cm"^) : 1652. [0868] 37 - (c) l-Benzyloxymethyl-2-bromo-3-(3-fluorobenzyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one To 1.07 g (2.94 mmol) of l-benzyloxymethyl-3-(3- fluorobenzyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 3 7-(b) were added 3 0 ml of acetonitrile and 30 ml of dichloromethane, then, 612 mg (3.44 mmol) of N-bromosuccineimide was added to the mixture, and the mixture was stirred at 50°C for 2 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with chloroform. The organic layer after separation was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:l->2 :1->1:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.18 g of the title compound as a white solid. (Yield: 91%) Mass Spectrum (CI, m/z) : 442 (M%1) . 'H-NMR Spectrum (cdci3, 5 ppm) : 4.24 (s, 2H) , 4.53 (s, 2H) , 5.60 (s, 2H), 6.81-6.92 (m, IH), 7.08-7.16 (m, IH), 7.19- 7.36 (m, 8H). IR Spectrum (KBr, cm"'): 1655. [869] Reference example 3 8 l-Benzyloxymethyl-2-bromo-3-(4-fluorobenzyl)-1,5-dihydro- pyrrolo [2,3-d]pyridazin-4-one [870] 38-(a) l-Benzyloxymethyl-3-[(4-fluorophenyl)hydroxymethyl]- 5-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo [2,3-d] - pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 33-(e) except for using 6.1 ml of IM 4-fluorophenyl magnesium bromide tetrahydro- furan solution in place of phenyl magnesium bromide, whereby 2.73 g of the title compound was obtained as a brownish oil. (Yield: 88%) Mass Spectrum (CI, m/z): 510 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): 0.00 (s, 9H), 0.95-1.04 (m, 2H), 3.70-3.77 (m, 2H), 4.40 (d, J=11.9 Hz, IH), 4.45 (d, J=11.9 Hz, IH), 5.39 (s, 2H), 5.60 (d, J=9.8 Hz, IH), 5.64 (d, J=9.8 Hz, IH) , 5.97 (brs, IH) , 6.51 (d, J=0 . 7 Hz, IH) , 7.06 (tt, J=8.8, 2.4 Hz, 2H), 7.18-7.23 (m, 2H), 7.29-7.36 (m, 3H), 7.41-7.49 (m, 2H), 8.17 (s, IH). [871] 38-(b) l-Benzyloxymethyl-3-(4-fluorobenzyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 21-(e) except for using 2.73 g (5.36 mmol) of l-benzyloxymethyl-3-[(4-fluoro- phenyl) hydroxymethyl] -5-(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 38-(a) in place of l-benzyloxymethyl-3-(1-hydroxy- 1-methylethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one, whereby 1.73 g of the title compound was obtained as a pale yellowish solid. (Yield: 89%) Mass Spectrum (CI, m/z) : 364 (M'"+l) . 'H-NMR Spectrum (cdci3, 8 ppm): 4.24 (brs, 2H), 4.42 (s, 2H), 5.40 (s, 2H), 6.67 (t, J=0.9Hz, IH), 6.95-7.03 (m, 2H) , 7.18-7.36 (m, 7H) , 8.07 (s, IH) , 9.81 (brs, IH) . IR Spectrum (KBr, cm"'): 1653. [872] 38- (c) l-Benzyloxymethyl-2-bromo-3-(4-fluorobenzyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 37-(c) except for using 1.73 g (4.78 mmol) of l-benzyloxymethyl-3-(4-fluorobenzyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 38-(b) in place of l-benzyloxymethyl-3- (3-fluorobenzyl)-1,5-dihydropyrrolo[2,3-d] pyridazin-4-one, whereby 473 mg of the title compound was obtained as a white solid. (Yield: 22%) Mass Spectrum (CI, m/z) : 442 (M"'+l) . 'H-NMR Spectrum (cdci3, 8 ppm): 4.24 (brs, 2H), 4.42 (s, 2H), 5.40 (s, 2H), 6.67 (t, J=0.9 Hz, IH), 6.95-7.03 (m, 2H) , 7.18-7.36 (m, 7H) , 8.07 (s, IH) , 9.81 (brs, IH) . [873] Reference example 3 9 Ethyl l-benzyloxymethyl-4-(2-cyanobenzyl)-5-(3-cycloprop- oxy-4 -difluoromethoxyphenyl)-2 -formyl-IH-pyrrol-3 -carboxyl- ate [874] (a) Ethyl l-benzyloxymethyl-4-(2-cyanobenzyl)-2-formyl- lH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 36-(d) except for using 195 mg (3.73 mmol) of 2-cyanobenzyl bromide in place of 2- fluorobenzyl bromide, whereby 817 mg of the title compound was obtained as a yellowish solid. (Yield: 54%) Mass Spectrum (CI, m/z) : 403 (MVl) . 'H-NMR Spectrum (cdci3, 8 ppm): 1.29 (t, J=7.1 Hz, 3H), 4.32 (brs, 2H), 4.32 (q, J=7.1 Hz, 2H), 4.53 (s, 2H), 6.80 (d, J=0.9 Hz, IH), 7.22-7.36 (m, 9H), 7.50 (td, J=7.7, 1.3 Hz, IH) , 7.66 (dd, J=7.7, 1.3 Hz, IH) , 10.38 (d, J=0.9 Hz, IH) . [875] 39-(b) Ethyl l-benzyloxymethyl-5-bromo-4-{2-cyanobenzyl)-2- formyl-IH-pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 779 mg (1.94 mmol) of ethyl l-benzyloxymethyl-4-(2-cyano- benzyl)-2-formyl-lH-pyrrol-3-carboxylate obtained in Reference example 39-(a) in place of 3-methyl-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one, whereby 809 mg of the title compound was obtained as a slightly yellowish oil. (Yield: 87%) Mass Spectrum (CI, m/z) : 481 (M^'+l) 'H-NMR Spectrum (cdci3, 5 ppm): 1.15 (t, J=7.2 Hz, 3H) , 4.23 (q, J=7.2 Hz, 2H), 4.36 (s, 2H), 4.65 (s, 2H), 6.04 (s, 2H), 6.89 (d, J=8.1 Hz, IH), 7.24-7.39 (m, 6H), 7.43 (td, J=7.7, 1.4 Hz, IH), 7.66 (dd, J=7.7, 1.4 Hz, IH), 10.28 (s, IH) . [876] 39-(c) Ethyl l-benzyloxymethyl-4-(2-cyanobenzyl)-5-(3- cyclopropoxy-4-difluoromethoxyphenyl)-2-formyl-lH-pyrrol-3- carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 36-(f) except for using 796 mg (1.65 mmol) of ethyl l-benzyloxymethyl-5-bromo-4-(2- cyanobenzyl)-2-formyl-lH-pyrrol-3-carboxylate obtained in Reference example 39-(b) in place of ethyl 1-benzyloxy- methyl-5-bromo-4-(2-fluorobenzyl)-2-formyl-lH-pyrrol-3- carboxylate, whereby 900 mg of the title compound was obtained as a yellowish brown oil. (Yield: 91%) Mass Spectrum (CI, m/z) : 601 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): 0.40-0.48 (m, 2H), 0.58-0.66 (m, 2H), 1.12 (t, J=7.2 Hz, 3H), 3.37-3.44 (m, IH), 4.21 (q, J=7.2 Hz, 2H), 4.24 (s, 2H), 4.63 (s, 2H), 5.71 (s, 2H), 6.53 (t, J-74.7 Hz, IH), 6.85 (dd, J=8.2, 2.1 Hz, IH), 7.02 (dd, J=8.2, 0.7 Hz, IH), 7.12 (d, J=8.2 Hz, IH), 7.20- 7.33 (m, 7H), 7.43 (td, J=7.8, 1.3 Hz, IH), 7.58 (dd, J=7.8, 1.3 Hz, IH), 10.50 (s, IH). [877] Reference example 40 Ethyl 1-benzyloxymethyl-4-(3-cyanobenzyl)-5-(3-cycloprop- oxy-4 -di fluoromethoxyphenyl)-2-formy1-IH-pyrrol- 3 - carboxylate [878] 40-(a) Ethyl l-benzyloxymethyl-4-(3-cyanobenzyl)-2-formyl- lH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 36-(d) except for using 195 mg (0.993 mmol) of 3-cyanobenzyl bromide in place of 2- fluorobenzyl bromide, whereby 3 90 mg of the title compound was obtained as a yellowish oil. (Yield: 97%) Mass Spectrum (CI, m/z) : 403 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): 1.30 (t, J=7.2 Hz, 3H), 4.11 (s, 2H), 4.32 (q, J=7.2 Hz, 2H), 4.54 (s, 2H), 5.78 (s, 2H), 6.75 (s, IH), 7.21-7.54 (m, 9H), 10.37 (d, J=0.7 Hz, IH) . [879] 40-(b) Ethyl l-benzyloxymethyl-5-bromo-4-(3-cyanobenzyl)-2- formyl-IH-pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 362 mg (0.900 mmol) of ethyl l-benzyloxymethyl-4-(3-cyano- benzyl)-2-formyl-lH-pyrrol-3-carboxylate obtained in Reference example 40-(a) in place of 3-methyl-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]- pyridazin-4-one, whereby 252 mg of the title compound was obtained as a colorless oil. (Yield: 58%) Mass Spectrum (CI, m/z) : 481 (M^l) . ^H-NMR Spectrum (cdci3, 8 ppm) : 1.26 (t, J=7.2 Hz, 3H) , 4.15 (s, 2H), 4.29 (q, J=7.2 Hz, 2H), 4.63 (s, 2H), 6.02 (s, 2H) , 7.22-7.52 (m, 9H) , 10.23 (s, IH) . [0880] 40- (c) Ethyl l-benzyloxymethyl-4-(3-cyanobenzyl)-5-(3- cyclopropoxy-4 -dif luoromethoxyphenyl )-2 -formyl-IH-pyrrol-3 - carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 36-(f) except for using 223 mg (0.685 mmol) of ethyl l-benzyloxymethyl-5-bromo-4- (3-cyanobenzyl)-2-formyl-lH-pyrrol-3-carboxylate obtained in Reference example 40-(b) in place of ethyl 1-benzyloxy- methyl-5-bromo-4-(2-fluorobenzyl)-2-formyl-lH-pyrrol-3- carboxylate, whereby 261 mg of the title compound was obtained as a yellowish brown oil. (Yield: 86%) Mass Spectrum (CI, m/z): 601 (M^+1). ^H-NMR Spectrum (cdci3, 8 ppm) : 0.41-0.50 (m, 2H) , 0.58-0.66 (m, 2H), 1.21 (t, J=7.2 Hz, 3H), 3.34-3.41 (m, IH), 4.05 (s, 2H), 4.27 (q, J=7.2 Hz, 2H), 4.63 (s, 2H), 5.70 (s, 2H), 6.55 (t, J-74.6 Hz, IH), 6.87 (dd, J=8.3, 2.0 Hz, IH), 7.16 (d, J=8.3 Hz, IH) , 7.20-7.54 (m, lOH) , 10.46 (s, IH) . [0881] Reference example 41 Ethyl l-benzyloxymethyl-4-(3-carboxybenzyl)-5-(3-cycloprop- oxy-4-difluoromethoxyphenyl)-2 -formyl-IH-pyrrol-3 -carboxyl- ate [0882] 41- (a) Ethyl l-benzyloxymethyl-M3-tert-butoxycarbonyl- benzyl) -2-formyl -IH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 36-(d) except for using 1.4 3 g (5.27 mmol) of 3-tert-butoxycarbonylbenzyl bromide in place of 2-fluorobenzyl bromide, whereby 1.55 g of the title compound was obtained as a yellowish solid. (Yield: 62%) Mass Spectrum (EI, m/z) : 477 (M") . 'H-NMR Spectrum (cdci3, 8 ppm): 1.34 (t, J=7.2 Hz, 3H), 1.58 (s, 9H), 4.11 (s, 2H), 4.34 (q, J=7.2 Hz, 2H), 4.50 (s, 2H), 5.73 (s, 2H), 6.65 (d, J=0.6 Hz, IH), 7.19-7.42 (m, 7H), 7.81-7.90 (m, 2H), 10.37 (d, J=0.6 Hz, IH). [883] 41-(b) Ethyl l-benzyloxymethyl-5-bromo-4-(3-tert-butoxy- carbonylbenzyl)-2-formyl-IH-pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 1.55 g (3.25 mmol) of ethyl l-benzyloxymethyl-4-(3-tert- butoxycarbonylbenzyl )-2 -formyl-IH-pyrrol-3 -carboxylate obtained in Reference example 41-(a) in place of 3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 1.22 g of the title compound was obtained as a slightly yellowish oil. (Yield: 67%) Mass Spectrum (CI, m/z): 557 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm): 1.26 (t, J=7.2 Hz, 3H), 1.57 (s, 9H), 4.16 (s, 2H), 4.28 (q, J=7.2 Hz, 2H), 4.62 (s, 2H), 6.02 (s, 2H), 7.21-7.36 (m, 7H), 7.77-7.83 (m, IH), 7.85 (d, J=0.7 Hz, IH) , 10.21 (s, IH) . [884] 41-(c) Ethyl l-benzyloxymethyl-4-(3-tert-butoxycarbonyl- benzyl)-5-(3-cyclopropoxy-4-difluoromethoxyphenyl)-2- formyl-IH-pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 36-(f) except for using 1.20 g (2.16 mmol) of ethyl l-benzyloxymethyl-5-bromo-4-(3- tert-butoxycarbonylbenzyl)-2 -formyl-IH-pyrrol-3 -carboxylate obtained in Reference example 41-(b) in place of ethyl 1- benzyloxymethyl-5-bromo-4-(2-fluorobenzyl)-2-formyl-IH- pyrrol-3-carboxylate , whereby 1.2 6 g of the title compound was obtained as an orange oil. (Yield: 86%) Mass Spectrum (CI, m/z): 676 (M"+l). 'H-NMR Spectrum (cdci3, 8 ppm): 0.37-0.46 (m, 2H), 0.55-0.62 (m, 2H), 1.20 (t, J=7.2 Hz, 3H), 1.56 (s, 9H), 3.30-3.37 (m, IH), 4.06 (s, 2H), 4.26 (q, J-7.2 Hz, 2H), 4.61 (s. 2H), 5.70 (s, 2H), 6.54 (t, J=74.8 Hz, IH), 6.92 (dd, J=8.2, 2.1 Hz, IH), 7.10-7.32 (m, 9H), 7.64 (t, J=1.3 Hz, IH) , 7.74 (dt, J=7.7, 1.3 Hz, IH) , 10.45 (s, IH) . [885] (d) Ethyl l-benzyloxymethyl-4-(3-carboxybenzyl)-5-(3- cyclopropoxy-4 -difluoromethoxyphenyl)-2 -formyl-IH-pyrrol-3 - carboxylate To 25 ml of dichloromethane solution containing 1.24 g (1.84 mmol) of ethyl l-benzyloxymethyl-4-(3-tert-butoxy- carbonylbenzyl)-5-(3-eyelopropoxy-4-difluoromethoxyphenyl)- 2-formyl-lH-pyrrol-3-carboxylate obtained in Reference example 41-(c) was added 5 ml of trifluoroacetic acid, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure, and azeotropic dehydration with toluene was further carried out, and then the residue was dried under reduced pressure to obtain 1.21 g of the title compound as a yellowish oil substantially quantitatively. Mass Spectrum (CI, m/z) : 620 (MVl) . 'H-NMR Spectrum (cdci3, 8 ppm): 0.37-0.47 (m, 2H), 0.55-0.64 (m, 2H), 1.20 (t, J=7.2 Hz, 3H), 2.36 (s, IH), 3.32-3.40 (m, IH), 4.09 (S, 2H), 4.26 (q, J=7.2 Hz, 2H), 4.62 (s, 2H), 5.71 (s, 2H), 6.53 (t, J=74.7 Hz, IH), 6.91 (dd, J=8.3, 2.0 Hz, IH), 7.12-7.38 (m, 9H), 7.73 (t, J=1.5 Hz, IH) , 7.87 (dt, J=7.2, 1.5 Hz, IH) , 10.45 (s, IH) . [886] Reference example 42 Ethyl l-benzyloxymethyl-5-(3-cyclopropoxy-4-difluoro¬methoxyphenyl) -2-formyl-4-(6-methoxy-2-pyridylmethyl)-IH- pyrrol-3 -carboxylate [0887] 42- (a) Ethyl l-benzyloxymethyl-2-formyl-4-(6-methoxy-2- pyridylmethyl )-IH-pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 36-(d) except for using 0.99 g (4.90 mmol) of 2-bromomethyl-6-methoxypyridine in place of 2-fluorobenzyl bromide, whereby 1.02 g of the title compound was obtained as a yellowish oil. (Yield: 89%) Mass Spectrum (CI, m/z) : 409 (M%1) . 'H-NMR Spectrum (cdci3, 8 ppm): 1.30 (t, J=7.2 Hz, 3H), 3.87 (s, 3H), 4.16 (s, 2H), 4.32 (q, J=7.2 Hz, 2H), 4.52 (s, 2H) , 5.78 (s, 2H) , 6.58 (d, J=8.2 Hz, IH) , 6.71 (d, J=7.3 Hz, IH), 6.94 (d, J=0.6 Hz, IH), 7.22-7.35 (m, 5H), 7.48 (dd, J=8.2, 7.3 Hz, IH), 10.35 (d, J=0.6 Hz, IH). [0888] 42-(b) Ethyl l-benzyloxymethyl-5-bromo-2-formyl-4-(6- methoxy-2-pyridylmethyl)-IH-pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 1.02 g (2.50 mmol) of ethyl l-benzyloxymethyl-2-formyl-4- (6-methoxy-2-pyridylmethyl)-IH-pyrrol-3 -carboxylate obtained in Reference example 42-(a) in place of 3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, whereby 897 mg of the title com¬pound was obtained as a slightly yellowish oil. (Yield: 74%) Mass Spectrum (CI, m/z): 487 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm): 1.22 (t, J=7.1 Hz, 3H), 3.84 (s, 3H), 4.22 (s, 2H), 4.25 (q, J=7.1 Hz, 2H), 4.61 (s, 2H) , 6.03 (s, 2H) , 6.55 (d, J=7.7 Hz, IH) , 6.58 (d, J=7.7 Hz, IH), 7.21-7.35 (m, 5H), 7.45 (t, J=7.7 Hz, IH), 10.21 (s, IH) . [0889] 42-(c) Ethyl l-benzyloxymethyl-5-(3-cyclopropoxy-4- difluoromethoxyphenyl)-2-formyl-4-(6-methoxy-2-pyridyl- methyl)-IH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 31 except for using 875 mg (1.80 mmol) of ethyl l-benzyloxymethyl-5-bromo-2-formyl- 4-(6-methoxy-2-pyridylmethyl)-IH-pyrrol-3-carboxylate obtained in Reference example 42-(b) in place of 2-chloro- 3-iodo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3-d] pyridazin-4-one, and using 880 mg (2.70 mmol) of 2- (3-cyclopropoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetra- methyl-[1,3,2]dioxaborolane obtained in Reference example 1-(a) in place of phenylboronic acid, respectively, whereby 1.15 g of the title compound was obtained as a yellowish oil substantially quantitatively. Mass Spectrum (CI, m/z) : 607 (M'"+l) . 'H-NMR Spectrum (cdci3, 5 ppm): 0.37-0.46 (m, 2H), 0.57-0.65 (m, 2H), 1.17 (t, J-7.2 Hz, 3H), 3.36-3.43 (m, IH), 3.79 (S, 3H), 4.08 (S, 2H), 4.23 (q, J=7.2 Hz, 2H), 4.61 (s, 2H), 5.74 (s, 2H), 6.50 (d, J=8.2 Hz, IH), 6.53 (t, J=74.7 Hz, IH), 6.55 (d, J-7.4 Hz, IH), 7.03 (dd, J=8.2, 2.0 Hz, IH) , 7.15 (d, J=8.2 Hz, IH) , 7.19-7.32 (m, 5H) , 7.35 (d, J=2.0 Hz, IH), 7.42 (dd, J=8.2, 7.4 Hz, IH), 10.45 (s, IH). [890] Reference example 4 3 Ethyl l-benzyloxymethyl-5-(3-eyelopropoxy-4-difluoro¬methoxyphenyl) -2-formyl-4-(6-methoxy-3-pyridylmethyl)-IH- pyrrol-3 -carboxylate [891] 43-(a) Ethyl l-benzyloxymethyl-2-formyl-4-(6-methoxy-3- pyridylmethyl)-IH-pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 36-(d) except for using 1.16 g (5.44 mmol) of 3-bromomethyl-6-methoxypyridine in place of 2-fluorobenzyl bromide, whereby 617 mg of the title compound was obtained as a greenish oil. (Yield: 54%) Mass Spectrum (CI, m/z): 409 (MVl). 'H-NMR Spectrum (cdci3, 5 ppm): 1.35 (t, J=7.1 Hz, 3H), 3.93 (s, 3H), 3.99 (s, 2H), 4.35 (q, J=7.1 Hz, 2H), 4.51 (s, 2H) , 5.74 (s, 2H) , 6.67 (d, J=0.7 Hz, IH), 6.69 (dd, J=8.5, 0.7 Hz, IH), 7.19-7.37 (m, 5H), 7.41 (dd, J=8.5, 2.4 Hz, IH), 8.02 (dd, J=2.4, 0.7 Hz, IH), 10.36 (d, J=0.7 Hz, IH). 43-(b) Ethyl l-benzyloxymethyl-5-bromo-2-formyl-4-(6- methoxy-3-pyridylmethyl)-lH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 617 mg (1.51 mmol) of ethyl l-benzyloxymethyl-2-formyl-4- (6-methoxy-3-pyridylmethyl)-IH-pyrrol-3 -carboxylate obtained in Reference example 43-(a) in place of 3-methyl- 1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2 , 3 -d] pyridazin-4 -one , whereby 322 mg of the title compound was obtained as a yellowish oil. (Yield: 44%) Mass Spectrum (CI, m/z): 487 (MVl). 'H-NMR Spectrum (cdci3, S ppm) : 1.30 (t, J=7.1 Hz, 3H) , 3.90 (s, 3H), 4.03 (s, 2H), 4.32 (q, J=7.1 Hz, 2H), 4.61 (s, 2H), 6.00 (s, 2H), 6.64 (dd, J-8.5, 0.5 Hz, IH), 7.22-7.35 (m, 5H), 7.40 (dd, J=8.5, 2.5 Hz, IH), 8.02 (dd, J=2.5, 0.5 Hz, IH), 10.20 (s, IH). [893] 43-(c) Ethyl l-benzyloxymethyl-5-(3-cyclopropoxy-4-di- fluoromethoxyphenyl)-2-formyl-4-(6-methoxy-3-pyridyl¬methyl) -IH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 31 except for using 322 mg (0.66 mmol) of ethyl l-benzyloxymethyl-5-bromo-2-formyl- 4-(6-methoxy-3-pyridylmethyl)-IH-pyrrol-3-carboxylate obtained in Reference example 43-(b) in place of 2-chloro- 3-iodo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo- [2,3-d]pyridazin-4-one, and using 323 mg (0.96 mmol) of 2- (3-eyelopropoxy-4-difluoromethoxyphenyl)-4,4,5,5-tetra- methyl-[1,3,2]dioxaborolane obtained in Reference example 1-(a) in place of phenylboronic acid, respectively, whereby 3 83 mg of the title compound was obtained as a slightly yellowish oil. (Yield: 96%) Mass Spectrum (CI, m/z): 607 (M^+1). 'H-NMR Spectrum (cdci3, 6 ppm) : 0.44-0.52 (m, 2H) , 0.59-0.67 (m, 2H) , 1.26 (t, J=:7.1 Hz, 3H) , 3.38-3.46 (m, IH) , 3.87 (s, 3H), 3.93 (s, 2H), 4.30 (q, J=7.1 Hz, 2H), 4.60 (s, 2H), 5.68 (s, 2H), 6.55 (t, J=74.7 Hz, IH), 6.60 (dd, J=8.4, 0.5 Hz, IH), 6.90 (dd, J=8.4, 2.0 Hz, IH), 7.13-7.33 (ra, 9H) , 10.43 (s, IH) . [894] Reference example 44 2,3-Dibromo-l-(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one 11.6 g of a concentrate of the mother liquor at the time of recrystallization of 2-bromo-l-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one in Reference example 15-(g) was applied to silica gel column chromatography (Eluent; toluene : ethyl acetate=:2 :1 (V/V) ) to obtain 0.81 g of the title compound was obtained as a gray solid. 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), 0.87-0.98 (m, 2H), 3.52-3.63 (m, 2H), 5.58 (s, 2H), 8.16 (s, IH), 10.25 (brs, IH). [895] Reference example 4 5 Ethyl 5-(3-Cyclopropylmethoxy-4-difluoromethoxyphenyl)-2- formyl-IH-pyrrol-3 -carboxylate [896] 45-(a) 2-Bromo-l-(3-cyclopropylmethoxy-4-difluoromethoxy¬phenyl) ethanone To 250 ml of isopropanol solution containing 10.8 g (42.3 mmol) of 1-(3-cyclopropylmethoxy-4-difluoromethoxy¬phenyl) ethanone (see WO 9206963) was added 36.5 g (97.1 mmol) of trimethylphenylammonium tribromide at room tem¬perature, and the mixture was stirred at room temperature for 5 hours. After completion of the reaction, a saturated aqueous solution of sodium hydrogencarbonate was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then. concentrated under reduced pressure to obtain 16.5 g of the title compound as a pale yellowish solid substantially quantitatively. 'H-NMR Spectrum (cdci3, 8 ppm) : 0.30-0.42 (m, 2H) , 0.59-0.72 (m, 2H), 1.24-1.38 (m, IH), 3.95 (d, J=7.1 Hz, 2H), 4.40 (s, 2H), 6.75 (t, J=74.7 Hz, IH), 7.24 (d, J=8.3 Hz, IH), 7.55 (dd, J=8.3, 2.0 Hz, IH), 7.59 (d, J=2.0 Hz, IH). [0897] 45-(b) Ethyl 2-[2-(3-cyclopropylmethoxy-4-difluoromethoxy- phenyl)-2-oxoethyl]-4-(4-methoxybenzyloxy)-3-oxobutyrate To 460 ml of an ethanol solution containing 13.5 g (50.7 mmol) of ethyl 4-(4-methoxybenzyloxy)-3-oxobutyrate (see WO 2004060890) was added 18.9 ml (50.6 mmol) of 21% sodium ethoxide-ethanol solution under ice-cooling, and the mixture was stirred at room temperature for 1 hour. Then, to the above mixture was added dropwise 3 00 ml of ethanol solution containing 16.5 g (42.3 mmol) of 2-bromo-l-(3- cyclopropylmethoxy-4 -di fluoromethoxyphenyl)ethanone obtained in Reference example 45-(a) under ice-cooling, and the mixture was further stirred at 10°C or lower for 2.5 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with chloroform. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:l->7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 14.0 g of the title compound as a pale yellowish oil. (Yield: 63%) 'H-NMR Spectrum (cdci3, 8 ppm) : 0.31-0.41 (m, 2H) , 0.59-0.70 (m, 2H), 1.12-1.36 (m, IH), 1,23 (t, J=7.1 Hz, 3H), 3.49 (dd, J=18.3, 4.9 Hz, IH), 3.71 (dd, J=18.3, 9.0 Hz, IH), 3.80 (s, 3H), 3.92 (d, J=7.1 Hz, IH), 4.17 (q, J=7.1 Hz, 2H), 4.33 (dd, J=9.0, 4.9 Hz, IH), 4.39 (s, 2H), 4.58 (s. 2H), 6.72 (t, J=74.8 Hz, IH), 6.82-6.93 (m, 2H), 7.19-7.36 (m, 2H) , 7.22 (d, J=8.3 Hz, IH) , 7.52 (d, J-2 .0 Hz, IH) , 7.57 (dd, J=8.3, 2.0 Hz, IH). [898] 45-(c) Ethyl 5-(3-cyclopropylmethoxy-4-difluoromethoxy- phenyl)-2-(4-methoxybenzyloxymethyl)-lH-pyrrol-3- carboxylate To 100 ml of ethanol solution containing 14.0 g (26.8 mmol) of ethyl 2-[2-(3-cyclopropylmethoxy-4-difluoro- methoxyphenyl)-2-oxoethyl]-4-(4-methoxybenzyloxy)-3-oxo- butyrate obtained in Reference example 45-(b) was added 10.3 g (134 mmol) of ammonium acetate, the mixture was stirred at room temperature for 1 hour, and further stirred at 80°C for 4 hours. After completion of the reaction, to the reaction mixture were added water and a saturated aqueous solution of sodium chloride, and the mixture was extracted with chloroform. The organic layer after separa¬tion was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 10.3 g of the title compound as a beige solid. (Yield: 77%) 'H-NMR Spectrum (cdci3, 5 ppm) : 0.29-0.43 (m, 2H) , 0.56-0.72 (m, 2H), 1.18-1.40 (m, IH), 1,34 (t, J=7.1 Hz, 3H), 3.81 (s, 3H), 3.91 (d, J=7.1 Hz, 2H), 4.28 (q, J=7.1 Hz, 2H), 4.60 (s, 2H), 4.93 (s, 2H), 6.62 (t, J=75.6 Hz, IH), 6.78 (d, J=2.9 Hz, IH), 6.86-6.93 (m, 2H), 6.95 (dd, J-8.3, 2.2 Hz, IH) , 7.03 (d, J=2.2 Hz, IH) , 7.15 (d, J=8.3 Hz, IH) , 7.23-7.35 (m, 2H), 8.89 (brs, IH). [899] 45-(d) Ethyl 5-(3-cyclopropylmethoxy-4-difluoromethoxy- phenyl)-2 -formyl-IH-pyrrol-3 -carboxylate To 10.3 g (20.6 mmol) of ethyl 5-(3-cyclopropyl- methoxy-4-difluoromethoxyphenyl)-2-{4-methoxybenzyloxy- raethyl)-lH-pyrrol-3-carboxylate obtained in Reference example 45-(c) were added 100 ml of dich.1 oromethane and 10 ml of water, then, 5.15 g (22.7 mmol) of 2,3-dichloro-5,6- dicyano-1,4-benzoquinone was added to the mixture under ice-cooling, and the mixture was stirred at room tempera¬ture for 3 hours. After completion of the reaction, the reaction suspension was filtered through Celite, the filtrate was successively washed with a saturated aqueous solution of sodium hydrogencarbonate, and then, with a saturated aqueous solution of sodium chloride. The organic layer after separation was dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. To the obtained concentrate was added 100 ml of a mixed solvent (diisopropyl ether/hexane=l/l (V/V)), and the precipitated solid was collected by filtration. The obtained solid was washed with diisopropyl ether, and dried under reduced pressure to obtain 3.98 g of the title compound as a pale yellowish solid. (Yield: 49%) 'H-NMR Spectrum (CDClj, 8 ppm) : 0.33-0.44 (m, 2H) , 0.59-0.72 (m, 2H), 1.25-1.48 (m, IH), 1,42 (t, J=7.1 Hz, 3H), 3.95 (d, J=6.8 Hz, 2H), 4.41 (q, J=7.1 Hz, 2H), 6.67 (t, J=75.2 Hz, IH), 7.00 (d, J=2.0 Hz, IH), 7.19 (dd, J=8.1, 2.0 Hz, IH), 7.22 (s, IH), 7.24 (d, J=8.1 Hz, IH), 10.10 (brs, IH), 10.26 (s, IH). [0900] Reference example 4 6 3-Ethyl-2-iodo-l,5-bis(2-trimethylsilylethoxymethyl)-1,5- dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(b) except for using 1.01 g (2.40 mmol) of 3-ethyl-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 19-(c) in place of 1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid¬azin-4 -one, whereby 1.12 g of the title compound was obtained as a white solid. (Yield: 85%) Mass Spectrum (CI, m/z): 550 (M"+l). 'H-NMR Spectrum (cdci3, 5 ppm) : -0.04, -0.03 (each s, 9H in total, rotational isomer), -0.02 (s, 9H), 0.86-1.02 (m, 4H), 1.21, 1.24 (each t, J=7.4 Hz, 3H in total), 2.89, 2.90 (each q, J=7.4 Hz, 2H in total), 3.51-3.59 (m, 2H), 3.68- 3.76 (m, 2H), 5.50 (s, 2H), 5.56 (s, 2H), 8.10, 8.13 (s, IH) . [901] Reference example 4 7 Ethyl 5-(3-cyclopentoxy-4-methoxyphenyl)-2-formyl-lH- pyrrol-3 -carboxylate [902] 47-(a) 2-Bromo-l-(3-cyclopentoxy-4-methoxyphenyl)ethanone To 200 ml of methanol solution containing 11.6 g (49.5 mmol) of 1-(3-eyelopentoxy-4-methoxyphenyl)ethanone (see Bioorg. Med. Chem. Lett. 2003, 13, 2355) was added 20.47 g (54.5 mmol) of trimethylphenylammonium tribromide at room temperature, and the mixture was stirred at room tempera¬ture for 40 minutes. After completion of the reaction, water was added to the reaction mixture, and the mixture was neutralized with a saturated aqueous solution of sodium hydrogencarbonate and then extracted with chloroform. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. To the obtained concentrate was added 50 ml of a mixed solvent (diisopropyl ether/hexane=l/2 (V/V)), and precipitated solid was collected by filtration. The obtained solid was washed with diisopropyl ether, and dried under reduced pressure to obtain 6.47 g of the title compound as a white solid. (Yield: 41%) 'H-NMR Spectrum (cdci3, S ppm) : 1.48-2.00 (m, 8H) , 3.92 (s, 3H), 4.40 (s, 2H), 4.81-4.91 (m, IH), 6.89 (t, J=8.5Hz, IH) , 7.54 (d, J=2.2 Hz, IH) , 7.58 (dd, J=8.5, 2.2 Hz, IH) . 47-(b) Ethyl 4-benzyloxy-2-[2-(3-cyclopentoxy-4-methoxy- phenyl) -2-oxoethyl]-3-oxobutyrate Reaction and post treatment were carried out in the same manner as in Reference example 45-(b) except for using 7.65 g (32.4 mmol) of ethyl 4-benzyloxy-3-oxobutyrate in place of ethyl 4-(4-methoxybenzyloxy)-3-oxobutyrate, and using 8.45 g (27 mmol) of 2-bromo-l-(3-cyclopentoxy-4- methoxyphenyl) ethanone obtained in Reference example 47-(a) in place of 2-bromo-l-(3-cyclopropylmethoxy-4-difluoro- methoxyphenyl)ethanone, respectively, whereby 9.4 9 g of the title compound was obtained as a yellowish oil. (Yield: 75%) 'H-NMR Spectrum (cdci3, 5 ppm) : 1.23 (t, J=7.1 Hz, 3H) , 1.52-2.06 (m, 8H), 3.51 (dd, J=18.1, 4.6 Hz, IH), 3.75 (dd, J=18.1, 9.3 Hz, IH), 3.91 (s, 3H), 4.17 (q, J=7.1 Hz, 2H), 4.32 (dd, J=9.3, 4.6 Hz, IH), 4.45 (s, 2H), 4.66 (s, 2H), 4.78-4.88 (m, IH), 6.88 (d, J=8.5 Hz, IH), 7.24-7.44 (m, 5H), 7.48 (d, J=2.0 Hz, IH), 7.60 (dd, J=8.5, 2.0 Hz, IH). [904] 47-(c) Ethyl 2-benzyloxymethyl-5-(3-cyclopentoxy-4-methoxy- phenyl) -IH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 45-(c) except for using 9.37 g (20 mmol) of ethyl 4-benzyloxy-2-[2-(3-cyclopentoxy- 4-methoxyphenyl)-2-oxoethyl]-3-oxobutyrate obtained in'Referentt e3i6mplt^7-(b)uiplace of ethyl 2-[2-(3-cyclopropylmethoxy-4-di- fluoromethoxyphenyl)-2-oxoethyl]-4-(4-methoxybenzyloxy)-3- oxobutyrate, whereby 7.27 g of the title compound was obtained as a reddish solid. (Yield: 80%) 'H-NMR Spectrum (cdci3, 6 ppm): 1.34 (t, J=7.1 Hz, 3H), 1.52-2.04 (m, 8H), 3.86 (s, 3H), 4.28 (q, J=7.1 Hz, 2H), 4.66 (s, 2H), 4.78-4.88 (m, IH), 4.97 (s, 2H), 6.71 (d, J=2 . 9 Hz, IH) , 6.86 (d, J=8.3 Hz, IH) , 6.94 (d, J=2 .2 Hz, IH), 6.99 (dd, J=8.3, 2.2 Hz, IH), 7.25-7.45 (m, 5H), 8.87 (brs, IH). [905] 47-(d) Ethyl 5-(3-cyclopentoxy-4-methoxyphenyl)-2-hydroxy- methyl-IH-pyrrol-3 -carboxylate To 280 ml of ethanol solution containing 3.15 g (7.0 mmol) of ethyl 2-benzyloxymethyl-5-(3-cyclopentoxy-4- methoxyphenyl) -lH-pyrrol-3-carboxylate obtained in Reference example 47-(c) was added 600 mg of 10% palladium- active carbon, and the mixture was stirred under 1 atm hydrogen atmosphere at room temperature for 11 hours. Then, the mixture was stirred at 3 0°C for 1.25 hours, and further at 40°C for 13 hours. After completion of the reaction, the reaction suspension was filtered through Celite, and the filtrate was concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:3-> 1:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.09 g of the title compound as a yellowish oil. (Yield: 43%) ^H-NMR Spectrum (cdci3, 8 ppm) : 1.38 (t, J=7.1 Hz, 3H) , 1.50-2.03 (m, 8H), 3.50 (t, J=6.2 Hz, IH), 3.86 (s, 3H), 4.32 (q, J=7.1 Hz, 2H), 4.80-4.95 (m, 3H), 6.70 (d, J=2.9 Hz, IH), 6.87 (d, J=8.1 Hz, IH), 6.98 (dd, J=8.1, 2.0 Hz, IH) , 7.01 (d, J=2.0 Hz, IH) , 8.86 (brs, IH) . [0906] 47-(e) Ethyl 5-(3-cyclopentoxy-4-methoxyphenyl)-2-formyl- lH-pyrrol -3 -carboxylate To 30 ml of dichloromethane solution containing 1.08 g (3.0 mmol) of ethyl 5-(3-cyclopentoxy-4-methoxyphenyl)-2- hydroxymethyl-lH-pyrrol-3-carboxylate obtained in Reference example 47-(d) was added 3.13 g (36 mmol) of manganese dioxide, and the mixture was stirred at room temperature for 1.2 hours. After completion of the reaction, the reaction suspension was filtered through Celite, and the obtained filtrate was concentrated under reduced pressure to obtain 1.05 g of the title compound as a yellowish solid. (Yield: 97%) Mass Spectrum (CI, m/z) : 358(M"+l) . ^H-NMR Spectrum (DMSO-dg, 5 ppm) : 1.33 (t, J=7.3. Hz, 3H) , 1.54-1.79 (m, 6H), 1.85-2.00 (m, 2H), 3.77 (s, 3H), 4.31 (q, J=7.3 Hz, 2H), 4.94-5.01 (m, IH), 6.98 (d, J=8.3 Hz, IH) , 7.05 (s, IH) , 7.47 (dd, J=8.3, 2.0 Hz, IH), 7.56 (d, J=2 . 0 Hz, IH) , 10 . 11 (s, IH) . [907] Reference example 4 8 Ethyl 5-(7-difluoromethoxy-2,3-dihydrobenzofuran-2-spiro- 1'-cyclopentan-4-yl)-2-formyl-lH-pyrrol-3-carboxylate [908] 48-(a) 1-(7-Difluoromethoxy-2,3-dihydrobenzofuran-2-spiro- 1'-cyclopentan-4-yl)ethanone To 80 ml of tetrahydrofuran solution containing 4.55 g (16 mmol) of 7-difluoromethoxy-2,3-dihydrobenzofuran-2- spiro-1'-cyclopentan-4-carboxylic acid (see WO 96/03399) was added 38 ml (43.3 mmol) of diethyl ether solution con¬taining 1.14M methyl lithium under ice-cooling, and the mixture was stirred at room temperature for 7.5 hours. After completion of the reaction, 2N hydrochloric acid was added to the reaction mixture, and the mixture was extract¬ed with ethyl acetate. The organic layer after separation was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:1- >1:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.32 g of the title compound as a yellowish oil. (Yield: 29%) ^H-NMR Spectrum (cdci3, 8 ppm): 1.68-2.19 (m, 8H), 2.56 (s, 3H), 3.55 (s, 2H), 6.81 (t, J=74.7Hz, IH), 7.03 (d, J=8.4 Hz, IH), 7.35 (d, J-8.4 Hz, IH). [909] 48-(b) 2-Bromo-l-(7-difluoromethoxy-2,3-dihydrobenzofuran- 2-spiro-l'-cyclopentan-4-yl)ethanone To 100 ml of tetrahydrofuran solution containing 1.43 g (5.1 mmol) of 1-(7-difluoromethoxy-2,3-dihydrobenzofuran- 2-spiro-l'-cyclopentan-4-yl)ethanone obtained in Reference example 48-(a) was added 1.71 g (4.5 mmol) of trimethyl- phenylammonium tribromide under ice-cooling, and the mixture was stirred at room temperature for 3 hours. After completion of the reaction, to the reaction mixture was added a saturated aqueous solution of sodium hydrogen- carbonate, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=19:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.25 g of the title compound as an oil. (Yield: 67%) ^H-NMR Spectrum (cdci3, 5 ppm): 1.69-2.19 (m, 8H), 3.55 (s, 2H), 4.40 (s, 2H), 6.83 (t, J=74.3Hz, IH), 7.05 (d, J=8.7 Hz, IH), 7.36 (d, J=8.7 Hz, IH). [0910] 48-(c) Ethyl 2-[2-(7-difluoromethoxy-2,3-dihydrobenzofuran- 2-spiro-l'-cyclopentan-4-yl)-2-oxoethyl]-4-(4-methoxy- benzyloxy)-3-oxobutyrate Reaction and post treatment were carried out in the same manner as in Reference example 45-(b) except for using 792 mg (2.20 mmol) of 2-bromo-1-(7-difluoromethoxy-2,3- dihydrobenzofuran-2-spiro-1'-cyclopentan-4-yl)ethanone obtained in Reference example 48-(b) in place of 2-bromo- 1-(3-cyclopropylmethoxy-4-difluoromethoxyphenyl)ethanone, whereby 1.08 g of the title compound as a yellowish oil. (Yield: 75%) ^H-NMR Spectrum (cdci3, 5 ppm): 1.23 (t, J-7.1 Hz, 3H), 1.65-2.16 (m, 8H), 3.47 (dd, J=18.3, 4.6 Hz, IH), 3.49 (s, 2H), 3.70 (dd, J-18.3, 9.0 Hz, IH), 3.81 (s, 3H), 4.15 (q, J=7.1 Hz, 2H), 4.28 (dd, J=9.0, 4.6 Hz, IH), 4.39 (s, 2H), 4.58 (s, 2H), 6.81 (t, J=74.6 Hz, IH), 6.87-6.91 (m, 2H), 7.04 (d, J=8.5 Hz, IH), 7.27-7.34 (m, 2H), 7.42 (d, J-8.5 Hz, IH). [911] 48-(d) Ethyl 5-(7-difluoromethoxy-2,3-dihydrobenzofuran-2- spiro-1'-cyclopentan-4-yl)-2-(4-methoxybenzyloxymethyl)-IH- pyrrol-3 -carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 45-(c) except for using 1.43 g (2.62 mmol) of ethyl 2-[2-(7-difluoromethoxy-2,3- dihydrobenzofuran-2-spiro-l'-cyclopentan-4-yl)-2-oxoethyl]- 4-(4-methoxybenzyloxy)-3-oxobutyrate obtained in Reference example 48-(c), whereby 1.23 g of the title compound was obtained as a brownish oil. (Yield: 89%) ^H-NMR Spectrum (cdci3, 8 ppm) : 1.34 (t, J=7.1 Hz, 3H) , 1.67-2.22 (m, 8H), 3.34 (s, 2H), 3.81 (s, 3H), 4.28 (q, J=7.1 Hz, 2H), 4.60 (s, 2H), 4.93 (s, 2H), 6.65 (d, J=3.2 Hz, IH) , 6.68 (t, J=75.1 Hz, IH) , 6.80 (d, J=8.5 Hz, IH) , 6.87-6.93 (m, 2H), 6.99 (d, J=8.5 Hz, IH), 7.27-7.32 (m, 2H), 8.91 (brs, IH). [912] 48-(e) Ethyl 5-(7-difluoromethoxy-2,3-dihydrobenzofuran-2- spiro-1'-cyclopentan-4-yl)-2-formyl-lH-pyrrol-3-carboxylate Reaction was carried out in the same manner as in Reference example 45-(d) except for using 1.22 g (2.31 mmol) of ethyl 5-(7-difluoromethoxy-2,3-dihydrobenzofuran- 2-spiro-l'-cyclopentan-4-yl)-2-(4-methoxybenzyloxymethyl)- lH-pyrrol-3-carboxylate obtained in Reference example 48- (d) in place of ethyl 5-(3-cyclopropylmethoxy-4-difluoro- methoxyphenyl)-2-(4-methoxybenzyloxymethyl)-lH-pyrrol-3- carboxylate. After completion of the reaction, the reaction suspension was filtered through Celite, and the filtrate was successively washed with a saturated aqueous solution of sodium hydrogencarbonate and the with a saturated aqueous solution of sodium chloride. The organic layer after separation was dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l->4:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 63 0 mg of the title compound as a yellowish solid. (Yield: 67%) Mass Spectrum (CI, m/z): 406 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): 1.42 (t, J=7.1 Hz, 3H), 1.70-2.25 (m, 8H), 3.41 (d, J-0.5 Hz, 2H), 4.41 (q, J=7.1 Hz, 2H) , 6.72 (t, J=74.7 Hz, IH) , 6.87 (d, J=2.9 Hz, IH) , 6.98 (d, J=8.3 Hz, IH), 7.07 (d, J=8.3 Hz, IH), 9.48 (brs, IH) , 10.22 (s, IH) . [913] Reference example 4 9 Ethyl 2-formyl-5-(2,3-dihydro-7-methoxybenzofuran-2-spiro- 1'-cyclopentan-4-yl)-lH-pyrrol-3-carboxylate [914] 49-(a) 1-(2,3-Dihydro-7-methoxybenzofuran-2-spiro-l'- cyclopentan-4-yl)ethanone To 250 ml of 1,2-dichloroethane solution containing 61.8 g (0.25 mol) of 2,3-dihydro-7-methoxybenzofuran-2- spiro-1'-cyclopentan-4-carboxylic acid (see WO 9603399) were added 3 6.5 ml (0.5 mol) of thionyl chloride and 2.5 ml of N,N-dimethylformamide, and the mixture was stirred at 80°C for 1.7 hours. The reaction mixture was concentrated under reduced pressure, to the residue was added 10 0 ml of 1,2-dichloroethane, and the obtained solution was added dropwise to 1.5L of dichloromethane solution containing a mixture comprising 122 g (1.25 mol) of N,0-dimethyl- hydroxylamine hydrochloride and 350 ml (2.5 mol) of triethylamine under ice-cooling. After completion of the dropwise addition, the mixture was further stirred at room temperature for 1 hour. After completion of the reaction. water was added to the reaction mixture, and the mixture was extracted with chloroform. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure to obtain 77.8 g of a black oily material. To 77.8 g of the black oily material obtained as mentioned above were added 500 ml of diethyl ether and 50 0 ml of tetrahydrofuran, 200 ml of diethyl ether solution containing 3M methyl magnesium bromide was added to the mixture under ice-cooling, and the mixture was stirred at room temperature for 2 hours. After completion of the reaction, ice-water was added to the reaction mixture, followed by adjusting a pH thereof to 1 with 4N hydrochloric acid, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with a saturated aqueous solution of sodium hydrogencarbonate and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 56.1 g of the title compound as a pale yellowish solid. (Yield: 91%) 'H-NMR Spectrum (cdci3, 8 ppm) : 1.67-2.20 (m, 8H) , 2.54 (s, 3H), 3.54 (s, 2H), 3.93 (s, 3H), 6.77 (d, J=8.5 Hz, IH), 7.40 (d, J=8.5 Hz, IH). [0915] 49-(b) 2-Bromo-l-(2,3-dihydro-7-methoxybenzofuran-2-spiro- 1'-cyclopentan-4-yl)ethanone Reaction was carried out in the same manner as in Reference example 45-(a) except for using 246 mg (1.0 mmol) of 1-(2,3-dihydro-7-methoxybenzofuran-2-spiro-l'-cyclo- pentan-4-yl)ethanone obtained in Reference example 49-(a) in place of 1-(3-cyclopropylmethoxy-4-difluoromethoxy- phenyl)ethanone. After completion of the reaction, to the reaction mixture was added a saturated aqueous solution of sodium hydrogencarbonate, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 287 mg of the title compound as a yellowish oil. (Yield: 88%) Mass Spectrum (CI, m/z): 326 (M''+l) . 'H-NMR Spectrum (cdci3, 5 ppm): 1.68-2.20 (m, 8H), 3.54 (d, J=0.5Hz, 2H), 3.94 (s, 3H), 4.41 (s, 2H), 6.79 (d, J=8.7 Hz, IH) , 7.42 (d, J=8.7 Hz, IH) . 49-(c) Ethyl 2-[2-(2,3-dihydro-7-methoxybenzofuran-2-spiro- 1'-cyclopentan-4-yl)-2-oxoethyl]-4-(4-methoxybenzyloxy)-3- oxobutyrate Reaction and post treatment were carried out in the same manner as in Reference example 45-(b) except for using 860 mg (2.64 mmol) of 2-bromo-l-(2,3-dihydro-7-methoxy- benzofuran-2-spiro-l' -cyclopentan-4-yl) ethanone obtained in Reference example 49-(b) in place of 2-bromo-1-(3-cyclo- propylmethoxy-4-difluoromethoxyphenyl)ethanone, whereby 906 mg of the title compound was obtained as a yellowish oil. (Yield: 67%) Mass Spectrum (CI, m/z): 511 (M"+l). ^H-NMR Spectrum (cdci3, 8 ppm): 1.23 (t, J=7.1 Hz, 3H), 1.66-2.19 (m, 8H), 3.48 (dd, J=18.0, 4.6 Hz, IH), 3.48 (s, 2H), 3.72 (dd, J=18.0, 9.0 Hz, IH), 3.81 (s, 3H), 3.93 (s, 3H), 4.17 (q, J=7.1 Hz, 2H), 4.27 (dd, J=9.0, 4.6 Hz, IH), 4.41 (s, 2H), 4.58 (s, 2H), 6.78 (d, J=8.5 Hz, IH), 6.85- 6.91 (m, 2H), 7.27-7.34 (m, 2H), 7.47 (d, J=8.5 Hz, IH). [917] 49-(d) Ethyl 5-(2,3-dihydro-7-methoxybenzofuran-2-spiro-l'- cyclopentan-4-yl)-2-(4-methoxybenzyloxymethyl)-lH-pyrrol-3- carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 45-(c) except for using 903 mg (1.77 mmol) of ethyl 2-[2-(2,3-dihydro-7-methoxy- benzofuran-2-spiro-l'-cyclopentan-4-yl)-2-oxoethyl]-4-(4- methoxybenzyloxy)-3-oxobutyrate obtained in Reference example 49-(c) in place of ethyl 2-[2-(3-cyclopropyl- methoxy-4-difluoromethoxyphenyl)-2-oxoethyl]-4-(4-methoxy- benzyloxy)-3-oxobutyrate, whereby 786 mg of the title compound was obtained as a yellowish foam. (Yield: 90%) Mass Spectrum (CI, m/z) : 492 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm) : 1.34 (t, J=7.1 Hz, 3H), 1.67-2.25 (m, 8H), 3.33 (s, 2H), 3.81 (s, 3H), 3.88 (s, 3H), 4.28 (q, J=7.1 Hz, 2H), 4.59 (s, 2H), 4.93 (s, 2H), 6.59 (d, J=2.9 Hz, IH), 6.77 (d, J=8.3 Hz, IH), 6.82 (d, J=8.3 Hz, IH), 6.87-6.93 (m, 2H), 7.26-7.33 (m, 2H), 8.85 (brs, IH). [0918] 49-(e) Ethyl 2-formyl-5-(2,3-dihydro-7-methoxybenzofuran-2- spiro-l' -cyclopentan-4-yl)-lH-pyrrol-3-carboxylate Reaction and post treatment were carried out in the same manner as in Reference example 45-(d) except for using 783 mg (1.59 mmol) of ethyl 5-(2,3-dihydro-7-methoxybenzo- furan-2-spiro-l'-cyclopentan-4-yl)-2-(4-methoxybenzyloxy¬methyl) -lH-pyrrol-3-carboxylate obtained in Reference example 49-(d) in place of ethyl 5-(3-cyclopropylmethoxy-4- dif luoromethoxyphenyl) -2-(4-methoxybenzyloxymethyl)-IH- pyrrol-3-carboxylate. After completion of the reaction, the reaction suspension was filtered through Celite, and the filtrate was successively washed with a saturated aqueous solution of sodium hydrogencarbonate and then with a saturated aqueous solution of sodium chloride. The organic layer after separation was dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=4:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 450 mg of the title compound as a greenish solid. (Yield: 76%) Mass Spectrum (CI, m/z) : 370 (M'"+l) . "H-NMR Spectrum (cdci3, 5 ppm): 1.42 (t, J=7.1 Hz, 3H), 1.68-2.27 (m, 8H), 3.39 (s, 2H), 3.91 (s, 3H), 4.41 (q, J=7.1 Hz, 2H), 6.83 (d, J=2.9 Hz, IH), 6.83 (d, J=8.5 Hz, IH), 7.00 (d, J=8.5 Hz, IH), 9.47 (brs, IH), 10.20 (s, IH). [0919] Reference example 5 0 2-Bromo-3 -cyclopropylmethoxymethyl-1-(2 -trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 10 ml of dehydrated tetrahydrofuran solution containing 0.92 g (13 mmol) of cyclopropylmethanol was added 0.2 5 g (6.2 mmol) of sodium hydride (6 0% dispersed material in mineral oil) under ice-cooling, the mixture was stirred at room temperature for 3 0 minutes, then, 10 ml of dehydrated tetrahydrofuran solution containing 0.56 g (1.3 mmol) of 2-bromo-3-bromomethyl-l-(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 24-(f) was further added to the mixture, and the mixture was stirred at room tempera¬ture for 2 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=2:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 157 mg of the title compound as a pale yellowish solid. (Yield: 29%) Mass Spectrum (CI, m/z): 428 (M^l). ^H-NMR Spectrum (DMSO-dg, 5 ppm): -0.10 (s, 9H), 0.08-0.16 (m, 2H), 0.37-0.45 (m, 2H), 0.77-0.85 (m, 2H), 0.90-1.04 (m, IH), 3.25 (d, J=6.8 Hz, 2H), 3.48-3.57 (m, 2H), 4.64 (s, 2H), 5.63 (s, 2H), 8.45 (s, IH), 12.47 (brs, IH). [920] Reference example 51 2-Bromo-3-isopropoxymethyl-l,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 2 ml of dehydrated tetrahydrofuran solution containing 1 ml of isopropanol was added 155 mg of sodium hydride (55% dispersed material in mineral oil), the mixture was stirred at room temperature for 2 0 minutes, then, 272 mg (0.48 mmol) of 2-bromo-3-bromomethyl-l,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Reference example 25-(a) was further added to the mixture, and the mixture was stirred at room temperature for 1 hour. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 176 mg of the title compound as a colorless oil. (Yield: 67%) Mass Spectrum (CI, m/z) : 546 (M^l) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), -0.02 (s, 9H), 0.87-1.02 (m, 4H), 1.22 (d, J=6.1Hz, 6H), 3.53-3.61 (m, 2H), 3.66-3.74 (m, 2H), 3.77-3.86 (m, IH), 4.80 (s, 2H) , 5.53 (s, 2H) , 5.56 (s, 2H) , 8.14 (s, IH) . IR Spectrum (KBr, cm'^) : 1669. [921] Reference example 52 2-Bromo-3-(2-fluoroethoxymethyl)-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 15 ml of dehydrated tetrahydrofuran solution containing 1.02 g (16 mmol) of 2-fluoroethanol was added 0.32 g (8.0 mmol) of sodium hydride (60% dispersed material in mineral oil) under ice-cooling, and the mixture was stirred at room temperature for 30 minutes. Then, 0.90 g (1.6 mmol) of 2-bromo-3-bromomethyl-l,5-bis(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 25-(a) was further added to the mixture, and the mixture was stirred at room tempera¬ture for 3 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 802 mg of the title compound as a white solid. (Yield: 91%) ^H-NMR Spectrum (cdci3, 8 ppm): -0.03 (s, 9H), -0.02 (s, 9H) , 0.87-1.01 (m, 4H) , 3.53-3.61 (m, 2H) , 3.66-3.74 (m, 2H) , 3.77-3.82 (m, IH) , 3.87-3.92 (m, IH) , 4.46-4.51 (m, IH) , 4.62-4.67 (m, IH) , 4.89 (s, 2H) , 5.55 (s, 2H) , 5.56 (s, 2H), 8.15 (s, IH). [0922] Reference example 53 2-Bromo-3 -isobutoxymethyl-1,5-bis(2 -trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 5 ml of dehydrated tetrahydrofuran solution containing 1 ml of isobutanol was added 0.4 9 g of sodium hydride (60% dispersed material in mineral oil) under cooling in ice-bath, and the mixture was stirred at room temperature for 15 minutes. Then, 0.99 g (1.75 mmol) of 2- bromo-3 -bromomethyl- 1 , 5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 25-(a) was added to the mixture under cooling in ice-bath, and the mixture was stirred at the same temperature for 1 hour. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=9:l->4 :1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.66 g of the title compound as a colorless oil. (Yield: 67%) Mass Spectrum (CI, m/z) : 562 (MVl) . 'H-NMR Spectrum (cdci3, 8 ppm): -0.03 (s, 9H), -0.02 (s, 9H), 0.86-1.01 (m, 4H), 0.89 (d, J-6.7 Hz, 6H), 1.82-1.97 (m, IH), 3.32 (d, J=6.7 Hz, 2H), 3.53-3.60 (m, 2H), 3.67- 3.74 (m, 2H), 4.80 (s, 2H), 5.55 (s, 2H), 5.56 (s, 2H), 8 . 15 (s, IH) . [0923] Reference example 54 2-Bromo-3-(sec-butoxymethyl)-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 4 ml of dehydrated tetrahydrofuran solution containing 0.96 ml of 2-butanol was added 0.3 0 g of sodium hydride (60% dispersed material in mineral oil), and the mixture was stirred at room temperature for 3 hours. Then, 0.85 g (1.50 mmol) of 2-bromo-3-bromomethyl-l,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Reference example 25-(a) was added to the mixture under cooling in ice-bath, and the mixture was stirred at the same temperature for 1 hour. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane : ethyl acetate=:=9 : l->4 :1 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.4 6 g of the title compound as a colorless oil. (Yield: 55%) Mass Spectrum (CI, m/z) : 562 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.02 (s, 9H), -0.02 (s, 9H), 0.89 (t, J=7.4 Hz, 3H), 0.90-0.94 (m, 2H), 0.95-0.99 (m, 2H), 1.21 (d, J=6.1 Hz, 3H), 1.42-1.51 (m, IH), 1.54- 1.64 (m, IH), 3.51-3.59 (m, 3H), 3.68-3.72 (m, 2H), 4.77 (d, J=10.8 Hz, IH) , 4.84 (d, J=10.8 Hz, IH) , 5.54 (s, 2H) , 5.55 (d, J=9.8 Hz, IH) , 5.58 (d, J=9.8 Hz, IH) , 8.14 (s, IH) . [0924] Reference example 55 2-bromo-3-(tert-butoxymethyl)-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 50 ml of N,N-dimethylformamide solution containing 2.52 g (4.44 mmol) of 2-bromo-3-bromomethyl-1,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 25-(a) was added 0.43 g (4.44 mmol) of sodium tert-butoxide at -10°C, and the mixture was stirred at the same temperature for 3 hours. The mixture was further stirred at 0°C for 10 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with toluene. The organic layer after separation was washed successively with water and then with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate = 98:2->65 : 35 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.61 g of the title compound as a pale yellowish solid. (Yield: 25%) Mass Spectrum (CI, m/z): 562 (M^+1). 'H-NMR Spectrum (cdci3, 6 ppm) : -0.02 (s, 18H) , 0.87-1.02 (m, 4H), 1.33 (s, 9H), 3.54-3.61 (m, 2H), 3.66-3.73 (m, 2H), 4.75 (s, 2H), 5.52 (s, 2H), 5.56 (s, 2H), 8.12 (s, IH) . [0925] Reference example 56 2-Bromo-3-(1-ethylpropoxymethyl)-1,5-bis(2 -trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 15 ml of dehydrated tetrahydrofuran solution containing 1.90 ml of 3-pentanol was added 0.3 8 g of sodium hydride (55% dispersed material in mineral oil) under cooling in ice-bath, and the mixture was stirred at room temperature for 3 hours. Then, 0.99 g (1.75 mmol) of 2- bromo-3 -bromomethyl- 1 , 5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 25-(a) was added to the mixture, and the mixture was stirred at 45°C for 2 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 0.66 g of the title compound as a slightly yellowish oil. (Yield: 65%) Mass Spectrum (CI, m/z): 576 (M^l) . 'H-NMR Spectrum (cdci3, 5 ppm) : -0.03 (s, 18H) , 0.86-1.00 (m, 4H), 0.90 (t, J=3.7 Hz, 6H), 1.51-1.64 (m, 4H), 3.29- 3.39 (m, IH), 3.52-3.60 (m, 2H), 3.65-3.74 (m, 2H), 4.81 (S, 2H), 5.54 (s, 2H), 5.56 (s, 2H), 8.14 (s, IH). [926] Reference example 57 2-Bromo-3-(2-methoxyethyl)-1,5-bis(2-triraethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d] pyridazin-4-one [927] 57-(a) 3-(1-Butoxyvinyl)-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 215 ml of N,N-dimethylformamide solution containing 10.1 g (21.2 mmol) of 3-bromo-1,5-bis(2-trimethylsilyl- ethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 20- (a) were added 13_^9 ml (108 mmol) of butyl vinyl ether, 5.5 9 g (21.2 mmol) of thallium acetate, 6.24 ml (36.7 mmol) of N,N-diisopropyl- ethylamine, 482 mg (2.15 mmol) of palladium acetate and 1.86 g (4.51 mmol) of 1,3-bis(diphenylphosphino)propane in this order, and after degassing under reduced pressure, the atmosphere was replaced by a nitrogen gas, and the mixture was stirred at 100°C for 2 hours. After completion of the reaction, water was added to the reaction mixture, and extracted with toluene. The organic layer was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 8.80 g of the title compound as a pale brownish oil. (Yield: 84%) Mass Spectrum (CI, m/z) : 494 (M"'+l) . ^H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), -0.02 (s, 9H), 0.88-0.92 (m, 2H), 0.96-1.00 (m, 2H), 0.98 (t, J-7.4 Hz, 3H) , 1.45-1.53 (m, 2H) , 1.73-1.79 (m, 2H) , 3.47-3.52 (m, 2H) , 3.70-3.74 (m, 2H) , 3.87 (t, J=6.5 Hz, 2H) , 4.48 (d, J=2.4 Hz, IH) , 5.42 (s, 2H) , 5.59 (s, 2H) , 6.08 (d, J=2.4 Hz, IH), 7.37 (s, IH), 8.16 (s, IH). [928] 57-(b) 3-(2-Bromoacetyl)-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 8.80 g (17.8 mmol) of 3-{1-butoxyvinyl)-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 57-(a) were added 21.1 ml of water and 341 ml of tetrahydrofuran, and 100 ml of tetrahydrofuran solution containing 4.70 g (26.4 mmol) of N-bromosuccinimide was added dropwise to the mixture under cooling in ice-bath. After the dropwise addition, the mixture was stirred at the same temperature 2 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure. The residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 6.64 g of the title compound as a white solid. (Yield: 72%) Mass Spectrum (CI, m/z): 518 (M"+l). 'H-NMR Spectrum (cdci3, 6 ppm): -0.02 (s, 9H), -0.01 (s, 9H), 0.90-0.95 (m, 2H), 0.97-1.02 (m, 2H), 3.50-3.54 (m, 2H), 3.71-3.76 (m, 2H), 5.14 (s, 2H), 5.49 (s, 2H), 5.62 (s, 2H), 7.87 (s, IH), 8.26 (s, IH). [0929] 57- (c) 3-(2-Bromo-l-hydroxyethyl)-1,5-bis(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 150 ml of dehydrated tetrahydrofuran solution containing 6.64 g (12.9 mmol) of 3 -(2-bromoacetyl)-1,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3- d]pyridazin-4-one obtained in Reference example 57-(b) was added dropwise 100 ml of tetrahydrofuran solution con¬taining 486 mg (12.8 mmol) of sodium borohydride under cooling in ice-bath. After dropwise addition, the mixture was stirred at the same temperature for 2 hours. After completion of the reaction, to the reaction mixture was added a saturated aqueous solution of sodium hydrogen- carbonate, and the mixture was extracted with ethyl acetate. The organic layer was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=7:3 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 5.67 g of the title compound as a white solid. (Yield: 85%) Mass Spectrum (CI, m/z) : 520 (M%1) . 'H-NMR Spectrum (cdci3, 6 ppm): -0.03 (s, 9H), -0.01 (s, 9H) , 0.88-0.93 (m, 2H) , 0.96-1.01 (m, 2H) , 3.47-3.52 (m, 2H), 3.55 (dd, J=9.9, 8.4 Hz, IH), 3.70-3.75 (m, 2H), 3.79 (dd, J=9.9, 5.4 Hz, IH), 4.94 (ddd, J=10.5, 8.4, 5.4 Hz, IH), 5.44 (d, J=11.0 Hz, IH), 5.47 (d, J=11.0 Hz, IH), 5.61 (s, 2H), 6.21 (d, J=10.5 Hz, IH), 7.15 (s, IH), 8.25 (s, IH) . [0930] 57-(d) 3-(1-Hydroxy-2-methoxyethyl)-1,5-bis(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 6 0 ml of dehydrated tetrahydrofuran solution containing 5.66 g (10.9 mmol) of 3-(2-bromo-l-hydroxy- ethyl) -1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one obtained in Reference example 57-(c) was added 1.22 g (10.9 mmol) of potassium tert- butoxide under ice-cooling, and the mixture was stirred at the same temperature for 1 hour. After completion of the reaction, to the reaction mixture were added ice-water and a saturated aqueous solution of ammonium chloride, and the mixture was extracted with ethyl acetate. The organic layer was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure to obtain 4.63 g of 3-oxylanyl-l,5-bis(2-trimethylsilylethoxymethyl)- 1,5-dihydropyrrolo[2,3-d]pyridazin-4-one as a colorless oil. To 2.33 g (5.32 mmol) of the obtained 3-oxylanyl-1,5- bis(2-trimethylsilylethoxymethyl)-1,5-dihydropyrrolo [2,3- d]pyridazin-4-one was added 5 0 ml of dehydrated methanol, and the mixture was stirred at room temperature for 24 hours. After completion of the reaction, the reaction mixture was concentrated under reduced pressure to obtain 2.50 g of the title compound as a pale yellowish oil substantially quantitatively. Mass Spectrum (CI, m/z) : 470 (M^l) . 'H-NMR Spectrum (cdci3, S ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.87-0.94 (m, 2H), 0.94-1.02 (m, 2H), 2.88 (dd, J=7.1, 5.4 Hz, IH), 3.44 (s, 3H), 3.46-3.55 (m, 2H), 3.68-3.76 (m, 2H), 3.78-3.92 (m, 2H), 5.07 (ddd, J=5.7, 4.8, 0.7 Hz, IH), 5.41 (d, J=11.0 Hz, IH), 5.45 (d, J=11.0 Hz, IH), 5.55 (d, J=9.8 Hz, IH), 5.59 (d, J=9.8 Hz, IH), 7.18 (d, J=0.7 Hz, IH) , 8 .19 (s, IH) . [0931] 57-(e) 3-(2-Hydroxyethyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 40 ml of acetic acid solution containing 2.30 g (4.90 mmol) of 3-(l-hydroxy-2-methoxyethyl)-1,5-bis(2- trimethylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 57-(d) was added 1.0 g of 10% palladium-carbon, and the mixture was stirred under 1 atm hydrogen atmosphere at 80°C for 2.5 hours. After completion of the reaction, insoluble material was filtered off from the reaction mixture, and the filtrate was concentrated under reduced pressure. Water was added to the residue, the mixture was neutralized with a saturated aqueous solution of sodium hydrogencarbonate, and extracted with ethyl acetate. The organic layer was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=3:7 (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.43 g of the title compound as a colorless oil. (Yield: 66%) Mass Spectrum (CI, m/z): 440 (M^+l). 'H-NMR Spectrum (cdci3, 8 ppm): -0.03 (s, 9H), -0.01 (s, 9H), 0.86-0.94 (m, 2H), 0.94-1.02 (m, 2H), 3.13 (t, J-5.4 Hz, 2H), 3.46-3.54 (m, 2H), 3.68-3.76 (m, 2H), 3.80-3.93 (m, 3H), 5.40 (s, 2H), 5.58 (s, 2H), 6.98 (s, IH), 8.19 (s, IH) . [0932] 57-(f) 3-(2-Methoxyethyl)-1,5-bis(2-trimethylsilylethoxy- methyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one To 5 ml of mixed solvent (dehydrated tetrahydro- furan:N,N-dimethylformamide=3:1 (V/V)) solution containing 1.29 g (2.93 mmol) of 3-(2-hydroxyethyl)-1,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 57-(e) was added 0.56 g (5.83 mmol) of sodium tert-butoxide under room temperature, and the mixture was stirred at the same temperature for 2 hours. Then, 1.1 ml (17.7 mmol) of methyl iodide was added to the mixture, and the mixture was further stirred for 16 hours. After completion of the reaction, water was added to the reaction mixture, and the mixture was extracted with ethyl acetate. The organic layer was washed with a saturated aqueous solution of sodium chloride, dried over anhydrous magnesium sulfate, and then, concentrated under reduced pressure. The obtained residue was applied to silica gel column chromatography (Eluent; hexane:ethyl acetate=l:l (V/V)), and the fractions containing the desired compound were concentrated under reduced pressure to obtain 1.18 g of the title compound as a slightly yellowish oil. (Yield: 89%) Mass Spectrum (CI, m/z): 454 (MVl) . 'H-NMR Spectrum (cdci3, 5 ppm): -0.04 (s, 9H), -0.01 (s, 9H), 0.85-0.94 (m, 2H), 0.94-1.03 (m, 2H), 3.17 (td, J=6.3, 0.6 Hz, 2H), 3.35 (s, 3H), 3.44-3.51 (m, 2H), 3.70-3.75 (m, 2H), 3.71 (t, J=6.3 Hz, 2H), 5.39 (s, 2H), 5.57 (s, 2H), 7.00 (t, J=0.6 Hz, IH) , 8.13 (s, IH) . [933] 57- (g) 2-Bromo-3-(2-methoxyethyl)-1,5-bis(2-trimethyl- silylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 1.12 g (2.47 mmol) of 3-(2-methoxyethyl)-1,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 57-(f) in place of 3-methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro- pyrrolo[2,3-d]pyridazin-4-one, whereby 1.13 g of the title compound was obtained as a pale yellowish solid. (Yield: 86%) Mass Spectrum (CI, m/z): 534 (M^+l). 'H-NMR Spectrum (cdci3, 8 ppm) : -0.03 (s, 9H), -0.02 (s, 9H), 0.86-0.94 (m, 2H), 0.94-1.02 (m, 2H), 3.15 (t, J=6.8 Hz, 2H), 3.35 (s, 3H), 3.52-3.59 (m, 2H), 3.68-3.75 (m, 2H), 3.69 (t, J=6.8 Hz, 2H), 5.52 (s, 2H), 5.56 (s, 2H), 8 . 12 (s, IH) . [934] Reference example 58 2-Bromo-3-(2-ethoxyethyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one [935] 58- (a) 3-(2-Ethoxyethyl)-1,5-bis(2-trimethylsilylethoxy¬methyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 57-(f) except for using 1.15 g (2.61 mmol) of 3-(2-hydroxyethyl)-1,5-bis(2-tri¬methylsilylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained by the same manner as in Reference example 57-(e), and using 1.3 ml (18.7 mmol) of ethyl iodide in place of methyl iodide, whereby 0.77 g of the title compound was obtained as a slightly yellowish oil. (Yield: 63%) Mass Spectrum (CI, m/z): 468 (M^+1). 'H-NMR Spectrum (cdci3, 8 ppm): -0.04 (s, 9H), -0.02 (s, 9H), 0.86-0.94 (m, 2H), 0.94-1.02 (m, 2H), 1.18 (t, J=7.0 Hz, 3H), 3.17 (td, J=6.4, 0.5 Hz, 2H), 3.44-3.51 (m, 2H), 3.51 (q, J=7.0 Hz, 2H), 3.68-3.75 (m, 2H), 3.74 (t, J=6.4 Hz, 2H) , 5.39 (s, 2H) , 5.56 (s, 2H) , 7.01 (t, J=0.5 Hz, IH) , 8 . 13 (s, IH) . [936] 58-(b) 2-Bromo-3-(2-ethoxyethyl)-1,5-bis(2-trimethyl- silylethoxymethyl) -1,5-dihydropyrrolo[2,3-d]pyridazin-4-one Reaction and post treatment were carried out in the same manner as in Reference example 18-(d) except for using 0.76 g (1.62 mmol) of 3-(2-ethoxyethyl)-1,5-bis(2-tri- methylsilylethoxymethyl)-1,5-dihydropyrrolo[2,3-d]pyrid- azin-4-one obtained in Reference example 58-(a) in place of 3-methyl-1,5-bis(2-trimethylsilylethoxymethyl)-1,5-dihydro¬pyrrolo [2 , 3 -d] pyridazin-4 -one , whereby 0.86 g of the title compound was obtained as a colorless oil. (Yield: 97%) Mass Spectrum (CI, m/z): 548 (M^+1). 'H-NMR Spectrum (cdci3, 5 ppm): -0.03 (s, 9H), -0.02 (s, 9H), 0.86-0.94 (m, 2H), 0.94-1.02 (m, 2H), 1.16 (t, J=7.1 Hz, 3H), 3.15 (t, J=7.1 Hz, 2H), 3.52-3.59 (m, 2H), 3.52 (q, J=7.1 Hz, 2H), 3.67-3.75 (m, 2H), 3.70 (t, J=7.1 Hz, 2H), 5.52 (s, 2H), 5.55 (s, 2H), 8.12 (s, IH). [937] Test example 1 Measurement of PDE4 enzyme inhibiting action Preparation of a PDE4 enzyme solution was carried out according to the method of Cooper et al. (Br. J. Pharma¬col., 126, 1863 (1999)) by modifying a part thereof. Heparin-treated peripheral blood from healthy volunteer was stratified by a blood cell separating solution (Polymorphprep™, available from AXIS-SHIELD PoC AS CO.), and centrifugation was carried out at 20°C with 1900 rpm for 27 minutes to obtain polymorphonuclear leukocytes. The polymorphonuclear leukocytes were washed with a Hanks' balanced salt solution, then, a mixed solution comprising 70% of 10 raM 3-morpholinopropane sulfonic acid buffer solution (pH 7.4) containing 1 mM EGTA, 1 mM magnesium acetate and 5 mM dithiothreitol and 30% of ethylene glycol was added thereto to dissolve the same under ice-cooling, and the obtained cell dissolved solution was used as a PDE4 enzyme solution. Measurement of PDE4 activity was carried out according to the method of Owens, et al. (Biochem. J., 326, 53 (1997)) by modifying a part thereof. The PDE4 enzyme solution was incubated with a compound to be tested dissolved in dimethylsulfoxide in 80 mM Tris-HCl buffer solution (pH 7.4) containing 0.2 ^M [^H] cAMP, 0. ImM cGMP, 2 0mM MgClj and 12 mM 2-mercaptoethanol at 3 0°C for 3 0 minutes. Trifluoroacetic acid (final concentration: 1%) was added to the mixture to stop the reaction, and the reaction mixture was added to neutral alumina column (BOND ELUT™, available from VARIAN INC.). After the column was washed with lOOmM Tris-HCl buffer solution (pH 8.0), ['H] 5'-AMP was eluted with 2N sodium hydroxide solution, and radioactivity of the eluent was measured by a liquid scintillation analyzer. A concentration of the compound to be tested which inhibits 50% of PDE4 activity was calculated from the relation between the concentration of the compound to be tested which had been added and PDE4 activity as an IC50 value. The test results are shown in Table 6. [0938] Table 6 Example No. of compound to be tested PDE4 inhibition IC50 value (nM) Example 3 5.2 Example 5 3.4 Example 8 1.7 Example 9 1. 8 Example 12 4.6 Example 13 0 . 65 Example 14 4 . 7 Example 16 13 Example 19 0.18 Example 2 0 0.23 Example 2 9 0 . 57 Example 31 9.1 Example 3 3 1.8 Example 34 8 . 7 Example 3 6 7 . 9 Example 3 7 6 . 6 Example 3 8 7.1 Example 41 9 . 9 Example 44 2.6 Example 4 9 3 . 5 Example 5 0 16 Example 52 8 . 0 Example 53 17 Example 57 11 Example 58 36 Example 6 0 3 . 0 Example 62 0.41 Example 67 1.4 Example 69 0 .38 Example 73 0.23 Example 7 5 1. 5 [939] In the present test, Compound (1) of the present invention showed excellent PDE4 inhibitory activity. Test example 2 [940] Pulmonary neutrophil infiltration-inhibiting activity in SD rats Inhalation of lipopolysaccharide (hereinafter abbrevi¬ated to as LPS) was carried out by modifying the method of Moraes et al. (Br. J. Pharmacol., 123. 631 (1998)). SD rats (male, 5-weeks old, supplied by CHARLES RIVER LABORATORIES JAPAN, INC.) fasted 24 hours before admini¬stration of a compound were kept in a plastic cage, and inhalated LPS (L2880-500MG, available from SIGMA Inc.) (0.1 mg/ml) dissolved in physiological saline for 30 minutes. An ultrasonic nebulizer (NE-U12, manufactured by Omron Corporation) was used for inhalation. A compound to be tested is dissolved (10 ml/Kg) in mixed solution of polyethylene glycol (hereinafter abbreviated to as PEG) and water, and orally administered 15 minutes before the inhalation of LPS. For the control group, 50% PEG solution was administered. Bronchoalveolar lavage (hereinafter abbreviated to as BAD was carried out as mentioned below 4 hours after the inhalation of LPS. SD rats were anesthetized by sodium pentobarbital (64.8 mg/Kg, i.p.), then, inferior vena cava was cut open to carry out exsanguination, trachea was exposed, a peroral sonde (manufactured by Fuchigami Kikai Co.) for mouse was inserted therein, and the trachea was ligated and fixed. 3.5 ml of physiological saline contain¬ing heparin (1 U/ml) was injected by using a disposable injection syrindge (5 ml volume, manufactured by Terumo Corporation), and immediately recovered. This operation was repeated four times to obtain a bronchoalveolar lavage fluid (hereinafter abbreviated to as BALF). BALF was centrifugated (at 2500 rpm, 10 minutes, 4°C), and 1 ml of 0.5% hexadecyltrimethylammonium bromide (030-02105, available from Wako Pure Chemical Industries, Ltd.) was added to the precipitated cells. Thereafter, a freeze-thaw operation (-80°C/37°C) was repeated three times to destroy the cells. As an index of a number of neutrophil, measurement of myeloperoxidase (hereinafter abbreviated to as MPO) activity was carried out as follows. Measurement of MPO activity was carried out by partially modifying the method of Krawisz et al. (GASTROENTEROLOGY, 1344 (1984)). To cell dissolved solution was added 50 mM phosphate buffer solution (pH 6.0) containing o-dianisidine hydrochloride (0.2 mg/ml) and 0.005% hydrogen peroxide, and change in absorbance at 450 nm was measured. As a MPO standard substance, MPO from human sputum (available from Elastin Products Company Inc.) was used. Measurement of absorbance was carried out by using a Microplate Reader (MTP-32, manufactured by Corona Electric Co., Ltd.). An inhibiting rate of the compound to be tested relative to the control was calculated. The test results are shown in Table 7. [0941] Table 7 Compound Example No. to be tested Rat pulmonary neutrophil infiltration-inhibiting activity (%) @3 mg/Kg Example 15 73 Example 22 78 Example 61 59 Example 6 6 69 Example 72 76 [0942] In the persent test. Compound (1) of the present invention showed excellent pulmonary neutrophil infiltration-inhibiting activity. Test example 3 Emetic action test in cynomulgus monkey To cynomulgus monkey (male, 3 to 5-years old, origin: China) fasted from the evening of the day before the administration was administered a compound to be tested, and presence or absence of emesis was observed for 24 hours. The compound to be tested was suspended in 0.5% aqueous methyl cellulose solution (5 ml/Kg), and administered nasally. With respect to each dose, each administered to 3 or 4 monkeys, and a dose in which emesis had not been admitted in all monkeys was made a maximum non-emesis dose. The test results are shown in Table 8. [0943] Table 8 Number of compound to be tested Monkey Maximum non-emesis dose (mg/Kg) Example 5 >30 Example 12 3 Example 62 >10 Example 66 >10 Example 72 >10 compound A 0 . 1 [944] Compound A of a compound to be tested is N-(3,5-di- chloro-4-pyridyl)-3-cyclopropylmethoxy-4-difluoromethoxy- benzamide which is a compound of Example 5 mentioned in WO 95/01338, and is a control compound having a PDE4 inhibitory activity. [945] In this experiment, the compounds of the present invention showed low emesis causing action as compared with those of the control compound. [946] Preparation example (Preparation example 1) (Hard capsule) 50 mg of powder state compound of Example 5, 128.7 mg of lactose, 70 mg of cellulose and 1.3 mg of magnesium stearate are mixed, passed through a sieve of 60 mesh, and then, the powder is charged in No. 3 gelatin capsule with 25 0 mg to prepare a capsule. [947] (Preparation example 2) (Tablets) 50 mg of the compound of Example 5, 124 mg of lactose, 25 mg of cellulose and 1 mg of magnesium stearate are mixed, and tabletted by a tabletting machine to prepare tablets each having 200 mg. This tablet may be sugar coated if necessary. UTILIZABLILITY IN INDUSTRY [948] The pyrrolopyridazinone compound represented by the formula (1) or a pharmaceutically acceptable salt thereof of the present invention shows excellent PDE4 inhibiting activity, and also, has excellent properties as a medical compound in the points of oral absorbability, continuity of medical effects, less occurrence in side effects, etc., so that, it is suitably useful as a medicine for the treatment or prevention of a respiratory disease (for example, bronchitic asthma (including atopic asthma), COPD, chronic bronchitis, pneumonial disease, adult respiratory distress syndrome (ARDS), etc.) to which PDE4 pertains to, and further as a medicine for the treatment or prevention of a disease to which cytokine (IL-1, IL-4, IL-6 and TNF (tumor necrosis factor)), etc., pertains to (for example, chronic rheumatism, ulcerative colitis, Crohn's disease, sepsis, septic shock, endotoxin shock. Gram-negative bacterial sepsis, toxic shock syndrome, nephritis, hepatitis, infection (bacteria and virus), circulatory failure (cardiac insufficiency, arteriosclerosis, cardiac infarc¬tion, cerebral apoplexy), etc.), etc., which has been known to be participated in PDE4.