Claims
[Claim 1] A compound of the formula (I) or a salt thereof:
[Chem. 261
(In the formula,
R1 is H or lower alkyl,
R2isHorCN,
any one of G1, G2, and G3 is O, and the other two of G1, G2, and G3 are CH2,
ring A is aryl, or nitrogen-containing heteroaryl,
ring B is cyclic amino,
R3 and R4 are the same as or different each other, and are H, halogen, lower alkyl, -lower alkylene-OH, halo-lower alkyl, -O-lower alkyl, -O-halo-lower alkyl, cycloalkyl, CN, OH, -N(lower alkyl)2, or -C(=0)NH2,
R5, R6, R7 and R8 are the same as or different from each other, and are H, halogen, lower alkyl, halo-lower alkyl, -O-lower alkyl, or CN, or
in the case where R5 and R6 are bonded to the same carbon atom, R5 and R6 may form cycloalkane or cyclic ether together with the carbon atom, and may form a spiro ring together with Ring B, or
ring B may form 6,7-dihydro[l,3]oxazolo[4,5-c]pyridin-5(4H)-yl together with R5 and R6.)
[Claim 2] The compound or a salt thereof according to claim 1, wherein
R1 is H, R2 is H, G1 is O,
G2andG3areCH2, ring A is phenyl, or nitrogen-containing heteroaryl,

ring B is 5- or 6-membered cyclic amino, and
R5, R6, R7 and R8 are the same as or different from each other, and are H, halogen, lower alkyl, halo-lower alkyl, -O-lower alkyl, or CN.
[Claim 3] The compound or a salt thereof according to claim 2, wherein
ring A is nitrogen-containing monocyclic heteroaryl,
R3 is H or lower alkyl, and
R4 is H, halogen, lower alkyl, -lower alkylene-OH, halo-lower alkyl, -O-lower alkyl, -O-halo-lower alkyl, cycloalkyl, CN, OH, -N(lower alkyl)2, or-C(=0)NH2.
[Claim 4] The compound or a salt thereof according to claim 2 or 3, wherein
ring B and R5, R6, R7, and R8 are the formula (II): [Chem. 27]
X is CH2, O, or a bond,
in the case where X is CHb, R5 and R6 may be substituted with X, and R5, R6, R7, and R8 are the same as or different from each other, and are H, halogen, lower alkyl, or halo-lower alkyl.
[Claim 5] The compound or a salt thereof according to claim 4, wherein
X is CH2 or O.
[Claim 6] The compound or a salt thereof according to claim 4, wherein
X is bond.
[Claim 7] The compound or a salt thereof according to claim 5, wherein
ring A is nitrogen-containing 6-membered heteroaryl having one or two nitrogen
atoms as ring atoms,
ring B, and, R5, R6, R7, and R8 are the formula (III): [Chem. 28]

R5 is halogen or lower alkyl,
R6 is H,
R7 is H, and
R8 is H or lower alkyl.
[Claim 8] The compound or a salt thereof according to claim 7, wherein
ring A is pyridyl, X is CH2, R5 is halogen, and R8isH.
[Claim 9] The compound or a salt thereof according to claim 7, wherein
ring A is pyridyl, X is O,
R5 is lower alkyl, and R8 is lower alkyl.
[Claim 10] The compound or a salt thereof according to claim 6, wherein
ring A is nitrogen-containing 6-membered heteroaryl having two nitrogen atoms as
ring atoms,
ring B, and, R5, R6, R7, and R8 are the formula (IV): [Chem. 29]
R5 is halogen or lower alkyl, R6 is H, R7 is H, and

R8 is H.
[Claim 11] The compound or a salt thereof according to claim 1, which is selected
from the group consisting of:
N-(5-chloropyridin-2-yl)-2-[(2R,6S)-2,6-dimethylmorpholin-4-yl]-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide,
N-(6-methoxypyridazin-3-yl)-2-[(2R)-2-methylpyrrolidin-l-yl]-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide,
N-(6-methylpyrazin-2-yl)-2-[(2S)-2-methylpyrrolidin-l-yl]-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide,
2-[(2R)-2-ethylmorpholin-4-yl]-N-(6-methylpyridin-3-yl)-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide,
2-(4-fluoropiperidin-l-yl)-N-(pyridazin-3-yl)-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide,
N-(5,6-dimethylpyrazin-2-yl)-2-[(2S)-2-methylpyrrolidin-l-yl]-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide,
2-[(2S)-2-methylpiperidin-l-yl]-N-(pyridazin-3-yl)-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide,
2-[(2S)-2-methylpiperidin-l-yl]-N-(pyrazin-2-yl)-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide, and,
N-(5-chloropyridin-2-yl)-2-[(3S)-3-fluoropiperidin-l-yl]-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide,
or a salt thereof.
[Claim 12] The compound or a salt thereof according to claim 11, which is N-(5-
chloropyridin-2-yl)-2-[(2R,6S)-2,6-dimethylmorpholin-4-yl]-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide or a salt thereof.
[Claim 13] The compound or a salt thereof according to claim 11, which is N-(6-
methoxypyridazin-3-yl)-2-[(2R)-2-methylpyrrolidin-l-yl]-5,6,8,9-tetrahydrooxepino[4,5-b]pyridine-4-carboxamide or a salt thereof.
[Claim 14] The compound or a salt thereof according to claim 11, which is N-(5-
chloropyridin-2-yl)-2- [(3 S)-3 -fluoropiperidin-1 -yl] -5,6,8,9-tetrahydrooxepino [4,5-b]pyridine-4-carboxamide or a salt thereof.
[Claim 15] A pharmaceutical composition comprising the compound or the salt
thereof according to claim 1, and a pharmaceutically acceptable excipient.

[Claim 16] The pharmaceutical composition according to claim 15, which is a
positive allosteric modulator on an a7 nicotinic acetylcholine receptor.
[Claim 17] The pharmaceutical composition according to claim 15, which is a
pharmaceutical composition for preventing or treating dementia, cognitive impairment, schizophrenia, Alzheimer's disease, CIAS, negative symptoms of schizophrenia, inflammatory diseases, or pain.
[Claim 18] Use of the compound or the salt thereof according to claim 1 for the
manufacture of a pharmaceutical composition for preventing or treating dementia, cognitive impairment, schizophrenia, Alzheimer's disease, CIAS, negative symptoms of schizophrenia, inflammatory diseases, or pain.
[Claim 19] Use of the compound or the salt thereof according to claim 1, for
preventing or treating dementia, cognitive impairment, schizophrenia, Alzheimer's disease, CIAS, negative symptoms of schizophrenia, inflammatory diseases, or pain.
[Claim 20] The compound or the salt thereof according to claim 1, for preventing or
treating dementia, cognitive impairment, schizophrenia, Alzheimer's disease, CIAS, negative symptoms of schizophrenia, inflammatory diseases, or pain.
[Claim 21] A method for preventing or treating dementia, cognitive impairment,
schizophrenia, Alzheimer's disease, CIAS, negative symptoms of schizophrenia, inflammatory diseases, or pain, comprising administering an effective amount of the compound or the salt thereof according to claim 1 to a subject.