DESCRIPTION
Title of Invention
PROCESS FOR THE PREPARATION OF
(IS, 4S, 5S) -4-BROMO-6-OXABICYCLO [3.2.1] OCTAN-7-ONE
Technical Field
The present invention relates to an improved and industriallyadvantageous
process for the preparation of
(IS, S ,5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one of formula (I) :
( I )
which is a key intermediate in the synthesis of edoxaban, a compound
that exhibits an inhibitory effect on activated blood coagulation
factor X (also referred to as activated factor X or FXa) , and is useful
as a preventive and/or therapeutic drug for thrombotic diseases.
Background Art
Chemically, edoxaban is
N - (5-chloropyridin-2-yl) -N2- ((IS, 2R/4S) -4- [(dimethylamino) carbo
nyl] -2- { [(5-methyl -4 ,5,6, 7-tetrahydrothiazolo [5 ,4-c] pyridin-2-yl
)carbonyl] amino} eye lohexyl) ethanediamide , represented by the
following formula (A) :
(A)
The p-toluenesulf onic acid monohydrate salt of compound A is
represented b the following formula (B) :
(B)
Edoxaban is known as a compound that exhibits an inhibitory
effect on activated blood coagulation factor X (also referred to as
activated factor X or FXa) , and is useful as a preventive and/or
therapeutic drug for thrombotic diseases.
Several processes are known in the literature for preparing
edoxaban for example, U.S. Patent No. 7365205; U.S. Publication No .
20090105491.
U.S. Patent No. 7365205 provides a process for the preparation
of edoxaban, wherein the process involves the use of
(IS, 4S, 5S) -4-iodo-6-oxabicyclo [3.2.1] octan-7-one, represented by
the following formula (C) :
(C)
as an intermediate.
The present inventors have identified that
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one, represented by
the following formula (I) :
( I )
could also be used as an intermediate for the preparation of FXa
inhibitory compounds like edoxaban. The present inventors have found
that replacement of
(IS, 4S, 5S) -4-iodo-6-oxabicyclo [3.2.1] octan-7-one (C) with
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one (I) has a better
atom economy and also an impact on cost.
A method for the synthesis of the
(IS, 4S, 5S) -4 -bromo- -oxabicyclo [3.2.1] octan-7-one (I) was
reported in Tetrahedron Letters, 51, (2010) Pages 3433-3435 which
involves the reaction of (IS) -cyclohex-3 -ene- 1-carboxylic acid
represented by the following formula (II) :
( )
with N-bromosuccinimide in the presence of molecular sieves using
dichloromethane as a solvent. However, this reaction is carried out
in dark over a period of 7 hours and does not provide a pure product .
Tetrahedron, Vol. 28, Pages 33 93 -33 99 , 1972 provides a process
for the preparation of 4-bromo- -oxabicyclo [3.2.1] octan-7-one which
involves the addition of 20% excess of a 2M solution of bromine in
chloroform to a stirred solution of cyclohex- 3-ene- 1-carboxylic acid
(0.04 mol) in chloroform (250 mL) in the absence of a base . Extraction
with aqueous sodium bicarbonate followed by acidification gave,
after extraction with ether and evaporation of the extract, a mixture
of cis & trans 3 ,4-dibromocyclohexanecarboxylic acid (6.7 g ) and
evaporation of the chloroform layer afforded the bromolactone (0.59
g ) . It further provides a process for the preparation of
4-bromo- -oxabicyclo [3 .2 .1 ]octan-7-one which involves the treating
of cyclohex-3-ene-l-carboxylic acid (0.08 mol) dissolved in
chloroform (450 mL) with 20% excess bromine in the presence of an
equimolar amount of triethylamine (8.1 g ) . After extraction of the
amine with 2N hydrochloric acid, and work-up, bromolactone (10.7 g )
and a mixture of cis & trans 3 ,4-dibromocyclohexanecarboxylic acid
(6.6 g ) were obtained.
Tetrahedron Vol. 48, No. 3 , Pages 53 9-544, 1992 provides a
process for the preparation of
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one (I) which
involves the addition of 1M solution of bromine in chloroform (3 0
mL) at 0°C to a solution of (IS) -cyclohex-3 -ene- 1-carboxylic acid
(0.024 mol) of formula (II) in chloroform (600 mL) in the presence
of an equimolar amount of triethylamine (3.33 mL) . After work-up,
the crude bromolactone obtained was recrystallized from petroleum
ether.
However, bromination using bromine does not provide a pure
product in good yield.
Heterocycles, Vol. 23, No. 8 , Pages 2035-2039, 1985 provides
a process for the 4-bromo-6-oxabicyclo [3 .2 .1 ]octan-7-one which
involves the addition of cyclohex-3-ene-l-carboxylic acid (1.0 mM)
in 1,2 -dime thoxye thane (2 mL) to a stirred solution of 90% Lead (IV)
acetate (1.1 or 2.2 mM) in 1,2-dimethoxyethane (4 mL) followed by
the addition of Zinc bromide (2.2 mM) in 1,2-dimethoxyethane (4 mL)
and continuing the stirring for 10-30 minutes at 0°C . The reaction
mixture was poured into a solution of ice-cold water (30 mL) and 10%
hydrochloric acid (10 mL) , and extracted with ether (50 mL X 3 ) . The
combined ether extract was washed successively with saturated sodium
hydrogen carbonate solution (2 0 mL) , 10% sodium thiosulphate
solution (5 mL) , and brine (10 mL) , and dried over sodium sulphate.
Evaporation of the solvent gave crude lactone which were separated
and purified (42% yield) . However, this reaction does not provide
a pure product in good yield.
Heterocycles, Vol. 31, No. 6 , Pages 987-991, 1990 provides a
method for bromolactonization using a
dimethylsulf oxide- trimethylsilyl bromide-amine system. The
bromolactonization is carried out for 10 to 72 hours using different
solvents and triethylamine or diisopropylethyl amine as base.
However, this process does not provide a product in high yield.
Further the process afforded the cis isomer exclusively.
Journal of the Chemical Society, Perkin Transactions 1 :
Organic and Bio-Organic Chemistry (1972-1999) (1994) , (7) , Pages
847-851 provides a method for bromolactonization using a
dimethylsulf oxide- trimethylsilyl bromide-amine system. The
bromolactonization is carried out for 12 hours using
dimethylsulf oxide and chloroform solvent system and triethylamine
or diisopropylethyl amine as base. However, this process resulted
in a low yield of about 55%.
Citation List
Patent Literature
PTLl: U.S. Patent No. 7365205
PTL2: U.S. Publication No. 20090105491.
Non Patent Reference
NPLl: Feng Chen et al ., Tetrahedron Letters, 51, (2 010) Pages
3433-3435.
NPL2 : G . Belluci et al ., Tetrahedron, Vol. 28, No. 13, Pages
3393-3399, 1972.
NPL3 : Marco Chini et al . , Tetrahedron Vol . 48, No. 3 , Pages 539-544 ,
1992.
NPL4 : Y . Fujimoto et a ., Heterocycles , Vol. 23, No. 8 , Pages
2035-2039, 1985.
NPL5: C . Iwata et al ., Heterocycles, Vol. 31, No. 6 , Pages 987-991,
1990. -
NPL6 : K . Miyashita et al ., Journal of the Chemical Society, Perkin
Transactions 1 : Organic and Bio-Organic Chemistry (1972-1999) (1994) ,
(7) , Pages 847-851 .
Summary of Invention
Technical Problem
It is an object of the present invention to solve the problems
associated with the prior art, and to provide an improved and
efficient method for the preparation of
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3 .2 .1 ] octan-7-one of formula (I).
Solution to Problem
As a result of conducting diligent studies to attain the object,
the present inventors have found that: surprisingly, the use of
N-bromosuccinimide or bromohydantoin (representative is
1 ,3-dibromo-5, 5-dimethylhydantoin) as brominating agent in the
presence of a base selected from calcium oxide or calcium hydroxide,
in specific mole ratios in a solvent selected from the group
consisting of dichloromethane , toluene, tetrahydrof uran, ethyl
acetate, hexanes, cyclopentyl methyl ether (CPME) or a mixture
thereof can efficiently produce a pure
(IS , S ,5S )-4 -bromo- -oxabicyclo [3.2.1] octan- 7-one (I) in better
yields. The process provides obvious benefits with respect to
economics, convenience to operate at a commercial scale.
The present invention also provides replacement of
(IS, 4S, 5S) -4 -iodo- -oxabicyclo [3.2.1] octan- 7-one (C) with
(IS, 4S, 5S) - -bromo- -oxabicyclo [3.2.1] octan-7-one (I) which has a
better atom economy and also an impact on cost in the preparation
of edoxaban, a compound that exhibits an inhibitory effect on
activated blood coagulation factor X (also referred to as activated
factor X or FXa) , and is useful as a preventive and/or therapeutic
drug for thrombotic diseases.
The present invention provides (1) to (4) shown below.
(1) A process for producing
(IS, 4S, 5S) -4 -bromo- 6-oxabicyclo [3.2.1] octan-7-one, represented by
the following formula (I) :
( I )
comprising (IS) -cyclohex-3-ene-l-carboxylic acid, represented by
the following formula (II) :
(II)
is treated with N-bromosucciniraide or
1,3-dibromo-5 ,5-dimethylhydantoin as brominating agent in the
presence of a base selected from calcium oxide or calcium hydroxide
in a solvent selected from the group consisting of dichloromethane ,
toluene, tetrahydrofuran, ethyl acetate, hexanes, cyclopentyl
methyl ether (CPME) or a mixture thereof.
(2) The production process according to (1) , wherein brominating
agent is N-bromosuccinimide .
(3) A process for producing
tert -butyl {(1 ,2S, 5S) -2-amino-5- [(dimethylamino) carbonyl]
eye lohexyl }carbamate oxalate:
the method using
(IS, S ,5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one (I) produced by
a method according to (1) and comprising the following steps a ) and
b ) :
a ) (IS, 4S, 5S) -4-bromo-6-oxabicyclo [3 .2 .1 ] octan-7-one (I) produced
by a production process according to (1) is treated with an aqueous
solution of dimethylamine followed by reacting with aqueous ammonia,
subsequently with a di- tert -butyl bicarbonate and further with
methanesulf onyl chloride to obtain methanesulf onic acid
(1 ,2R ,4S)-2-tert -butoxycarbonylamino -4-dime thylcarbamoyl -cycloh
exyl ester,
b ) treating methanesulf onic acid
(1R, 2R, 4S) -2 -tert -butoxycarbonylamino -4 -dimethylcarbamoyl-cycloh
exyl ester with sodium azide, followed by subjecting the resultant
compound to hydrogenolysis in the presence of Palladium-Carbon and
ammonium formate and reacting the resultant compound with oxalic acid
to obtain
tert-Butyl{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohe
xyl }carbamate oxalate.
(4) A process for producing
N - (5-chloropyridin-2-yl) -N2- ((IS, 2R, 4S) -4- [(dimethylamino) carbo
nyl] -2 -{ [(5 -methyl - ,5,6, 7-tetrahydrothiazolo [5 ,4-c] pyridin-2-yl
)carbonyl] amino} eye lohexyl) ethanediamide p-toluenesulf onate
monohydrate :
the method using
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one (I) produced by
a method according to (1) and comprising the following steps a ) to
e ) :
a ) (IS ,4S ,5S) -4 -bromo- 6-oxabicyclo [3.2.1] octan-7-one (I) produced
by a production process according to (1) is treated with an aqueous
solution of dimethylamine followed by reacting with aqueous ammonia,
subsequently with a di-tert -butyl dicarbonate and further with
methanesulf onyl chloride to obtain methanesulf onic acid
(1R ,2R ,4S)-2-1ert -butoxycarbonylamino- 4 -dime thylcarbamoyl -cycloh
exyl ester,
b ) treating methanesulf onic acid
(1R, 2R, 4S) -2 -tert -butoxycarbonylamino- 4-dimethylcarbamoyl -cycloh
exyl ester with sodium azide, followed by subjecting the resultant
compound to hydrogenolysis in the presence of Palladium- Carbon and
ammonium formate and reacting the resultant compound with oxalic acid
to obtain
tert-Butyl {(1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohe
xyl }carbamate oxalate
c ) reacting
tert-Butyl{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohe
xyl }carbamate oxalate with
ethyl [5 -chloropyridin-2-yl] amino] (oxo) acetate hydrochloride in
the presence of a triethylamine to obtain
tert-Butyl [(1R, 2S, 5S) -2- ({ [(5-chloropyridin-2-yl) amino] (oxo) acet
yl} amino) -5- (dimethylaminocarbonyl )cyclohexyl] carbamate,
d ) deprotecting the tert-Butoxycarbonyl group from
tert-Butyl [(1R, 2S, 5S) -2- ({[(5-chloropyridin-2-yl) amino] (oxo) acet
yl}amino) -5- (dimethylaminocarbonyl) cyclohexyl] carbamate by using
methanesulphonic acid followed by reacting the deprotected compound
with
5-methyl -4 ,5,6, 7-tetrahydro [1,3] thiazolo [5 ,4-c] pyridine -2 -carbox
ylic acid hydrochloride or its activated ester to obtain
N1- (5-chloropyridin-2-yl) -N2- ((IS, 2R, 4S) -4- [(dimethylamino) carbo
nyl] -2- { [(5 -methyl -4 ,5,6, 7-tetrahydrothiazolo [5 ,4-c] pyridin-2 -yl
)carbonyl] amino} eye lohexyl) ethanediamide,
e ) treating
N - (5-chloropyridin-2-yl) -N2- ((IS, 2R, 4S) -4- [(dimethylamino) carbo
nyl] -2- { [(5 -methyl -4 ,5,6, 7-tetrahydrothiazolo [5 ,4-c] pyridin-2-yl
)carbonyl] amino} eye lohexyl) ethanediamide with p -toluenesulf onic
acid in aqueous ethanol to obtain
N - (5-chloropyridin-2-yl) -N2- ((IS, 2R, 4S) -4- [(dimethylamino) carbo
nyl] -2 -{ [(5-methyl -4 ,5,6, 7-tetrahydrothiazolo [5 ,4-c] pyridin-2 -yl
)carbonyl] amino }cyclohexyl) ethanediamide p -toluenesulf onate
monohydrate .
Advantageous Effects of Invention
The present invention provides a novel method for an improved
and efficient method for the preparation of
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3 .2 .1 ]octan-7-one (I) which has a
better atom economy and also an impact on cost in the preparation
of edoxaban, a compound that exhibits an inhibitory effect on
activated blood coagulation factor X (also referred to as activated
factor X or FXa) , and is useful as a preventive and/or therapeutic
drug for thrombotic diseases.
Description of Embodiments
More particularly, the present invention relates to a process
for the preparation of
(IS ,4S ,5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one , represented by
the following formula (I) :
( I )
which comprises reacting (IS) -cyclohex-3 -ene- 1-carboxylic acid,
represented by the following formula (II) :
[0000]
(")
with a brominating agent selected from the group consisting of
N-bromosuccinimide or 1,3-dibromo-5 ,5-dimethylhydantoin in the
presence of a base selected from calcium oxide or calcium hydroxide
in a solvent selected from the group comprising of dichloromethane ,
toluene, tetrahydrof uran, ethyl acetate, hexanes, cyclopentyl
methyl ether (CPME) or a mixture thereof.
The process further includes the optional step of
recrystallization of-
(IS, S ,5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one (I) from a
single or a mixed solvent system.
The starting material , (IS) -cyclohex-3-ene-l-carboxylic acid
of formula (II) may be prepared according to the methods provided
in the art for example as per US 2011/0257401.
N-Bromosuccinimide is suitably used in an amount of 1.0 to 1.1
molar equivalents of compound of formula (II) , preferably in an
amount of 1.02 to 1.08 molar equivalents and more preferably in an
amount of 1.05 molar equivalents of compound of formula (II) . The
present inventors have found that the quality of N-Bromosuccinimide
also has an impact in the purity of
(IS ,4S ,5S )- -bromo- -oxabicyclo [3.2.1] octan- 7-one (I). The
present inventors have found that
(1S,4S, 5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one (I) prepared by
using unpurif ied N-bromosuccinimide contains an impurity of about
5.6% which corresponds to the methoxy derivative of
N-bromosuccinimide.
1 ,3-Dibromo-5, 5-dimethylhydantoin is suitably used in an
amount of 0.5 to 0.6 molar equivalents of compound of formula (II) ,
preferably in an amount of 0.51 to 0.55 molar equivalents and more
preferably in an amount of 0 .52 molar equivalents of compound of
formula (II) .
Calcium oxide is suitably used in an amount of 0.07 to 0.13
molar equivalents of compound of formula (II) , preferably in an
amount of 0.08 to 0.12 molar equivalents and more preferably in an
amount of 0.1 molar equivalents of compound of formula (II).
Calcium hydroxide is suitably used in an amount of 0.05 to 0.5
molar equivalents of compound of formula (II) .
The reaction of (IS) -cyclohex- 3-ene- 1-carboxylic acid of
formula (II) with a brominating agent selected from the group
consisting of N-bromosuccinimide or
1 ,3-dibromo-5, 5-dimethylhydantoin in the presence of a base selected
from calcium oxide or calcium hydroxide is carried out at a selected
temperature range of 15 to 40°C, preferably at 20 to 25 °C, during
a period of 15 minutes to several hours, preferably for about 15
minutes to 1 hour.
In an embodiment, a solution of
(IS) -cyclohex- 3-ene- 1-carboxylic acid of formula (II) in a solvent
selected from the group comprising of dichloromethane , toluene,
tetrahydrof uran, ethyl acetate, hexanes, cyclopentyl methyl ether
(CPME) or a mixture thereof is added in a drop-wise manner or in lots
to the reaction mixture comprising a brominating agent selected from
the group consisting of N-bromosuccinimide or
1 ,3 -dibromo- 5 ,5-dimethylhydantoin, a base selected from calcium
oxide or calcium hydroxide in a solvent selected from the group
comprising of dichloromethane, toluene, tetrahydrof uran, ethyl
acetate, hexanes, cyclopentyl methyl ether (CPME) or a mixture
thereof .
(IS ,4S ,5S) - -Bromo- -oxabicyclo [3.2.1] octan- 7-one of
formula (I) may be isolated by the common isolation technique such
as cooling, extraction, one or more of washing, crystallization,
precipitation, filtration, filtration under vacuum, decantation and
centrif ugation or a combination thereof.
(IS ,4S ,5S) -4 -Bromo- -oxabicyclo [3.2.1] octan- 7-one of
formula (I) may be isolated from the reaction mixture by optionally
adding water to the reaction mixture followed by filtration and/or
concentration followed by isolation from water.
More preferably, the desired compound,
(IS, 4S, 5S) - -bromo- -oxabicyclo [3.2.1] octan-7-one of formula (I)
is isolated by complete removal of the solvent from the organic layer
and the solid thus separated is charged with pre-heated water at 50
°C, stirred for 15 minutes at 50 ± 2 °C, filtered and dried to get
the pure desired compound.
The compound of formula (I) is optionally dried further and/or
recrystallized from a single or a mixed solvent system. The solvent
may be an organic solvent selected from the group consisting of
alcohols, ketones, ethers or a mixture thereof.
In an embodiment ,
(1S,4S, 5S) -4-bromo-6-oxabicyclo [3 .2 .1 ] octan-7-one of formula (I)
may be recrystallized from acetone and water. The recrystallization
of compound of formula (I) comprises the steps of a ) providing a
solution of (IS, 4S, 5S) -4 -bromo- -oxabicyclo [3.2.1] octan-7-one (I)
in acetone, b ) combining the solution obtained in step a ) with water,
and c ) isolating
(IS, S ,5S) -4-bromo-6-oxabicyclo [3.2. 1 ] octan- 7-one (I) .
Step a ) of providing a solution of
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3 .2 .1 ]octan-7-one (I) in acetone
includes dissolving
(IS ,4S ,5S )-4 -bromo- -oxabicyclo [3.2.1] octan- 7-one (I) in acetone
at a temperature of about 45 °C to 60 °C optionally under stirring.
Step b ) involves combining the solution obtained in step a )
with water. The term "combining" includes adding, dissolving,
slurrying, stirring, or a combination thereof. The water can be added
at about 40 to 60 °C, preferably at 40 to 50 °C during a period of
15 minutes to several hours, preferably for about 15 minutes to 2
hours, followed by stirring the reaction mass at 0 to 8 °C, preferably
at 5 to 8 °C for a period of 15 minutes to 2 hour, preferably for
about 15 minutes to 1 hour.
In step c ) (IS, S ,5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one
(I) can be isolated by the common isolation technique such as cooling,
extraction, one or more of washing, crystallization, precipitation,
filtration, filtration under vacuum, decantation and centrif ugation
or a combination thereof.
(IS, 4S, 5S) -4 -Bromo- -oxabicyclo [3.2.1] octan-7-one of (I)
thus synthesized is useful as an intermediate for the preparation
of edoxaban or its pharmaceutically acceptable salts or hydrates
thereof, a compound that exhibits an inhibitory effect on activated
blood coagulation factor X (also referred to as activated factor X
or FXa) , and is useful as a preventive and/or therapeutic drug for
thrombotic diseases.
Edoxaban of formula (A) or p-toluenesulf onic acid monohydrate
salt of compound A of formula (B) as disclosed in, for example, U.S.
Patent No. 7365205 and U.S. Publication No. 20090105491, may be
produced from (IS, 4S, 5S) -4 -bromo- -oxabicyclo [3 .2 .1 ]octan-7-one
of formula (I) prepared as per the present invention, in accordance
with a process steps as described herein, or as described in, for
example, U.S. Publication No. 20090105491 and U.S. Patent No.
7365205 .
The steps comprises of :
a ) treating (IS ,4S ,5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one of
(I) with an aqueous solution of dimethylamine followed by reacting
with aqueous ammonia, subsequently with a di-tert-butyl dicarbonate
and further with methanesulf onyl chloride to obtain methanesulf onic
acid
(1R,2R,4S) -2- 1ert -butoxycarbonylamino -4-dime thylcarbamoyl -eye loh
exyl ester,
b ) treating methanesulf onic acid
(1R, 2R, 4S) -2 -tert-butoxycarbonylamino-4 -dimethylcarbamoyl-cycloh
exyl ester with sodium azide, followed by subjecting the resultant
compound to hydrogenolysis in the presence of Palladium- Carbon and
ammonium formate and reacting the resultant compound with oxalic acid
to obtain
tert-Butyl{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohe
xyl }carbamate oxalate,
c ) reacting
tert-Butyl{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohe
xyl} carbamate oxalate with
ethyl [5-chloropyridin-2 -yl] amino] (oxo) acetate hydrochloride in
the presence of a triethylamine to obtain
tert-Butyl [(1R, 2S, 5S) -2- ({ [(5-chloropyridin-2-yl) amino] (oxo) acet
yl}amino) -5- (dimethylaminocarbonyl) cyclohexyl] carbamate,
d ) deprotecting the tert-Butoxycarbonyl group from
tert-Butyl [(1R, 2S, 5S) -2- ({ [(5-chloropyridin-2-yl) amino] (oxo) acet
yljamino) -5- (dimethylaminocarbonyl) cyclohexyl] carbamate by using
methanesulphonic acid followed by reacting the deprotected compound
with
5-methyl -4 ,5,6, 7-tetrahydro [1,3] thiazolo [5 ,4-c] pyridine -2 -carbox
ylic acid hydrochloride or its activated ester to obtain edoxaban,
and optionally,
e ) converting edoxaban to its pharmaceutically acceptable salts or
hydrates thereof, for example, treating edoxaban with
p -toluenesulf onic acid in aqueous ethanol as solvent to obtain
edoxaban p -toluenesulf onate monohydrate (salt and hydrate form) of
formula (B) .
While the present invention has been described in terms of its
specific embodiments, certain modifications and equivalents will be
apparent to those skilled in the art and are intended to be included
within the scope of the present invention.
Examples
Example 1
Preparation of (IS, 4S, 5S) -4-Bromo-6-oxabicyclo [3.2.1] octan-7-one
(I)
Controlled addition of (IS) -Cyclohex-3-ene-l-carboxylic acid
to a mixture of N-bromosuccinimide and calcium oxide
Solution A : To a suspension of dichloromethane (150 mL) , water
(90 mL) , (IS) -cyclohex-3-ene-l-carboxylic acid - (R) -phenyl ethyl
amine salt (30 g ) , cone hydrochloric acid (35%, 13.9 mL) was added.
The reaction mass was stirred for 15 minutes and the layers were
separated. The aqueous layer was extracted with dichloromethane (90
mL) . The combined organic layer was washed with water (90 mL) and
recovered under vacuum at 35 °C to afford an oil. Dichloromethane
(75 mL) was charged to the above oil to get Solution A .
Solution B : N-Bromosuccinimide (22.22 g ) and calcium oxide
(0.6 g ) was dissolved in dichloromethane (3 0 mL) to get Solution B .
Solution A of (IS) -cyclohex-3-ene-l-carboxylic acid (II) in
dichloromethane (75 mL) was added drop wise to Solution B in a time
period of 1 hour at 23 ± 3 °C. The reaction mass was stirred for 1
hour at 23 ± 3°C, filtered through hyflo bed and washed with
dichloromethane (30 mL) . The filtrate was recovered under vacuum at
34 °C to get a solid. Pre-heated water (75 mL) was added to the above
solid and the reaction mass was stirred at 50 °C for 15 minutes. The
solid was filtered, washed with pre-heated water (30 mL) and isolated
Pre-heated water (75 mL) was again charged to the above solid and
the reaction mass was stirred at 50 °C for 15 minutes. The solid was
filtered and washed with pre-heated water (30 mL) .The solid was dried
under vacuum at 35 to 40 °C for 14 hours to get the title compound
(I) •
Yield: 84.43 %
Chromatographic purity: 99.56 %
Example 2
Preparation o f (IS, 4S, 5S) -4 -Brorao- 6 -oxabicyclo [3.2.1] octan-7-one
(I)
Addition o f N-Bromosuccinimide and calcium oxide to
(IS) -Cyclohex-3-ene-l-carboxylic acid in lots
(IS) -Cyclohex-3-ene-l-carboxylic acid (II) (5 g ) was dissolved in
dichloromethane (25 mL) . To this solution N-bromosuccinimide (1.1 mole)
was added at room temperature. Calcium oxide (0.25 mole) was charged to
the suspension in two lots. The reaction mixture was stirred at 20 to 25
°C for 1 hour and filtered. The bed was washed with dichloromethane (10
mL) . The washings were combined with the filtrate and the solvent was
recovered under vacuum at 35 to 40 °C. Deionized water (50 mL) was charged
to the solid, heated to 50 °C, stirred for 10 minutes and filtered. The
bed was washed with deionized water (10 mL) and suck dried. The solid was
dried under vacuum at 45-50 °C to get. the title compound (I) .
Yield: 61 %
Chromatographic purity: 96.98 %
Example 3
Preparation o f (IS, 4S, 5S) -4 -Bromo- 6 -oxabicyclo [3.2.1] octan-7-one
(I)
(IS) -Cyclohex-3-ene-l-carboxylic acid (II) (20.4 g ) was dissolved in
dichloromethane (100 mL) . This solution was added to a solution of
N-bromosuccinimide (30.22 g ) and calcium oxide (0.906 g ) dissolved in
dichloromethane (40 mL) in 30 minutes at room temperature. The reaction
mass was stirred for 30 minutes and filtered. The filtrate was concentrated
to give a solid. Deionized water (100 mL) was added to the solid and heated
to 50 °C and stirred for 15 minutes. The solid was filtered and recharged
into a reaction flask. Deionized water (100 mL) was added to the solid,
heated to 50 °C and stirred for 15 minutes. The solid was filtered and dried
under vacuum to obtain the title compound (I) .
Yield: 77.7 %
Chromatographic purity: 96.11 %
Water content: 0.02 % w/w
Example 4
Preparation of (IS, S ,5S) -4-Bromo-6-oxabicyclo [3.2.1] octan-7-one
(I)
(IS )-Cyclohex- 3 -ene -1-carboxyl ic acid (II) (20.4 g ) was dissolved
in ethyl acetate (100 mL) . This solution was added to a solution of
N-bromosuccinimide (30.22 g ) and calcium oxide (0.906 g ) dissolved in ethyl
acetate (4 0 mL) in 30 minutes at r.oom temperature. The reaction mass was
stirred for 2 hours, filtered to obtain a residue. The filtrate was
concentrated to give a solid. Deionized water (10 0 mL) was added to the
solid, heated to 50 °C and stirred for 15 minutes. The solid was filtered
and recharged into a reaction flask. Deionized water (100 mL) was added
to the solid, heated to at 50 °C and stirred for 15 minutes. The solid was
filtered and dried under vacuum to obtain the title compound.
Dichloromethane (100 mL) was added to the residue, stirred for 10
minutes and filtered. The filtrate was concentrated to give a solid.
Deionized water (50 mL) was added to the solid, heated to 50 + 2°C and stirred
for 15 minutes. The solid was filtered and recharged into a reaction flask.
Deionized water (50 mL) was added to the solid, heated to 50 °C and stirred
for 15 minutes. The solid was filtered and dried under vacuum to obtain
the title compound (I) .
Combined yield: 67.67%
Chromatographic purity of combined solids: 95.74 .%
Water content of combined solids: 0.03 % w/w
Example 5
Preparation of (IS, 4S, 5S) -4-Bromo-6-oxabicyclo [3.2.1] octan-7-one
(I)
(IS) -Cyclohex-3-ene-l-carboxylic acid (II) (20.4 g ) was dissolved
in toluene (100 mL) . This solution was added to a solution of
N-bromosuccinimide (3 0.22 g ) and calcium oxide (0.906 g ) dissolved in
toluene (40 mL) in 25 minutes at 18 to 33 °C. The reaction mass was stirred
for 1 hour and filtered to obtain a residue. The filtrate was concentrated
to give a solid. Dichloromethane (100 mL) was added to the residue, stirred
for 10 minutes, filtered and the filtrate was concentrated to give a solid.
The solids were combined and deionized water (100 mL) was added to the
solid, heated to 50 °C and stirred for 15 minutes. The solid was filtered
and recharged into a reaction flask. Deionized water (100 mL) was added
t the solid, heated to 50 °C and stirred for 15 minutes. The solid was
filtered and dried under vacuum to obtain the title compound (I) .
Yield: 79.31 %
Chromatographic purity: 81.54 %
Water content: 0.06 % w/w
Example 6
Preparation o f (IS, 4S, 5S) -4 -Bromo- -oxabicyclo [3 .2 .1] octan-7-one
(I)
(IS) -Cyclohex-3-ene-l-carboxylic acid (II) (20.4 g ) was dissolved
in tetrahydrof uran (100 mL) . This solution was added to a solution of
N-bromosuccinimide (30.22 g ) and calcium oxide (0.906 g ) dissolved in
tetrahydrof uran (40 mL) in 35 minutes at 20 °C. The reaction mass was stirred
for I hour, filtered and the filtrate was concentrated to give a solid.
Deionized water (100 mL) was added to the solid, heated to 50 °C and stirred
for 15 minutes. The solid was filtered and recharged into a reaction flask.
Deionized water (100 mL) was added to the solid and heated to 50 °C and
stirred for 15 minutes. The solid was filtered and dried under vacuum to
obtain the title compound (I) .
Yield: 66.34 %
Chromatographic purity: 89.95 %
Water content: 0.04 % w/w
Example 7
Preparation o f (IS, 4S, 5S) - -Bromo- -oxabicyclo [3.2.1] octan-7-one
(I)
(IS) -Cyclohex-3-ene-l-carboxylic acid (II) (20.4 g ) was dissolved
in cyclopentyl methyl ether (100 mL) . This solution was added to a solution
of N-bromosuccinimide (30.22 g ) and calcium oxide (0.906 g ) dissolved in
cyclopenyl methyl ether (CPME) (4 mL) in 35 minutes at 20 to 33 °C. The
reaction mass was stirred for 1 hour, filtered to obtain a residue.
Dichloromethane (100 mL) was added to the residue, stirred for 10 minutes
and filtered. The filtrates were combined and the solvent was recovered
under vacuum. Deionized water (100 mL) was added to the solid, heated to
50 °C and stirred for 15 minutes. The solid was filtered and recharged into
a reaction flask. Deionized water (100 mL) was added to the solid, heated
to 50 °C and stirred for 15 minutes. The solid was filtered and dried under
vacuum to obtain the title compound (I) .
Yield: 74 .63 %
Chromatographic purity: 94.17%
Water content: 0.02 % w/w
Example 8
Preparation of (IS, 4S, 5S) -4-Bromo-6-oxabicyclo [3.2.1] octan-7-one
(I)
(IS) -Cyclohex-3 -ene-l-carboxylic acid (II) (10.2 g ) was dissolved
in dichloromethane (50 mL) . This solution was added to a solution of
N-bromosuccinimide (0.979 mole) and calcium hydroxide (0.49 mole)
dissolved in dichloromethane (20 mL) in 50 minutes. The reaction mass was
stirred for 1 hour at 30 to 35 °C and filtered through hyflo bed. The bed
was washed with dichloromethane (20 mL) . The filtrate was concentrated
under vacuum at 35 °C to give a solid. The solid obtained was washed twice
by making slurry in water (50 mL) at 50 °C. The solid was filtered and
dried under vacuum at 45 °C for 14 hours to obtain the title compound (I) .
Yield: 70 %
Chromatographic purity: 96. 13 %
Example 9
Preparation of (IS, 4S, 5S) -4-Bromo-6-oxabicyclo [3.2.1] octan-7-one
(I)
(IS) -Cyclohex-3-ene-l-carboxylic acid (II) (10.4 g ) was dissolved
in toluene (50 mL) . This solution was added to a solution of
1 ,3-dibromo- 5 ,5-dimethylhydantoin (0.55mole) and calcium oxide (O.lmole)
dissolved in toluene (20 mL) at 20 to 25 °C in 60 minutes. The reaction
mass was stirred for 1 hour at 20 to 25 °C and filtered. The bed was washed
with toluene (50 mL) and dichloromethane (50 mL) . The filtrate was
concentrated under vacuum to give a solid. Deionized water (50 mL) was
added to the solid, heated to 50 °C and stirred for 15 minutes. The solid
was filtered and recharged into a reaction flask. Deionized water (50 mL)
was added to the solid, heated t o 50 °C and stirred for 15 minutes. The
solid was filtered and dried under vacuum to obtain the title compound
(I).
Yield: 78.31 %
Chromatographi c puri t : 66.89%
Example 10
Preparation o f (IS, 4S, 5S) -4 -Bromo- -oxabicyclo [3.2.1] octan-7-one
(I)
(IS) -Cyclohex-3 -ene- 1-carboxylic acid (II) (20.6 g ) was dissolved
in toluene (100 mL) . This solution was added to a solution of
1 ,3-dibromo-5 ,5-dimethylhydantoin (0.52mole) and calcium hydroxide (0.09
mole) dissolved in toluene (40 mL) at 20 to 30 °C in 45 minutes. The reaction
mass was stirred for 1 hour at 25 to 30 °C and filtered. The bed was washed
with toluene (40 mL) and the filtrate was concentrated under vacuum to
give a solid. The bed was again washed with toluene (200 mL) and the filtrate
was concentrated under vacuum to give a solid. The solids were combined.
Deionized water (100 mL) was added to the solid, heated to 50 °C and stirred
for 15 minutes. The solid was filtered and recharged into a reaction flask.
Deionized water (100 mL) was added to the solid, heated to 50 °C and stirred
for 15 minutes. The solid was 'filtered and dried under vacuum to obtain
the title compound (I) .
Yield: 78.4 %
Chromatographic purity: 75.21 %
Example 11
Purification o f
(IS, S ,5S) -4 -Bromo- -oxabicyclo [3.2.1] octan-7-one (I)
(IS, 4S, 5S) -4 -bromo- -oxabicyclo [3.2.1] octan-7-one (I) (120
g ) was added to acetone (480 mL) at 45 °C and stirred at 45 to 47 °C
to get a clear solution. Water (720 mL) was charged drop-wise at 45
to 50 °C in a time period of 40 minutes. The reaction mass was cooled
to 5 °C under stirring and further stirred for 1 hour at 5 to 8 °C.
The solid was filtered and washed with a mixture of acetone (48 mL)
and water (72 mL) . The product was suck dried on the Buckner funnel
and then in vacuum dryer under vacuum at 40 to 45 °C to obtain the
title compound (I) .
Yield: 112 g (dry weight) (93.3%)
Chromatographic Purity of crude: 82.46 %
Chromatographic Purity of pure: 98.96 %
Example 12
Preparation of Methanesulf onic acid
(1R ,2R ,4S)-2-1ert -butoxycarbonylamino- 4-dime thylcarbamoyl -cycloh
exyl ester
(IS, 4S, 5S) -4-Bromo-6-oxabicyclo [3.2.1] octan-7-one (20 g ) was
dissolved in acetonitrile (125 ml) and 50% dimethylamine aqueous
solution (35.2 g ) was added to the mixture at around 10 °C. The
reaction mass was stirred for 15 hours at around 10 °C and the solvent
was recovered under vacuum at a temperature less than 15 °C. 28%
Ammonia solution (125 ml) was added to the residue. The resulting
mixture was warmed to 35 to 45 °C for 8 hours and further stirred
at about 25 °C for 14 hours. The solvent was recovered under vacuum.
Deionized water (63 ml) was added to the residue, and the mixture
was concentrated again under vacuum. Deionized water (88 ml) ,
di-tert-butyl dicarbonate (31 . g ) and 48% sodium hydroxide (20.3
g ) were added to the residue, and the resulting mixture was stirred
at 40 to 45 °C for 2 hours. 4-Methyl-2-pentanone (175 ml) was added
to the reaction mass and the layers were separated. The aqueous layer
was extracted with -methyl -2 -pentanone (175 ml) . The organic
layers were combined, and the solvent was recovered under vacuum
until the total volume was about 175 ml. 4-Methyl -2 -pentanone (100
ml) was added to the residue, and the mixture was concentrated again
to about 175 ml under vacuum. Then, the volume of the solution was
adjusted to 250 ml by adding 4-Methyl -2 -pentanone . After adding
methanesulf onyl chloride (17.9 g ) to the solution, triethylamine
(18.8 g ) was slowly added to the mixture at 15-3 0 °C, and the reaction
mass was stirred for 1 hour at the same temperature. After the
completion of the reaction, methanol (43 ml) and Deionized water (63
ml) were added to the reaction mass, and the resulting mixture was
stirred for 15 minutes . The organic layer was separated, washed with
5% aqueous sodium bicarbonate solution (50 ml), and concentrated
under vacuum to adjust the volume to 100 ml. Then, the resulting
slurry was stirred for 3 hours at around 0 °C. The precipitates were
collected by filtration, washed with 4-methyl-2-pentanone (25 ml) ,
and dried under vacuum to give the title compound.
Yield: 22.4 g (62.9%)
Chromatographic purity: 99.23%
Referential Examples
Referential Example 1
tert-Butyl{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl]
cyclohexyl }carbamate oxalate
Sodium azide (7.14 g ) and dodecylpyridinium chloride (7.80 g )
were added at room temperature to a solution (100 mL) of
Methanesulf onic acid
(1R, 2R, 4S) -2-tert-butoxycarbonylamino-4-dimethylcarbamoyl-cycloh
exyl ester (20.0 g ) in toluene, followed by stirring at 60 °C for
72 hours. Water was added to the reaction mixture, and the organic
layer was washed with aqueous saturated sodium bicarbonate solution
and water. Methanol, 7.5% Pd-C, and ammonium formate were added to
the washed organic layer, followed by stirring at 40 °C for 1 hour.
Pd-C was removed by filtration, and the solvent was evaporated under
reduced pressure. Hydrated acetonitrile (200 mL) and anhydrous
oxalic acid (4 .94 g ) were added to the residue .The mixture was stirred
at room temperature for 17 hours, and the formed crystals were
collected by filtration. Acetonitrile (200 mL) was added to the
collected crystals, followed by stirring at 40 °C for 24 hours. The
formed crystals were recovered by filtration and dried, to thereby
yield 12.7 g of the title compound.
Referential Example 2
tert-Butyl [(1R, 2S, 5S) -2- ({ [(5-chloropyridin-2-yl) amino] (oxo) acet
yl}amino) -5- (dimethylaminocarbonyl) cyclohexyl] carbamate
W
22
Triethylamine (169 mL) was added at 60 °C to a suspension (550
L ) of tert -butyl
{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohexyl }carbam
ate oxalate (100.1 g ) in acetonitrile .At the same temperature, ethyl
[5-chloropyridin-2-yl] amino] (oxo) acetate hydrochloride (84.2 g )
was added to the mixture , followed by stirring for 6 hours . Thereafter ,
the mixture was stirred at room temperature for 16 hours. Water was
added to the reaction mixture, followed by stirring at 10 °C for 1.5
hours. The formed crystals were recovered by filtration, to thereby
yield 106.6 g of the title compound.
Referential Example 3
N - (5-Chloropyridin-2-yl) -N2- [(IS, 2R, 4S) -4- (dimethyl carbamoyl) -2
-{ [(5 -methyl -4 ,5,6, 7-tetrahydro [1,3] thiazolo [5 ,4-c] pyridin-2 -yl )
carbonyl] amino} cyclohexyl] ethanediamide (Edoxaban)
Methanesulf onic acid (66 mL) was added at room temperature to
a suspension of
tert-butyl [(1R, 2S, 5S) -2- ({ [(5-chloropyridin-2-yl) amino] (oxo)acet
yl }amino) -5- (dimethylaminocarbonyl) cyclohexyl] carbamate (95.1 g )
in acetonitrile (1,900 mL) , and the mixture was stirred at the same
temperature for 2 hours. Triethylamine (155 mL) ,
5-methyl -4 ,5,6, 7-tetrahydro [1,3] thiazolo [5 ,4-c] pyridine-2 -carbox
ylic acid hydrochloride (52.5 g ) , 1-hydroxybenzotriazole (33.0 g ) ,
and l-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride
(46.8 g ) were added to the reaction mixture under ice-cooling, and
the mixture was stirred at room temperature for 16 hours.
Triethylamine and water were added thereto, followed by stirring
under ice -cooling for 1 hour. The formed crystals were recovered by
filtration, to thereby yield 103.2 g of the title compound.
Industrial Applicability
The present invention can be used as an industrial
process for producing an
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one of formula (I)
which is a key intermediate in the synthesis of edoxaban, a compound
that exhibits an inhibitory effect on activated blood coagulation
factor X (also referred to as activated factor X or FXa) , and is useful
as a preventive and/or therapeutic drug for thrombotic diseases.
CLAIMS
[Claim 1 ]
A process for producing
(IS, S ,5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one represented by
the following formula (I) :
( I )
comprising (IS) -cyclohex-3-ene-l-carboxylic acid represented by the
following formula (II) :
()
is treated with N-bromosuccinimide or
1 ,3-dibromo-5, 5-dimethylhydantoin as brominating agent in the
presence of a base selected from calcium oxide or calcium hydroxide
in an organic solvent .
(1) A process for producing
(IS , S ,5S) -4-bromo-6-oxabicyclo [3.2.1] octan- 7-one , represented by
the following formula (I) :
( I )
comprising (IS) -cyclOhex-3-ene-l-carboxylic acid, represented by
the following formula (II) :
( )
is treated with N-bromosuccinimide or
1 ,3-dibromo-5, 5-dimethylhydantoin as brominating agent in the
presence of a base selected from calcium oxide or calcium hydroxide
in a solvent selected from the group consisting of dichloromethane ,
toluene, tetrahydrofuran, ethyl acetate, hexanes, cyclopentyl
methyl ether (CP E ) or a mixture thereof.
[Claim 2 ]
The production process according to claim 1 , wherein
brominating agent is N-bromosuccinimide.
[Claim 3 ]
A process for producing
tert-butyl{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl]
eye lohexyl }carbamate oxalate:
the method using
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one (I) produced by
a method according to claim 1 and comprising the following steps a )
and b ) :
a ) (IS, 4S, 5S) -4 -bromo- 6-oxabicyclo [3.2.1] octan-7-one (I) produced
by a production process according to (1) is treated with an aqueous
solution of dimethylamine followed by reacting with aqueous ammonia,
subsequently with a di-tert-butyl dicarbonate and further with
methanesulf onyl chloride to obtain methanesulf onic acid
(1 R ,2R ,4S)-2-1ert -butoxycarbonylamino -4-dime thylcarbamoyl -cycloh
exyl ester,
b ) treating methanesulf onic acid
(1R ,2R ,4S)-2- tert -butoxycarbonylamino -4-dime thylcarbamoyl -cycloh
exyl ester with sodium azide, followed by subjecting the resultant
compound to hydrogeno lysis in the presence of Palladium- Carbon and
ammonium formate and reacting the resultant compound with oxalic acid
to obtain
tert-Butyl{ (1R,2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohe
xyl }carbamate oxalate.
[Claim 4 ]
A process for producing
N - (5-chloropyridin-2-yl) -N2- ((IS, 2R, 4S) -4- [(dimethylamino) carbo
nyl] -2- { [(5-methyl - ,5,6, 7-tetrahydrothiazolo [5 ,4-c] pyridin-2 -yl
)carbonyl] amino }cyclohexyl) ethanediamide p -toluenesulf onate
monohydrate
the method using
(IS, 4S, 5S) -4-bromo-6-oxabicyclo [3.2.1] octan-7-one (I) produced by
a method according to claim 1 and comprising the following steps a )
to e ) :
a ) (1S,4S, 5S) -4 -bromo- -oxabicyclo [3.2. 1 ]octan- 7-one (I) produced
by a production process according to (1) is treated with an aqueous
solution of dimethylamine followed by reacting with aqueous ammonia,
subsequently with a di-tert -butyl dicarbonate and further with
methanesulf onyl chloride to obtain methanesulf onic acid
(1R,2R,4S) -2- 1ert -butoxycarbonylamino -4-dimethylcarbamoyl -eye loh
exyl ester,
b ) treating methanesulf onic acid
(1R,2R,4S) -2- tert -butoxycarbonylamino -4-dimethylcarbamoyl -cycloh
exyl ester with sodium azide, followed by subjecting the resultant
compound to hydrogenolysis in the presence of Palladium- Carbon and
ammonium formate and reacting the resultant compound with oxalic acid
to obtain
tert-Butyl{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohe
xyl }carbamate oxalate.
c ) reacting
tert-Butyl{ (1R, 2S, 5S) -2-amino-5- [(dimethylamino) carbonyl] cyclohe
xyl }carbamate oxalate with
ethyl [5 -chloropyridin-2 -yl] amino] (oxo) acetate hydrochloride in
the presence of a triethylamine to obtain
tert -Butyl [(1R, 2S ,5S) -2 - ({ [(5-chloropyridin-2-yl) amino] (oxo) acet
yl}amino) -5- (dimethylaminocarbonyl) cyclohexyl] carbamate,
d ) deprotecting the tert- But oxycarbonyl group from
tert-Butyl [(1R, 2S, 5S) -2- ({ [(5-chloropyridin-2 -yl) amino] (oxo) acet
yl}amino) -5- (dimethylaminocarbonyl) cyclohexyl] carbamate by using
methanesulphonic acid followed by reacting the deprotected compound
with
5-methyl-4, 5,6, 7-tetrahydro [1, 3 ] thiazolo [5, 4-c] pyridine-2 -carbox
ylic acid hydrochloride or its activated ester to obtain
N - (5-chloropyridin-2-yl) -N2- ((IS, 2R, 4S) -4- [(dimethylamino) carbo
nyl] -2- { [(5-methyl -4 ,5,6, 7 -tetrahydrothiazolo [5 , -c] pyridin-2 -yl
)carbonyl] amino} eye lohexyl) ethanediamide ,
e ) treating
N1- (5-chloropyridin-2-yl) -N2- ((IS, 2R, 4S) -4- [(dimethylamino) carbo
nyl] -2- { [(5 -methyl -4 ,5,6, -tetrahydrothiazolo [5 ,4-c] pyridin-2 -yl
)carbonyl] amino} eye lohexyl) ethanediamide with p -toluenesulf onic
acid in aqueous ethanol to obtain
N - (5-chloropyridin-2-yl) -N2- ((IS, 2R, 4S) -4 - [(dimethylamino) carbo
nyl] -2 -{ [(5-methyl -4 ,5,6, 7-tetrahydrothiazolo [5 ,4-c] pyridin-2 -yl
)carbonyl] amino} eye lohexyl) ethanediamide p -toluenesulf onate
monohydrate .