Indian Patents. 231762:"PROCESS FOR THE SYNTHESIS OF THE PERINDOPRIL COMPOUNDS OF FORMULA(I)AND ITS PHARMACEUTICALLY ACCEPTABLE SALTS"

Title of Invention	"PROCESS FOR THE SYNTHESIS OF THE PERINDOPRIL COMPOUNDS OF FORMULA(I)AND ITS PHARMACEUTICALLY ACCEPTABLE SALTS"
Abstract	Process for the synthesis of the perindopril compounds of formula (I): and its pharmaceutically acceptable salts.

Full Text	The present invention relates to process for the synthesis of the perindopril compounds of formula (I) and its pharmaceutically acceptable salts. The present invention relates to a process for the synthesis of perindopril of formula (I): (Formula Removed) and its pharmaceutically acceptable salts. Perindopril and its pharmaceutically acceptable salts, and more especially its tert- butylamine salt, have valuable pharmacological properties. Their principal property is that of inhibiting angiotensin I converting enzyme (or kininasell), which allows, on the one hand, prevention of the conversion of the decapeptide angiotensin I to the octapeptide angiotensin 11 (a vasoconstrictor) and, on the other hand, prevention of the degradation of bradykinin (a vasodilator) to an inactive peptide. Those two actions contribute to the beneficial effects of perindopril in cardiovascular diseases, more especially in arterial hypertension and heart failure. Perindopril, its preparation and its use in therapeutics have been described in the European patent specification EP 0 049 658. In view of the pharmaceutical value of this compound, it has been important to be able to obtain it by an effective synthesis process, readily transposable to an industrial scale, that leads to perindopril in a good yield and with excellent purity starting from reasonably priced starting materials. Patent specification EP 0 308 341 describes the synthesis of perindopril by the coupling of (2S',3aS',7aS)-octahydroindole-2-carboxylic acid benzyl ester with N-[(S)-l-carboxybutyl]- (5)-alanine ethyl ester, followed by deprotection of the carboxylic group of the heterocycle by catalytic hydrogenation. The Applicant has now developed a new process for the synthesis of perindopril. More specifically, the present invention relates to a process for the synthesis of perindopril and its pharmaceutically acceptable salts which is characterised in that a compound of formula (11) : (Figure Removed) wherein RI represents a benzyl or linear or branched (Ci-C6)alkyl group, is reacted with a compound of formula (III) having the S configuration : wherein X represents a halogen atom and R2 represents a protecting group for the amino function, in the presence of a base, to yield, after deprotection of the amino function, a compound of formula (IV) (Figure Removed) wherein R\| is as defined hereinbefore, which is reacted with ethyl 2-oxopentanoate under hydrogen pressure, in the presence of platinum-on-carbon, to yield a compound of formula (V): (Figure Removed) wherein R\| is as defined hereinbefore, which is deprotected to yield the compound of formula (I). Among the protecting groups for the amino function that can be used in the process of the present invention there may be mentioned, without implying any limitation, the groups tert-butoxycarbonyl, benzyloxycarbonyl and benzyl. RI preferably represents the benzyl group. In that case the protecting group for the amino function is preferably the tert-butoxycarbonyl group. Among the bases that can be used in the reaction between the compounds of formulae (II) and (III) there may be mentioned, without implying any limitation, organic amines such as triethylamme, pyridine, N-methylmorpholine or diisopropylethylamine, and mineral bases such as NaOH, KOH, Na2CO3, K2CO3, NaHCO3 or KHCO3. The reaction between the compound of formula (IV) and ethyl 2-oxopentanoate is preferably carried out in ethyl acetate, acetic acid or in an alcoholic solvent, under atmospheric pressure, at a temperature of from 20 to 60°C. EXAMPLE : (2S,3aS,7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino)- propionyI}-octahydro-l#-indole-2-carboxylic acid tert-butylamine salt Step A : Benzyl (2S)-l-{(2S)-2-[(tert-butoxycarbonyl)amino]propionyl}-2,3,4,5,6,7-hexahydro- l\\-indole-2-carboxylate Introduce 200 g of benzyl (2S)-2,3,4,5,6,7-hexahydro-lH-indole-2-carboxylate and 1.5 litres of dichloromethane into a reactor, then bring the temperature of the reaction mixture to ()°C and add 107 ml of triethylamine and then 162 g of (2S)-2-[(tert-butoxycarbonyl)ammo]propionyl chloride. Subsequently, bring the mixture to ambient temperature. After stirring for 1 hour at that temperature, wash the mixture with water and then with a dilute acetic acid solution. The benzyl (2S)-l-{(2S)-2-[(tert-butoxycarbonyl)amino]propionyl} -2,3,4,5,6,7-hexahydro- l//-indole-2-carboxylate solution so obtained is used as it is in the following Step. Step B : Benzyl (2S)-l-{(2S)-2-aminopropionyl}-2,3,4,5,6,7-hexahydro-7H-in dole -2-carboxylate Introduce the solution obtained in the above Step into a reactor, and then add 133 g of trifluoroacetic acid. After stirring for 1 hour 30 minutes at ambient temperature, wash the mixture with water and then with a saturated solution of sodium hydrogen carbonate and evaporate off the solvents to yield benzyl (2S)-l-{(2S)-2-aminopropionyl}-2,3,4,5,6,7-hexahydro~l//-indole-2-carboxylate. Step C : Benzyl (2S,3aS, 7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]-propionyl}octahydro-ll{-indole-2-carboxylate Introduce into a hydrogenation vessel 200 g of the compound obtained in the above Step and 88 g of ethyl 2-oxopentanoate in solution in ethyl acetate, followed by 5 g of 10 % Pt/C. Hydrogenate under atmospheric pressure at 40°C until the theoretical amount of hydrogen has been absorbed. Remove the catalyst by filtration, then cool to from 0 to 5°C and collect the resulting solid by filtration, wash the cake and dry it to constant weight. Benzyl (2S,3aS,7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]propionyl}-octahydro-l//~indole-2-carboxylate is thereby obtained in a yield of 85 %. Step D : (2$, 3aS, 7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]propionyl}-octahydro-lH-indole-2-carboxylic acid Introduce into a hydrogenation vessel 200 g of the compound obtained in the above Step in solution in ethanol, followed by 5 g of 10 % Pd/C. Hydrogenate under atmospheric pressure at 30°C until the theoretical amount of hydrogen has been absorbed. Remove the catalyst by filtration and then evaporate off the solvent. (2S,3aS,7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]propionyH-octahydro-l//-indole-2-carboxylic acid is thereby obtained in a yield of 85 %. Step E : (2S,3aS, 7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]propionyl}-octahydro-l\\-indole-2-carboxylic acid tert-butylamine salt 'The compound obtained in the above Step (200 g) is dissolved in 2.8 litres of acetonitrile, and then 40 g of tert-butylamine and 0.4 litres of ethyl acetate are added. "The suspension obtained is then refluxed until dissolution is complete, and the solution obtained is subsequently filtered hot and cooled, with stirring, to a temperature of from 15 to 20°C. The resulting precipitate is then filtered off, made into a paste again with acetonitrile, dried and then recrystallised from ethyl acetate to give the expected product in a yield of 95 % and with an enantiomeric purity of 99 %. WE CLAIM: 1. Process for the synthesis of the perindopril compounds of formula (I): (Formula Removed) and its pharmaceutically acceptable salts, characterised in that a compound of formula (II): (Formula Removed) wherein R1 represents a benzyl or linear or branched (C1-C6)alkyl group, is reacted with a compound of formula (III) having the S configuration: (Formula Removed) wherein X represents a halogen atom and R2 represents a protecting group for the amino function, in the presence of a base, to yield, after deprotection of the amino function, a compound of formula (IV) (Formula Removed) wherein R1 is as defined hereinbefore, which is reacted with ethyl 2-oxopentanoate under hydrogen pressure, in the presence of platinum-on-carbon, to yield a compound of formula (V): (Formula Removed) wherein R1 is as defined hereinbefore, which is deprotected to yield the compound of formula (I). 2. Process as claimed in claim 1, wherein the protecting group for the amino function is a tert-butoxycarbonyl, benzyloxycarbonyl or benzyl group. 3. Process as claimed in claim 2, wherein R1 represents a benzyl group and the protecting group for the amino function is a tert-butoxycarbonyl group. 4. Process as claimed in any one of claims 1 to 3, wherein the base used for the reaction between the compounds of formulae (II) and (III) is an organic amine selected from trie thy lamine, pyridine, N-methylmorpholine and diisopropyl-ethylamine, or a mineral base such as NaOH, KOH, Na2C03, K2CO3, NaHCO3 or KHCO3. 5. Process as claimed in any one of claims 1 to 4, wherein the reaction between the compound of formula (IV) and ethyl 2-oxopentanoate is carried out in ethyl acetate, acetic acid or in an alcoholic solvent. 6. Process as claimed in any one of claims 1 to 5, wherein the reaction between the compound of formula (IV) and ethyl 2-oxopentanoate is carried out at atmospheric pressure. 7. Process as claimed in any one of claims 1 to 6, wherein the reaction between the compound of formula (IV) and ethyl 2-oxopentanoate is carried out at a temperature of from 20 to 60°C. 8. Process as claimed in any one of claims 1 to 7 for the synthesis of perindopril in the form of its tert-butylamine salt.

Full Text

The present invention relates to process for the synthesis of the perindopril compounds of formula (I) and its pharmaceutically acceptable salts.
The present invention relates to a process for the synthesis of perindopril of formula (I):
(Formula Removed)
and its pharmaceutically acceptable salts.
Perindopril and its pharmaceutically acceptable salts, and more especially its tert-
butylamine salt, have valuable pharmacological properties.
Their principal property is that of inhibiting angiotensin I converting enzyme (or
kininasell), which allows, on the one hand, prevention of the conversion of the
decapeptide angiotensin I to the octapeptide angiotensin 11 (a vasoconstrictor) and, on the
other hand, prevention of the degradation of bradykinin (a vasodilator) to an inactive
peptide.
Those two actions contribute to the beneficial effects of perindopril in cardiovascular
diseases, more especially in arterial hypertension and heart failure.
Perindopril, its preparation and its use in therapeutics have been described in the European patent specification EP 0 049 658.
In view of the pharmaceutical value of this compound, it has been important to be able to obtain it by an effective synthesis process, readily transposable to an industrial scale, that leads to perindopril in a good yield and with excellent purity starting from reasonably priced starting materials.
Patent specification EP 0 308 341 describes the synthesis of perindopril by the coupling of (2S',3aS',7aS)-octahydroindole-2-carboxylic acid benzyl ester with N-[(S)-l-carboxybutyl]-

(5)-alanine ethyl ester, followed by deprotection of the carboxylic group of the heterocycle by catalytic hydrogenation.
The Applicant has now developed a new process for the synthesis of perindopril.
More specifically, the present invention relates to a process for the synthesis of perindopril and its pharmaceutically acceptable salts which is characterised in that a compound of formula (11) :

(Figure Removed)
wherein RI represents a benzyl or linear or branched (Ci-C6)alkyl group,
is reacted with a compound of formula (III) having the S configuration :
wherein X represents a halogen atom and R2 represents a protecting group for the amino function,
in the presence of a base,
to yield, after deprotection of the amino function, a compound of formula (IV)
(Figure Removed)
wherein R| is as defined hereinbefore,
which is reacted with ethyl 2-oxopentanoate under hydrogen pressure, in the presence of platinum-on-carbon,
to yield a compound of formula (V):
(Figure Removed)
wherein R| is as defined hereinbefore,
which is deprotected to yield the compound of formula (I).
Among the protecting groups for the amino function that can be used in the process of the present invention there may be mentioned, without implying any limitation, the groups tert-butoxycarbonyl, benzyloxycarbonyl and benzyl.
RI preferably represents the benzyl group. In that case the protecting group for the amino function is preferably the tert-butoxycarbonyl group.
Among the bases that can be used in the reaction between the compounds of formulae (II) and (III) there may be mentioned, without implying any limitation, organic amines such as triethylamme, pyridine, N-methylmorpholine or diisopropylethylamine, and mineral bases such as NaOH, KOH, Na2CO3, K2CO3, NaHCO3 or KHCO3.
The reaction between the compound of formula (IV) and ethyl 2-oxopentanoate is preferably carried out in ethyl acetate, acetic acid or in an alcoholic solvent, under atmospheric pressure, at a temperature of from 20 to 60°C.
EXAMPLE : (2S,3aS,7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino)-
propionyI}-octahydro-l#-indole-2-carboxylic acid tert-butylamine salt
Step A : Benzyl (2S)-l-{(2S)-2-[(tert-butoxycarbonyl)amino]propionyl}-2,3,4,5,6,7-hexahydro- l\\-indole-2-carboxylate
Introduce 200 g of benzyl (2S)-2,3,4,5,6,7-hexahydro-lH-indole-2-carboxylate and 1.5 litres of dichloromethane into a reactor, then bring the temperature of the reaction mixture to ()°C and add 107 ml of triethylamine and then 162 g of (2S)-2-[(tert-butoxycarbonyl)ammo]propionyl chloride. Subsequently, bring the mixture to ambient temperature. After stirring for 1 hour at that temperature, wash the mixture with water and then with a dilute acetic acid solution. The benzyl (2S)-l-{(2S)-2-[(tert-butoxycarbonyl)amino]propionyl} -2,3,4,5,6,7-hexahydro- l//-indole-2-carboxylate solution so obtained is used as it is in the following Step.
Step B : Benzyl (2S)-l-{(2S)-2-aminopropionyl}-2,3,4,5,6,7-hexahydro-7H-in dole -2-carboxylate
Introduce the solution obtained in the above Step into a reactor, and then add 133 g of trifluoroacetic acid. After stirring for 1 hour 30 minutes at ambient temperature, wash the mixture with water and then with a saturated solution of sodium hydrogen carbonate and evaporate off the solvents to yield benzyl (2S)-l-{(2S)-2-aminopropionyl}-2,3,4,5,6,7-hexahydro~l//-indole-2-carboxylate.
Step C : Benzyl (2S,3aS, 7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]-propionyl}octahydro-ll{-indole-2-carboxylate
Introduce into a hydrogenation vessel 200 g of the compound obtained in the above Step and 88 g of ethyl 2-oxopentanoate in solution in ethyl acetate, followed by 5 g of 10 % Pt/C. Hydrogenate under atmospheric pressure at 40°C until the theoretical amount of hydrogen has been absorbed.
Remove the catalyst by filtration, then cool to from 0 to 5°C and collect the resulting solid by filtration, wash the cake and dry it to constant weight.
Benzyl (2S,3aS,7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]propionyl}-octahydro-l//~indole-2-carboxylate is thereby obtained in a yield of 85 %.
Step D : (2$, 3aS, 7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]propionyl}-octahydro-lH-indole-2-carboxylic acid
Introduce into a hydrogenation vessel 200 g of the compound obtained in the above Step in solution in ethanol, followed by 5 g of 10 % Pd/C. Hydrogenate under atmospheric pressure at 30°C until the theoretical amount of hydrogen has been absorbed. Remove the catalyst by filtration and then evaporate off the solvent. (2S,3aS,7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]propionyH-octahydro-l//-indole-2-carboxylic acid is thereby obtained in a yield of 85 %.
Step E : (2S,3aS, 7aS)-l-{(2S)-2-[(lS)-l-(ethoxycarbonyl)butylamino]propionyl}-octahydro-l\\-indole-2-carboxylic acid tert-butylamine salt
'The compound obtained in the above Step (200 g) is dissolved in 2.8 litres of acetonitrile, and then 40 g of tert-butylamine and 0.4 litres of ethyl acetate are added. "The suspension obtained is then refluxed until dissolution is complete, and the solution obtained is subsequently filtered hot and cooled, with stirring, to a temperature of from 15 to 20°C. The resulting precipitate is then filtered off, made into a paste again with acetonitrile, dried and then recrystallised from ethyl acetate to give the expected product in a yield of 95 % and with an enantiomeric purity of 99 %.

WE CLAIM:
1. Process for the synthesis of the perindopril compounds of formula (I):

(Formula Removed)
and its pharmaceutically acceptable salts, characterised in that a compound of formula (II):

(Formula Removed)
wherein R1 represents a benzyl or linear or branched (C1-C6)alkyl group, is reacted with a compound of formula (III) having the S configuration:

(Formula Removed)
wherein X represents a halogen atom and R2 represents a protecting group for the amino function, in the presence of a base,

to yield, after deprotection of the amino function, a compound of formula (IV)

(Formula Removed)
wherein R1 is as defined hereinbefore,
which is reacted with ethyl 2-oxopentanoate under hydrogen pressure, in
the presence of platinum-on-carbon,
to yield a compound of formula (V):

(Formula Removed)
wherein R1 is as defined hereinbefore,
which is deprotected to yield the compound of formula (I).
2. Process as claimed in claim 1, wherein the protecting group for the amino function is a tert-butoxycarbonyl, benzyloxycarbonyl or benzyl group.
3. Process as claimed in claim 2, wherein R1 represents a benzyl group and the protecting group for the amino function is a tert-butoxycarbonyl group.

4. Process as claimed in any one of claims 1 to 3, wherein the base used for the reaction between the compounds of formulae (II) and (III) is an organic amine selected from trie thy lamine, pyridine, N-methylmorpholine and diisopropyl-ethylamine, or a mineral base such as NaOH, KOH, Na2C03, K2CO3, NaHCO3 or KHCO3.
5. Process as claimed in any one of claims 1 to 4, wherein the reaction between the compound of formula (IV) and ethyl 2-oxopentanoate is carried out in ethyl acetate, acetic acid or in an alcoholic solvent.
6. Process as claimed in any one of claims 1 to 5, wherein the reaction between the compound of formula (IV) and ethyl 2-oxopentanoate is carried out at atmospheric pressure.
7. Process as claimed in any one of claims 1 to 6, wherein the reaction between the compound of formula (IV) and ethyl 2-oxopentanoate is carried out at a temperature of from 20 to 60°C.
8. Process as claimed in any one of claims 1 to 7 for the synthesis of perindopril in the form of its tert-butylamine salt.

Documents:

919-DELNP-2006-Abstract-(08-10-2008).pdf

919-delnp-2006-abstract.pdf

919-DELNP-2006-Claims-(08-10-2008).pdf

919-delnp-2006-claims.pdf

919-delnp-2006-correspondence -others.pdf

919-DELNP-2006-Correspondence-Others-(08-10-2008).pdf

919-DELNP-2006-Description (Complete)-(08-10-2008).pdf

919-delnp-2006-description (complete).pdf

919-DELNP-2006-Form-1-(08-10-2008).pdf

919-delnp-2006-form-1.pdf

919-delnp-2006-form-18.pdf

919-DELNP-2006-Form-2-(08-10-2008).pdf

919-delnp-2006-form-2.pdf

919-DELNP-2006-Form-3-(08-10-2008).pdf

919-delnp-2006-form-3.pdf

919-delnp-2006-form-5.pdf

919-DELNP-2006-GPA-(08-10-2008).pdf

919-delnp-2006-gpa.pdf

919-delnp-2006-pct-210.pdf

919-delnp-2006-pct-237.pdf

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Patent Number

231762

Indian Patent Application Number

919/DELNP/2006

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

09-Mar-2009

Date of Filing

22-Feb-2006

Name of Patentee

LES LABORATOIRES SERVIER

Applicant Address

12, PLACE DE LA DEFENSE, F-92415 COURBEVOIE CEDEX, FRANCE,

Inventors:

#	Inventor's Name	Inventor's Address
1	THIERRY DUBUFFET	17, ALLEE DES CHARMILLES, F-76190 AUTETOT, FRANCE
2	JEAN-PIERRE LECOUVE	93, RUE DU DOCTEUR VIGNE, F-76600 LE HAVRE, FRANCE

PCT International Classification Number

C07K 5/06

PCT International Application Number

PCT/FR2004/002198

PCT International Filing date

2004-08-27

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	03292133.0	2003-08-29	EPO