FR2883874A1 - Preparation of perhydroindole compounds comprises enantiomeric resolution of an ester by enzymatic hydrolysis in presence of protease, isolation ester/acid, saponification or hydrolysis of ester to an acid, reduction of acid - Google Patents

Abstract

Preparation of perhydroindole compounds (I) and (II) and their salts, comprises enantiomeric resolution of an ester (III) by enzymatic hydrolysis in the presence of a protease, isolation of an ester (IV) and an acid (V); saponification or hydrolysis of ester (IV) to an acid (VI); reduction of acid (VI) by catalytic hydrogenation to form (I); isolation of the acid (I); esterification of the acid (I) to obtain the ester compound (II); and optional isolation of ester (II). Preparation of perhydroindole compounds of formulae (I) or (II) and their salts, comprises enantiomeric resolution by enzymatic hydrolysis of an ester of formula (III) in the presence of a protease, isolation of an ester of formula (IV) and an acid of formula (V); saponification or hydrolysis of ester (IV) to an acid of formula (VI); reduction of acid (VI) by catalytic hydrogenation to form (I); isolation of the acid (I); esterification of the acid (I) to obtain the ester compound of formula (II); and optional isolation of ester (II). R : H or 1-6C alkyl; and R3H, 1-6C alkyl or alkenyl (optionally substituted by 3-6C cycloalkyl, 3-6C heterocycloalkyl or (hetero)aryl). An independent claim is also included for the preparation of (III). [Image] [Image].

Description

H

  The invention relates to a novel process for the synthesis of (2S, 3aS, 7aS) -perhydroindole-2-carboxylic acid and its esters, and their application to the industrial synthesis of perindopril and of pharmaceutically acceptable salts thereof.

  (2S, 3aS, 7aS) -perhydroindole-2-carboxylic acid (I) and its esters of formula CO2H CO2CH2R

N N

  H H (I) H H are useful in the synthesis of perindopril, of formula (VIII): H (VIII) as well as in that of these pharmaceutically acceptable salts.

  Perindopril and its salts have interesting pharmacological properties. They mainly allow the inhibition of the angiotensin I converting enzyme (or kininase II), which on the one hand prevents the transformation of the decapeptide angiotensin I into octapeptide angiotensin II (vasoconstrictor), and on the other hand prevents the degradation of the bradykinin (vasodilator) into an inactive peptide. Thus, perindopril is useful in the treatment of cardiovascular diseases, including arterial hypertension and heart failure.

  Some methods for preparing (2S, 3aS, 7aS) -perhydroindole2-carboxylic acid of formula (I) and its esters of formula (II) are already known.

  Patent Application EP 0 037 231 describes a process in which 2-carboxylic acid indole is used as starting material. This acid is subjected to catalytic hydrogenation on rhodium to give a mixture of the two cis and endo isomers of respective configurations (2S, 3aS, 7aS) and (2R, 3aR, 7aR). This mixture is then separated by a laborious process: synthesis of the N-benzoyl derivative, fractional crystallization of the salt of the diastereoisomer with (S) -alpha-phenyl-ethylamine, release of the two derivatives (S, S, S) and (R, R, R) N-benzoylated, followed by removal of the benzoyl group, followed by passage over an ion exchange column and recrystallization.

  Patent Application EP 0 115 345 describes a process using as raw material 2-carboxylic acid indole and comprising the esterification of the carboxylic acid function with benzyl alcohol, the salification of the amino ester by N-benzyloxycarbonyl (S) -phenylalanine, the separation by fractional crystallization of the (S, S, S) isomer, the release of the amine function optionally followed by the release of the carboxylic acid group.

  Patent applications EP 0 308 339 and EP 0 308 341 describe a synthetic process which also uses as raw material indole 2 carboxylic acid. This acid is initially reduced to indoline 2-carboxylic acid (using the tin / hydrochloric acid pair). A mixture of 2R and 2S indoline carboxylic acid is then obtained. The 2S isomer is then separated by adding to said mixture a solution of (+) methyl benzylamine in a lower aliphatic alcohol. The precipitate of indoline carboxylic acid-2 (S) with methyl benzylamine is recovered and decomposed to give indoline carboxylic acid-2 (S). The 2S isomer is then catalytically hydrogenated to yield the desired compound. These applications also describe the synthesis of perindopril from (2S, 3aS, 7aS) perhydroindole-2-carboxylic acid.

  Since perindopril has interesting pharmaceutical activities, it is important to be able to synthesize (2S, 3aS, 7aS) -perhydroindole-2-carboxylic acid and its esters by a high-performance industrial synthesis process, enabling the desired diastereoisomer to be obtained with a good yield and excellent purity, from cheap raw materials.

  The inventors have developed a new process for the industrial synthesis of (2S, 3aS, 7aS) -perhydroindole-2-carboxylic acid and its esters which allows the selective production of the desired diastereoisomer in good yield and excellent enantiomeric purity.

  The present invention thus relates to a process for the synthesis of the compounds of formula (I) or (II), as well as their addition salts with an acid or a mineral or organic base, comprising the following successive steps: resolution by enzymatic hydrolysis, in the presence of a protease, of an ester of formula (III) (R, S) CO2CH2R1 (III) in which R1 represents a hydrogen atom, a C1-C6 alkyl or alkenyl radical; linear or branched, optionally substituted by a radical selected from the group consisting of C3-C6 cycloalkyl radicals, C3-C6 heterocycloalkyl, aryl or heteroaryl, to isolate on the one hand an ester of formula (IV)

H N

  CO2CH2R1 (IV) in which R1 has the same meaning as for formula (III), and on the other hand an acid of formula (V) CO2H (V) b) saponification or hydrolysis of ester IV obtained following the step a) acid of formula (VI); CO2H (VI) c) reduction of the acid VI obtained following step b) by catalytic hydrogenation to form the compound of formula (I)

H CO2H (I)

  (d) where appropriate, isolation of acid I; e) where appropriate, esterifying the acid (I) obtained following step c) to obtain the compound of formula (II) CO2CH 2 R NHH (II) in which R represents a hydrogen atom, an alkyl radical or straight or branched C1-C6 alkenyl, optionally substituted with a radical selected from the group consisting of C3-C6 cycloalkyl, C3C6 heterocycloalkyl, aryl or heteroaryl; f) possible isolation of the ester II.

  In the context of the present invention, the term alkyl denotes a hydrocarbon residue straight or branched chain containing from 1 to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl.

  In the context of the present invention, the term alkenyl denotes a straight or branched chain hydrocarbon residue containing from 1 to 6 carbon atoms and at least one olefinic bond, such as allyl, vinyl and isoprenyl.

  As an example of an aryl radical, mention may be made especially of phenyl and naphthyl. As an example of a heteroaryl radical, there may be mentioned imidazole, indole, furan, thiophene, pyrrole, pyridine.

  In the context of the present invention, the term cycloalkyl denotes a cyclic alkyl group containing from 3 to 6 carbon atoms, for example cyclopropyl, cyclobutyl, cyclopentyl and cyclohexyl, and the term heterocycloalkyl denotes a cyclic alkyl group containing 3 to 6 carbon atoms, one or more carbon atoms of which may be replaced by heteroatoms selected from the group consisting of N, O and S. Examples of heterocycloalkyl radicals include pyrrolidine, piperidine and tetrahydrofuran , pyran, morpholine.

  R1 and / or R preferably represent a hydrogen atom or a linear or branched C1-C6 alkyl or alkenyl radical, still more advantageously a hydrogen atom.

  Ester III can be a mixture of esters, for example a mixture of methyl ester and ethyl ester.

  During the enzymatic hydrolysis of the ester III in the presence of a protease (step a), the R enantiomer of the ester III will be hydrolyzed while the S enantiomer will not be hydrolyzed. The protease used during this step is characterized by its ability to enantioselectively orient the hydrolysis of only one of the enantiomers (R enantiomer).

  The protease used is advantageously chosen from the group consisting of alkalase, chymotrypsin and papain. According to an advantageous variant of the invention, the protease used is subtilisin, commonly called alkalase.

  Step a) of resolution by enzymatic hydrolysis is advantageously carried out in a homogeneous aqueous medium. According to an advantageous variant of the invention, the resolution by enzymatic hydrolysis comprises the following successive stages: i) homogeneous mixture, at a temperature of between 10 and 30 ° C., of the ester III and of a solvent; then ii) adjusting the pH of the mixture to between 6.5 and 7.5; then iii) slow stirring and adjustment of the temperature between 30 and 70 C; then iv) adding the protease to said mixture; finally v) adding a strong base while maintaining the temperature of the mixture between 10 and 30 C and the pH between 6.5 and 7.5.

  The solvent used in stage i) is advantageously water or a combination of water and organic solvent, especially a water-soluble solvent such as acetone, acetonitrile, dimethylformamide, tert-butyl alcohol. The maximum amount of organic solvent is advantageously 50% by weight, more preferably 10% by weight, still more preferably 5% by weight, relative to the total weight of the solvent mixture (organic solvent plus water).

  In step ii) the pH is advantageously adjusted to a value of 7 + 0.2.

  The temperature during stage i) or iv) is advantageously between 35 and 60 C. It is more advantageously 37 C + 1 C.

  The hydrolysis (step v)) is advantageously followed by addition of a strong base such as sodium hydroxide, at a rate of addition advantageously between 20 microliter / min and 3 ml / min. The addition rate is adjusted so that the pH of the mixture remains between 6.5 and 7.5, preferably between 6.8 and 7.2.

  The acid of formula (V) (about 50 mol%) and the ester of formula (IV) (about 50 mol%), which has the configuration required to achieve the desired product, are easily separated extractively or by any other means. another route of separation known to those skilled in the art.

  If necessary, the ester of formula (IV) recovered may be purified by short-path distillation or by any other purification method known to those skilled in the art.

  The acid of formula (V) can be recovered, for example after adjustment of the pH of the solution containing it to 3.5 0.2 and separation of the insoluble product formed by filtration, and racemized after formation of its ester by routes. conventional, well known to those skilled in the art. After racemization, the process according to the invention can again be used to isolate an ester of formula (IV).

  The reduction of the acid of formula (VI), during step c), is advantageously carried out using a catalyst, selected from the group consisting of nickel, platinum, palladium and rhodium, on a support such as coal.

  The ester III is advantageously obtained by chemical reduction of the alkyl indoyl-2-carboxylate of formula (VII) CO2CH 2 R 2 (VII) in which R 2 represents a hydrogen atom, a linear C 1 -C 6 alkyl or alkenyl radical, or branched, optionally substituted with a radical selected from the group consisting of C3-C6 cycloalkyl, C3-C6 heterocycloalkyl, aryl or heteroaryl. R 2 advantageously represents a hydrogen atom or a linear or branched C 1 -C 6 alkyl or alkenyl radical.

  The reduction can be carried out by any method known to those skilled in the art.

  According to an advantageous variant of the invention, the reduction is carried out by adding magnesium, advantageously magnesium in turn, suspended in methanol.

  The reaction is advantageously followed by gas chromatography which shows a transesterification to the methyl ester (IIIa) followed by the reduction reaction of the C2-C3 double bond, which is the subject of a part of the present invention. Thus, in this variant, the radical R1 in formulas (III) and (IV) advantageously represents a hydrogen atom.

  This reduction process is safer and less aggressive for the equipment used than a reduction process using the tin / hydrochloric acid pair. In addition, it is carried out at atmospheric pressure.

  The following example illustrates the invention, but does not limit it in any way.

  Example: synthesis of (2S, 3aS, 7aS) -perhydroindole-2-carboxylic acid and its esters: 1-Synthesis of the methyl and ethyl esters of (2R, S) 2,3-dihydroindolyl-2-acid Carboxylic acid (reduction):

H

  N Mg in turn CO2Et In a 5 liter reactor equipped with an effective stirrer are introduced: - 100 g of ethyl indolyl-2 carboxylate, - 200 ml of anhydrous toluene, - 200 ml of anhydrous methanol.

  The mixture is stirred and heated to 60 C (slight reflux) to obtain a solution. Then 25 g of magnesium in turn are added in ten times over a period of 6 hours. The hydrogen thus liberated reduces the ethyl indolyl-2 carboxylate to the 2,3-dihydro-2,3-indolyl-2-carboxylic acid derivative in the form of a majority methyl ester and a minor ethyl ester (transesterification). The evolution of the reaction is monitored by gas chromatography of the reaction mixture as a function of time.

  At the end of the reaction, which is verified by gas chromatography, the mixture is stirred at room temperature for about 18 hours, and then the reaction medium is hydrolysed with 300 ml of a sulfuric acid solution obtained. from 50 ml of concentrated sulfuric acid and 250 ml of water or a solution of citric or acetic acid.

  Methanol CO2Et + CO2Me The toluene phase is separated, the lower phase is washed with 200 ml of toluene and added to the organic phase.

  The solvent is evaporated in vacuo and the resulting residue is distilled on a short glass distillation apparatus with an area of 0.05 m 2. The distillation conditions are: temperature: 150 ° C., vacuum: 3.30 Pa (3 mbar), flow rate: 600 ml / h, weight obtained: 70 g of a straw-yellow oil.

  2 - enzymatic duplication with subtilisin (enzymatic hydrolysis):

H +

H

  alkalase ONa H 2H 2S 2SCO 2t CO2Me In a 500 ml flask heated to 37 ° C. and provided with magnetic stirring, 19.7 g of ((R, S) dihydro-2,3 are successively introduced: methyl indolyl-2 carboxylate + (R, S) dihydro-2,3-indolyl-2-ethyl carboxylate), 5 ml of acetone, 100 ml of water.

  When the mixture is homogeneous, the pH is adjusted to 7 with sodium hydroxide at a concentration of 2 mol / l (2N sodium hydroxide). 2 ml of an alkalase solution are then added, and the kinetics of the reaction are monitored using a pHstat, while maintaining the temperature at 37 C. The conditions of the selective hydrolysis are: - sodium hydroxide 2N, - pH set point = 7, - regulation range = 1, - mini flow rate = 20 microliters / min, max flow = 3 ml / min.

  The reaction is stopped when the slope of the graph (volume of sodium hydroxide as a function of time) shows a sharp break (20 ml of sodium hydroxide added).

  The reaction medium is made alkaline at pH = 9 with 2N sodium hydroxide.

  Acetone is evaporated under vacuum in the cold to avoid any risk of saponification of the residual ester. The residual medium is extracted with methylene chloride (2 x 100 ml). This medium is dried with magnesium sulfate and the solvent is evaporated under vacuum.

  8.1 g of a slightly colored oil is obtained which is (2S) 2,3-dihydroindolyl-2-carboxylic acid methyl ester. Molar yield: 83% If necessary, the enantiomer (S) recovered can be purified on a distillation apparatus with a short glass path, with a surface area of 0.05 m2, under the same distillation conditions as before ( cf 1).

  The aqueous phase is acidified with 2N hydrochloric acid to a pH in the region of 3.5, to which 2,3-dihydro-2,3-indolyl-2-carboxylic acid (2R) precipitates, which is recovered by filtration and it can be racemized in an alkaline medium, after formation of its methyl or ethyl ester by conventional routes.

  3 - (2S) 2,3-dihydro-2-indolyl carboxylic acid (saponification):

H H N

  CO2Me + CO2Et In a 250 ml reactor equipped with a magnetic stirring system: - 7.7 g of ((2S) 2,3-dihydroindolyl-2-carboxylate methyl + (2S) dihydro-2 Ethyl 3-indolyl-2-carboxylate), 40 ml of 2N sodium hydroxide, 32 ml of ethanol.

  Stirred at 20 ° C. for 18 hours. The ethanol is then evaporated under vacuum, and the pH is adjusted to 3.5 with 4N hydrochloric acid, which makes it possible to precipitate the expected acid.

  6.6 g of a white crystalline product are obtained which is (2S) 2,3-dihydro-2-indolyl carboxylic acid, characterized by the NMR and mass spectra, its rotatory power and the chromatographic profile of the product. amide formed with (S) - (-)? - methylbenzylamine. Molar yield: 92%

COOH

  4 - (2S, 3aS, 7aS) perhydroindole-2 carboxylic acid (catalytic hydrogenation):

H CO2H

  In a 250 ml autoclave, 2.9 g of (2S) 2,3-dihydro-indolyl-2-carboxylic acid previously dissolved in 32 ml of methanol are introduced, followed by 18 ml of water and 6 g of rhodium on charcoal. .

  The solution obtained is hydrogenated at 30 bar at 60 ° C. for 24 hours. After: filtration of the mixture obtained on Clarcel, evaporation of the solvents under vacuum, addition of 30 ml of dioxane and water, in order to obtain a clear solution at 90 ° C.

  The medium is allowed to cool, and the crystals obtained are collected by filtration; the weight obtained is 2.7 g (16.2 mmol). Molar yield: 90% Analysis of the product obtained: The product obtained was analyzed by nuclear magnetic resonance (1 H NMR and 13 C NMR).

  NMR 1H 400 MHz, D 2 O (δppm): 1.16-1.75 (8H, m, -CH 2 -), 1.88 (1H, m, -CH 2 CH-), 2.15-2.28 (2, m, -CH2-CaH-), 3.58 (1H, ddd, 3J = 1.75 Hz, 3J = 6.5 Hz, 3J = 12 Hz, -NH-CH-), 3.99 (1H, dd , 3J = 6.75 Hz, 3J = 9.5 Hz, -C H-) 13C NMR 100 MHz, D20 (Sppm): 22.5 and 23.0 (2C, 2s, -CH2-CH2-), 26 , 0 and 26.7 (2C, 2s, -CH-CH2-), 33.9 (1C, s, -CH2-38.5 (1C, s, -CH2-CaH-), 60, 9 and 61, 3 (2C, 2s, CH 2 CH 2), 177.1 (1C, s, -COOH).

  The product obtained by mass spectrometry (Electron Impact at 70eV (6750kJ)) was also analyzed.

  m / z calculated 169 (C9H15NO2); m / z (%): 124 (MW-COOH, 100), 170 (MW, 4). Finally, the enantiomeric purity of (2s) 2,3-dihydro-2-indolyl carboxylic acid was determined. rotary: (concentration 10 mg / ml water) [a] D25 = -45.9 2) Synthesis of a diastereoisomeric amide with Rl-phenylethylamine: Principle: The goal is to be able to measure the enantiomeric purity of indoline acid after enzymatic resolution.

  The principle of this assay is therefore to form diastereomers so that they can then be separated easily on a HPLC column (High Performance Liquid Chromatography).

  The preparation of the sample will therefore consist in the derivation of (2S) 2,3-dihydro-2-indolyl carboxylic acid with R-1-phenylethylamine to form the amide R, R optionally present and the amide R, S which will then be analyzed in HPLC. Preparation of the sample: In a 50 ml flask, about: - 20 mg of R-1-phenylethylamine - 10 ml of CH2C12 mg of the analyte acid mg HOBT (1-hydroxybenzotriazole) mg DCC (dicyclohexylcarbodiimide) This mixture is stirred for 2 hours, filtered on a syringe with a PTFE (poly-tetrafluoroethylene) filter, the solvent is evaporated off, 10 ml of methanol are added and then 10 l of this mixture is injected into HPLC.

  HPLC conditions Appliance used: diode array detector Column: apolar stationary phase (C18) Eluent: acidic H2O / MeOH: 50/50; Flow rate: 1 ml / min; Detection: 238 nm Results: The chromatographic profile of the amide of 2 (S) -dihydro-2,3-indolyl-2-carboxylic acid (amide R, S) is given in FIG.

  Figure 1: Diastereoisomeric purity of the amide of 2 (S) -dihydro-2,3-indolyl-2 carboxylic acid, obtained by enzymatic resolution, with R1 phenyl ethylamine. Purity> 99%.

  The peak observed at 28.057 minutes corresponds to the amide of 2 (S) -dihydro-2,3-indolyl-2-carboxylic acid.

  The chromatographic profile of the amide of 2 (R) -dihydro-2,3-indolyl-2-carboxylic acid (amide R, R) is given in FIG.

  Figure 2: Diastereoisomeric purity of the amide of 2 (R) -dihydro-2,3-indolyl-2 carboxylic acid, obtained by enzymatic resolution, with R1 phenyl ethylamine. The peak observed at 25.376 minutes corresponds to the amide of 2 (R) -dihydro-2,3-indolyl-2-carboxylic acid.

  Conclusion: (2S) 2,3-dihydro-2-indolyl carboxylic acid is therefore obtained with an enantiomeric purity greater than 99%.

  5 - esters of (2S, 3aS, 7aS) perhydroindole-2 carboxylic acid:

H

H CO2 R

  The (2S, 3aS, 7aS) perhydroindole-2 carboxylic acid can then be esterified by conventional methods. For example, the (2S, 3aS, 7aS) perhydroindole-2 carboxylic acid can be esterified to the desired alcohol (R-OH) ester by using dicyclohexyl carbodiimide as coupling agent in the presence of DMAP, which accelerates the reaction.

Claims (8)

claims   Process for the synthesis of the compounds of formula (I) or (II): ## STR2 ## in which R represents a hydrogen atom or a linear or branched C 1 -C 6 alkyl group, as well as their salts; addition to a mineral or organic acid or base, comprising the following successive steps: a) resolution by enzymatic hydrolysis, in the presence of a protease, of an ester of formula (III) (III) in which R1 represents a hydrogen atom, a linear or branched C1-C6 alkyl or alkenyl radical, optionally substituted by a radical chosen from the group consisting of C3-C6 cycloalkyl, C3-C6 heterocycloalkyl, aryl or heteroaryl radicals, to isolate on the one hand an ester of formula (IV) H N   CO2CH2R1 (IV) in which R1 has the same meaning as for formula (III), and on the other hand an acid of formula (V) CO2H (V) b) saponification or hydrolysis of ester IV obtained following the step a) acid of formula (VI); H   N (R, S) CO2CH2R1 CO2H c) reduction of the acid VI obtained following step b) by catalytic hydrogenation to form the compound of formula (I) CO2H (I) d) if necessary, isolation of the acid I; e) if appropriate, esterification of the acid (I) obtained following step c) to obtain the compound of formula (II) CO2CH2R NOT H H (II)   in which R represents a hydrogen atom, a linear or branched C1-C6 alkyl or alkenyl radical, optionally substituted by a radical chosen from the group consisting of C3-C6 cycloalkyl, C3-C6 heterocycloalkyl, aryl or heteroaryl; f) possible isolation of the ester II.   2. Process according to claim 1, characterized in that the enzymatic resolution step a) comprises the following successive stages: i) homogeneous mixture, at a temperature of between 10 and 30 ° C., of the ester II and of a solvent; then ii) adjusting the pH of the mixture to between 6.5 and 7.5; then iii) slow stirring and adjustment of the temperature between 30 and 70 C; then iv) adding the protease to said mixture; finally v) adding a strong base while maintaining the temperature of the mixture between 10 and 30 C and the pH between 6.5 and 7.5.   3. Method according to any of the preceding claims, characterized in that the protease used in step a) is selected from the group consisting of alkalase, chymotrypsin and papain.   4. Method according to claim 3, characterized in that the protease used in step a) is the alkalase.   5. Method according to any one of the preceding claims, characterized in that the reduction of the acid, during step c), is carried out using a catalyst selected from the group consisting of nickel, platinum, palladium and rhodium, on a support such as charcoal.   6. Process according to any one of the preceding claims, characterized in that the ester III is obtained by chemical reduction of the alkyl indoyl-2-carboxylate of formula (VII) CO2CH2R2 (VII) in which R2 represents an atom of hydrogen, a linear or branched C1-C6 alkyl or alkenyl radical, optionally substituted with a radical selected from the group consisting of C3-C8 cycloalkyl radicals, C3-C8 heterocycloalkyl radicals, C6-C11 aryl radicals or heteroaryl radicals; C5-C11.   7. Process according to any one of the preceding claims, characterized in that R1 represents a hydrogen atom.   8. Process according to claim 7, characterized in that the reduction is carried out by adding magnesium, advantageously magnesium in turn, suspended in methanol.