A PROCESS FOR THE PREPARATION OF S-(+)-2-(3-BENZOYLPHENYL)PROPIONIC ACID BY ENZYME-CATALYSED ENANTIOSELECTIVE HYDROLYSIS

Abstract: A process for the preparation of optically active S-(+)-2-(3-benzoylphenyl)propionic acid (I), by resolution of the racemate through enantioselective hydrolysis of a reactive ester (II) in an organic medium, which hydrolysis is catalysed by an extracellular lipase of microbial origin. The separation of the resulting free acid from the remaining ester is carried out by extraction in basic medium, to leave the S-ester in the organic phase and the R-acid in the aqueous one. Finally, the desired S isomer is obtained either by aqueous hydrolysis of the remaining reactive S-ester, at constant pH, or enzymatically.

Description: A PROCESS FOR THE PREPARATION OF S-(+)-2-(3-BENZOYL- PHENYL)PROPIONIC ACID BY ENZYME-CATALYSED ENANTIOSELEC- TIVE HYDROLYSIS. FIELD OF THE INVENTION The present invention relates to a process for the preparation of optically active S-(+)-2-(3-benzoyl- phenyl)propionic acid (I) , by resolution of the race- 5 mate through enantioselective hydrolysis of a reactive ester (II) in an organic medium, which hydrolysis is catalysed by an extracellular lipase of microbial ori¬ gin. The separation of the resulting free acid from the remaining ester is carried out by extraction in basic 10 medium, to leave the S-ester in the organic phase and the R-acid in the aqueous one. Finally, the desired S isomer is obtained either by aqueous hydrolysis of the remaining reactive S-ester, at constant pH, or enzyma- tically. 15 TECHNOLOGICAL BACKGROUND A number of antiinflammatory agents of the family of the aryl or alkylarylpropionic acids (i.e. naproxen, ibuprofen, flurbiprofen, etc.) are known, having a chi- ral center in the o carbon and therefore existing in 20 two optically different forms. The higher activity of the S enantiomer compared with that of the R one is f' also known [Muller N. et al. , Fundam. Clin. Pharmacol. ! 4, 617 (1990)]. This is also the case of ketoprofen (S- (+)-2-( 3-benzoylphenyl)propionic acid) , the physiologi 25 cal activity of which mainly resides in the S enantio mer [Yamaguchi T. et al. , Folia Pharmacol. Japon. 90, 295 (1987)]. The achievement of the chiral S-(+) -2-(3-benzoyl- phenyl)propionic acid (I) was approached both by enan- tioselective synthesis [Fadel A., Synlett. 1, 48 (1992), FR 2,659,968 (21.3.1991)] and by resolution of the racemate, and particularly remarkable is the reso¬ lution by diastereomeric crystallization of a (-)-l- phenylpropylamine salt, whereby the S-(+) isomer is ob¬ tained in a 22% yield after two recrystallizations and in an optical purity higher than 99% [Nohira H. et al. EP 423,467] . Among the enzymatic methods for the optical resolution, only the stereoselective hydrolysis in aqueous medium has been applied to the racemic 2-(3- benzoylphenyDpropionic acid. Sih et al. [Sih C.L. et al. , EP 227,078] describe the resolution of this com¬ pound by hydrolysis of the methyl ester thereof, ca¬ talysed by a purified form of the lipase from Candida cylindracea, with optical purity values higher than 95% and in a 78% yield. In spite of these results, the pro- cedure seems to be poorly economically convenient due to the need to modify-purify the enzyme . On the other hand, Cerbelaud D. et al. [EP 330529 and EP 2626288] describe the resolution by enantioselective hydrolysis of the nitrile and the corresponding amide catalysed by microorganisms such as Corynebacterium 1-774 or Brevi- bacterium R-312, to obtain the acid in an 88% yield and with an optical purity higher than 95%, even though it should be noted the disadvantage that these reactions are carried out at a high dilution (0.05 M) . The enantioselective hydrolysis carried out in an apolar organic solvent saturated with water was never applied to the optical resolution of ketoprofen or other antiinflammatory agents of this family, even though such a procedure showed remarkable advantages in the separation of the enantiomers of some chiral li- pophilic alcohol acetates [Akita H. , et al., Chem. Pharm. Bull. 37, 2876 (1989)], due to the high enantio- selectivity of the enzyme in this reaction medium, the higher solubility of the substrate, which allows working at high concentrations and an easy separation of the reaction product, a free acid, from the remai¬ ning ester by simple alkali extraction. DISCLOSURE OF THE INVENTION ' The present invention relates to a process for the preparation of optically active S-(+)-2-(3-benzoyl- phenyl)propionic acid (I), I by resolution of the racemate through enantioselectiv hydrolysis in organic medium of a reactive ester (II), π which hydrolysis is catalysed by an extracellular li pase of microbial origin. The separation of the resul ting free acid from the remaining ester is carried ou by extraction in basic medium, leaving the S-ester i the organic phase and the R-acid in the aqueous one. Finally, the desired S isomer is obtained either by aqueous hydrolysis of the remaining reactive S-ester, at constant pH, or enzymatically. In formula (II), R is a C,-C, 0 straight, branched or cyclic alkyl group, substituted by one or more elec¬ tron-withdrawing groups, such as halogen, nitro, cyano, -OR 2 , -SR2, -COR2 [wherein R2 can be C,-Cg alkyl or cy- cloalkyl], NR 3 R 4 [wherein R 3 and R 4 can be H, C 1 -C 8 straight, branched or cyclic alkyl or they can be part of a C 4 -C fi cycle together with the nitrogen and optio¬ nally with another heteroatom]. The electron- withdrawing group can be at the -- or β- positions of the R " group, thus the ester being referred to as "reactive" due to the faster hydrolysis rate observed for these derivatives. Some specific examples of R groups are 2-chloroethyl, 2,2,2,-trichloroethyl, 2- fluoroethyl, 2,2,2-trifluoroethyl, cyanomethyl, 2-ni- tropropyl, 2-aminoethyl and N,N-dimethyl-2-aminoethyl. The process consists in subjecting the substrate (II) to the action of an extracellular carboxylesterase (which enzymes are also named "upases") of microbial origin, in an organic medium saturated with water, as described in the scheme below. The reaction is carried out in a mixture of tw organic solvents, a main water-immiscible one (fo example a straight or branched aliphatic ether, or a aliphatic or aromatic hydrocarbon, either halogenate or not) and the other, in a 5 to 25% v/v proportion which is totally or partially water-miscible, such a an alcohol, a ketone or a straight or branched alipha tic nitrile or a cyclic ether, typically 1,4-dioxane o tetrahydrofuran, which allows to solubilize some wate in the mixture, no more than 5% (v/v). ,Among the carboxylesterases capable to catalys this type of reactions, those derived from microorga nisms of the genus Candida, Rhizopus, Mucor, Aspergil lus, Penicillium and Pseudomonas showed a special acti vity, particularly the lipase from Mucor meihei commer cialized by Amano Pharm. CO. Ltd. (Nagoya, JP) unde the commercial name Amano MAP-10. In all cases, a pre ference for the R enantiomer was observed, as the (-)-2-(3-benzoylphenyl)propionic acid (III) i obtained, whereas the optical antipode thereof, the isomer, remains in the ester form (IV). The concentration of the starting ester (II) c be from 0.1 to 1 M, preferably 0.2-0.3 M. The worki temperature is from 0 to 60°C, but preferably the rea tion is carried out at 20-30°C. The reaction time ra ges from 2 to 15 days, preferably 6 days. In some c ses, the reaction will be carried out until conversio higher than 50%, since, according to the general theo of the irreversible enzyme reactions, [C.S. Chen, A gew. Chem. Int. Ed. Engl., 28, 695 (1989)], and sin the interesting compound (S isomer) is the remaini substrate, the optical purity thereof can be optimized only reaching or excessing a 50% conversion. Once the reaction is over, an alkali is added to allow the separation of the resulting acid (III) from the ester (IV), either by extraction of the latter with a water-immiscible organic solvent (for example ethyl acetate, dichloromethane , diethyl ether or toluene), or by centrifugation or filtration of the resulting su¬ spension, to obtain the remaining S-ester (IV), whereas the acidification of the aqueous phase and the subse¬ quent extraction with an organic solvent give the R- acid (III). The ester (IV) is hydrolysed to S-(+)-2-(3- benzoylphenyl)propionic acid (I) in aqueous media, at controlled pH from 7 to 12, preferably pH 9-10; in this step one of the above mentioned partially water-misci- ble co-solvents can be added, or a lipase, an esterase or any other hydrolase at their pH optimum can also be used as the catalysts, generally at about neutrality. When the hydrolysis is over, the acid (I) is obtained either by acidification and extraction with a water-im¬ miscible organic solvent as mentioned above, or by centrifugation or filtration of the resulting suspension. The following example further illustrates the in- vention. Example la: Synthesis of the 2-(3-benzoylphenyl)propio- nic acid chloride (V) In a 500 ml three-necked flask, 50 g (0.197 mole) of 2-(3-benzoylphenyl)propionic acid are dissolved in 200 ml of dry CC1 4 . Subsequently, 50 ml (81.87 g, 0.688 mole) of thionyl chloride dissolved in 100 ml of the same solvent are slowly added. The mixture if refluxed for 5 hours. Solvent is evaporated off under vacuum, 50 ml of CC1. are added and the mixture is left to evapo¬ rate, repeating the procedure to remove thionyl chlo- ride. 53.2 g of an oily liquid are obtained which is directly used in the subsequent reaction step. Example lb: Synthesis of (±)-2-(3-benzoylphenyl)propio- nic acid trifluoroethyl ester (II, R = -CH CF.. ) In a 1000 ml three-necked flask, 30.19 ml (21.92 g, 0.217 mole) of triethylamine and 15.60 ml (21.67 g, 0.217 mole) of 2,2,2-trifluoroethanol are dissolved in 200 ml of dry dichloromethane. The mixture is stirred on an ice-bath for some minutes and a solution of 53.72 g (0.197 mole) of the acid chloride (V) dissolved in 500 ml of dry dichloromethane is added, keeping tempe¬ rature below 10°C. The mixture is left under stirring at room temperature for .12 to 24 hours. The crude reac¬ tion product is evaporated under reduced pressure. The residue is extracted with 0.1 N NaOH (3x200 ml) and ethyl ether (3x100 ml). The organic phase is washed with 0.1N NaOH (2x50 ml) and dried over sodium sulfate. After that, solvent is removed under vacuum to obtain 66.3 g (97,5% overall yield) of the title ester. 1H N.M.R. (300 MHz, CDC1 3 ): 7.4-7.9 (m, 9H; Ph-H) ; 4.35 (m, 2H; CH 2 CF 3 ) ; 3.88 (dd J=3.7, 1H; CHCOO) ; 1.56 (d J=3, 3H; CH 3 ) . Example lc: Reaction of enantioselective hydrolysis of the ester (II) (R = -CH^F.) catalysed by the lipase from Mucor meihei, Amano M-AP-10 150 g (0.446 mole) of the ester (II) (R 1 -CH-CF-,) are dissolved in 1700 ml of a mixture of dii sopropyl ether/1,4-dioxane/H,,0 (80/20/2.25). Subsequen- tly 223 g of lipase of Mucor meihei (Amano MAP-10 ) are added thereto, to obtain a suspension which is kept un¬ der strong stirring for 6 days at 27°C. The final mix- ture is filtered, washing the residue with diethyl ether, extracted with 0.1 N NaOH (3 x 200 ml), dried and the solvent is evaporated off under vacuum to ob¬ tain 75.2 g (100% yield) of the trifluoroethyl ester (IV) (R 1 = -CH 2 CF 3 ) of S configuration, in a 98% opti- cal purity. The basic aqueous phase is acidified with 0.5 N HC1 to pH 1 and extracted with diethyl ether (3 x 100 ml), dried and the solvent is evaporated under va¬ cuum to obtain 59.4 g of the acid (III) of R-(-) confi¬ guration, in an 80% optical purity. Trifluoroethyl ester (IV) (R 1 = -CH 2 CF 3 ) : 1H N.M.R. (300 MHz, CDC1..): 7.4-7.9 (m, 9H; Ph-H) ; 4.35 (m, 2H; CH 2 CF 3 ) ; 3.88 (dd J=3.7, 1H; CHCOO) ; 1.56 (d J=3, 3H; CH3) ; optical pu¬ rity = 98%. Acid (III): IR (CHCl 3 ) 3000-3400, 1730, 1650, 1600, 1460, 1410, 1290, 1200, 1150, 1075 cm-1; [0fl 23 D = " 44.46° (c 0.98, CHC1 3 ); optical purity = 80%. The optical purity of the chiral compounds cited in this and in other embodiments was determined by high performance liquid chromatography (HPLC) by means of a Chiralcel OJ column manufactured by Daicel Chem Ind, Ltd. and a n-hexane/i-propanol/AcOH (80/19.5/0.5) mo¬ bile phase. Example Id: Hydrolysis of the trifluoroethyl ester (IV) (R 1 = -CH 2 CF 3 ) 30 g of trifluoroethyl ester (IV) (R = -CH 2 CF 3 , optical purity = 98%,) are dissolved in 2550 ml of a mixture of water and tetrahydrofuran (50% v/v). The mixture is adjusted to pH 9.5 and maintained to this pH for 4 days, by addition of 0.1 N NaOH with a pH-Stat. The volume of the suspension is reduced to 1/5 by eva- poration under vacuum, pH is adjusted to 12 by addition of 1 N NaOH and the mixture is extracted with diethyl ether (5 x 100 ml). The aqueous phase is acidified to pH 1 by addition of 1 N HCl, then is extracted with ethyl ether (3 x 10 ml) and dried. After evaporating the solvent under vacuum, 20.4 g (90% yield) of the acid (I) of 93.5% optical purity are obtained. 1H N.M.R. (CDC1 3 , 300 MHz) 7.35-7.80 (m, 9H; pH-H) ; 3.77 (q J=4, 1H; CHCOOH) ; 1.50 (d J=4, 3H; CH 3 ); IR (CHC1 3 ) 3000-3400, 1730, 1650, 1600, 1460, 1410, 1290, 1200, 1150, 1075 cm-1; M.p. = 87-92°C; [C{] 23 ' = + 51.96° (c 1.0, CHC1 3 ) ; optical purity = 93.5%. Alternatively, the hydrolysis is carried out by the action of an enzyme in an aqueous medium. For this purpose, 168 mg (0.5 mmole) of trifluoroethyl ester (IV) (R 1 = -CH 2 CF 3 ) are dissolved in 5 ml of a buffer solution at pH 7.2 and 100 mg of lipase from Mucor meihei (Lipozyme 10000 ) are added. The mixture is kept for 6 hours at room temperature. pH is adjusted to 1 b addition of 1 N HCl, the mixture is extracted wit ethyl ether (3 x 5 ml) , dried and the crude product is analysed by chiral HPLC, showing to contain the aci (I) , in an 87% optical purity.

Claims: CLAIMS 1. A process for the preparation of S-(+)-2-(3-ben- zoylphenyl)propionic acid, according to formula (I), I which process comprises the following steps: a) stereoselective hydrolysis in an organic medium, ca¬ talysed by a carboxylesterase enzyme of microbial ori¬ gin, of the R enantiomer of a racemic reactive ester of formula (II) π wherein R is a C,-C, Q straight, branched or cyclic alkyl group which is substituted at the of or β posi¬ tions by one or more electron-withdrawing groups, sai hydrolysis being carried out in a mixture of two orga¬ nic solvents, a main water-immiscible one, and anothe (in a 5 to 25% v/v proportion) which is totally or par tially water-miscible, which solvent allows to dissolv a certain amount of water, no more than 5% (v/v), th concentration of the starting ester (II) being from 0. to 1 M, at a temperature from 0 to 60°C for a time fro 2 to 15 days; b) separation of the remaining ester (IV) , of configuration by extraction in alkaline medium with water-immiscible organic solvent, or centrifugation o filtration of the resulting suspension; c) hydrolysis of the ester (IV) to S-(+)-2-(3-benzoyl phenyl)propionic acid (I) in aqueous medium, at pH fro 7 to 12, in an aqueous pure medium or in the presenc of a partially water-miscible co-solvent; or hydrolysi by means of a lipase, an esterase or any other hydro lase as catalysts, at the pH optimum thereof. 2. A process according to claim 1, in which the elec tron-withdrawing group present in R is halogen, nitro 2 2 2 2 cyano, -OR , -SR , -COR [wherein R can be C.-C 6 alky or cycloalkyl], NR 3R4 [wherein R3 and R4 can be H, C, Cg straight, branched or cyclic alkyl, or they can b part of a C.-C 8 ring, together with the nitrogen an optionally another heteroatom] . 3. A process according to any one of claims 1 or 2 in which the substrate (II) is a reactive ester with R -CH 2 CF 3 , -CH 2 CH 2 F, -CH^Cl, -CH 2 CC1 3 , -CH 2 C -CH(CH 3 )N0 2 , -CH 2 CH 2 H 2 and -CH 2 CH 2 N(CH 3 ) 2 . 4. A process according to any one of the abov claims, in which the R group is -CH-CF, . 5. A process according to any one of the abov claims, in which the enzyme used is the lipase from Mu cor meihei. 6. A process according to any one of the abov claims, in the which the main water-immmiscible reac tion solvent is a straight or branched aliphatic ether or an aliphatic or aromatic hydrocarbon which can b halogenated or not. 7. A process according to any one of the abov claims, in which the main water-immmiscible reaction solvent is diisopropyl ether. 8. A process according to any one of the above claims, in which the minor reaction solvent is a strai- ght or branched aliphatic alcohol, ketone or nitrile or a cyclic ether. 9. A process according to any one of the above claims, in which the minor reaction solvent is 1,4- dioxane. 10. A process according to any one of the above claims, in which the concentration of the starting ester (II) is 0.2-0.3 M. 11. A process according to any one of the above claims, in the which the reaction time is 5-7 days. 12. A process according to any one of the above claims, in which the remaining ester (IV) of S configu¬ ration is separated from the acid formed in the reac¬ tion by partition between a 0.1 N NaOH aqueous phase and an organic one of diethyl ether. 13. A process according to any one of the above claims, in which the remaining ester (IV), of S confi¬ guration, is hydrolysed to S(+)-2-(3-benzoyl- phenyl)propionic acid (I) in aqueous medium, at pH from 9.0 to 10. 14. A process according to any one of the above claims, in which the hydrolysis of the remaining ester (IV) is carried out in aqueous medium, at pH 9-10, with a partially water-miscible co-solvent in a 10 to 60% (v/v) proportion. 15. A process according to any one of the above claims, in which the co-solvent is tetrahydrofuran in a % (v/v) proportion.

Inventors: CARGANICO GERMANO, MAULEON CASELLAS DAVID, PALOMER BENET ALBERT, CARGANICO, GERMANO, MAULEON CASELLAS, DAVID, PALOMER BENET, ALBERT
Applicants: CARGANICO GERMANO, MAULEON CASELLAS DAVID, MENARINI LAB, PALOMER BENET ALBERT, LABORATORIOS MENARINI S.A.
Application year: 1993
Main classification: C12P41
IPC codes: C12P7, C12P41