Patent ID: 8207352
Filing Date: 2012-06-26
Classification: C07D

Abstract:
1. A process for the preparation of enantiomerically pure compound of general forumla (I), having the 2R, 3R configuration, wherein R which comprises a) a resolution step of the racemic compound of formula (I), having the 2R/S, 3R/S configuration, by adding a chiral acid, crystallizing the mixture, collecting the desired diastereomeric salt of formula (I) either from the precipitate or from mother liquid and then converting the salt of formula (I) into an enantiomerically pure from of the compound of formula (I) by treatment with an appropriate organic or inorganic base or using an ion-exchange resin; b) a resolution step of the racemic compound of formula (II), having the 2R/S, 3R/S configuration, wherein R by adding a chiral acid, crystallizing the mixture, collecting the desired diastereomeric salt of formula (II), having the 2R,3R configuration, either from the precipitate or from mother liquid and then converting the salt of formula (II) into an enantiomerically pure form of the compound of formula (II) by treatment with an organic or inorganic base or an ion-exchange resin, or alternatively using the salt of formula (II) directly, and after removal of the nitrogen protective groups R c) a resolution step of the racemic compound of formula (III), having the 2S/R, 3R/S configuration, wherein R by adding a chiral acid, crystallizing the mixture, collecting the desired diastereomeric salt of formula (III), having the 2S,3R configuration, either from the precipitate or from mother liquid and then converting the salt of formula (III) into an enantiomerically pure form of the compound (III) by treatment with an organic or inorganic base or an ion-exchange resin, or using the enantiomerically pure form of the salt of formula (III) directly, and reacting with hydrogen sulfide followed by reaction of the resulting enantiomerically pure form of the compound of formula (II) with 2-chloro-4′-cyanoacetophenone.