PROCESS TO PREPARE HIGHLY PURE (S)-PREGABALIN

摘要

A process for the preparation of (S)-pregabalin of formula I containing cyanide ion content less than 5 ppm or free from the cyanide ion,by extracting its cyano diester intermediate of formula III, wherein R 1 and R 2 are the same or different and are hydrogen, C 1 -C 6 alkyl, aryl, benzyl, substituted benzyl, or C 3 -C 6 cycloalkyl. with an aqueous solution containing a cyanide quenching agent to remove free cyanide ion from the reaction mixture.