ENANTIOSPECIFIC PROCESS FOR THE PREPARATION OF PAROXETINE INTERMEDIATE

摘要

A novel, improved, and enantiospecific process for the preparation of (-)-trans-4-(4-fluorophenyl)-3-hydroxymethyl-1-methylpiperidine of formula-(I), an advanced intermediate in the manufacture of antidepressant drug paroxetine is disclosed in the present invention. Compound of formula-(XXII) is prepared by resolution of compound of formula-(XX) using a chiral acid followed by hydrogenation of the resolved amine. Michael addition of the compound of formula-(XXII) onto acrylate esters gave the compounds of formula-(XXIII). Conversion of the hydroxy group present in compound of formula-(XXIII) into a leaving group followed by treatment with a strong base gave the enantiospecific intramolecularly cyclized piperidine derivative of formula-(XXV). Reduction of the ester group present in compound of formula-(XXV) with a metal hydride reducing agent gave the compound of formula-I with more than 97% chiral purity. Further purification of compound of formula-I to >99.5% is achieved by one recrystallization from a number of solvents. Present process is easily adaptable for commercial preparation of (-)-trans-4-(4-fluorophenyl)-3-hydroxymethyl-1-methylpiperidine of formula-(I).