| abstract |
An improved process for the manufacture of Clopidogrel starting from 2-(2-thienyl)ethylamine, which eliminates the isolation of an unstable intermediate like 2-(2-thienyl)ethyl formimine by subjecting it to a one pot cyclization to get 4,5,6,7-tetrahydrothieno (3,2-c) pyridine of Formula II and further reacting with halo-compound of formula III (where X is Cl or Br) at 20 to 90° C. temperature characterized in a solvent like water and/or dichloroethane in presence of organic or inorganic bases is disclosed herein. This inventions also discloses Crystalline Form I of (+)-(S)-clopidogrel hydrogen sulphate and its preparation thereof. |