Process for the recovery of S -(+)-methyl- (2-chlorophenyl)- (6,7-dihydro- 4H-thieno [3,2-c] pyrid-5-yl) acetate hydrogen sulfate (clopidogrel bisulfate) from its (R) and mixture of (R) and (S)- isomers

A process for the recovery of compound of formula (I) where X represents hydrogen, fluoro, chloro, bromo or iodo atom, preferably 2-chloro which comprising the steps of f. preparing compound (-) or (±)-(2-chloro phenyl)-(6,7-dihydro-4H-thieno[3,2-c]pyrid-5-yl)acetate methyl ester hydrogen sulfate from its corresponding camphorsulfonic acid salt compound. g. transforming the obtained compound of step (a), into the compound of (2-chlorophenyl)-(6,7-dihydro-4H-thieno[3,2-c]pyrid-5-yl)acetic acid. h. converting the compound of step (b) into racemic compound (±)-(2-chloro phenyl)-(6,7-dihydro-4H-thieno[3,2-c]pyrid-5-yl)acetate methyl ester hydrogen sulfate. i. resolving the obtained racemic compound of step (c), into the optically active (+)-(2-chloro phenyl)-(6,7-dihydro-4H-thieno[3,2-c]pyrid-5-yl)acetate methyl ester camphor sulfonic acid salt. j. further transforming the optically active (+) form compound of step (d) into their pharmaceutically acceptable salts.