| abstract |
Racemization of the R(-) isomer of the (2-chlorophenyl) -6, 7-dihydrothieno [3, 2-c]pyridine- 5 (4H) -acetic acid methyl ester (Formula II) (also called R clopidogrel) is performed via conversion of a portion thereof to the S (+) isomer and it takes place in an organic solvent selected from alcohols , esters, ketones or ethers, or in their mixtures, in the presence of a base selected from substances of formula R1R2R3R4N+OH' wherein R1, R2, R3 and R4 are identical or different substituents selected from C1-C5 alkyls or C5, C6 cycloalkyls or aryls, C7-C9 alkyl-cycloalkyls or alkyl-aryls, the molar ratio of the base to the starting substance being 1: 1 to 1: 10. ,OMe Cl I Cl <VOMe II |