METHOD OF SYNTHESIS OF ENANTIOMERS OF O-DEMETHYL-TRAMADOL Russian patent published in 2002 - IPC

FIELD: organic chemistry, chemical technology, pharmacy. SUBSTANCE: invention relates to the improved method of synthesis of enantiomers of O-demethyltramadol showing strong analgetic effect being without the known adverse effects in contrast to opioid analgetics. Racemic salt of tramadol is converted to a base using L-(+)-tartaric acid in medium of a suitable solvent, (-)-enantiomer of tramadol is separated and after release of tramadol base converted to (-)-enentiomer of O-demethyltramadol by interaction with diisobutylaluminium hydride. (+)-Enantiomer of O-demethyltramadol is obtained from mother liquor precipitate using tartaric acid by release of tramadol base and interaction with diisobutylaluminium hydride. Racemic tramadol hydrochloride is used as a parent racemic salt mainly. L-(+)-tartaric acid is used mainly in the presence of an organic solvent, for example, aliphatic C_1-5--alcohol. Usually, (-)-enantiomer of tramadol is separated by crystallization. Before carrying out the interaction with diisobutylaluminium hydride it is possible to convert the corresponding enantiomer of tramadol base to salt distinct from tartrate, for example, to hydrochloride and a base is released from the latter. EFFECT: improved method of preparing. 6 cl, 1 tbl, 3 ex