A method of preparing the enantiomers of o-demethyltramadol

摘要

Preparation of the enantiomers of O-demethyltramadol (II) comprises: (a) converting racemic tramadol (I) salt to its base form; (b) separating the (-)-(I)-enantiomer by precipitation using L-(+)-tartaric acid; (d) reaction of the (-)-(I)-enantiomer with diisobutyl aluminium hydride (DIBAL) to give (-)-(II); (e) separation of the (+)-(I)-enantiomer as a free base from the mother liquor obtained in step (b); and (f) reaction of the (+)-(I) enantiomer with DIBAL to give (+)-(II).