PROCESS FOR THE PREPARATION OF D-THREO-(R,R)-METHYLPHENIDATEAND RECYCLING OF UNDESIRED ENANTIOMERS BY EPIMERISATION

摘要

A process for obtaining a single enantiomer, d or l, of threo-methylphenidat e, comprises resolution of a mixture of the enantiomers; racemisation of the unwanted enantiomer, to give a mixture of all four stereoisomers; and separation of the erythro stereoisomers, to leave the said mixture of enantiomers for resolution.