Concise and facile synthesis of (R,R)-dexmethylphenidate hydrochloride and its three stereoisomers

A new and concise route is reported for the first time for the preparation of four stereoisomers of dexmethylphenidate hydrochloride starting from a single reactant, 2-benzyolpyridine, through an eight-step reaction process, which includes hydrogenation, protection, oxidation, chiral separation, Wittig reaction, hydroboration, pyridinium dichromate oxidation, and methyl esterification. The absolute configuration of the two chiral centers of each stereoisomer was confirmed by X-ray and chiral HPLC analyses.