A Convenient Method for Synthesis of Optically Active Methylphenidate from N-Methoxycarbonylpiperidine by Utilizing Electrochemical Oxidation and Evans Aldol-type Reaction

A new method to prepare optically active methylphenidate starting from piperidine is described. The method consists of a transformation of N-methoxycarbonylated piperidine to the corresponding α-methoxylated carbamate utilizing electrochemical oxidation followed by the coupling reaction with optically active Evans imides to produce optically active methylphenidate derivatives with high stereoselectivity (erythro/threo=5.3/94.7, the threo isomer; 99.6%ee).