An Oxidation and Ring Contraction Approach to the Synthesis of (±)-1-Deoxynojirimycin and (±)-1-Deoxyaltronojirimycin

A reaction sequence involving the chemoselective olefinic oxidation of N(1)-benzyl-2,7-dihydro-1H-azepine with m-CPBA in the presence of HBF4 and BnOH followed by ring contraction facilitates the stereoselective preparation of either of the epoxide diastereoisomers of (2RS,3SR)-N(1)-benzyl-2-chloromethyl-3-benzyloxy-4,5-epoxypiperidine by simple modification of the reaction conditions. Epoxide ring opening, functional group interconversion, and deprotection allow the synthesis of (±)-1-deoxynojirimycin and (±)-1-deoxyaltronojirimycin.