Syntheses of the Enantiomers of 1-Deoxynojirimycin and 1-Deoxyaltronojirimycin via Chemo- and Diastereoselective Olefinic Oxidation of Unsaturated Amines

Oxidation of enantiomerically pure (R)-N(1)-1′-(1′′-naphthyl)ethyl-2,7-dihydro-1H-azepine with m-CPBA in the presence of HBF4 and BnOH gave (3S,4R,5S,6S,1′R)-N(1)-1′-(1′′-naphthyl)ethyl-3-hydroxy-4-benzyloxy-5,6-epoxyazepane as the major product and as a single diastereoisomer after chromatography. Elaboration of this highly functionalized intermediate via ring contraction to (2S,3R,4S,5S,1′R)-N(1)-benzyl-2-chloromethyl-3-benzyloxy-4,5-epoxypiperidine followed by regioselective epoxide ring opening, functional group manipulation, and deprotection gave (+)-1-deoxyaltronojirimycin. Alternatively, resolution of (RS,RS)-N(1)-benzyl-3-hydroxy-4-benzyloxy-2,3,4,7-tetrahydro-1H-azepine or (3RS,4SR,5RS,6RS)-N(1)-benzyl-3-hydroxy-4-benzyloxy-5,6-epoxyazepane by preparative chiral HPLC and subsequent elaboration allows access to the enantiomers of 1-deoxynojirimycin and 1-deoxyaltronojirimycin, respectively.