Asymmetric synthesis of (+)-1-deoxynojirimycin and (+)-castanospermine

Asymmetric total syntheses of (+)-1-deoxynojirimycin () and (+)-castanospermine () are described. Starting from diene , the required absolute stereochemistry is introduced by an asymmetric hydroxylation followed by epoxidation. An intramolecular cyclization of amine gives access to the corresponding tetrasubstituted piperidine , which is a precursor to compounds and . (+)-Deoxynojirimicyn () was obtained in 36% yield over 11 steps from diene , while (+)-castanospermine () was achieved in 13% after 19 steps from the same starting material.