Stereoselective synthesis of _D-1-deoxynojirimycin and its stereoisomers

A stereoselective synthesis of _D-l-deoxynojirimycin (1), _D-1-deoxymannojirimycin (2), and _D-1-deoxyallonojirimycin (3) was achieved via the regioselective and diastereoselective amination of anti-l,2-dibenzyl ether using chlorosulfonyl isocyanate (CSI), ring-closing metathesis, diastereoselective dihydroxylation, and the regioselective stereochemical inversion of the resulting diol.