Azidation of anomeric nitro sugars: application in the synthesis of spiroaminals as glycosidase inhibitors

6,5-Fused sugar-derived spiroaminals have been synthesized from the azido esters obtained via the nucleophilic substitution reactions of unstable Michael adducts derived from 1-nitro sugars. Most of the spiroaminals synthesized showed moderate but selective inhibitory activities toward some glycosidases.