A series of enantiomerically pure azasugars (2, 5-dideoxy-2, 5-imino-d-mannitol, 1- deoxynojirimycin, 1-deoxymannojirimycin, and related compounds) was synthesized from d- mannitol via aminoheterocyclization of C2-symmetric bis-epoxides and subsequently followed by ring isomerization in few cases. These compounds have been evaluated as inhibitors of several glycosidases (α-and β-d-glucosidases, α-d-mannosidase and α-l- ...