Facile aza-Claisen rearrangement of glycals: application in the synthesis of 1-deoxy-L-iminosugars

2-C-Methylene-N-glycosyl amides have been obtained from 2-(hydroxymethyl)glycals through a facile aza-Claisen rearrangement. This rearrangement has also been utilized in the synthesis of L-allo-deoxynojirimycin, a moderate inhibitor of human lysosomal α-mannosidase (IC<SUB>50</SUB>=64 μM), and two new C-5-(hydroxymethyl) analogues of L-altro-deoxynojirimycin and L-ido-deoxynojirimycin