One-Pot Regioselective and Stereoselective Synthesis of C-Glycosyl Amides from Glycals Using Vinyl Azides as Glycosyl Acceptors

The reaction of glycals containing good leaving groups with aromatic vinyl azides to give alpha-C-glycosyl amides in good yields is described. Various vinyl azides with different groups undergo the reaction smoothly. In these reactions, an iminodiazonium intermediate is generated by the attack of the vinyl azide onto the glycal under Lewis acid conditions. This undergoes Schmidt-type denitrogenative 1,2-migration to form a nitrilium ion, which, upon hydrolysis, gives the desired C-glycosyl amide.