Ruthenium trichloride catalyzed synthesis of 2,3-unsaturated-N-glycosides via Ferrier azaglycosylation

An efficient, economical and mild protocol for the synthesis of 2,3-unsaturated-N-glycosides has been developed using ruthenium(III) chloride. The Ferrier azaglycosylation of glycals with various N-nucleophiles such as sulfonamides, benzamides, carbamates and N-substituted sulfonamides proceeded smoothly to afford the corresponding 2,3-unsaturated-N-glycosides or ‘N-pseudoglycals’ in good yields (64–98%). High α-anomeric selectivity was observed with N-substituted sulfonamides such as N-benzyl or N-phenyl sulfonamides under similar conditions.