Stereoselective glycosidation of glycosyl acetates using ytterbium(III) trifluoromethanesulfonate

Abstract

We investigated the glycosidation of 2-acetoamido-3,4,6-tri-O-benzyl-D-glucopyranosyl acetate using the combined activators of ytterbium (III) trifluoromethanesulfonate-3 mol% boron trifluoride. The reactions using aromatic alcohols stereoselectively gave the corresponding aryl α-O-glycosides. And the reactions using alcohols afford the alkyl β-O-glycosides. The species of acceptors remarkably changed the stereoselectivities of the obtained glycosides, which was not found in the conventional glycosidations of N-acetyl-D-glucosamine derivatives. We speculated that the novel glycosyl intermediate, which was influenced by ytterbium metal, would be generated from N-acetyl-D-glucosamine derivatives.