N-Thiodiglycoloyl derivatives of glucosamine as glycosyl donors

N-Thiodiglycoloyl (TDG) protection of O-acetylated glucosamine could be readily carried out with thiodiglycolic anhydride and then treatment with acetic anhydride in pyridine. Ensuing reaction with hydrazinium acetate and then base-catalyzed activation with trichlorocetonitrile afforded N-TDG protected glucosamine donor 3. Glycosylation of acceptors 8 and 5 in dichloromethane with TMSOTf as the catalyst gave β-glycosides 6 and 9 in high yields. For TDG cleavage MeONa/MeOH treatment followed by radical desulfurization with Bu3SnH/AIBN and reacetylation with Ac2O/pyridine was employed, thus giving N-acetyl glucosamine containing compounds 7 and 10 in a convenient, high-yielding procedure.