A straightforward alpha-selective aromatic glycosylation and its application for stereospecific synthesis of 4-methylumbelliferyl alpha-T-antigen.

A practical and efficient alpha-selective aromatic glycosylation with simple per-O-acetyl glycopyranosyl trichloroacetimidates is reported. The method is particularly effective for L-fucosyl and 2-azido-2-deoxy-D-galatosaminyl imidates, with which exclusive alpha-selectivity was achieved. The synthetic utility of this method was demonstrated in the stereoselective synthesis of 4-methylumbelliferyl alpha-T-antigen.