The Reaction of 2,3,4-Thi-O-Bknzyl-D-Glucose with Diethylaminosulfur Trifluoride (Dast)

Abstract
Treatment of 2,3,4-tri-O-benzyl-d-glucose (1) with diethylaminosulfur trifluoride (DAST) yielded 3,6-anhydro-2,4-di-O-benzyl-β-d-glucopyranosyl fluoride (11) as the main product (44%), by way of 3-benzyloxy group participation in the displacement of the intermediate 6-sulfoxo derivative. The desired 6-deoxy-6-fluoro-2,3,4-tri-O-benzyl-α- (2) and -β-d-gluco-pyranosyl fluoride (3) were formed in a combined yield of <20%. The combined yield of 2 and 3 could be increased three-fold by conducting the reaction in the presence of triethylamine.