A CONVENIENT SYNTHESIS OF TYPE-IV GLYCOSYL DONORS FROM TYPE-I DISACCHARIDES

The synthesis of 4,6-di-O-acetyl-3-O-(tetra-O-acetyl-β-D-galactopyranosyl)-2-deoxy-2-phthalimido-α,β-D-galactopyranosyl chloride 1 4 and its 6–0 -benzyl derivative 1 2 was achieved in a 5-step sequence starting from the readily available type I disaccharide derivative 3. The key step in the synthesis involved the preparation of trifluoromethanesulfonate (triflate) derivatives 7 and 9 and their subsequent SN2 displacement by acetate ion for conversion of 2-deoxy-2-phthalimido-β-D-glucopyranosyl moiety to the corresponding galacto configuration. © 1990, Taylor & Francis Group, LLC. All rights reserved.