One-stage glycosylation using protected glycose: the synthesis of O-β-D-glucopyranosyl-(1 → 3)-O-[β-D-glucopyranosyl-(1 → 6)]-D-glucopyranose

Abstract

The one-stage β-glucosylation of benzyl 3-O-acetyl-2,4-di-O-benzyl-α-D-glucopyranoside (1) with 2,3,4,6-tetra-O-benzyl-α-D-glucopyranose (2) using a mixture of p-nitrobenzenesulfonyl chloride, silver trifluoromethanesulfonate, and triethylamine, followed by deacetylation, gave benzyl O-(2,3,4,6-tetra-O-benzyl-β-D-glucopyranosyl)-(1 → 6)-2,4-di-O-benzyl-α-D-glucopyranoside (3). The disaccharide derivative 3 was then subjected to the β-glucosylation, followed by catalytic hydrogénation, to afford O-β-D-glucopyranosyl-(1 → 3)-O-[β-D-glucopyranosyl-(1 → 6)]-D-glucopyranose (4). The key intermediate 1 was prepared from D-glucose by way of a Fischer reaction, triphenylmethylation, a controlled benzylation, and detriphenylmethylation.