Synthesis of an Asparagine-Linked Core Pentasaccharide by Means of Simultaneous Inversion Reactions

Abstract

A novel route for the synthesis of the asparagine-linked pentasaccharide 1, the core unit of all asparagine-linked sugar chains, is described. To construct this pentasaccharide derivative, we first employed a regioselective coupling of a mannosyl donor to the C-3 and C-6 positions of a galactosyl chitobiose acceptor, and then by means of a conversion involving two simultaneous inversion reactions of the stereochemistry of the C-2 and C-4 hydroxyl groups of a galactose residue, a branched pentasaccharide containing the difficult to synthesize β-mannose unit was easily obtained.