Synthesis of a branched pentasaccharide: one of the core oligosaccharides of human blood-group substances

Abstract

Condensation of the lactosamine-derived per-O-acetyl oxazoline (6) with the trisaccharide derivative (1) followed by removal of the protecting groups, gave the branched pentasaccharide, β-D-Galp(1→3)-β-D-GlcpNAc(1→3)-[β-D-Galp(1→4)-β-D-GlcpNAc(1→6)]-D-Gal (4); the reduced form of this compound has been previously reported as present among the degradation products of soluble Le^a-active glycoprotein from ovarian cysts.