Large scale synthesis of a derivative of an alpha-galactosyl trisaccharideepitope involved in the hyperacute rejection of xenotransplantation

A derivative of an alpha-galactosyl trisaccharide xenoactive antigen, (2,3, 4,6-tetra-O-benzyl-alpha-D-galactopyranosyl)-(1-->3)-(2,4,6-tri-O-acetyl-be ta-D-galactopyranosyl)-(1-->4)-2,3,6-tri-O-acetyl-beta-D-glucopyranosyl azi de (5), was synthesized on a large scale (50 gram). The synthesis involved a high yielding and highly stereoselective (alpha \beta>20:1) glycosylation reaction utilizing a thiogalactoside as the donor and a selectively protec ted lactose azide as the acceptor. This derivative serves as a versatile in termediate that can be transformed into a variety of alpha-Gal containing g lycoconjugates highly desired in xenotransplantation research and pharmaceu tical development.