Synthesis of Gal-beta-(1-->4)-GlcNac-beta-(1-->6)-[Gal-beta-(1-->3]-GalNAc-alpha- OBn oligosaccharides bearing O-methyl or O-sulfo groups at C-3 of the Gal residue: specific acceptors for Gal: 3-O-sulfotransferases.

Abstract

Our recent studies have revealed the existence of two distinct Gal: 3-O-sulfotransferases capable of acting on the C-3 position of galactose in a Core 2 branched structure, e.g., Galbeta1-->4GlcNAcbeta1-->6(Galbeta1-->3)GalNacalph a1-->OBenzyl as acceptor to give 3-O-sulfoGalbeta1-->4GlcNAcbeta1-->3(Galbeta1-->3)G alNAcalpha1-->OB 20 and Galbeta1-->4GlcNAcbeta1-->6(3-O-sulfoGalbeta1-->3)G alNAcalpha1-->OB 23. We herein report the synthesis of these two compounds and also that of other modified analogs that are highly specific acceptors for the two sulfotransferases. Appropriately protected 1-thio-glycosides 7, 8, and 10 were employed as glycosyl donors for the synthesis of our target compounds.