Synthesis of β-d-GalNAc(4,6-diS)(1–4)[α-l-Fuc(2,4-diS)(1–3)]-β-d-GlcA, a novel trisaccharide unit of chondroitin sulfate with a fucose branch

Novel glycosaminoglycans isolated from the body wall of sea cucumbers consist of chondroitin sulfates like polysaccharides. We have synthesized a representative repeating trisaccharide composed of a chondroitin backbone having a fucose (Fuc) branch at O-3 of glucuronic acid (GlcA), β-d-GalNAc(4,6-diS)(1–4)[α-l-Fuc(2,4-diS)(1–3)]-β-d-GlcA, in a stereocontrolled manner. Regiospecific sulfation at O-4,6 and O-2,4 of the N-acetylgalactosamine (GalNAc) and Fuc residues, respectively, was successfully achieved.