Synthetic approach towards sulfated chondroitin di-, tri- and tetrasaccharides corresponding to the repeating unit.

Chondroitin di-, tri- and tetrasaccharides, as well as their 4-, 6-mono- and 4,6-disulfates as their 4-methoxyphenyl glycosides, were systematically synthesized. Target disaccharides having beta GalNAc-(1-->4)-beta GlcA sequences were obtained starting from the corresponding pivotal chondroitin disaccharide precursor. A trisaccharide intermediate, which was synthesized by coupling of glucuronate imidate with a known disaccharide acceptor, was transformed into the sulfated and non-sulfated chondroitin trisaccharides. Chondroitin tetrasaccharide and the corresponding 4-disulfate, 6-disulfate as well as 4,6-tetrasulfate were also obtained based on the strategy developed above starting from the reported tetrasaccharide having [beta GalN3-(1-->4)-beta GlcA2] sequence.