Synthesis of two hyaluronan trisaccharides

The synthesis of two hyaluronan trisaccharides, methyl O(beta-D-glucopyrano syluronic acid)-(1,3)-O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1,4)-O -beta-D-glucopyranosiduronic acid and methyl O-(2-acetamido-2-deoxy-beta-D- glucopyranosyl)-(1,4)-O-beta-D-glycopyranosyluronic acid)-(1,3)-O-(2-acetam ido-2-deoxy-beta-D-glucopyranoside are described. Construction of the targe t molecules was achieved though a combination of the phenyl sulfoxide and t richloroacetimidate glycosylation methodologies. This is the first report o n the synthesis of the beta-methyl derivatives, which represent the smalles t fragments that incorporate all the structural features of polymeric hyalu ronan.