Glucuronidation of serine and threonine

The synthesis of N-diphenylmethylene-O-(methyl(2,3,4-tri-O-acetyl)-β-D-glucuronosyl)-threonine benzyl ester (2) and N-diphenylmethylene-O-(methyl(2,3,4-tri-O-acetyl)-α/β-D-glucuronosyl)-serine benzyl ester (3) byHanessian's modification of theKoenigs-Knorr reaction is presented. Highly nucleophilic benzophenoneSchiff bases are used for the protection of the N-moiety of serine and threonine.