The synthesis of (2,3,4-triO-acetyl)-beta-D-glucuronosyl)-threonine be
nzyl ester (2) and ,4-tri-O-acetyl)-alpha/beta-D-glucuronosyl)-serine
benzyl ester (3) by Hanessian's modification of the Koenigs-Knorr reac
tion is presented. Highly nucleophilic benzophenone Schiff bases are u
sed for the protection of the N-moiety of serine and threonine.