A New Approach to the Neoglycopeptides:  Synthesis of Urea- and Carbamate-Tethered N-Acetyl-d-glucosamine Amino Acid Conjugates

A novel approach to the synthesis of Fmoc-protected neoglycopeptide building blocks is described. Oxidation of N-acetyl-d-glucosamine isonitrile afforded the corresponding highly reactive glycopyranosyl isocyanate, which reacted with amino acid derivatives to furnish the corresponding urea- and carbamate-tethered Fmoc-protected N-acetyl-d-glucosamine amino acid conjugates in good yields.