A PRACTICAL, CONVERGENT METHOD FOR GLYCOPEPTIDE SYNTHESIS

Glycopeptides are useful compounds to model the conformational effects of the biosynthetic glycosylation of asparagine (N) residues in glycoproteins. We report herein a practical, convergent method for the synthesis of N-glycopeptides. The key reaction involves the acetylation of a beta-glycosyl amine with a partially protected peptide. Commercially-available protected amino acids and peptide-synthesis resin are used. The beta-glycosyl amine can be derived from any reducing sugar by a simple procedure. Optimized experimental protocols are included for each step. Several glycosylations involving complex and acid-sensitive oligosaccharides are reported, including the coupling of a heptasaccharide (8) with a pentapeptide (14) in 55% purified yield.