11] Direct synthesis of glycosylated amino acids from carbohydrate peracetates and Fmoc amino acids: Solid-phase synthesis of biomedicinally interesting glycopeptides

Abstract

This chapter describes solid-phase synthesis of biomedicinally interesting glycopeptides. It summarizes the use of peracetylated carbohydrates in Lewis acid-catalyzed glycosylations of 3-mercaptopropionic acid and different Fmoc amino acids. The glycosylated building blocks are prepared without protection of the carboxyl groups of the glycosyl acceptors to give aliphatic and phenolic O- and S -glycosides in one step. The procedure uses commercial or readily available starting materials and does not require extensive experience in synthetic carbohydrate chemistry. Most proteins found in nature carry carbohydrate residues that are covalently attached to amino acid side chains through O- or N-glycosidic linkages. The chapter also covers Fmoc solid-phase glycopeptide synthesis, including a discussion of methods for Fmoc cleavage and the choice of protective groups for the carbohydrate moiety of glycosylated amino acids. Some applications of glycopeptides in pharmacology and immunology are outlined.