New approaches to glycoconjugate synthesis

Absnuct: Generally convergent strategies are employed in glyconjugate synthesis, hence the oligosaccharide moiety and the aglycon moiety are separately prepared and then linked to yield the target molecule; for glycopeptides linear synthesis strategies are more successful. The importance of p-glycosidic linkages of glucosamine and galactosamine in glycoconjugates was reason for the development of new methods which are based on N,N-diacetyl, N-tetrachlorophthaloyl, and Ntrichloroethoxycarbonyl protection. Another important goal in the construction of oligosaccharides is solid phase synthesis; the application of 0-glycosyl trichloroacetimidates as donors, thiolinkers to the solid phase, and MALDI-MS for product analysis led to improvements in this regard. Trichloroacetimidate-based glycosylation can be also applied to the synthesis of acid labile glycosyl phosphates and their lipid and nucleoside derivatives. Hydrolytically more stable glycophospholipids are GPI anchors; a general approach for ceramide1-phosphate and phosphatidic acid derived GPI anchors is based on a versatile building block strategy.