New solid-phase oligosaccharide synthesis on glycopeptides bound to a solid phase

A solid-phase oligosaccharide synthesis has been developed which utilises glycopeptides bound to the solid phase. The products are glycopeptides elongated at the saccharide chain. The glycosyl accepters, which are assembled by simple solid-phase glycopeptide synthesis, contain 2-azido-2-deoxy-alpha-D-galactose with unsubstituted 3-OH or 6-OH groups, which can be glycosylated. Suitable glycosyl donors are perbenzoylated trichloroacetimidates of D-galactose or 2-amino-2-deoxy-D-glucose, although the 2-amino group must be protected with Teoc. A corresponding additional saccharide unit is added with a beta-glycosidic linkage. With disaccharide donors, glycopeptides with linear trisaccharide side chains are obtained. By performing the solid-phase glycosylation synthesis twice in succession glycopeptides with branched trisaccharide chains have been obtained.