Synthesis of a nona- and an undeca-saccharide that form part of the complex type of carbohydrate moiety of glycoproteins.

Silver trifluoromethanesulfonate-promoted condensation of 3,6-di-O-acetyl-2-deoxy-2-phthalimido-4-O-(2,3,4,6-tetra-O-acetyl-beta-D- galactopyranosyl)-beta-D-glucopyranosyl bromide with benzyl 2,4,-di-O-benzyl-6-O-(3,4-di-O-benzyl-alpha-D-mannopyranosyl)-3-O-(3,6-di-O- benzyl-alpha-D-mannopyranosyl)-alpha-D-mannopyranoside gave nonasaccharide and undecasaccharide derivatives. The nonasaccharide 2 and the undecasaccharide 3 were obtained by removal of the protecting groups followed by N-acetylation. (formula; see text).