Chemoselective glycosidation strategy based on glycosyl donors and acceptors carrying phosphorus-containing leaving groups: a convergent synthesis of ganglioside GM3

A convergent synthesis of ganglioside GM3 has been achieved by capitalizing on three different phosphorus-containing leaving groups, in which the key features involve a chemo- and regioselective α-glycosidation of sialyl phosphite with partially benzylated galactosyl tetramethylphosphorodiamidate by the aid of trifluoromethanesulfonic acid and a traditionally uncommon coupling of an α-sialyl-(2→3)-galactosyl donor with a glucosylceramide building block which has the β-O-linked ceramide prebuilt into the glucose by a diphenyl phosphate method.