Development of an efficient α-glycoside synthesis of sialic acids is critically significant for the syntheses of sialoglycoconjugates, especially gangliosides which carry important biological functions1in biological systems. Previously, we demonstrated2a new α-glycosylation of sialic acids by use of dimethyl(methylthio)sulfonium triflate (DMTST)3as the glycosyl promoter, the suitably protected glycosyl acceptors and the methyl 2-thioglycoside 1 of N-acetylneuraminic acid (Neu5Ac) as the donor in acetonitrile under kinetically controlled conditions, and accomplished4the syntheses of a variety of gangliosides and their analogs.