Simple Construction of Neu5Ac(α2-8)Neu5Ac and Total Synthesis of Ganglioside GD3

ABSTRACT Glycosylation of an 8-unprotected sialyl fluoride 16 with 2β-chloro-3β-phenylthio-Neu5Ac 2 gave the desired α-disialate 23. Subsequent glycosylation of a thiolactoside 19 with the disialyl fluoride 23 gave the tetrasaccharide 28. Synthesis of GD3 1 was realized by condensation of the tetrasaccharide 28 with azidosphingosine 31, following our previously reported GM3 synthesis procedure.