Synthetic studies on sialoglycoconjugates. Part 146. Total synthesis of 6-O-sulfo-sialylparagloboside: a widely useful glycoprobe for biochemical research

摘要

The total synthesis of 6-O-sulfo-sialylparaglobo side is described. A suitably protected beta-D-GlcpNAc-(1 -> 3)-beta-D-Galp-(1 -> 4)-D-GlcpOSE derivative was glycosylated with an alpha-D-Neup5Ac-(2 -> 3)-D-Galp derived imidate to give the corresponding protected alpha-D-Neup5Ac-(2 -> 3)-beta-D-Galp-(1 -> 4)-beta-D-GlcpNAc-(1 -> 3)-beta-D-Galp-(1 -> 4)-D-GlcpOSE pentasaccharide derivative. Proper manipulation of the protecting groups of the pentasaccharide afforded the corresponding glycosyl imidate, which was coupled with (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol. Selective reduction of the azido group, N-acylation with octadecanoic acid, 6-O-sulfation of the GlcpNAc residue, and complete removal of the protecting groups gave the desired 6-O-sulfo-sialylparaglobo side.