Synthetic Studies on Sialoglycoconjugates 61: Synthesis of α-Series Ganglioside GM1α

Publisher Website
Google Scholar
Abstract
A stereocontrolled synthesis of α-series ganglioside GM1α (III6Neu5AcGgOse4Cer) is described. Glycosylation of 2-(trimethylsilyl)ethyl O-(2,3,6-tri-O-benzyl-β-d-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-d-glucopyranoside (1) with the suitably protected galactosamine donor, methyl 3-O-acetyl-4,6-O-benzylidene-2-deoxy-2-phthalimido-1-thio-β-d-galactopyranoside (4) gave the desired trisaccharide, which was transformed into the trisaccharide acceptor via removal of the phthaloyl and O-acetyl groups followed by N-acetylation. Glycosylation of this acceptor with methyl 3-O-benzyl-2,4,6-tri-O-benzoyl-1-thio-β-d-galactopyranoside (7) gave the asialo GM1 saccharide derivative, which was transformed into the acceptor by removal of benzylidene group. Coupling of this gangliotetraose acceptor with phenyl (methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-d-glcero-d-galacto-2-nonulopyranosyl)onate by use of NIS-TfOH afforded the desired GM1α oligosaccharide derivative in high yield, which was transformed, via removal of the benzyl group followed by O-acetylation, selective removal of the 2-(trimethylsilyl)ethyl group and subsequent imidate formation, into the final glycosyl donor. Condensation of this imidate derivative with (2S, 3R, 4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (15) gave the β-glycoside, which on channeling through selective reduction of azido group, coupling of the amino group with octadecanoic acid, O-deacylation and saponification of the methyl ester group, gave the title compound GM1α.

This publication has 32 references indexed in Scilit: