SYNTHETIC STUDIES ON SIALOGLYCOCONJUGATES .20. SYNTHESIS OF CEREBROSIDE, LACTOSYL CERAMIDE, AND GANGLIOSIDE GM3 ANALOGS CONTAINING BETA-THIOGLYCOSIDICALLY LINKED CERAMIDE

Coupling of the sodium salt of 2,3,4,6-tetra-O-acetyl-1-thio-beta-D-glucopyranose, -beta-D-galactopyranose, O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-(1 --> 4)-2,3,6-tri-O-acetyl-1-thio-beta-D-glucopyranose, or O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosylonate)-(2,3-di-O-acetyl-6-O-bezoyl-beta-D-galactopyranosyl)-(1 --> 4)-3-O-acetyl-2,6-di-O-benzoyl-1-thio-beta-D-glucopyranose, which were prepared from the corresponding 1-S-acetates, 1, 3, 6, and 9, with (2S,3R,4E)-2-azido-3-O-benzoyl-1-O-(p-tolylsulfonyl)-4-octadecene-1,3-diol (12) derived by tosylation of 11, gave the corresponding beta-thioglycosides 13, 17, 21, and 25, respectively in good yield. The beta-thioglycosides obtained were converted, via selective reduction of the azide group, condensation with octadecanoic acid, and removal of the protecting groups, into the title compounds.