Synthetic Studies on Sialoglycoconjugates 81: Synthesis of Positional Isomers of Sialyl Lewis X Epitope Containing 1-Deoxy-dGlucose in Place ofN-Acetylglucosamine, and Their Inhibitory Activity to Selectin-Mediated Adhesion

Abstract

Abstract Three sialyl-Lex epitope analogs, which carry fucose and α-sialyl-(2→3)-galactose residues at O-2 and O-3, O-3 and O-2, and O-4 and O-6 positions of 1-deoxy-D-glucose backbone, respectively, have been synthesized. Glycosylation of 1,5-anhydro-4,6-O-benzylidene-D-glucitol (1) or 1,5-anhydro-6-O-benzoyl-2,3-di-O-benzyl-d-glucitol (4) prepared from 1,5-anhydro-d-glucitol, with methyl 2,3,4-tri-O-benzyl-1-thio-β-L-fucopyranoside (5) using dimethyl(methylthio)sulfonium triflate (DMTST) as a promoter, afforded the corresponding fucosyl 1,5-anhydro-d-glucitol derivatives 7, 8 and 9. Glycosylation of 7, 8 or 10 derived from 9, with methyl O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-d-glyceroα-d-galacto-2-nonulopyranosylonate)-(2→3)-2,4,6-tri-O-benzoyl-1-thio-β-d-galactopyranoside (11) in the presence of DMTST gave the expected tetrasaccharide derivatives 12, 16 and 20. Hydrolysis of the benzylidene group in 12 and 16 gave compounds 13 and 17. Finally 13, 17 and 20 were transformed, by reduct...