Stereocontrolled syntheses of biotin-labeled oligosaccharide portions containing the non reducing end oligosaccharides of glycosphingolipids from Ascaris suum have been accomplished. Galα1→3GalNAcβ1→OR (1), Galβ1→3Galα1→3GalNAcβ1→OR (2), Galβ1→6Galα1→3GalNAcβ1→OR (3), Galβ1→6(Galβ1→3)Galα1→3GalNAcβ1→OR (4) and GlcNAcβ1→6Galβ1→6(Galβ1→3)Galα1→3GalNAcβ1→OR (5) (R = biotinylated probe) were synthesized by stepwise condensation (1-4) and block synthesis (5) using 5-(methoxycarbonylpentyl) 2-O-benzoyl-3-O-2-napthylmethyl-4,6-O-di-tert-butylsilylene-α-D-galactopyranosyl-(1→3)-4,6-O-benzylidene-2-deoxy-2-phthalimido-β-D-galactopyranoside (12) as a common precursor. Compound 12 was converted into two kinds of glycosyl acceptors and was condensed with suitable galactosyl donors, respectively.
Keywords: Ascaris suum; biotin probe; glycosphingolipid; host–parasite interaction; stereocontrolled synthesis.