ABSTRACT
Stereocontrolled syntheses of biotin-labeled oligosaccharide portions containing the non reducing end oligosaccharides of glycosphingolipids from Ascaris suum have been accomplished. Galα1â3GalNAcß1âOR (1), Galß1â3Galα1â3GalNAcß1âOR (2), Galß1â6Galα1â3GalNAcß1âOR (3), Galß1â6(Galß1â3)Galα1â3GalNAcß1âOR (4) and GlcNAcß1â6Galß1â6(Galß1â3)Galα1â3GalNAcß1âOR (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-(1â3)-4,6-O-benzylidene-2-deoxy-2-phthalimido-ß-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.