Synthesis of the Non Reducing End Oligosaccharides of Glycosphingolipids from Ascaris suum.

Stereocontrolled syntheses of biotin-labeled oligosaccharide portions containing the non reducing end oligosaccharides of glycosphingolipids from Ascaris suum have been accomplished. Gal alpha 1 -> 3GalNAc beta 1 -> OR (1), Gal beta 1 -> 3Gal alpha 1 -> 3GalNAc beta 1 -> OR (2), Gal beta 1 -> 6Gal alpha 1 -> 3GalNAc beta 1 -> OR (3), Gal beta 1 -> 6(Gal beta 1 -> 3) Gal alpha 1 -> 3GalNAc beta 1 -> OR (4) and GlcNAc beta 1 -> 6Gal beta 1 -> 6(Gal beta 1 -> 3)Gal alpha 1 -> 3GalNAc beta 1 -> 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-alpha-D-galactopyranosyl-(1 -> 3)-4,6-O-benzylidene-2-deoxy-2-phthalimido-beta-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.