SYNTHETIC STUDIES ON AN OLIGOSACCHARIDE OF A GLYCOLIPID FROM THE 27ERMATOZOA OF BIVALVES .9. SYNTHESES OF LIPID-I, LIPID-II, AND LIPID-IV

Glycosphingolipids isolated from the spermatozoa of the freshwater biv alve, Hyriopsis schlegelii, have a unique structure containing one or two mannosyl residues and novel linkages, including an internal fucopy ranosyl residue, as well as terminal xylosyl and 4-O-methyl-D-glucopyr anosyluronic acid groups. The octasaccharide of lipid IV was synthesiz ed as follows. Condensation of methyl acetamido-4,6-di-O-acetyl-2-deox y-3-O-methyl-alpha -D-galactopyranosyl)-(1 --> acetyl-4-O-methyl-beta- D-glucopyranosyluronate)-(1 --> 4)]-2-O-benzyl-1-thio-alpha,beta-L-fuc opyranoside (18) with yl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl)- (1 --> 2)-(3,4,6-tri-O-acetyl-alpha-D-mannopyranosyl)-(1 --> 3)-[(2,3, 4-tri-O-acetyl-beta-D-xylopyranosyl)-(1 --> 2)]-(4,6-di-O-acetyl-beta- D-mannopyranosyl)-(1 --> )-2,3-di-O-acetyl-1,6-anhydro-beta-D-glucopyr anose (14), in the presence of dimethyl (methylthio) sulfonium triflat e (DMTST), gave the corresponding octasaccharide (19). Removal of the protecting groups gave ido-2-deoxy-3-O-methyl-alpha-D-galactopyranosyl -(1 --> 3)-[4-O-methyl-beta-D-glucopyranosyl uronic acid-(1 --> 4)]-al pha-L-fucopyranosyl(1 --> 4)-2-acetamido-2-deoxy-beta-D-glucopyranosyl -(1 --> 2)-alpha-D-mannopyranosyl-(1 --> 3)-[beta-D-xylopyranosyl-(1 - -> 2)]-beta-D-mannopyranosyl-(1 --> 4)-1,6-anhydro-beta-D-glucopyranos e (22). The other two oligosaccharides that constitute the partial str ucture of lipid IV, called lipid I and II, were also synthesized.