SYNTHESIS OF A HEXASACCHARIDE CORRESPONDING TO A PORCINE ZONA-PELLUCIDA FRAGMENT THAT INHIBITS PORCINE SPERM-OOCYTE INTERACTION IN-VITRO

The synthesis of hexasaccharide 1, [Gal beta(1-4)GlcNAc[6OSO(3)(-)]bet a(1-3)Gal beta(1-4)GlcNAc beta(1-3)Gal beta(1-3)GalNAc alpha-O(CH2)(3) NH2], which corresponds to a porcine zona pellucida fragment that inhi bits porcine sperm-oocyte interaction, is described. Compound 1 was ob tained from fully protected hexasaccharide 2, which was in rum constru cted from protected Gal beta(1-3)GalNAc disaccharide 5, containing an alpha-linked 3-azidopropyl spacer, and from lactosamine derivatives 3 and 4. Disaccharide 3 and 4 were prepared by coupling of selenophenyl glycoside 6 with glycosyl accepters containing anomeric thioethyl grou ps. NIS/TfOH promoted coupling of disaccharide 4 with 5 afforded 29, w hich was transformed into the tetrasaccharide acceptor 30 by selective removal of the levulinoyl group. Glycosylation of 30 with 3 afforded protected hexasaccharide 2. Removal of the phthalimido groups, acetyla tion, followed by selective removal of the allyl group and sulphation, and finally complete deprotection afforded hexasaccharide 1. Copyrigh t (C) 1996 Elsevier Science Ltd