Synthesis of a hexasaccharide corresponding to a porcine zona pellucida fragment that inhibits porcine sperm-oocyte interaction in vitro

Article abstract of DOI:10.1016/0040-4020(96)00225-6

The synthesis of hexasaccharide 1, [galβ(1-4)GlcNAc[6OSO₃]β(1-3)Galβ(1-4)GlcNAcβ(1-3)Galβ(1-3)GalNA cα-O(CH₂)₃NH₂], which corresponds to a porcine zona pellucida fragment that inhibits porcine sperm-oocyte interaction, is described. Compound 1 was obtained from fully protected hexasaccharide 2, which was in turn constructed from protected Galβ(1-3)GalNAc disaccharide 5, containing an α-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 acceptors containing anomeric thioethyl groups. NIS/TfOH promoted coupling of disaccharide 4 with 5 afforded 29, which 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, acetylation, followed by selective removal of the allyl group and sulphation, and finally complete deprotection afforded hexasaccharide 1.