ChemInform Abstract: Tumor-Associated Antigen Synthesis. Synthesis of the Gal-α-(1 → 3)-Gal-β-(1 → 4)-GlcNAc Epitope. A Specific Determinant for Metastatic Progression?

Abstract

A versatile synthesis of the Gal-α-(13)-Gal-β-(14)-GlcNAc epitope coupled to an alkyl spacer molecule could be developed. The important building block 3′-allyl-D-lactal 6 was prepared in high yield by the action of dibutyltin oxide and allyl bromide on D-lactal and converted in several steps into the lactosamine derivative 13 with free 3′-OH group. Stereoselective glycosidation with the β-trichloroacetimidate of benzylated D-galactose 18 led to the trisaccharide in high yield. Activation of the protected Gal-α-(13)-Gal-β-(14)-GlcNAc derivative 21 by desilylation and trichloroacetimidate formation followed by glycosidation with ethyl 9-hydroxynonanoate furnished the spacer-bound trisaccharide hapten 24 in excellent yield after simple two-step deprotection. The trisaccharide hapten 24 can easily be used as immunogen after coupling to an immunogenic carrier.