Application of the trichloroacetimidate method to the synthesis of glycopeptides of the mucin type containing a β- d-Gal p-(1→3)- d-Gal pNAc unit

Abstract

Mucin-type O-glycopeptides containing the β- d-Gal p-(1→3)- d-Gal pNAc disaccharide core unit, which is also the T-antigenic determinant, were synthesized from d-galactose, 2-azido-2-deoxy- d-galactose, 2-azido-2-deoxylactose, and l-serine precursors by applying the trichloroacetimidate method. Thus, β- d-Gal p-(1→3)-α- d-Gal pNAc-(1→3)-Ser ( 1) and β- d-Galp-(1→4)-β- d-Glc pNAc-(1→6)-[β- d-Gal p-(1→3)]-α- d-Gal pNAc-(1→3)-Ser ( 2) were obtained. A protected precursor of 2 having free OH groups at C-4 and C-6 of the inner sugar unit is a valuable intermediate for the synthesis of further O-glycopeptides of this core-unit type.