Total synthesis of sialylated and sulfated oligosaccharide chains from respiratory mucins.

Abstract

The total syntheses of several complex oligosaccharide moieties that occur in the core structure of sulfated mucins are reported. A trisaccharide acceptor was obtained through regio- and stereoselective sialylation of methyl (6-O-pivaloyl-beta-D-galactopyanosyl)(1-->3)-4,6-O-benzylidene-2-a cetamido-2-deoxy-alpha-D-galactopyranoside with a novel sialyl donor. A tetrasaccharide, pentasaccharide, and hexasaccharide were constructed in predictable and controlled manner with high regio- and stereoselectivity after the successful preparation and employment of a disaccharide donor, trisaccharide donor, disaccharide acceptor, and trisaccharide acceptor building blocks. Finally, a mild oxidative cleaving method was adopted for the selective removal of 2-naphthylmethyl (NAP) in the presence of benzyl groups.