Towards the First Chemical Synthesis of the Hexasaccharide O-Antigen of Vibrio cholerae O139

Abstract

The hexasaccharide O-antigen of Vibrio cholerae O139 was synthesized in its protected form from thioglycosides and glycosyl bromides as glycosyl donors by a stepwise and blockwise approach. The synthesis was designed to permit a global, one-step deprotection (H 2 , Pd/C). It allows the transformation of 15 functionalities in one operation, namely the removal of ten benzyl protecting groups, the removal of a trichloroethyl phosphate protecting group, the conversion of two N-trichloroacetyl into N-acetyl groups, a bromomethyl into a methyl group, and the conversion of an azido into an amino group.