Synthesis of the conjugation-ready β-mannosamine-containing O-antigen repeat from Vibrio cholerae O14

Abstract

Chemical synthesis of the trisaccharide repeating unit of the O-antigen from Vibrio cholerae has been accomplished through a linear strategy. The reducing end 1,2-cis mannosamine unit has been achieved through the azide inversion of the 2-OH position of a suitably protected glucose moiety. The crucial (S)-3-hydroxybutyric acid is inserted successfully at the last stage through EDC–HOBt coupling. The target trisaccharide, in the form of its 2-aminoethyl glycoside, is ready for further conjugation.