Synthesis of a spacer-containing disaccharide fragment of Bordetella pertussis lipopolysaccharide Original Research Article

The disaccharide 2-(p-aminophenyl)ethyl 4-O-(2-acetamido-2-deoxy-α-d-glucopyranosyl)-2,3-diacetamido-2,3-dideoxy-α-d-mannopyranoside uronate, which is assumed to be a partial structure of the Bordetella pertussis polysaccharide, was synthesized starting from d-glucose and d-glucosamine, respectively. The major synthetic transformations were conversion of d-glucosamine into the donor ethyl 3,4,6-tri-O-acetyl-2-azido-2-deoxy-1-thio-β-d-glucopyranoside and conversion of glucose, by a sequence involving 2,3-epoxide formation/opening, nucleophilic triflate displacement in the 3-position, and necessary protecting group manipulations, into the acceptor 2-(p-trifluoroacetamidophenyl)ethyl 6-O-benzyl-2,3-diazido-2,3-dideoxy-α-d-mannopyranoside. Coupling of the donor and acceptor units promoted by dimethyl(methylthio)sulfonium triflate followed by selective oxidation of the 6′-position and deprotection gave the target disaccharide.