The synthesis is described of p-nitrophenyl acetamido(deoxyglucopyranosyl)deoxymannopyranosiduronic acid I (R = C6H4NO2-4), corresponding to the disaccharide repeating unit of the capsular polysaccharide of Haemophilus influenzae type d, which, after conversion of the p-nitro- into a p-aminophenyl residue, may be attached to a protein to make an artificial antigen for immunol. studies. The synthesis incorporates a facile route to the 2-acetamido-2-deoxy-b-D-mannopyranosyl unit. [on SciFinder (R)]