Expedite synthesis of the pentasaccharide corresponding to the cell wall O-polysaccharide of Proteus penneri O80 strain

Synthesis of a d-glucuronic acid containing acidic pentasaccharide repeating unit corresponding to the cell wall O-polysaccharide of Proteus penneri O80 has been successfully achieved in very good yield by stereoselective sequential glycosylations of judiciously functionalized monosaccharide intermediates. Exclusive (1 → 2)-cis glycosylation was achieved using a combination of copper(II) bromide and tetra-n-butylammonium bromide (TBAB) as glycosylation activator in a mixed solvent. A regioselective TEMPO mediated bis(acetoxy)iodobenzene (BAIB) oxidation of the primary hydroxyl groups to a carboxylic acid was carried out at the late stage of the synthetic scheme.