Straightforward synthesis of the pentasaccharide repeating unit of the cell wall O-antigen of Escherichia coli O43 strain.

A concise synthetic strategy has been developed for the synthesis of the pentasaccharide repeating unit of the cell wall O-antigen of Escherichia coli O43 strain involving stereoselective β-D-mannosylation and α-L-fucosylation using corresponding trichloroacetimidate intermediates and perchloric acid supported over silica (HClO-SiO) as glycosylation promoter. The yield and stereoselectivity of the glycosylations were very good.