Facile synthesis of the pentasaccharide repeating unit of the cell wall O-antigen of Escherichia coli 19ab

► A pentasaccharide corresponding to the O-antigen of E. coli 19ab has been synthesized. ► Minimum number of protecting group manipulations was involved in the synthesis. ► A generalized glycosylation reaction was used in all glycosylation steps. ► Triethylsilane and Pearlman's catalyst was used for removal of functional groups.