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

A straightforward synthesis of the pentasaccharide with all α-linked glycosyl linkages corresponding to the cell wall O-antigen of Escherichia coli 19ab has been achieved in excellent yield using sequential glycosylations of monosaccharide intermediates. The structure of the target compound and its synthetic intermediates were unambiguously characterized using their spectral analysis. A generalized glycosylation condition has been used in all glycosylations and minimum number of protecting group manipulations were involved during the synthesis of the target compound.