Synthesis of the tetrasaccharide repeating unit of the O-antigen of the Escherichia coli O69 strain and its conformational analysis

Abstract

A straightforward synthesis of the tetrasaccharide repeating unit of the O-antigen of the Escherichia coli O69 strain as its 2-aminoethyl glycoside has been accomplished by carrying out two iterative glycosylations in one pot. The stereochemical outcome of the glycosylations was very good. The conformational analysis of the synthesized tetrasaccharide was carried out using NOE based two-dimensional ROESY spectroscopy in conjugation with all atom explicit molecular dynamics simulation studies. The solvent-perturbation induced conformations of the tetrasaccharide 1 were found quite stable in solution.