The total chemical synthesis of the pentasaccharide repeating unit of the O-polysaccharide from E. coli O132 is accomplished in the form of its 2-aminoethyl glycoside. The 2-aminoethyl glycoside is particularly important as it allows further glycoconjugate formation utilizing the terminal amine without affecting the stereochemistry of the reducing end. The target was achieved through a [3 + 2] strategy where the required monosaccharide building blocks are prepared from commercially available sugars through rational protecting group manipulation. The NIS-mediated activation of thioglycosides was used extensively for the glycosylation reactions throughout.
Keywords: 2-aminoethyl glycoside; O-specific polysaccharide; diarrhea; galactofuranose; total synthesis.
Copyright © 2019, Pal and Mukhopadhyay; licensee Beilstein-Institut.