Synthesis of the acidic pentasaccharide repeating unit of the cell wall O-antigen of Providencia alcalifaciens O45:H25 strain

Synthesis of an acidic pentasaccharide repeating unit corresponding to the cell wall O-antigen of the human pathogen, Providencia alcalifaciens O45:H25 strain has been achieved by multi-step stereoselective glycosylations. p-Methoxybenzyl (PMB) group was used as in situ removable protecting group, which was removed from the glycosylated products in the same pot after stereoselective glycosylations. The D-glucuronic acid moiety in the pentasaccharide derivative was installed by converting the primary hydroxyl group of the D-glucose moiety to a carboxylic group using a late-stage TEMPO-bis(acetoxy) iodobenzene (BAIB) mediated selective oxidation condition. Only thioglycoside donors were used for glycosylation steps with satisfactory stereochemistry and chemical yields. (c) 2023 Elsevier Ltd. All rights reserved.