Chemical Synthesis of the Linker-Armed Trisaccharide Repeating Unit of the O-Antigen from Pseudomonas putida BIM B-1100

The manuscript reports the concise chemical synthesis of the trisaccharide repeating unit of the O-antigen from Pseudomonas putida BIM B-1100 in the form of its aminoethyl glycoside through a linear strategy with rational protecting group manipulations. The challenging aspects of this synthesis include the incorporation of the beta-D-ManpNAcA and the alpha-D-GlcpNAc residues. The introduction of the desired carboxylic acid moiety has been achieved through late-stage TEMPO-mediated oxidation of the primary OH group on the protected trisaccharide. 1,2-cis aminoethyl glycoside with central glucosamine is used at the reducing end to the leave the scope for further glycoconjugate formation with suitable aglycone without hampering the anomeric stereochemistry.