Total Synthesis of Trisaccharide Repeating Unit of O-Specific Polysaccharide of Pseudomonas fluorescens BIM B-582

The first total synthesis of the trisaccharide repeating unit of the O-specific polysaccharide of Pseudomonas fluorescens BIM B-582 is reported. This efficient synthesis involves consecutive 1,2-cis glyco-sylations including beta-L-rhamnosylation and alpha selective coupling of rare 4-deoxy-D-xylo-hexose as the key steps. The synthetic trisaccharide is equipped with an aminopropyl linker at the reducing end to allow for conjugation to proteins and microarrays for further immunological studies.