Chemical Synthesis of Conjugation-Ready Trisaccharides Corresponding to Biological Repeating Units of Pseudomonas aeruginosa Serotype 10 and 19 O -Antigens.

Here we report the chemical synthesis of conjugation-ready trisaccharides, representing biological repeating units of Pseudomonas aeruginosa serotype 10 and 19 O -antigens. The α-d-QuiN ₃ glycosidic bond was stereoselectively synthesized through TMSI─Ph ₃ P═O mediated 1,2- cis glycosylation. Selective oxidation of the C6-OH group at the disaccharide stage allowed for benzylidene-promoted construction of the α-l-GalN ₃ glycosidic bond and simplification of the postglycosylation process at the trisaccharide stage. The low reaction temperature and neighboring electron-donating effect facilitated the efficient synthesis of the trisaccharide.