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

Here we report the chemical synthesis of conjugation-ready trisaccharides, representing biological repeating units of Pseudomonas aeruginosaserotype 10 and 19 O-antigens. The α-d-QuiN3glycosidic bond was stereoselectively synthesized through TMSI─Ph3P═O mediated 1,2-cisglycosylation. Selective oxidation of the C6–OH group at the disaccharide stage allowed for benzylidene-promoted construction of the α-l-GalN3glycosidic 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.