Chemical Synthesis of Conjugation-Ready Oligosaccharide Haptens of <i>Pseudomonas aeruginasa</i> O11 and <i>Staphylococcus aureus</i> Type 5

Chemical synthesis of the di- to tetrasaccharides resembling the <i>Pseudomonas aeruginasa</i> O11 <i>O</i>-antigen and a trisaccharide repeating unit of <i>Staphylococcus aureus</i> type 5 capsular polysaccharides was efficiently achieved. All of the glycosyl linkages, including the challenging 1,2-<i>cis</i>-glycosidic bonds of l-FucNAc and d-ManNAcA, were constructed with high yields and excellent stereoselectivity. These synthetic targets contained an identical α-l-FucNAc-(1→3)-β-d-FucNAc-(1→ moiety and an amino group functionalized linker at the reducing end, facilitating additional elaboration and biological studies.