Chemical synthesis of the Pseudomonas aeruginosa O11 O-antigen trisaccharide based on neighboring electron-donating effect

Abstract

Pseudomonas aeruginosa O11 O-antigen is immunologically active but an exact protective epitope has not yet been identified. Synthesis of O11 O-antigen trisaccharide is of importance for identifying the epitopes. Here, neighboring electron-donating effects are keys to enhance the nucleophilicity of the C3 hydroxyl groups of D- and L-fucosamines, to facilitate the efficient synthesis of the trisaccharide. The disarmed peracetylated glycosyl donor with low glycosylation reactivity and glycosyl trifluoroacetimidate with good stability allowed for the glycosylation under mild conditions. The C6 nucleophilic tosylate substitution of D-galactose with iodine was found to be dependent on the steric effect of the axial C4.

Keywords:

• Chemical synthesis
• Pseudomonas aeruginosa
• O-antigen
• protecting group
• glycosylation

Supplemental material

NMR spectra for all pure products. This material is available free of charge via the Internet https://www.tandfonline.com/toc/lcar20/current.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the [National Natural Science Foundation of China] under Grant [number 21877052, 21907039]; [Natural Science Foundation of Jiangsu Province] under Grant [number BK20180030, BK20190575]; [National First-class Discipline Program of Light Industry Technology and Engineering] under Grant [number LITE2018-14]; [Max Planck Society International Partner Group Program]; [China Scholarship Council (CSC)] and [Open Project of Key Laboratory of Carbohydrate Chemistry and Biotechnology (Jiangnan University), Ministry of Education] under Grant [number KLCCB-KF202005]. P.H.S. thanks the Max-Planck Society for generous financial support.