Synthesis of the Tetrasaccharide Repeating Unit from Acinetobacter baumannii Serogroup O18 Capitalizing on Phosphorus-Containing Leaving Groups

• Published in: Journal of organic chemistry Vol. 80; no. 9; pp. 4278 - 4288
• Main Authors: Arihara, Ryoichi, Kakita, Kosuke, Yamada, Kazuhiro, Nakamura, Seiichi, Hashimoto, Shunichi
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.05.2015; Amer Chemical Soc
• Subjects: Acinetobacter baumannii - chemistry; Carbohydrate Conformation; Carbohydrate Sequence; Chemistry; Chemistry, Organic; Molecular Sequence Data; Oligosaccharides - chemical synthesis; Oligosaccharides - chemistry; Phosphorus - chemistry; Physical Sciences; Science & Technology; DIPHENYL PHOSPHATES; BENZYL; GLYCOSYL PHOSPHATES; CONSTRUCTION; MONOALKYLATION; CHEMISTRY; STEREOSELECTIVE-SYNTHESIS; GLYCOSIDATION; POLYSACCHARIDE
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.5b00139

The first convergent synthesis of the tetrasaccharide repeating unit of the polymeric O antigen isolated from Acinetobacter baumannii serogroup O18 has been achieved. The ManNAcβ1→4Gal and GalNAcβ1→3Gal units were successfully obtained through β-selective glycosylation with 2-azido-4,6-O-benzylidene-2-deoxymannosyl diphenyl phosphate and Tf2NH-promoted glycosylation with 2-acetamido-2-deoxygalactosyl diethyl phosphite, respectively. The disaccharide units could be coupled with the aid of TMSClO4 as an activator of the diphenyl phosphate leaving group, and global deprotection completed the synthesis of the tetrasaccharide.