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Stereoselective Synthesis of the O-antigen of A. baumannii ATCC 17961 Using Long-Range Levulinoyl Group Participation |
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| Authors: | Liangshen Duan Qin Nie Yongxin Hu Liming Wang Kaiyan Guo Zhuoyi Zhou Xu Song Yuanhong Tu Hui Liu Thomas Hansen Jian-song Sun Qingju Zhang |
| Affiliation: | 1. National Research Centre for Carbohydrate Synthesis, Jiangxi Normal University, 99 Ziyang Avenue, Nan Chang, 330022 China These authors contributed equally to this work.;2. National Research Centre for Carbohydrate Synthesis, Jiangxi Normal University, 99 Ziyang Avenue, Nan Chang, 330022 China;3. Department of Chemistry and Pharmaceutical Sciences, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam (The, Netherlands;4. National Research Centre for Carbohydrate Synthesis, Jiangxi Normal University, 99 Ziyang Avenue, Nan Chang, 330022 China Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, and Wuxi School of Medicine, Jiangnan University, Wuxi, 214122 China |
| Abstract: | Herein, we described the first synthesis of the pentasaccharide and decasaccharide of the A. baumannii ATCC 17961 O-antigen for developing a synthetic carbohydrate-based vaccine against A. baumannii infection. The efficient synthesis of the rare sugar 2,3-diacetamido-glucuronate was achieved using our recently introduced organocatalytic glycosylation method. We found, for the first time, that long-range levulinoyl group participation via a hydrogen bond can result in a significantly improved β-selectivity in glycosylations. This solves the stereoselectivity problem of highly branched galactose acceptors. The proposed mechanism was supported by control experiments and DFT computations. Benefiting from the long-range levulinoyl group participation strategy, the pentasaccharide donor and acceptor were obtained via an efficient [2+1+2] one-pot glycosylation method and were used for the target decasaccharide synthesis. |
| Keywords: | Glycosylation Long-Range Group Participation One-Pot A. Baumannii ATCC 17961 β-Selectivity |