AbstractHerein, 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.
摘要在本文中,我们首次合成了鲍曼不动杆菌 ATCC 17961 O 抗原的五糖和十糖,用于开发基于碳水化合物的合成疫苗以预防鲍曼不动杆菌感染。我们采用最近推出的有机催化糖基化方法高效合成了稀有糖 2,3-二乙酰氨基葡萄糖醛酸。我们首次发现,通过氢键参与长程左旋酰基可显著提高糖基化的 β 选择性。这解决了高支化半乳糖受体的立体选择性问题。所提出的机理得到了对照实验和 DFT 计算的支持。得益于长程左旋酰基参与策略,通过高效的 [2+1+2] 一锅糖基化方法获得了五糖供体和受体,并用于目标十糖的合成。