A “Traceless” Directing Group Enables Catalytic S N 2 Glycosylation toward 1,2- cis -Glycopyranosides

作者：Xu Ma, Zhitong Zheng, Yue Fu, Xijun Zhu, Peng Liu, Liming Zhang · 发表于：Journal of the American Chemical Society · 年份：2021 · DOI：10.1021/jacs.1c04584 · 被引用次数：75 · 研究领域：Carbohydrate Chemistry and Synthesis、Glycosylation and Glycoproteins Research、Legume Nitrogen Fixing Symbiosis

Generally applicable and stereoselective formation of 1,2- cis -glycopyranosidic linkage remains a long sought after yet unmet goal in carbohydrate chemistry. This work advances a strategy to this challenge via stereoinversion at the anomeric position of 1,2- trans glycosyl ester donors. This S N 2 glycosylation is enabled under gold catalysis by an oxazole-based directing group optimally tethered to a leaving group and achieved under mild catalytic conditions, in mostly excellent yields, and with good to outstanding selectivities. The strategy is also applied to the synthesis of oligosaccharides.