A “Traceless” Directing Group Enables Catalytic S<sub><i>N</i></sub>2 Glycosylation toward 1,2-<i>cis</i>-Glycopyranosides
作者:Xu Ma、Zhitong Zheng、Yue Fu、Xijun Zhu、Peng Liu、Liming Zhang
DOI:10.1021/jacs.1c04584
日期:2021.8.11
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 SN2 glycosylation is enabled under gold catalysis by an oxazole-based directing group optimally tethered to a
1,2-顺式-吡喃糖苷键的普遍适用和立体选择性形成仍然是碳水化合物化学中长期追求但尚未实现的目标。这项工作通过在 1,2-反式糖基酯供体的异头位置上的立体倒置推进了应对这一挑战的策略。这种 S N 2 糖基化是在金催化下通过以恶唑为基础的导向基团实现的,该导向基团最佳地束缚在离去基团上,并在温和的催化条件下以大多数优异的产率和良好的选择性实现。该策略也适用于寡糖的合成。