Enantioselective Addition-Alkylation of α,β-Unsaturated Carbonyls via Bisguanidinium Silicate Ion Pair Catalysis
作者:Wenchao Chen、Esther Cai Xia Ang、Siu Min Tan、Zhijie Chua、Jingyun Ren、Ziqi Yang、Bo Teng、Richmond Lee、Haihua Lu、Choon-Hong Tan
DOI:10.1021/jacs.0c00183
日期:2020.11.11
Silicon hydrides, alkynylsilanes, and alkoxylsilanes were activated by fluoride in the presence of bisguanidinium catalyst to form hypervalent silicate ion pairs. These activated silicates undergo 1,4-additions with chromones, coumarins, and α-cyanocinnamic esters generating enolsilicate intermediates, for a consequent stereoselective alkylation reaction. The reduction-alkylation reaction proceeded
氢化硅、炔基硅烷和烷氧基硅烷在双胍催化剂存在下被氟化物活化,形成高价硅酸盐离子对。这些活化的硅酸盐与色酮、香豆素和 α-氰基肉桂酸酯发生 1,4-加成,生成烯醇硅酸盐中间体,用于随后的立体选择性烷基化反应。使用聚甲基氢硅氧烷(一种廉价且环保的氢化物来源)在温和条件下进行还原-烷基化反应。与炔基硅烷和烷氧基硅烷的加成烷基化反应导致构建了两个具有优异对映选择性和非对映选择性(高达 99% ee,> 99:1 dr)的邻位手性碳中心。