Light-Driven Enantioselective Organocatalytic β-Benzylation of Enals.
Light-Driven Enantioselective Organocatalytic β-Benzylation of Enals.
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DOI：
10.1002/anie.201612159
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发表时间：
2017-03-13
期刊：
影响因子：
--
通讯作者：
Melchiorre P
中科院分区：
文献类型：
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作者：
Dell'Amico L;Fernández-Alvarez VM;Maseras F;Melchiorre P
报道了一种光化学有机催化α，β-不饱和醛的直接对映选择性β-苄基化反应。该化学利用2-烷基-二苯甲酮的光触发烯醇化以提供羟基-邻-喹啉基甲烷。这些短暂的中间体被手性亚胺离子立体选择性地拦截，在仲胺催化剂与烯醛缩合时瞬时形成。密度泛函理论（DFT）研究提供了一个解释，为什么反应通过非常规的迈克尔型加成流形进行，而不是经典的环加成机制和随后的开环。
A photochemical organocatalytic strategy for the direct enantioselective β‐benzylation of α,β‐unsaturated aldehydes is reported. The chemistry capitalizes upon the light‐triggered enolization of 2‐alkyl‐benzophenones to afford hydroxy‐o‐quinodinomethanes. These fleeting intermediates are stereoselectively intercepted by chiral iminium ions, transiently formed upon condensation of a secondary amine catalyst with enals. Density functional theory (DFT) studies provided an explanation for why the reaction proceeds through an unconventional Michael‐type addition manifold, instead of a classical cycloaddition mechanism and subsequent ring‐opening.