电化学手性NHC催化简单酯类化合物的C−H不对称官能团化

电化学是实现自由基反应的重要手段。由于能够有效避免外加氧化还原剂，相较于其它产生自由基策略具有高原子经济性。正因如此，电化学合成已成为近年来合成领域的研究热点。然而，电化学不对称催化合成的发展仍然较为滞后，其主要原因在于自由基高反应活性、易于电极表面淬灭以及反应体系一般需使用极性电解质等。发展适用于简便易得底物并能实现多种反应类型的模块化电化学不对称催化策略，实现重要手性化合物的高效精准构建，一直是化学家追求的目标。申请人基于前期基础，提出建立电化学与手性氮杂卡宾不对称催化体系，并探索简单酯类化合物即饱和酯及酯活化烯烃与多类型底物的自由基加成或偶联反应，实现在酯基α-或β-位构建富有挑战的全碳四级碳手性中心。将利用不同手性氮杂卡宾的电性以及位阻差异，实现反应的高产率及高对映选择性。本课题不但为电化学不对称催化合成建立新的催化体系，同时有助于明确相关规律以进一步推动这一重要领域的新发展。

Electrochemistry has long been recognized as a powerful tool in radical chemistry. Due to the ability of avoiding the use of oxidants and reductants, this method features higher atom economy than other established radical-producing strategies. As such, the investigation on electrochemical transformations has been a sought-after area in recent years. Nevertheless, control over the stereochemistry of electrochemical reactions remains a significant challenge in organic synthesis, owing to the high reactivity of free radicals, strong tendency of radical quenching on the electrode surface and the inevitable use of polar electrolytes; as a result, this important area in the synthetic union is still underdeveloped, and very limited examples have been reported. In this context, the development of efficient and modular strategies that enable a variety of reaction patterns with diverse readily accessible feedstock chemicals as substrates to precisely construct important enantioenriched compounds is always pursued by chemists. Based on our research works in both electrochemistry and asymmetric organocatalysis, we were intriguing in introducing chiral NHC catalysis into electrochemistry. We would explore the potential of this new catalysis platform in various radical addition and radical cross coupling reactions of simple ester compounds, such as aliphatic esters and ester-activated olefins, with distinct substrates, leading to a large array of valuable ester derivatives containing different highly challenging all-carbon quaternary stereocenters at the α- or β-position of esters. The steric and electronic effects of chiral NHC catalysts as crucial factors would be carefully investigated, to obtain high yields and enantioselectivities for all attempted transformations. We believe that this work will not only provide a novel electrochemical asymmetric catalytic system, but importantly, present feasible inspirations to develop novel cooperative electrochemistry and asymmetric catalysis in the future.