Highly Enantioselective 6π Photoelectrocyclizations Engineered by Hydrogen Bonding
Highly Enantioselective 6π Photoelectrocyclizations Engineered by Hydrogen Bonding
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DOI：
10.1021/jacs.3c10782
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发表时间：
2023-12-05
影响因子：
15
通讯作者：
Yoon，Tehshik P.
中科院分区：
文献类型：
--
作者：
Swords，Wesley B.;Lee，Hanna;Yoon，Tehshik P.
光化学电环化反应因其产生结构复杂分子的能力和在阐明光化学基本机制原理方面的核心作用而受到重视。本文提出了一种手性Ir（III）光敏剂催化的高对映选择性6π光电环化反应。这种转化是通过在催化剂上的吡唑基团和底物上的咪唑基酮之间的强氢键相互作用而成功实现的。为了阐明立体感应的起源，我们进行了实验和计算机制研究相结合的全面调查。密度泛函理论计算的结果强调了前手性和扭矩选择性在电环化过程中的关键作用，以及随后[1,4]-H移位步骤中的空间需求。本研究结果不仅为开发手性光催化剂提供了有价值的指导，而且为在6π光电环化反应中实现高水平的对映体选择性提供了重要参考。
Photochemical electrocyclization reactions are valued for both their ability to produce structurally complex molecules and their central role in elucidating fundamental mechanistic principles of photochemistry. We present herein a highly enantioselective 6π photoelectrocyclization catalyzed by a chiral Ir(III) photosensitizer. This transformation was successfully realized by engineering a strong hydrogen-bonding interaction between a pyrazole moiety on the catalyst and a basic imidazolyl ketone on the substrate. To shed light on the origin of stereoinduction, we conducted a comprehensive investigation combining experimental and computational mechanistic studies. Results from density functional theory calculations underscore the crucial role played by the prochirality and the torquoselectivity in the electrocyclization process as well as the steric demand in the subsequent [1,4]-H shift step. Our findings not only offer valuable guidance for developing chiral photocatalysts but also serve as a significant reference for achieving high levels of enantioselectivity in the 6π photoelectrocyclization reaction.