Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, Department of Chemistry, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, P. R. China.
Chem Commun (Camb). 2022 Mar 22;58(24):3847-3864. doi: 10.1039/d2cc00369d.
In this review, we summarise the recent applications of pyridinium salts in the radical-mediated difunctionalization of alkenes. Pyridinium salts are a privileged class of compounds that show great utility in natural products and synthetic chemistry. Various organic transformations of pyridinium salts, especially in radical chemistry, have been developed in recent years. We prepared this review based on the two distinguished properties of pyridinium salts in radical transformation: (1) pyridinium salts can easily undergo single electron reduction to deliver X radicals. (2) Pyridinium salts are highly electrophilic so that alkyl radical intermediates can easily add to the pyridine core. Based on the role of pyridinium salts in difunctionalization of alkenes, the main body of this review is divided into three parts: (1) using pyridinium salts as X transfer reagents. (2) Using pyridinium salts as novel pyridine transfer reagents. (3) Using pyridinium salts as bifunctional reagents (X and pyridine). The C2 and C4 selectivity during pyridylation is discussed in detail. We hope that this review will provide a comprehensive overview of this topic and promote the wider development and application of pyridinium salts.
在这篇综述中，我们总结了近年来吡啶盐在烯烃自由基双官能团化反应中的应用。吡啶盐是一类具有重要应用价值的化合物，在天然产物和合成化学中都有广泛的应用。近年来，人们已经开发出了各种吡啶盐的有机转化反应，尤其是在自由基化学中。我们根据吡啶盐在自由基转化中的两个显著特性来准备这篇综述：(1)吡啶盐容易发生单电子还原，生成 X 自由基。(2)吡啶盐具有高亲电性，因此烷基自由基中间体容易与吡啶环加成。基于吡啶盐在烯烃双官能团化反应中的作用，本文综述主要分为三部分：(1)使用吡啶盐作为 X 转移试剂。(2)使用吡啶盐作为新型吡啶转移试剂。(3)使用吡啶盐作为双功能试剂（X 和吡啶）。详细讨论了吡啶化过程中的 C2 和 C4 选择性。我们希望这篇综述能够提供对该主题的全面概述，并促进吡啶盐的更广泛发展和应用。
