Guo Shi-Yu, Yang Fan, Song Ting-Ting, Guan Yu-Qing, Min Xiang-Ting, Ji Ding-Wei, Hu Yan-Cheng, Chen Qing-An
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, 116023, Dalian, China.
University of Chinese Academy of Sciences, 100049, Beijing, China.
Nat Commun. 2021 Nov 11;12(1):6538. doi: 10.1038/s41467-021-26857-w.
The Mizoroki-Heck reaction and its reductive analogue are staples of organic synthesis, but the ensuing products often lack a chemical handle for further transformation. Here we report an atom-economical cross-coupling of halopyridines and unactivated alkenes under photoredox catalysis to afford a series of alkene halopyridylation products. This protocol with mild and redox neutral conditions contributes broad substrate scope. As a complement to conventional Heck-type reaction, this radical process avoids the involvement of β-H elimination and thus useful pyridyl and halide groups could be simultaneously and regioselectively incorporated onto alkenes. The success depends on TFA-promoted domino photocatalytic oxidative quenching activation and radical-polar crossover pathway. Plausible mechanism is proposed based on mechanistic investigations. Moreover, the reserved C - X bonds of these products are beneficial for performing further synthetic elaborations.
宫泽-赫克反应及其还原类似反应是有机合成的常用方法，但所得产物往往缺乏用于进一步转化的化学官能团。在此，我们报道了在光氧化还原催化下卤代吡啶与未活化烯烃的原子经济性交叉偶联反应，得到了一系列烯烃卤代吡啶化产物。该反应条件温和且氧化还原中性，底物范围广泛。作为传统赫克型反应的补充，这种自由基过程避免了β-H消除的参与，因此可以将有用的吡啶基和卤化物基团同时且区域选择性地引入到烯烃上。该反应的成功依赖于三氟乙酸促进的多米诺光催化氧化猝灭活化和自由基-极性交叉途径。基于机理研究提出了合理的反应机理。此外，这些产物中保留的C-X键有利于进行进一步的合成修饰。
