We report a pyridine-based donor–acceptor molecule that exhibits high reactivity as a visible-light photoredox catalyst. This photoredox catalyst enables the formation of radicals from alkyl bromides, which are useful radical precursors that unfortunately do not perform well under reductive conditions, by a direct, photocatalytic reductive cleavage of the C–Br bond. A wide variety of alkyl bromides including unactivated ones can be used under ambient conditions without any additional activating agents to give the C–C coupling products in good yield. Mechanistic studies indicated that the photocatalyst interacts with alkyl bromides through halogen bonding and that the pyridine moiety is important for the progress of the reaction.

中文翻译：

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吡啶基供体-受体分子：一种高反应性有机光催化剂，可通过卤素键还原裂解 C-Br 键

我们报告了一种基于吡啶的供体-受体分子，它作为可见光光氧化还原催化剂表现出高反应性。这种光氧化还原催化剂能够通过 C-Br 键的直接光催化还原裂解，从烷基溴形成自由基，这是有用的自由基前体，不幸的是在还原条件下表现不佳。包括未活化的烷基溴在内的多种烷基溴可在环境条件下使用，无需任何额外的活化剂即可以良好的收率得到 C-C 偶联产物。机理研究表明，光催化剂通过卤素键与烷基溴相互作用，吡啶部分对反应的进行很重要。