Taming Halogen Radicals via Electrophotocatalysis: Direct Access to Alkenyl Halides

Radical halogenation is a fundamental and important reaction in organic synthesis. However, the short lifetimes and high reactivity of halogen radicals hinder the control over reaction selectivity. In this study, an electrophotocatalytic protocol is proposed that enables the selective haloarylation of alkenes using halogen radicals. This protocol circumvents the use of unfriendly radical initiators, toxic halogenating agents, and excessive waste generation and features a low oxidation potential (∼0.25 V vs Ag/AgCl) and effective reaction selectivity control. The robustness of the proposed method is demonstrated on a preparative scale and applied to the late-stage diversification of anti-inflammatory drugs and biologically active molecules. Anticancer treatments in cell lines have demonstrated the pharmacological activities of alkenyl halides, establishing the potential of the proposed method for drug discovery.