The synthesis of difluoromethylated (CF 2 R) (R=H, alkyl/aryl, CO 2 R, etc.) compounds has received considerable attention in recent years. In this study, the cobalt(III)−carbon-mediated catalytic C−H difluoroacylation of unactivated arenes and heteroarenes using BrCF 2 CO 2 Et is reported. This catalytic cycle is based on a valence change of the cobalt catalyst, a naturally derived vitamin B 12 derivative, driven by controlled-potential electrolysis at −0.8 V vs. Ag/AgCl under visible-light irradiation in dimethyl sulfoxide. A broad substrate scope is demonstrated, and two compounds were characterized according to their X-ray crystal structures. Mechanistic studies showed that the reaction proceeds through a radical pathway mediated by homolytic cleavage of the cobalt(III)–carbon bond. A turnover number of more than 100 was observed, owing to the inherent stability of the vitamin B 12 framework. This naturally derived catalytic system has potential applications in medicinal chemistry and materials science.
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