Manganese Porphyrin‐Catalyzed C–H Iodination and Bromination with Alkyl Halides through Biomimetic Oxidation

Comprehensive Summary Heme oxygenases catalyze C–H oxidation primarily via the oxygen rebound mechanism to form hydroxylated products. While hydroxylation is the principal pathway in iron‐containing oxygenases and corresponding biomimetic systems, manganese porphyrin analogues can mediate alternative reaction pathways. The oxygen rebound step is much slower in manganese porphyrin systems, permitting radical escape and thereby enabling interception by various nucleophiles. Based on these findings, chlorination, bromination, fluorination, azidation, and isocyanation of unactivated C–H bonds have been accomplished via bioinspired oxidation reactions when related anions were introduced (such as F – , Cl – , Br – , N 3 – and NCO – ). However, the iodination of hydrocarbons in biomimetic systems remains unreported. The susceptibility of I – to oxidation by common oxidants ( e.g. , PhIO) to form I 2 precludes its use as a direct halogen source in biomimetic C–H functionalization. Recently, it has been found that carbon radicals generated by hydrogen atom abstraction (HAA) with a Mn(IV)‐oxo porphyrin can escape the solvent cage and react with halohydrocarbon solvents ( e.g. , CH 2 Cl 2 ) to form chlorinated products. Inspired by this finding, we have achieved manganese porphyrin‐catalyzed C–H iodination using CHI 3 as the halogen source. Furthermore, when the halogen source was replaced with CBr 4 , the bromination of unactivated C–H bonds was also accomplished. In all cases, only the halogenated products were detected, exhibiting satisfactory yields. Mechanistic studies indicate that the active intermediate, Mn(V)‐oxo porphyrin complex (or Mn(IV)‐oxo porphyrin complex), generates carbon radicals by abstracting hydrogen atoms from hydrocarbon substrates. These radicals undergo cage escape and ultimately react with halogen sources to form halogenated products. This strategy offers a potential route for synthesizing iodinated hydrocarbons from simple hydrocarbons under mild conditions.