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Direct C(sp3)–H Cross Coupling Enabled by Catalytic Generation of Chlorine Radicals
- Shields, Benjamin
J., Doyle, Abigail G.
- Journal of the American Chemical Society 2016 v.138 no.39 pp. 12719-12722
- catalytic activity, chlorides, chlorine, cyclohexanes, ethers, free radicals, nickel, oxidation, photolysis, photons, toluene
- Here we report the development of a C(sp³)–H cross-coupling platform enabled by the catalytic generation of chlorine radicals by nickel and photoredox catalysis. Aryl chlorides serve as both cross-coupling partners and the chlorine radical source for the α-oxy C(sp³)–H arylation of cyclic and acyclic ethers. Mechanistic studies suggest that photolysis of a Ni(III) aryl chloride intermediate, generated by photoredox-mediated single-electron oxidation, leads to elimination of a chlorine radical in what amounts to the sequential capture of two photons. Arylations of a benzylic C(sp³)–H bond of toluene and a completely unactivated C(sp³)–H bond of cyclohexane demonstrate the broad implications of this manifold for accomplishing numerous C(sp³)–H bond functionalizations under exceptionally mild conditions.