Electrochemically Driven Nickel-Catalyzed Halogenation of Unsaturated Halide and Triflate Derivatives |
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Authors: | Ming-Yu Chen Sylvain Charvet Dr. Pierre-Adrien Payard Dr. Marie-Eve L. Perrin Dr. Julien C. Vantourout |
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Affiliation: | UMR 5246, ICBMS, Université de Lyon, Université Claude Bernard Lyon I, CNRS, INSA, CPE Lyon, 1 rue Victor Grignard, 69622 Villeurbanne cedex, France |
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Abstract: | A robust electrochemically driven nickel-catalyzed halogen exchange of unsaturated halides and triflates (Br to Cl, I to Cl, I to Br, and OTf to Cl) is reported. A combination of NiCl2 ⋅ glyme as the precatalyst, 2,2′-bipyridine as a ligand, NMP as the solvent, and electrochemistry allowed the generation of a nickel species that promotes reductive elimination of the desired product. This paired electrochemical halogenation is compatible with a range of unsaturated halides and triflates, including heterocycles, dihaloarenes, and alkenes with good functional-group tolerance. Joint experimental and theoretical mechanistic investigations highlighted three catalytic events: i) oxidative addition of the aryl halide to a Ni(0) species to deliver a Ni(II) intermediate; ii) halide metathesis at Ni(II); iii) electrochemical oxidation of Ni(II) to Ni(III) to enable the formation of the desired aryl halide upon reductive elimination. This methodology allows the replacement of heavy halogens (I or Br) or polar atoms (O) with the corresponding lighter and more lipophilic Cl group to block undesired reactivity or modify the properties of drug and agrochemical candidates. |
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Keywords: | halogenation electrosynthesis nickel catalysis reaction mechanisms electrochemistry |
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