Reaction of CuI with Dialkyl Peroxides: CuII-Alkoxides, Alkoxy Radicals, and Catalytic C–H Etherification

Kinetic analysis of the reaction of the copper­(I) β-diketiminate [Cl2NN]Cu ([CuI]) with tBuOOtBu to give [CuII]–OtBu (1) reveals first-order behavior in each component implicating the formation of free tBuO• radicals. Added pyridine mildly inhibits this reaction indicating competition between tBuOOtBu and py for coordination at [CuI] prior to peroxide activation. Reaction of [CuI] with dicumyl peroxide leads to [CuII]–OCMe2Ph (3) and acetophenone suggesting the intermediacy of the PhMe2CO• radical. Computational methods provide insight into the activation of tBuOOtBu at [CuI]. The novel peroxide adduct [CuI]­(tBuOOtBu) (4) and the square planar [CuIII]­(OtBu)2 (5) were identified, each unstable toward loss of the tBuO• radical. Facile generation of the tBuO• radical is harnessed in the catalytic C–H etherification of cyclohexane with tBuOOtBu at rt employing [CuI] (5 mol %) to give the ether Cy–OtBu in 60% yield.