Reaction of Cu(I) with dialkyl peroxides: Cu(II)-alkoxides, alkoxy radicals, and catalytic C-H etherification.

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