Creating, Preserving, and Directing Carboxylate Radicals in Ni-Catalyzed C(sp³)–H Acyloxylation of Ethers, Ketones, and Alkanes with Diacyl Peroxides

The reaction of Ni(II) acetate with diacyl peroxides produces high-valence Ni-species capable of catalytic oxidative acyloxylation of C(sp³)–H bonds in ethers, ketones, and alkanes. The desired esters were obtained in 20–82% yields. Computational analysis suggests that activation of the peroxide moiety produces a dynamically interconverting mixture of catalytic Ni-species in the formal Ni(III) state. Remarkably, in these species, coordination of the RCO₂ group at Ni preserves radical character at the carboxylate moiety (i.e., carboxylate radical acts as an “L-ligand”), so the latter can induce fast C–H abstraction. The spirocyclopropyl moiety prevents premature radical decarboxylation via a combination of hybridization factors and stereoelectronic effects. A variety of viable C–H activation patterns were identified experimentally and computationally.