Electrocatalytic C–H Activation

Abstract

C–H activation has emerged as a transformative tool in molecular synthesis, but until recently oxidative C–H activations have largely involved the use of stoichiometric amounts of expensive and toxic metal oxidants, compromising the overall sustainable nature of C–H activation chemistry. In sharp contrast, electrochemical C–H activation has been identified as a more efficient strategy that exploits storable electricity in place of byproduct-generating chemical reagents. Thus, transition-metal catalysts were shown to enable versatile C–H activation reactions in a sustainable manner. While palladium catalysis set the stage for C(sp2)–H and C(sp3)–H functionalizations by N-containing directing groups, rhodium and ruthenium catalysts allowed the use of weakly coordinating amides and acids. In contrast to these precious 4d transition metals, the recent year has witnessed the emergence of versatile cobalt catalysts for C–H oxygenations, C–H nitrogenations, and C–C-forming [4+2] alkyne annulations. Thereby, the use of toxic and expensive silver(I) oxidants was prevented, improving the environmentally benign nature of C–H activation catalysis. Herein, we summarize the recent major advances in organometallic activations of otherwise inert C–H bonds by electrocatalysis through May 2018.