C–H functionalization by high-valent Cp*Co(III) catalysis

Significant progress has been accomplished in directed C–H functionalization through the use of earth-abundant and inexpensive first-row transition metals. Among these base metals, Co is especially attractive in view of its versatile applications in C–H functionalization, in both low- and high-valent states. In this vein, catalytic Co(III) species can be generated from the dissociation of a Cp*Co(III) catalyst or through the oxidation of a low-valent cobalt catalyst in the presence of an oxidant. In this feature article, we will discuss the breakthroughs in Cp*Co(III)-promoted C–H functionalization. In this field, C(sp²)–H functionalization has been extensively studied and developed. In contrast, few C(sp³)–H functionalization reactions have been reported.