Cobalt-Catalyzed C-C Bond-Forming Reactions via Chelation-Assisted C-H Activation

抄録

The development of chelation-assisted C-H functionalization reactions has long been driven by noble transition metal catalysts, despite the obvious economic benefits of using earth-abundant transition metals. In this context, seminal reports in the literature suggest the potential of cobalt complexes as catalysts for C-H functionalization. This account summarizes our studies on the development of a series of cobalt-based catalysts for chelation-assisted C-H functionalization reactions such as addition of C-H bonds across carbon-carbon multiple bonds (hydroarylation), and coupling between C-H bonds and organic electrophiles. These studies have demonstrated that cobalt catalysts not only serve as mild and cost-effective alternatives to noble metal catalysts for existing C-H functionalizations, but also enable hitherto unknown or difficult transformations, including branched-selective hydroarylation of styrenes and ortho-alkylation using unactivated secondary alkyl halides.