This doctoral thesis was divided into two main parts. In the first part, ruthenium(II)-catalyzed ortho-C–H alkynylations of diverse benzoic acids were achieved for the synthesis of aromatic alkynes. And meta-C–H activations, including mono- or difluoromethylation and alkylation through the σ-activation of the cyclometallated intermediate were also efficiently developed by ruthenium catalysis. In the second part, the first nickela-electrochemical C–H activation, including C–H amination, challenging secondary alkoxylation and phosphorylation in a dehydrogenative manner employing green and cheap electricity as the oxidant, providing an expedient approach to arylamines, aryl ethers and arylphosphonates. Detailed mechanistic studies including the isolation of catalytically relevant nickel(III) complex, cyclovoltammetry, and computation provided strong support for an oxidation-induced reductive elimination at nickel(III).
