Sequential meta-/ortho-C-H Functionalizations by One-Pot Ruthenium(I/III) Catalysis

Sequential twofold meta-C-H/ortho-C-H functionalization was achieved by means of versatile ruthenium(II) biscarboxylate catalysis. The double C-H activation proved viable in a one-pot fashion with the assistance of synthetically useful imidates. The operationally simple twofold C-H functionalization occurred with high levels of positional selectivity control and was conducted in a nonsequential manner by the judicious choice of the reaction temperature. Detailed experimental mechanistic studies, including unprecedented electron paramagnetic resonance (EPR) experiments, provided strong support for homolytic C-X bond cleavage and facile C-H ruthenation, while a computational density functional theory (DFT) analysis was supportive of a novel mechanistic scenario involving synergistic catalysis via cyclometalated ruthenium(III) complexes as key intermediates.