Sequential meta-/ortho-C–H Functionalizations by One-Pot Ruthenium(II/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.