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m-CAr-H bond functionalization of tertiary phosphines was developed using [Ru(p-cymene)Cl2]2 as a catalyst. Desired product structures were confirmed by single-crystal X-ray diffraction. Mechanistic experiments indicated that m-CAr-H bond functionalization was a radical reaction and that a hexagonal ruthenacycle complex was a crucial intermediate in the process. Therefore, this study provides a novel method for the late-stage meta-position modification of biphenyl monophosphine ligands.

A meta-dehydrogenative alkylation of arenes with cyclic ethers, ketones, and esters catalyzed by ruthenium is achieved in the presence of a di-tert-butyl peroxide (DTBP) oxidant. Interestingly, when quinoline and isoquinoline are employed as the directing group, or a chain ether as alkylation reagent, the system produces Minisci reaction products. Mechanistic study indicates that meta-dehydrogenative alkylation is a radical process initiated by DTBP with the assistance of a CAr-Ru bond ortho/para-directing effect.

The meta-CAr–H alkylation of arenes with radicals produced from AIBN in the presence of a RuCl3 catalyst is presented. This development not only confirmed that ruthenium-catalyzed meta-CAr–H bond functionalization is a radical process, but also provided an efficient and practical strategy for the preparation of aromatic compounds containing a nitrile group, which are prevalent in a diverse range of biologically active molecules and other functional materials.