Catalytic C-Demethylation of Phenols and Anilines Enabled by a Removable Mono-Directing Group

The activation of unstrained nonpolar C-C bonds, such as C(aryl)-C(alkyl) bonds, remains challenging to achieve. Existing catalytic strategies predominantly rely on bidentate chelating directing groups (DGs) or special substrates. Herein, we report a Ru-catalyzed activation of C(aryl)-C(methyl) bonds enabled by a removable mono-DG. By employing a bulky phosphinite or aminophosphine-DG that can be easily installed and removed later, a methyl group at the ortho position of phenols and anilines can be smoothly deleted under the hydrogenolysis condition. This reaction exhibits a broad substrate scope and excellent functional group tolerance. Mechanistic studies suggest that a Ru-hydride species generated in situ is responsible for the C(aryl)-C(methyl) bond activation, with methane identified as a byproduct.