Electroreductive room-temperature C–H activations with RuCl₃·<i>n</i>H₂O precatalyst <i>via</i> cathodic ruthenium(<scp>iii</scp>/<scp>ii</scp>) manifold

We, herein, disclose a strategy to directly utilize user-friendly RuCl₃·<i>n</i>H₂O for <i>ortho</i>- as well as <i>meta</i>-C-H functionalizations at low temperatures. The key to success was the <i>in situ</i> formation of the active ruthenium catalyst through cathodic electron transfer, setting the stage for C-H activations under exceedingly mild reaction conditions. The robustness of our electrocatalysis process was highlighted by the late-stage diversification of compounds of relevance to chemical, agrochemical, and pharmaceutical industries, as well as simple amines as terminal reductants for the electroreduction. Detailed mechanistic studies by, among others, spectroelectrochemical analysis provided strong evidence for a cathodic reduction manifold.