A Cathodic Hydrogen Atom Transfer Strategy for Electrochemical Carboxylation of Dibenzylic C(sp ³ )H Bonds With CO ₂

Direct carboxylation of C(sp 3 )H bonds with carbon dioxide (CO 2 ) offers an attractive route to value‐added carboxylic acids but remains challenging due to the inertness of both reaction partners. Here, we report a fundamentally distinct electrochemical strategy that enables carboxylation of dibenzylic C(sp 3 )H bonds using hydrogen atom transfer (HAT) species reductively generated at the cathode. This represents a rare example of C(sp 3 )H bond functionalization mediated by cathodically generated HAT species. In contrast to anodic HAT systems that require interelectrode diffusion of reactive intermediates, the present method allows all the elementary steps (HAT species generation, C(sp 3 )H bond cleavage, and CO 2 incorporation) to occur at the same cathode. Consequently, the reaction proceeds efficiently under mild conditions (room temperature, 1 atm CO 2 ) without requiring an external sacrificial redox reagent, affording carboxylation products in good yields (up to 69%) within a short reaction time (2 h). Mechanistic studies support a pathway involving sequential electron transfer‐chemical reaction (EC) and CO 2 ‐coupled electron transfer processes for HAT species generation. This work establishes a mechanistically defined platform for electrochemical dibenzylic C(sp 3 )H bond functionalization.