Electro-reductive carboxylation of acyclic C(sp³)–C(sp³) bonds in aromatic hydrocarbons with CO₂

Despite the recent advances in the selective functionalization of C–C bonds in specific substrates, cleavage and functionalization of C–C bonds in acyclic substrates, such as ethane derivatives, remains challenging. In contrast to the well-developed functionalization of one carbon fragment after C–C bond cleavage, herein, we report a novel electro-reductive carboxylation of C (sp³)–C(sp³) bond in multi-aryl ethanes with carbon dioxide (CO₂) by utilizing both carbon fragments. Thus, this reaction exhibits an atom-, step-economic approach for the synthesis of carboxylic acids, fulfilling principal aspirations of organic synthesis. Moreover, this method features mild reaction conditions, broad substrate scope, and good functional group tolerance. Symmetric and asymmetric substrates bearing primary, secondary, or tertiary C(sp³)–C(sp³) bonds are all amenable to this strategy, enabling one or two structurally different carboxylic acids to be facilely constructed at the same time. Mechanistic investigations indicate that carbanions might be the key intermediates in this reaction, which could be captured by CO₂ efficiently.