Site-selective electrochemical carboxylation of aromatic C(sp2)–H bonds with CO2

We present a facile and economical method for synthesizing aromatic carboxylic acid derivatives through direct electrochemical C(sp2)–H carboxylation of (hetero)arenes with CO2. The reaction is carried out using a graphite felt anode and a nickel foam cathode in a user-friendly undivided cell setup under constant current conditions. Corresponding methyl carboxylates are obtained smoothly with good site-selectivity without the need of harsh chemical reductants or toxic transition metal catalysts. A cyclic voltammetry study was conducted, to distinguish between two potential mechanistic pathways. Additionally, nBu4NI was identified to serve as both electrolyte and anodic mediator. Notably, the methodology allows direct access to the desired product in a scale up manner.