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

Abstract

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.