Pd(II)-catalyzed carboxylation of aromatic C─H bonds with CO₂

The carboxylation of nonactivated C─H bonds provides an attractive yet hitherto largely elusive chemical process to synthesize carboxylic acids by incorporation of CO₂ into the chemical value chain. Here, we report on the realization of such a reaction using simple and nonactivated arenes as starting materials. A computationally designed Pd(II) complex acts as organometallic single-component catalyst, and apart from a base, necessary for thermodynamic stabilization of the intermediates, no other additives or coreagents are required. Turnover numbers up to 10² and high regioselectivities are achieved. The potential of this catalytic reaction for "green chemistry" is demonstrated by the synthesis of veratric acid, an intermediate for pharmaceutical production, from CO₂ and veratrol.