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

The carboxylation of nonactivated C─H bonds provides an attractive yet hitherto largely elusive chemical process to synthesize carboxylic acids by incorporation of CO 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 10 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 CO and veratrol.