As one of the major greenhouse gases, carbon dioxide (CO₂) plays a crucial role in global warming and climate change. In another aspect, CO₂ could serve as a green, nontoxic, abundant, and renewable C1 building block for organic synthesis. Thus, the chemical fixation and utilization of carbon dioxide gained increasing interest, especially to construct valuable carboxylic acids, which are pivotal building blocks in the various natural products and pharmaceuticals. In recent years, direct carboxylation reactions of halogenated aromatics and their analogues with CO₂ have been reported successively, but direct carboxylation reactions of complex molecular skeletons with CO₂ are still unachievable.

Recently, Baiquan Wang’ group achieved an efficient copper-catalyzed carboxylation of aryl thianthrenium salts with CO₂ at room temperature. The reaction employs low loading of cuprous chloride catalyst under 1atm CO₂ and exhibits good functional group tolerance. In combination with C−H thianthrenation of aromatic hydrocarbons, this work provides an efficient method for the site-selective C−H carboxylation of aromatic hydrocarbons. It may serve as a significant late-stage carboxylation tool for the modification of drug molecules in the future. Relevant achievements were published in Angew. Chem. Int. Ed., 2022, DOI: 10.1002/anie.202212975.