Visible-light-driven photocatalytic carboxylation to aromatic carboxylic acids with CO₂

(Hetero)aromatic carboxylic acids and their derivatives attract attention due to their role in the synthesis of several biologically active molecules, active pharmaceutical ingredients, polymers, etc. Carbon dioxide (CO₂) is a prime C1 source for the synthesis of aromatic carboxylic acids because of its nontoxicity, nonflammability, abundance and renewability. Owing to the thermodynamic and chemical inertness of CO₂, traditional carboxylation to aromatic carboxylic acids with CO₂ is always performed under harsh reaction conditions or using stoichiometric metallic reductants. Visible-light-driven carboxylation with CO₂ provides an environmentally benign, mild, and high-efficiency route for the production of aromatic carboxylic acids. This review comprehensively introduces the visible-light-driven preparation of aromatic carboxylic acids through a visible-light-driven oxidative addition and reductive elimination mechanism, binding of aryl (radical) anions which are produced by photoinduced electron transfer (PET) to CO₂, binding of carbon dioxide anion radicals (CO₂˙^-) which are formed by PET to aryl compounds, radical coupling between CO₂˙^- and aryl radicals, and other mechanisms. Finally, this review provides a summary and the future work direction. This article offers a theoretical guidance for efficient synthesis of aromatic carboxylic acids via photocatalysis.