Controllable tertiary amine-promoted photoactivation metal-free carbonylation of aryl sulfonium salts to aryl carboxylic acid derivatives†

Conventional transition metal-catalyzed carbonylative reactions are a powerful tool for the direct incorporation of electrophilic reagents, CO, and nucleophilic reagents into high-value-added products. Although these metal-catalyzed carbonylation strategies can efficiently synthesize carbonylated compounds, metal-free systems remain an attractive direction in carbonylative reactions. Inspired by the achievements in metal-free radical carbonylation, herein we describe a photochemical method for the carbonylation of aryl sulfonium salts using photoexcitation of electron donor–acceptor (EDA) complexes. This strategy is metal-free and widely applicable, enabling ready access to a wide range of aryl carboxylic acid derivatives in a simplified manner. Notably, by choosing different amines, the reaction intermediates can be captured and then quenched stepwise. It has the potential to be a direct green alternative to conventional carbonylation methods for the synthesis of aryl carboxylic acid derivatives.