Aryl-Radical-Avoiding Decarbonylative Deuteration of Aromatic Carboxylic Acids with D2O via Photoredox–Cobalt Co-Catalysis

Decarboxylative deuteration of readily available aromatic carboxylic acids offers a valuable route to synthesize deuterium-labeled arenes. However, the mainstream aryl-radical pathways are often restrained by the slow generation of aryl radicals and uncontrollable side reactions, making synthesis of deuterated arenes with high activity, chemoselectivity, and functional tolerance markedly challenging. Herein, we report a photoredox/cobalt co-catalyzed aryl-radical-avoiding strategy, enabling the decarbonylative deuteration of aromatic carboxylic acids to deuterated arenes with up to 93% yield and 98% deuterium incorporation using D2O as deuterium source. Multiple characterizations validate that the pathways of arene addition/cyclization, and hydrogen or halogen atom transfer associated with aryl carboxyl radicals and aryl radicals can be suppressed. Furthermore, the wide substrate scope, broad functional-group compatibility, and facile applications to the late-stage deuteration of structurally complex pharmaceuticals and natural product derivatives demonstrate the potential utility.