Red and Orange-Light-Accelerated Rhodium-Catalyzed Oxidative Olefination of Arenes

Transition metal (TM)-catalyzed photoreactions have emerged as powerful tools for synthesizing products that are challenging to obtain under conventional thermal conditions. However, most protocols rely on short-wavelength visible light, such as purple or blue light (<500 nm). Although long-wavelength light (>500 nm) allows for milder conditions, higher chemical selectivity, and deep light penetration, its application in single TM-catalyzed photocatalytic systems is rare. Herein, we present the long-wavelength visible-light-accelerated Rh(III)-catalyzed olefination of arenes bearing an anilide moiety as a directing group. This methodology circumvents the use of external photosensitizers and short-wavelength blue light, owing to the use of a cationic Rh(III) complex. Experimental and computational analyses suggest that the Rh(III) complex initially acts as a C─H activation catalyst, and oxidation of the generated Rh(III) hydride intermediate by oxygen is accelerated by absorption of long-wavelength visible light (> 500 nm).