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).