Merger of Heterogeneous and Homogeneous Photocatalysis for Arene C-H Amination

Given the well-documented photochemical behavior of heterogeneous catalysts and organophotocatalysts, designing a catalysis process that interweaves mechanisms of these distinct catalyst classes is highly desirable. Here, we report a photocatalysis platform that merges heterogeneous and homogeneous photocatalysis for arene C-H amination. In this system, a heterogeneous photochemical looping process is coupled with homogeneous 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) photocatalysis. The catalysis cycle is initiated by the photoexcitation of DDQ that leads to the oxidative coupling of inactivated arenes and nitrogen nucleophiles, yielding aminated products. The reduced DDQ is then involved in a photochemical looping process as a photoreductant, reducing Ag⁺ ions to form Ag nanoparticles, while regenerating DDQ. The resultant Ag nanoparticles reduce molecular oxygen to water, regenerating Ag⁺ ions and, thereby, completing the sustainable catalytic loop. This approach enables aryl C-N bond formation from diverse arenes and nucleophiles with catalytic amounts of DDQ and AgNO₃ under air and visible light irradiation.