Photocatalyst‐Free Visible Light‐Induced C(sp2)−H Arylation of Quinoxalin‐2(1H)‐ones and Coumarins

Abstract

AbstractHerein, we describe a visible light‐induced C(sp2)−H arylation method for quinoxalin‐2(1H)‐ones and coumarins using iodonium ylides without the need for external photocatalysts. The protocol demonstrates a broad substrate scope, enabling the arylation of diverse heterocycles through a simple and mild procedure. Furthermore, the photochemical reaction showcases its applicability in the efficient synthesis of biologically active molecules. Computational investigations at the CASPT2//CASSCF/PCM level of theory revealed that the excited state of quinoxalin‐2(1H)‐one facilitates electron transfer from its π bond to the antibonding orbital of the C−I bond in the iodonium ylide, ultimately leading to the formation of an aryl radical, which subsequently participates in the C−H arylation process. In addition, our calculations reveal that during the single‐electron transfer (SET) process, the C−I bond cleavage in iodonium ylide and new C−C bond formation between resultant aryl radical and cationic quinoxaline species take place in a concerned manner. This enables the arylation reaction to efficiently proceed along an energy‐efficient route.