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

Herein, 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. We have disclosed a method for obtaining 3‐aryl heterocycles with good yield and excellent regioselectivity without the need for additional photosensitizers or strong oxidants, and have successfully synthesized bioactive compounds using this method. Computational investigations at the CASPT2//CASSC F/PCM level of theory revealed that a single electron transfer has occurred between the excited state of quinoxalin‐2(1H)‐one and iodonium ylide.