ABSTRACT We report a visible‐light‐induced, metal‐free approach to the selective N ‐alkylation of quinoxalin‐2(1 H )‐ones using aryl diazo esters. This mild, catalyst‐free protocol runs under ambient conditions and allows access to a wide variety of N‐alkylated products with excellent functional group tolerance. Mechanistic studies suggest the formation of a donor–acceptor carbene intermediate that undergoes selective N–H insertion. This study illustrates the usefulness of visible‐light activation of aryl diazo esters and their utilization as alkylating agents to achieve N–H bond functionalization in heterocycles in a sustainable and efficient manner. Density functional theory calculations provide insight into the mechanism and elucidate the role of π−π interactions in facilitating the reaction.
Hota et al. (Sat,) studied this question.