Visible-Light Promoted Catalyst-Free Imidation of Arenes and Heteroarenes

We described herein a catalyst‐free visible‐light photolytic protocol for the imidation of arenes and heteroarenes. N‐Bromosaccharin was identified as a viable and chemoselective nitrogen radical precursor that undergoes controllable homolytic cleavage under ambient light irradiation. The reaction can be applied to a number of arenes and heteroarenes with good chemo‐ and regioselectivity. Mechanistic studies revealed that radical chain termination by electron transfer‐proton transfer (ET‐PT) is the leading productive pathway for the reaction. Light oN: Visible light was found to promote homolysis of N‐bromosaccharin. The generated imidyl radical undergoes facile homolytic substitutions with arenes and heteroarenes to give imidated adducts with good chemo‐ and regioselectivity. Mechanistic studies revealed that radical quenching by electron transfer–proton transfer (ET–PT) is the leading productive pathway for this CH imidation reaction (see scheme).