Acyl Radicals from α‑Keto Acids: Metal-Free Visible-Light-Promoted Acylation of Heterocycles

A general and metal-free visible-light-induced decarboxylative arylation procedure at room temperature was described for the construction of acylated heterocyclic derivatives, such as benzimidazo/indolo­[2,1-a]­isoquinolin-6­(5H)-ones, aroylazaspiro[4.5]­trienones, thioflavones, and so on. This practical arylation procedure was conducted by using 2,4,5,6-tetra­(9H-carbazol-9-yl)­isophthalonitrile (4CzIPN) as a photocatalyst under mild conditions, which avoided the use of an additional base, traditional heating, and metal reagents.