4CzIPN-^<i>t</i>Bu-Catalyzed Proton-Coupled Electron Transfer for Photosynthesis of Phosphorylated <i>N</i>-Heteroaromatics

2,4,5,6-Tetrakis(3,6-di-<i>tert</i>-butyl-9<i>H</i>-carbazol-9-yl)isophthalonitrile (4CzIPN-^<i>t</i>Bu) was developed as a photocatalyst for the phosphorus-radical-initiated cascade cyclization reaction of isocyanides. By using 4CzIPN-^<i>t</i>Bu as catalyst, we developed a visible-light-induced proton-coupled electron transfer strategy for the generation of phosphorus-centered radicals, via which a wide range of phosphorylated phenanthridines, quinolines, and benzothiazoles were successfully constructed.