Metal-Free Induced Tandem Cyclization of 2-Aryl- <i>N</i> -Methacryloyl Indoles via 1,2-Hydrogen Atom Transfer

This article reports a photoredox-catalyzed tandem cyclization of 2-aryl-N-methacryloyl indoles via 1,2-hydrogen atom transfer (1,2-HAT) to rapidly synthesize indolo[2,1-a]isoquinoline derivatives under mild conditions. This method affords a variety of indolo[2,1-a]isoquinoline compounds in good to excellent yields. In contrast to previous reports that relied on transition-metal catalysis or harsh reaction conditions, this strategy offers multiple advantages, including mild and metal-free reaction conditions, a radical tandem reaction mechanism involving a 1,2-HAT process, a wide range of compatible substrates, and excellent tolerance toward functional groups.