Progress in Synthesis of Oxindoles by Radical Addition-Cyclization

In recent years, there are many reports about the synthesis of oxindoles by radical addition-cyclization. Most of these approaches are catalyzed by different transition metals, or under metal-free and photoredox catalysis conditions using N-arylacrylamides as main substrates. These methods have been a powerful strategy to obtain oxindoles in organic synthesis. At present, the studies on the synthesis of oxindoles by radical addition-cyclization are mainly focused on the types of radicals and the reaction mechanisms. This review will summarize the recent progress of the synthesis of oxindoles by radical addition-cyclization according to the different catalyst systems.