Photocatalyst‐free Synthesis of Oxindoles and Isoquinolinediones via the Radical Reaction of N‐Arylacrylamides with Monoalkyl Cesium Oxalate Salts by Visible Light Catalysis

A photocatalyst‐free cascade reaction of N ‐alkyl‐ N ‐arylmethacrylamides with monoalkyl cesium oxalate salts is described. In the presence of visible light and (NH 4 ) 2 S 2 O 8 , monoalkyl cesium oxalate salts undergo single‐electron oxidation/CO 2 extrusion to generate alkyl radicals, followed by the addition and subsequent cyclization to give alkylated oxindoles. In addition, N ‐alkyl‐ N ‐methacryloylbenzamides could be applied for the cascade reaction, providing a series of alkylated isoquinolinediones, which are completely different from the products obtained with monoalkyl oxalates as substrates.