Rhodium-Catalyzed Decarbonylative Intramolecular Arylation of 2-(1H-Indole-1-carbonyl)benzoic Acids

We developed a redox-neutral synthesis of isoindoloindolone via intramolecular arylation of 2-(1H-indole-1-carbonyl)benzoic acids. This protocol facilitates the formation of various substituted isoindoloindolones in yields ranging from 17% to 80%. Our mechanistic investigations indicate the pivotal role of NaI: the iodide anion promotes the formation of the desired isoindoloindolone, and the sodium cation suppresses the formation of acylated byproducts, thereby enabling the selective formation of isoindoloindolones in acceptable yields.