Palladium-Catalyzed Carbonylative Annulation Reactions Using Aryl Formate as a CO Source: Synthesis of 2-Substituted Indene-1,3(2H)-dione Derivatives.

An efficient synthesis of 2-substituted indene-1,3(2H)-diones from stable and readily available 1-(2-halophenyl)-1,3-diones by employing phenyl formate as a CO source has been developed. The reaction occurred via palladium-catalyzed intramolecular carbonylative annulation using K3PO4 as a base and DMSO as a solvent at 95 °C. In this protocol, the reaction showed a broad substrate scope with good to excellent yields.