Synthesis of Pyrrolone‐ and Isoindolinone‐Fused Benzimidazole‐4,7‐diones by Stepwise Palladium‐Catalyzed Carbonylative Cyclization and Oxidation

Abstract

Abstract2‐(2‐Bromovinyl)‐ and 2‐(2‐bromoaryl)‐4,7‐dimethoxybenzimidazoles react with carbon monoxide (10 atm) in toluene in the presence of a catalytic amount of PdCl2 and PPh3 along with NaOAc to produce the corresponding pyrrolone‐ and isoindolinone‐fused 4,7‐dimethoxybenzimidazoles, respectively, in good yields. Oxidation of such binuclear N‐fused hybrid scaffolds with ceric ammonium nitrate in acetonitrile‐H2O gives unprecedented pyrrolone‐ and isoindolinone‐fused benzimidazole‐4,7‐diones in high yields.