Fe(CO)5Catalyzed [2+2+1] Cycloaddition of Alkyne, Carbodiimide and CO for the Synthesis of 5-Iminopyrrolones

Under photolytic conditions, mixture of a terminal alkyne, a carbodiimide and CO, in presence of Fe(CO)5, undergoes [2+2+1] cocyclization to form 5-iminopyrrolone. Its formation has been shown to occur via a stable tetracarbonyl(2-aryl/alkyl maleoyl)iron intermediate. Addition of carbodiimide to the intermediate leads to the formation of 5-iminopyrrolone. This work highlights the role of Fe(CO)5 as a catalyst.