A Simple and Efficient Metal-Free Synthesis of Tetrasubstituted Pyrroles by Iodine-Catalyzed Four-Component Coupling Reaction of Aldehydes, Amines, Dialkyl Acetylenedicarboxylates, and Nitromethane

The four-component coupling reaction of aldehydes, amines, dialkyl acetylenedicarboxylates, and nitromethane in the presence of molecular iodine as a catalyst furnished the corresponding 1,2,3,4-tetrasubstituted pyrroles under reflux. The products are formed in high yields (65-88%) within 8 hours. The method is simple, efficient, cost-effective, and metal-free.