Imidazolium Zwitterionic Molten Salt: An Efficient Organocatalyst under Neat Conditions at Room Temperature for the Synthesis of Dipyrromethanes as well as Bis(indolyl)methanes

Abstract

Abstract An imidazole‐based zwitterionic‐salt, 4‐(3‐methylimidazolium)butane sulfonate (MBS), has been found to be an efficient organocatalyst for the synthesis of dipyrromethanes as well as bis(indolyl)methanes at room temperature under solvent‐free conditions (neat) in high yields. The reaction procedure is very simple and a large variety of aldehydes have been examined under similar conditions for indoles and pyrroles. The catalytic reaction proceeded very smoothly and showed high chemoselectivity. Clean reaction, ease of product isolation/purification, easily accessible reactants, metal and solvent‐free and environmentally friendly reaction conditions are the notable advantages of the present methodology.