PEG1000-Based Dicationic Acidic Ionic Liquid/Solvent-Free Conditions: An Efficient Catalytic System for the Synthesis of Bis(Indolyl)methanes

An efficient procedure has been researched for the solvent-free synthesis of bis(indolyl)methanes via a one-pot reaction of indoles and aldehydes or ketones promoted by PEG1000-based dicationic acidic ionic liquid (PEG1000-DAIL). The catalyst PEG1000-DAIL could be reused seven times with excellent results. Furthermore, through this method, a highly chemoselective reaction of benzaldehyde and acetophenone with indole could be achieved.Keywords:bis(indolyl)methanes;ionic liquids;solvent-free conditions