Tetrabutylammonium bromide (TBAB) in isopropanol: An efficient, novel, neutral and recyclable catalytic system for the synthesis of 2,4,5-trisubstituted imidazoles

A simple, efficient and eco-friendly procedure has been developed using tetrabutylammonium bromide (TBAB, 10 mol%) as novel neutral ionic liquid catalyst for the synthesis of 2,4,5-triaryl imidazoles by a three-component, one-pot condensation of benzil, aryl aldehydes and ammonium acetate in refluxing isopropanol. The present methodology offers several advantages such as excellent yields, shorter reaction times (15-30 min) and environmentally benign milder reaction conditions: moreover, the catalyst in isoproparrol solvent exhibited reusable activity. (C) 2008 Elsevier B.V. All rights reserved.