An expeditious and greener one-pot synthesis of 4H-chromenes catalyzed by Ba(OTf)2 in PEG-water

An expeditious synthesis of 4H-chromenes has been achieved by three-component one-pot condensation of 1,3-diketone, aldehyde, and malononitrile using Ba(OTf)(2) as catalyst in PEG-water at room temperature. Results from various reaction media and different metal triflates as catalysts show that choice of proper catalyst and the solvent system play a key role in the synthesis of 4H-chromene-3-carbonitrile derivatives. The catalyst can be recovered and reused at least five times without loss of activity. The application of an eco-friendly, noncorrosive, and reusable catalytic system with high isolated yield of the products makes this method advantageous.