Synthesis of Arylfurans by Organic‐Solvent‐Free Method Using Phosphoric Acid as a Solvent and Catalyst

Abstract Phosphoric acid when being used as a solvent readily catalysed the cyclization reaction of 1,4‐dicarbonyl compounds to furnish a broad range of arylfuran compounds using the Paal‐Knorr furan synthetic method. The advantages of this synthetic method include an organic‐solvent‐free system, cheap and recyclable catalyst, easy experimental setup under air, short reaction time, wide substrate scope, broad functional group tolerance, eminent atom economy and excellent yields. The recovered acidic catalyst could be reused many times without significant loss in the catalytic activity. The photophysical properties of some selected arylfurans were examined in dilute solution. We found that most of the arylfurans emit in deep blue or violet region with moderate to high absolute quantum yields.