A Sustainable Synthesis of Functionalized Pyrrole Fused Coumarins under Solvent‐Free Conditions Using Magnetic Nanocatalyst and a New Route to Polyaromatic Indolocoumarins

Abstract A general and environmentally benign one‐pot method has been developed for the library synthesis of biologically important chromeno[ 4, 3‐b ]pyrrol‐4( 1H )‐one derivatives. A three‐component domino condensation of 4‐aminocoumrins, arylglyoxal monohydrates and various nucleophilic substrates, such as, arylamines, malononitrile, ethyl cyanoacetate and cyanoacetamide produced functionalized chromeno[ 4, 3‐b ]pyrrol‐4( 1H )‐ones in presence of magnetically separable Fe 3 O 4 @SiO 2 ‐SO 3 H nanoparticles as solid acid catalyst under solvent free conditions. Furthermore, a two‐component condensation of 4‐aminocoumrins and arylglyoxal monohydrates furnished a series of hydroxy functionalized chromeno[ 4, 3‐b ]pyrrol‐4( 1H )‐ones under similar reaction conditions. The salient features of the present method are mild reaction conditions, reduced reaction time, elimination of hazardous solvents, good…