ZrO2 nanoparticles: a highly efficient catalyst for solvent-free and mild synthesis of indeno(1,2-b)quinoline derivatives

A novel and practically useful protocol has been designed herein, by a one-pot four-component coupling reaction of 1,3-indanedione, aromatic aldehydes, primary amines, and dimedone catalyzed by commercially available ZrO2 nanoparticles (ZrO2 Nps) to afford the corresponding indeno[1,2-b]quinolinediones in high yields under solvent-free conditions