Facile Heteropolyacid-Promoted Synthesis of Indeno[1,2-b]quinoline-9,11(6H,10H)-dione Derivatives

An efficient synthesis of indeno[1,2-b]quinoline-9,11(6H,10H)-dione derivatives was reported via four-component coupling reaction of aldehydes, dimedone, 1,3-indandione, and amines in refluxing ethanol or three-component condensation of aldehydes, 1,3-indandione, and 5,5-dimethyl-3-arylamino-cyclohex-2-enone derivatives at 120 degrees C under solvent-free conditions in the presence of a catalytic amount of Preyssler-type heteropolyacid, H14[NaP5W30O110], as a green and reusable catalyst.