H3PW12O40 as an efficient catalyst for one-pot- tricomponent synthesis of chromeno[4,3-b]quinolones under microwave irradiation

Some Chromeno[4,3-b]quinoline derivatives were synthesized in a tricomponents one-pot reaction of 1,3-cyclohexadione arylaldehydes and 4-aminocoumarin under Microwave irradiation in the solventless system by using a heteropolyacid catalyst ,H3[PW12O40] in 80-95% yields and high rates. The shorter reaction times, one-pot, good yields, simple work-up procedure and environmentally friendly conditions are the main advantages of this method compared to the two step method. Heteropolyacid is separated by filtration and the products were purified by flash column chromatography. The reactions were monitored by TLC and subsequent work-up afforded a single compound by TLC in each case. The product was identified by its 1H NMR, mass and IR spectra, which were compared to those reported previously.

Keywords:

Chromeno[4 , 3-b]quinoline , heteropolyacid , 1 , 4-dihydropyridines