Facile, four-component, domino reactions for the regioselective synthesis of tetrahydrobenzo[g]quinolines

Facile, four-component domino reactions of 2-hydroxy-1,4-naphthaquinone, aromatic aldehydes, methyl/ethyl acetoacetate and ammonium acetate in ethanol under microwave irradiation at 100 °C afforded tetrahydrobenzo[g]quinoline-5,10-diones regioselectively in good yields. This transformation presumably proceeds via α,β-unsaturated triketone generation/Michael addition/regioselective annulation via intramolecular condensation domino sequence.