Heteropoly Acid in Ionic Liquid - An Efficient Catalyst for the Preparation of 2H-Indazolo[2,1-b]Phthalazine-Triones

2H-Indazolo[2,1-b]phthalazine-1,6,11(13H)-trione derivatives were synthesized in a simple and efficient method from the three-component condensation reaction of phthalhydrazide, dimedone, and aromatic aldehydes by H3PW12O40 in ionic liquid in good to excellent yields and short reaction times. The ionic liquid 1-butyl-3- methylimidazolium tetrafluoroborate ([bmim]BF4) offered the best results in terms of yield of the products. It was observed that a homogeneous reaction medium proved beneficial for the yield of the reaction.