An Improved Procedure for the Three-Component Synthesis of 1 H -Pyrazolo[1,2-B]Phthalazine-5,10-Dione Derivatives Using Basic Ionic Liquid

Abstract

An efficient and green method for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives has been achieved through the one-pot, three-component condensation of aromatic aldehydes, malononitrile or ethyl cyanoacetate, and phthalhydrazide in the presence of 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH) as catalyst in EtOH. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid can be recovered and recycled for subsequent reactions. Moreover, this protocol has the advantages of easy work-up, short reaction time, mild reaction conditions and environmentally benign procedures compared with the reported methods.