A Rapid and an Efficient Route to the One-pot, Multicomponent Synthesis of 1H-Pyrazolo[1,2-b]phthalazine-5,10-dione Ring Systems

CAN is found to be an efficient catalyst for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives via one-pot coupling reaction of phthalhydrazide, aromatic aldehydes, and malononitrile or ethyl cyanoacetate in PEG as solvent. The major attributes of this synthetic protocol are the use of nontoxic, inexpensive, and readily available catalyst, mild conditions, easy work up, improved yields, and the PEG 400 as solvent that is environmentally benign as well as recyclable.