Phthalazine derivatives have attracted considerable interest over the past decade due to their excellent and wide variety of pharmacological and biological activities[1], such as anticonvulsant, cardiotonic, and vasorelaxant activities[2]. Moreover, fused phthalazines have multiple biological activities such as anti-cancer, anti-fungal, anti-microbial, and antiinflammatory activities[3]. Therefore, the introduction of new methods for the efficient synthesis of fused phthalazines can be useful. In the present study, Ni0.5Mg0.5AlFeO4 magnetic nanoparticles were synthesized using natural gel by the sol-gel method. Ni0.5Mg0.5AlFeO4 MNPs were investigated using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX) vibrating sample magnetometer (VSM) and Transmission electron microscopy (TEM). The magnetic nanoparticles were used as a highly effective and reusable catalyst for the production of 2H-indazolo[2,1-b]phthalazine-triones by the multicomponent reaction of dimedone, arylaldehydes and phthalhydrazide without solvent under microwave irradiation (scheme 1). This new procedure has notable advantages such as operational simplicity, excellent yields, short reaction time, mild reaction condition and easy work up. Also, the catalyst can be easily recovered by a magnetic field and reused for five consecutive reaction cycles without significant loss of activity.
