One-pot synthesis of 1H-pyrazolo [1,2-b] phthalazine- 5,10-diones catalyzed by Fe3O4/Caffeine under solvent-free conditions

Multi-component reactions (MCRs) are considered to be important concepts of organic chemistry[1]. Heterocyclic compounds containing phthalazine moiety are important in medicinal field due to their pharmacological and biological activities. Pyrazolo[1,2]. Phthalazine-dione derivatives were reported as anti-inflammatory, analgesic, antihypoxic, and antipyretic agents [2]. Fe3O4 magnetite nanoparticles are well known as the most promising nanomaterials for biomedical and catalyst purposes. Easy separation, high thermal stability, high surface area and low toxicity for biological systems make these nanoparticles as an excellent catalyst in organic synthesis even in large scales [3]. Herein, we have reported an eco-friendly multicomponent reaction for the synthesis of Pyrazolo[1,2] phthalazine-dione derivatives using a recyclable Fe3O4/Caffeine hydrogen sulfate as a catalyst. The reaction proceeds by mixing the pthalhydrazide, malononitrile, aldehydes and the catalyst in 80 oC under solvent-free condition to afford the desired products in excellent yield.