Synthesis of 1H-pyrazolo [1,2-b] phthalazine-5, 10 dione derivatives using [SuSA-H]HSO4 as an efficient catalyst

Pyrazoles are important classes of heterocyclic compounds that occur widely in pharmaceutical industry. Synthesis of these compounds is of interest because of their very important pharmacological and biological activities such as antimalarial, antifungal, anti-inflammatory, antimicrobial, fungicide and antitumor [1]. Among these compounds, the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10 dione derivatives is so attracted the attention of many organic chemists that in the past decade [2-3]. Although these procedures provide an improvement, some of these methods suffer from disadvantages such as long reaction times, harsh reaction conditions, need to excess amounts of the reagent, use of toxic solvents or reagents and non-recoverability of the catalyst. Therefore, introducing of simple, efficient and mild procedures to overcome these problems is still in demand. In this work, [SuSA-H]HSO4, is used as an efficient and reusable catalyst for the promotion of the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10 dione derivatives (scheme 1). All reactions were performed under mild conditions and the products were formed over short reaction times in excellent yields.