Zirconium dioxide efficiently promoted the synthesis of pyrano[2,3-c] pyrazole derivatives under Solvent-free conditions

Pyranopyrazoles are an important class of heterocyclic compounds. They have some applications such as pharmaceutical ingredients and biodegradable agrochemicals. At first, pyranopyrazole was synthesized by the reaction of 3-methyl-1-phenylpyrazolin-5-one with tetracyanoethylene [1]. Various pyrano[2,3-c] pyrazoleswere prepared by the different methods [2-5]. In this work, we have reported an efficient and eco-friendly four-component reaction condensation protocol in solvent less and neutral media using ZrO2 as catalyst at 80oC (Figure1). Some advantages for the presented methodology are efficiency, generality, high yields, very short reaction times, cleaner reaction profile and simplicity.