Nano‐ZnO Catalyzed Green and Efficient One‐Pot Four‐Component Synthesis of Pyranopyrazoles

An efficient zinc oxide nanoparticle catalyzed one‐pot, four‐component synthesis of 6‐amino‐3‐methyl‐5‐cyano‐4‐aryl‐1,4‐dihydropyrano[2,3‐c]pyrazoles from aromatic aldehyde, malononitrile, ethyl acetoacetate, and hydrazine hydrate in aqueous medium is described. Since water was employed as the reaction medium, it serves as a green route for the synthesis of pyrano[2,3‐c]pyrazoles. The advantages associated with the present protocol include nonchromatographic purification technique, use of recyclable heterogeneous nano‐ZnO catalyst in aqueous medium, and short reaction time. It combines successfully the synergistic effect of green chemistry with nanocatalysis.