Rapid Four-Component Reactions in Water: Synthesis of Pyranopyrazoles Catalyzed by Ammonium Chloride and Their Antimicrobial Evaluation

Abstract

An environmentally benign synthesis of pyranopyrazoles derivatives has been developed by a four-component reaction between aldehyde, malononitrile, hydrazine hydrate and ethyl acetoacetate in the presence of ammonium chloride in water medium. This method follows the principle of green chemistry by using environmentally benign synthetic method along with use of ammonium chloride as a catalyst and green reaction medium. All the derivatives were evaluated for antimicrobial screening against two Gram-negative bacteria, two Gram-positive bacteria and three fungal species. Among all the tested compounds, it was found that compounds N-3, N-4 and N-9 revealed better activity against the Gram-positive rather than the Gram-negative bacteria.