Synthesis of pyrazolopyranopyrimidines catalyzed by caffeine supported on boehmite nanoparticles and their evaluation for anti-bacterial activities

Abstract

The reaction of 3-chloropropyl boehmite nanoparticles with caffeine and sulfuric acid afforded BNPs-3-propyl-imidazolopyridinium hydrogen sulfate [BNPs-Caff]HSO₄ as a new BNPs-supported ionic liquid (IL) catalyst. [BNPs-Caff]HSO₄ proved to be an efficient heterogeneous catalyst for the synthesis of pyrazolopyranopyrimidines <em>via</em> a one-pot four-component reaction of hydrazine hydrate, ethyl acetoacetate, barbituric acid, and an aldehyde. The attractive features of this method are simple procedure, clean reaction, use of a reusable catalyst, easy workup, and performing a multi-component reaction (MCR) in water. A number of synthesized compounds were screened for their <em>in vitro</em> anti-bacterial activities against the Gram-positive and Gram-negative bacteria using a well-diffusion method.