Abstract A rapid, improved, and environmentally benign synthesis of 4, 4′-aryl or alkyl methylene-bis (1 H-pyrazol-5-ols) has been accomplished by tandem Knoevenagel– Michael reaction of 1-aryl-3-alkyl-1 H-pyrazol-5-ol with various aldehydes catalyzed by ammonium acetate. All the synthesized compounds 3a–v were evaluated in vitro for their antibacterial activity against Pseudomonas aeruginosa, Xanthomonas protophormiae, ...
