Synthesis and in vitro antimicrobial evaluation of 4H-pyrazolopyran, -benzopyran and naphthopyran derivatives of 1H-pyrazole

A new series of eight derivatives each of 4-pyrazolyl-4H-pyrazolopyran, -benzopyran and sixteen derivatives of naphthopyran has been synthesized by one-pot base-catalyzed cyclocondensation reactions of 1-phenyl-3-(het) aryl-pyrazole-4-carbaldehyde, malononitrile and substituted pyrazolin-5-ones or dimedone or naphthols respectively. All the synthesized compounds were subjected to in vitro antimicrobial screening against a panel of pathogenic strains of bacteria and fungi. Some of the compounds were found to be equipotent or more potent than commercial antibiotics against most of employed strains.