Antibacterial activity and efficient synthesis of 3,4 dihydropyrano [c] chromene derivatives by using ammonium trifluoroacetate (CF3COONH4) catalyst

In this research, we present a three-component method for the preparation of 3,4-dihydropyrano[c]chromene derivatives in the presence of ammonium trifluoroacetate. All the compounds were evaluated for their in vitro antimicrobial activity against different bacterialstrains. Antibacterial behavior of product was studied based on reference Gram-positive and Gram- negative bacteria.
3,4-Dihydropyrano[c]chromenes were synthesized using an efficient condensation of 4-hydroxycoumarin, aryl aldehydes and malononitrile catalyzed by ammonium trifluoroacetate. Different concentrations of analogs and positive control drugs were prepared in DMSO. Inoculums and sterile water were added to the fourteen test tubes each containing 1 mL of test solution at different concentrations. The tubes were incubated for 24h at 37 °C. After the incubation time, the antimicrobial activity was carefully evaluated.
In an optimized reaction condition, the products 4a-j were obtained in high yields under reflux conditions. The antimicrobial screening data revealed that the compounds 4b and 4e have shown good activity against Gram-negative Escherichia spp.
Present methodology offers several advantages such as short reaction time, simple procedure with an easy work-up and mild reaction conditions. We anticipated that the present method will receive the attention of medicinal chemists and be used for elaborate synthesis and pharmaceutical screening of chromenes based molecules.