Synthesis and evaluation of the antimicrobial activity of novel esters, β-diketones, chromones and pyrazoles

In the present investigation, a new series of 2-acetylphenyl 6-chloropyridine-2-carboxylate derivatives were synthesised as the key intermediates and converted into 1,3-diketone derivatives via the Baker-Venkataraman rearrangement, which played a crucial role in the construction of the target chromone and pyrazole frameworks. 1-(6-Chloropyridin-2-yl)-3-(2-hydroxyphenyl)propane-1,3-diones, 2-(6-chloropyridin-2-yl)-4H-chromen-4-ones and 2-(5-(6-chloropyridin-2-yl)-1H-pyrazol-3-yl)phenols were synthesised. 1H-NMR, 13C-NMR and HRMS techniques were used to identify the structures of the synthesized compounds. The in vitro antimicrobial activity of the synthesized compounds was evaluated against three bacterial strains, one yeast and two filamentous fungi using the agar well diffusion method. The synthesized derivatives exhibited variable and organism-dependent antimicrobial activity, with selected compounds showing appreciable inhibition against the tested microorganisms. These results demonstrate the promising antibacterial activity of the synthesized compounds and encourage additional cytotoxicity and quantitative susceptibility testing to assess their biological potential.