Synthesis and Antibacterial Evaluation of Novel 3,6-Disubstituted Coumarin Derivatives

<div><p></p><p>A novel series of 3,6-disubstituted coumarin derivatives were synthesized by the reaction of ethyl-2-(3-acetyl-2-oxo-2<i>H</i>-chromen-6-yl)-4-methylthiazole-5-carboxylate with thiosemicarbazide and various phenacyl bromides / 3-(2-bromoacetyl)-2<i>H</i>-chromen-2-ones / 2-(2-bromoacetyl)-3<i>H</i>-benzo[<i>f</i>]chromen-3-one in ethanol having catalytic amount of acetic acid under reflux conditions with good yields. All the synthesized compounds were fully characterized by spectral studies and evaluated for their in vitro antibacterial activity against <i>Pseudomonas aeruginosa</i>, <i>Bacillus subtilis</i> (Gram positive), <i>Escherichia coli</i>, and <i>Azatobacter</i> (Gram negative) bacterial strains. Activity results revealed that the compound <b>6h</b> against <i>Escherichia coli</i> and compound <b>6i</b> against <i>Pseudomonas aeruginosa</i> and <i>Escherichia coli</i> have shown maximum zones of inhibition. Remaining compounds showed moderate to good activity against all the tested bacterial strains compared with the standard drug cefotaxime.</p></div