Synthesis and in vitro antimicrobial activity of new 2-[p-substituted-benzyl]-5-[substituted-carbonylamino]benzoxazoles

Some new 2-(benzyl/p-chlorobenzyl)-5-[(substituted-thienyl/phenyl/phenylthiomethyl/benzyl)carbonylamino]benzoxazole derivatives have been synthesized by reacting 5-amino-2-(benzyl/p-chlorobenzyl)benzoxazoles with appropriate carboxylic acid chlorides. The structures of the synthesized compounds were confirmed by IR, 1H NMR and MASS spectral data. In vitro antimicrobial activities of the compounds were investigated using twofold serial dilution technique against different two Gram-positive, two Gram-negative bacteria and three Candida spp. in comparison with standard drugs. Microbiological results indicated that the newly synthesized 2-(benzyl/p-chlorobenzyl)-5-[(substituted-thienyl/phenyl/phenylthiomethyl/benzyl)carbonylamino]benzoxazole derivatives (3–12) possessed a broad spectrum of activity having MIC values of 6.25–100 μg/ml against the tested microorganisms. Especially, with an MIC value of 6.25 μg/ml, 2-(p-chlorophenyl)-5-[(2,5-dimethylphenyl)carbonylamino]benzoxazole 4 displayed the same activity against Candida albicans as the standard drug clotrimazole.

In this study, a new series of 2-(benzyl/p-chlorobenzyl]-5-[substituted-thienyl/phenyl/phenylthiomethyl/benzyl)carbonylamino]benzoxazole derivatives (3–12) has been synthesized as the target compounds in order to examine their in vitro microbiological activity against various Gram-positive, Gram-negative bacteria and the different fungi in comparison with several control drugs, including their structure–activity relationship (SAR) studies.Figure optionsDownload as PowerPoint slide