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, (1)H 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 microg/ml against the tested microorganisms. Especially, with an MIC value of 6.25 microg/ml, 2-(p-chlorophenyl)-5-[(2,5-dimethylphenyl)carbonylamino]benzoxazole 4 displayed the same activity against Candida albicans as the standard drug clotrimazole.