2-Substituted benzimidazoles 3a-c was prepared via condensation of ethyl pyruvates 2a-c with 2-phenylenediamine in glacial acetic acid. Pyrrolo[1,2-a]benzimidazole derivatives 5 and 8 were prepared via cyclocondensation of compounds 3a,b with phosphorus oxychloride or acetic anhydride in presence of sodium acetate respectively. Reactivity of pyruvate 2 towards 2-aminophenol, hydroxylamine and cyanothioacetamide was also investigated. They exhibited potent antimicrobial activity comparable to clinical drugs such as ciprofloxacin and ketoconazole. Compounds 3a, 11 and 13 showed excellent antimicrobial activity against all the tested microbes, and Compound 11 showed lower MIC values against all the tested organisms