1,5-Diaryl-2-ethyl pyrrole derivatives as antimycobacterial agents: design, synthesis, and microbiological evaluation

During the search of novel antitubercular drugs related to BM 212, new diarylpyrroles were designed and synthesized on the basis of a structure–activity relationship analysis of many pyrroles previously described by us. Among them, 1-(4-fluorophenyl)-2-ethyl-3-(thiomorpholin-4-yl)methyl-5-(4-methylphenyl)-1H-pyrrole (2b) proved to be particularly active, with a minimum inhibitory concentration (MIC, expressed as μg/mL) and a protection index (PI) better than or comparable to those of reference compounds. Also the remaining compounds were very active, although their MIC and PI were in general lower than those of their parent 2-methyl analogues.