Generation and exploration of new classes of antitubercular agents: The optimization of oxazolines, oxazoles, thiazolines, thiazoles to imidazo[1,2-a]pyridines and isomeric 5,6-fused scaffolds

Tuberculosis (TB) is a devastating disease resulting in a death every 20 s. Thus, new drugs are urgently needed. Herein we report ten classes of compounds-oxazoline, oxazole, thiazoline, thiazole, pyrazole, pyridine, isoxazole,imidazo[1,2-a] pyridine, imidazo[1,2-a] pyrimidine and imidazo[1,2-c] pyrimidine-which have good (micromolar) to excellent (sub-micromolar) antitubercular potency. The 5,6-fused heteroaromatic compounds were the most potent with MIC's as low as < 0.195 mu M (9 and 11). Overall, the imidazo[1,2-a] pyridine class was determined to be most promising, with potency similar to isoniazid and PA-824 against replicating Mtb H(37)Rv, clinically relevant drug sensitive, multi-and extensively resistant Mtb strains as well as having good in vitro metabolic stability. (C) 2012 Elsevier Ltd. All rights reserved.