*2.1. Nitroimidazole as a Starting Point*

Among the diverse scaffolds tested in this approach, the 'nitroimidazole' starting point has been the most successful. The antibiotic 5-nitroimidazole was used for treating bacterial infections of the gut and was also shown to be active on anaerobic bacteria [13]. Metronidazole, a drug still in use for the treatment of amoebic infections, was one of the first successful derivatives of 5-nitroimidazole. CGI-17341, a bicyclic imidazofuran, was one of the derivatives and was found to be a potent anti-Tb molecule [14]. Continued chemistry on this molecule led to several analogs, among which PA-824 (Pretomanid) [15], OPC-67683 (Delamanid) [16] have recently been registered as anti-TB drugs and are constituents of the current Multi drug resistant (MDR) regimen [15,16]. This progression is shown in Figure 1.

**Figure 1.** The progression of 5-Nitoimidazole derivatives.
