Synthesis of indolizine derivatives with selective antibacterial activity against Mycobacterium tuberculosis

1-substituted indolizines with activity against Mycobacterium tuberculosis have been synthesized. The most active compounds carry an hydroxyphenylmethyl- or hydroxyalkyl substituent in the indolizine 1-position. The alkyl chain should be moderately long (C-5 or C-6). Aryl groups in the 2- and 3-position of the indolizine are also required. Removal of the 3-substituent resulted in significant loss of activity. A nitrile substituent in the 7-position is beneficial for both chemical stability and bioactivity. The compounds studied display a narrow antibacterial spectrum and appear to be quite selective antimycobacterial compounds. Moderate activity against certain pathogenic protozoa was also observed.