Synthesis and Biological Activities of Camphor Hydrazone and Imine Derivatives

Both sonochemical and classical methodologies have been employed to convert camphor, 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one, C₉H16C=O, into a number of derivatives including hydrazones, C₉H16C=N-NHAr 3, imines, C₉H16C=N-R 7, and the key intermediate nitroimine, C₉H16C=N-NO₂ 6. Reactions of nitroamine 6 with nucleophiles by classical methods provided the desired compounds in a range of yields. In evaluations of activity against Mycobacterium tuberculosis, compound 7j exhibited the best activity (minimal inhibitory concentration (MIC) = 3.12 µg/mL), comparable to that of the antitubercular drug ethambutol. The other derivatives displayed modest antimycobacterial activities at 25-50 µg/mL. In in vitro tests against cancer cell lines, none of the synthesized camphor compounds exhibited cytotoxic activities.