The highly favourable first reports about the antibacterial merits of 5∶5′-dihalogenated salicils and the essentially sulphonamide-like nature of their action on bacteria, led to an improved method of preparation of 5∶5′-dichlorosalicil or “chlorosalicil” for ascertaining its usefulness in human tuberculosis.
The ineffectiveness of chlorosalicil onP. pestis in vivo directed attention to the synthesis of a series of biologically interesting heterocyclic ring-systems, particularly the imidazole and pyrazine types, starting with chlorosalicil, benzil, 2∶2′-dichlorobenzil, anisil, diacetyl andorthoquinones, regarded as cyclic α-diketones.
A total of twenty-eight heterocyclic compounds have been synthesised in this connection. Synthesis of these furnished interesting information regarding the chemistry of imidazoles.
A few representative heterocyclics, now prepared, have been subjected to examination for efficacyin vivo againstP. pestis, which definitely demonstrated reduction of the original toxicity for infected mice of the initial α-diketones following heterocyclic synthesis from the ketones. However these failed to exhibit any curative action. The failure in experimental plague of the compounds studied has not yet been correlated with their possible anti-mycobacterial activities.