Synthesis, hydrolytic stability, and the reaction with nucleophiles of 5(3)-substituted N-isonicotinoyl-3(5)-ferrocenyl-1H-pyrazoles

A series of N-isonicotinoyl-3(5)-ferrocenyl-5(3)-substituted 1H-pyrazoles was obtained as the mixtures of the products by acylation of tautomeric forms of 3-ferrocenyl-5-substituted 1H-pyrazoles with isonicotinoyl chloride. The rate of hydrolysis of the synthesized compounds depended on the electronic effects of the substituents in the pyrazole ring and increased in the following order Me < Ph ≈ COOEt ≪ CF₃. The hydrolysis rate of the synthesized compounds in acidic medium is significantly higher than under neutral conditions, which is associated with the possibility of the redistribution of electron density in the aromatic pyrazole ring upon the pyrazole protonation. The revealed regularities can be used for designing the redox and pH sensors, acylating agents, and antituberculosis agents active against isoniazid-resistant mycobacterium strains.