Synthesis and Study of Analgesic Activity of Some Novel Ferrocenyl Derivatives of Pyrazole Analogues

Pyrazoles have been studied for over a century as an important class of heterocyclic compounds and continue to attract considerable interest due to the broad range of biological activities they possess. The incorporation of the essential structural features of pyrazoles with a ferrocene moiety could provide new derivatives with unexpected and/or enhanced biological activities since several ferrocene derivatives have already been shown to be active against a number of tumors. For this reason, we investigated the synthesis of ferrocenyl-substituted pyrazoles, such as sI-alkyl/aryl-5ferrocenylpyrazoles, by employing the reaction between (2-formyl-1-chlorovinyl) ferrocene and hydrazine derivatives. Although this reaction is known, it was not studied in much detail and the low yields of ferrocenyl pyrazoles were obtained. Thus, I had reinvestigated this reaction and improved the yields of pyrazoles by optimizing the reaction conditions. (2-Formyl-1-chlorovinyl) ferrocene was first reacted with the excess amount (3 equivalents) of hydrazine derivative at 25 0 C in dioxane under argon for 2 hours, and the resulting mixture was then heated at 100 0 C for 6 hours in the same solvent.