Synthesis of Novel 1,3,5-Trisubstituted Pyrazoles as Potential Hypoglycemic Agents

A novel series of 1,3,5-trisubstituted pyrazoles was synthesized. Thus, ethyl 2,4-dioxo-6-phenylhex-5-enoate (I) was condensed with phenylhydrazine to afford 3-ethoxycarbonyl-1-phenyl-5-styrylpyrazole (II) which on fusion with hydrazine hydrate gave the corresponding acid hydrazide (III). Reaction of III with the appropriate isothiocyanate yielded the disubstituted thiosemicarbazides (IVa-e) which were cyclized into thiotriazoles (Va-e), thiadiazoles (Vla-e) and oxadiazoles (VIIa-). The structure of the newly synthesized compounds was elucidated by elemental analyses, IR and ¹H NMR spectra.