Synthesis and characterization of new heterocyclic compounds derived from substituted pyrazole-4-carbaldehyde

The pyrazole ring is a five-membered aromatic heterocyclic compound containing two adjacent nitrogen atoms. Moreover, the pyrazole scaffold is considered one of the most important core structures in drug discovery studies. This is due to the wide spectrum of biological activities exhibited by pyrazole derivatives. These activities include antimicrobial, cytotoxic, analgesic, anti-inflammatory, antihypertensive, antiepileptic, and antidepressant effects. In addition, the intensive investigation of pyrazole derivatives as potential drug candidates particularly as antitumor and anti-inflammatory agents has significantly advanced our understanding of treatments for cancer and inflammation-related diseases. Consequently, research into the synthesis, structural analysis, and properties of pyrazoles continues to grow rapidly. In this thesis study, the aim was to contribute to pyrazole chemistry by synthesizing novel pyrazole derivatives with potential biological activity. Initially, a substituted hydrazone derivative was obtained through the condensation of a substituted hydrazine and a substituted acetophenone compound. Based on the synthesized hydrazone, a new substituted pyrazole-4-carbaldehyde derivative was synthesized under Vilsmeier–Haack reaction conditions. Subsequently, novel chalcone derivatives containing the pyrazole ring were obtained via Claisen–Schmidt condensation of the aldehyde derivative with various substituted acetophenones. Finally, various hydrazide hydrazones, cyclic chalcone and thiosemicarbazone derivatives were synthesized from the reaction of the aldehyde compound with various substituted hydrazides, cyclic 1,3-dicarbonyl and thiosemicarbazide compounds. The structures of the synthesized compounds were elucidated using FT-IR, 1H NMR, 13C NMR, and Mass Spectral analyses.