Synthesis of pyrazole derivatives containing carbothiohydrazide skeleton via mild approach

Many pyrazole derivatives are acknowledged to possess a wide range of bioactivities. The pyrazole motif makes up the core structureof numerous biologically active compounds [1]. Much attention was paid to pyrazole as a potential antimicrobial agent after the discovery of the natural pyrazole C-glycoside, pyrazofurin which demonstrated a broad spectrum of antimicrobial activity [2]. Pyrazole derivatives containing carbothiohydrazide skeleton are not only useful fragments of antibiotics, but are also used as intermediates and synthons for the production of several organic compounds [3]. This research involved the syntheses of chalcones 1, the cyclization of these chalcones by thiocarbonohydrazide 2 and synthesis of pyrazoline derivatives 3 (Scheme 1). In our studies, we found that ethanol was the solvent most appropriate for these reactions, giving the best results. Under catalysts scanning, the yield of products 3 increased.