(Pd/C/K-10)-Catalyzed One-Pot Synthesis of Substituted Pyrazoles

Significance

Reported is a one-pot synthesis of 1,3,5-trisubstituted pyrazoles from chalcones and hydrazines. This strategy involves a tandem cyclization-dehydrogenation process, which combines bifunctional (metal/solid acid) heterogeneous catalysis with microwave irradiation under solvent-free condition. The presence of solid acid ensures rapid cyclization to dihydropyrazoles which effectively undergo dehydrogenation by Pd metal to afford the trisubstituted pyrazoles in good yields. The functional group tolerance and scope of substrates were not adequately investigated.