Regioselective one-pot synthesis of 3,5-diarylpyrazoles

摘要

The 3,5-diarylpyrazolines and pyrazoles have been easily synthesized in excellent yields by the reaction of 2'-hydroxy-chalcones with hydrazinc hydrate.The 2'-hydroxychalcones arc converted into flavanones and flavones by simple cyclisation methods and then into pyrazolines and pyrazoles,respectively.Alternatively,one-pot synthesis of pyrazoles has also been achieved by converting 2'-hydroxychalcones into pyrazolines and thereafter their dehydrogcnation using I_2-DMSO reagent.The regiochemistry of pyrazoles obtained via pyrazolines and from flavones has been compared.