A novel approach to the synthesis of 5-trifluoromethyl-3-substituted pyrazoles

The 3-cyano-4-trifluoromethyl-6-phenyl or substituted phenyl 2(1H) pyridones (1) on reaction with hydrazine hydrate, gave exclusively in 5-trifluoromethyl-3-substituted pyrazoles (3) through a novel method. A possible mechanistic pathway for change in the site of nucleophilic attack due to the CF3 group in 2(1H) pyridones is described.