Electrochemical Trifluoromethylation/Cyclization of <i>N</i>′-Arylidene-<i>N</i>-acryloyltosylhydrazides for the Synthesis of CF₃-Substituted Pyrazolones

Herein, a mild and efficient synthesis of pyrazolones is disclosed through a sustainable electrochemical method. This electrolysis relied on cascade trifluoromethylation/cyclization by using CF 3 SO 2 Na as a trifluoromethyl source, which occurred directly at the anode. Two C–C bonds were formed to afford a series of novel trifluoromethyl-containing pyrazolone scaffolds without the addition of metals and redox reagents. Further mechanistic results showed that the reaction process may undergo a radical pathway.