Regioselective Synthesis of 3‐Trifluoromethyl 4‐Subtituted Pyrazoles by [3+2] Cycloaddition of Trifluoroacetonitrile Imines and Nitroalkenes

Abstract An efficient cycloaddition reaction of trifluoroacetohydrazonoyl bromides with nitroolefins was developed, which regioselectively produced 3‐trifluoromethyl‐4‐substituted pyrazoles. The reaction has the advantages of mild conditions, good tolerance of functional groups and simple operation.