Synthesis of difluoromethylated spiropyrazolones via [3 + 2] cycloaddition of difluoroacetohydrazonoyl bromides with alkylidene pyrazolones

Highly functionalized fluoroalkyl spiropyrazolones are synthesized via an effective [3 + 2] cycloaddition of di/trifluoromethyl hydrazonoyl bromides and alkylidene pyrazolones in good yields.