Thermal or Photoinduced Radical Cascade Cyclization to Access CF₃/SCF₃-Containing Small- and Medium-Membered-Sized...

In this report, an efficient copper-catalyzed radical cascade cyclization of aryl aldehyde-derived hydrazones with a Togni reagent or AgSCF₃ in two directions to access a series of trifluoromethylated five/six/seven-membered heterocycles and trifluoromethylthiolated five-membered heterocycles was developed. The model reaction was extrapolated with 74 examples, affording satisfactory yields for desired products. Further transformation and large-scale experiments were conducted and gave positive results, which paved the way to a broad application of the protocol. Additionally, the same cascade reaction of trifluoromethylation can also be realized through a photochemical approach using 4CzIPN as an organic photocatalyst at room temperature, which might provide a more mild method for constructing valuable heterocycles with biological potential.