Synthesis of Trifluoroethyl Pyrazolines via Trichloroisocyanuric Acid Promoted Cascade Cyclization/Trifluoromethylation of β,γ‑Unsaturated Hydrazones

A novel and efficient protocol for
the construction of trifluoroethyl
pyrazolines has been developed by cascade cyclization/­trifluoro­methyl­ation
reaction of β,γ-unsaturated hydrazones. This strategy
uses cheap and commercially available trichloroisocyanuric acid as
promoter and TMSCF3 as the trifluoromethylating reagent,
which make the trifluoro­methyl­ating process much cheaper.
A wide range of substrates can be applied in this process to afford
the trifluoro­ethyl pyrazolines in good yield.