A three-component cycloaddition of alkyl trifluorodiazoethane for the synthesis of trifluoromethylated isoxazolines

n efficient [2+2+1] cycloaddition reaction of alkyl trifluorodiazoethane with nitrosoarenes and alkynes has been described. This reaction is conducted under mild conditions with CuI as a catalyst in the presence of diisopropylamine, affording a series of trifluoromethylated isoxazolines in up to 96% yield. Furthermore, the reaction tolerates various nitrosoarenes and alkynes and can be applied in large-scale synthesis, which provides an efficient access to trifluoromethylated isoxazolines.