Trifluoromethylation of Aromatic Isoxazoles

Significance

In this work a trifluoromethylation of substituted aromatic isoxazoles is described. The direct nucleophilic addition to the C5 position is achieved by the presence of an electron-withdrawing nitro group on the adjacent C4 position. This reaction leads to 5-trifluoromethyl-2-isoxazolines with the CF₃ substituent on a quaternary carbon center, which is a common structural element of heterocyclic compounds in agro- and medicinal chemistry.