The reaction of hydroxylamine with aryl trifluoromethyl-β-diketones: Synthesis of 5-hydroxy-5-trifluoromethyl-Δ2-isoxazolines and their dehydration to 5-trifluoromethylisoxazoles

Reaction of hydroxylamine hydrochloride with aryl trifluoromethyl-β-diketones affords 5-hydroxy-5-trifluoromethyl-Δ2-isoxazolines rather than the reported 3-trifluoromethylisoxazoles. The structural assignment is based on the analysis of their NMR (1H, 13C and 19F) spectral data and of their dehydration products, 5-trifluoromethylisoxazoles.