The preparation of perfluoroaryl substituted isoxazoles via nucleophilic aromatic substitution with lithioalkylisoxazoles

The lithioalkylisoxazoles obtained from C-5 lateral metalation of alkylisoxazoles, 1 , add to hexafluorobenzene. When the C-4 substituent was an electron withdrawing tertiary amide moiety, the yields were highest for mono-perfluoroarylation to give 5-pentafluorophenylmethylisoxazoles, 2 .