Metal-Free Synthesis of Benzisoxazolones Utilizing -Ester and -Cyano-Functionalized Diaryliodonium Salts with Protected Hydroxylamines.

Herein, we report the development of metal-free one/two-pot procedures for the synthesis of benzo[]isoxazol-3(1)-one (benzisoxazolone) heterocycles by designing diaryliodonium salts featuring -ester or nitrile functional groups. These react smoothly with protected hydroxylamines under mild conditions to produce -arylhydroxylamine intermediates, which readily cyclize to give benzisoxazolone derivatives under acidic conditions. This metal-free process maintains the weak N-O bond, tolerates a wide range of diaryliodonium salts and protected hydroxylamines with diverse functional/protecting groups, thereby overcoming the challenges associated with previous transformations.