TEMPO‐Mediated Selective Synthesis of Isoxazolines, 5‐Hydroxy‐2‐isoxazolines, and Isoxazoles via Aliphatic δ ‐C(sp3)‐H Bond Oxidation of Oximes

Selective synthesis of three different bioactive heterocycles; isoxazolines, 5‐hydroxy‐2‐isoxazolines and isoxazoles from the same starting material using TEMPO (2,2,6,6‐Tetramethylpiperidin‐1‐oxyl) as a radical initiator is reported. Selectivity was achieved using different oxidants with TEMPO. The reaction goes through a 1,5‐HAT (hydrogen atom transfer) process resulting in products with good yields. This strategy offers a straightforward route to three different heterocycles from oximes via radical‐mediated C( sp 3 )‐H oxidation.