Synthesis of 4H-1,3-Benzoxazines via Metal- and Oxidizing Reagent-Free Aromatic C-H Oxygenation

An unprecedented electrochemical aromatic C-H oxygenation reaction for the synthesis of 4H-1,3-benzoxazines from easily available N-benzylamides is reported. These oxidative cyclization reactions proceed in a transition metal- and oxidizing reagent-free fashion and produce H₂ as only theoretical byproduct. Adapting the C-H oxygenation reaction in an electrochemical microreactor has been demonstrated.