BF₃·OEt₂‑Mediated Cascade Synthesis of 4H‑3,1-Benzoxazines from 2‑Azidobenzaldehydes and Homoallylic Alcohols

Herein, we developed a methodology for the synthesis of 4H-3,1-benzoxazine derivatives by utilizing 2-azidobenzaldehydes and homoallylic alcohols in the presence of BF₃·OEt₂ in moderate to good yields. This reaction proceeds via retro-Prins reaction, followed by nucleophilic attack by azide and subsequent elimination of nitrogen and proton. In addition, the method was successfully applied for the synthesis of triazole compounds via the click reaction.