Oxygen-Promoted 6-<i>endo</i>-trig Cyclization of β,γ-Unsaturated Hydrazones/Ketoximes with Diazonium Tetrafluoroborates for Pyridazin-4(1<i>H</i>)-ones/Oxazin-4(1<i>H</i>)-ones
An oxidative 6-endo-trig cyclization and [2 + 2] cycloaddition of β,γ-unsaturated hydrazones/ketoximes and diazonium tetrafluoroborates for a synthetic strategy to pyridazin-4(1H)-ones/oxazin-4(1H)-ones under metal-free conditions is presented in a one-pot procedure. This protocol features excellent functional group tolerance and remarkable regioselectivity. A mechanistic study has been verified via
β,γ-不饱和腙/酮肟和四氟硼酸重氮盐的氧化6-内三环化和[2 + 2]环加成合成哒嗪-4(1 H)-酮/恶嗪-4(1 H )-在无金属条件下的产物以一锅法进行呈现。该方案具有优异的官能团耐受性和显着的区域选择性。通过18 O 标记和 H 2 18 O 标记方法验证了机理研究,其中 O 2既充当反应组分又充当氧化剂。