Visible‐Light Induced and PIFA Enabled [4+2] Annulation of Alkenes with N‐Aryl Substituted Hydroxamic Acids

In this paper, we reported a facile approach for the preparation of benzo[ c ][1,2]oxazine scaffolds via visible light induced phenyl iodine bis(trifluoroacetate) (PIFA) oxidative [4+2] annulation of vinyl benzenes with N ‐aryl substituted hydroxamic acids. In the transformation, amidoxyl radicals are readily generated via covalent I−O bond formation and photo‐induced I−O cleavage from N ‐aryl substituted hydroxamic acids, and their coupling with vinyl arenes in the form of [4+2] annulation delivers benzo[ c ]‐[1,2]oxazines derivatives. This reaction proceeds in the absence of transition metals and catalysts, exhibiting broad substrate scope of both alkenes and N ‐aryl substituted hydroxamic acids.