Oxidative Cyclization of 1,7‐Dienes Induced by α‐Oxyalkyl/Acyl Radicals to Access Functionalized Benzo[<i>b</i>]azepin‐2‐Ones

A metal‐free cascade oxidative cyclization method has been developed for synthesizing functionalized benzo[ b ]azepin‐2‐ones from 1,7‐dienes using alcohols, ethers, or aryl aldehydes. The reaction generates α‐oxyalkyl or acyl radicals by direct C(sp 3 )H or C(sp 2 )H cleavage, avoiding photocatalysts and transition metals. This approach offers a mild strategy for the synthesis of benzo[ b ]azepine derivatives with high atom economy and efficiency. Mechanistic studies, including radical trapping and high‐resolution mass spectrometry analysis, confirm a radical‐mediated pathway involving cyclization and single‐electron transfer.