Selenification/Cyclization Reactions of Nonactivated Allyl 1,7-Diene: Access to Seleno-Benzo[<i>b</i>]oxepine Derivatives

A convenient protocol for the synthesis of selenated benzoxepine derivatives via iron(III)-catalyzed 7-endo-trig cyclization has been first established via reaction of 1,7-diene containing nonactivated allyl and dialkyl diselenides under room temperature and air conditions. Research has shown that different dialkyl diselenides could react with a wide range of 1,7-diene to achieve seven-membered products in good to excellent yields. Furthermore, this synthesis was directed to obtain the desired target products, indicating that this approach has an excellent chemical selectivity. With this novel strategy, various benzoxepines bearing different seleno groups could be obtained, making this protocol more efficient and of practical value.