Photocatalytic Radical Cascade Cyclization of Unsaturated Aldehyde Hydrazones: Access to Difluoroalkylated 1,2‐Diazepines

1,2‐Diazepines as a representative seven‐membered ring azaheterocycles are widely present in natural products and bioactive compounds. The efficient method to construct 1,2‐diazepine motif is still a challenge and is rare. Here, a visible‐light‐catalytic radical cascade cyclization of unsaturated aldehyde hydrazones for the synthesis of difluoroalkylated 1,2‐diazepines was developed for the first time. The reaction was carried out by using Eosin Y as an organic photocatalyst and alkyl difluoroacetates as the key difluoroalkylation reagent. Under mild and metal‐free conditions, various difluoroalkylated 1,2‐diazacyclononanes were efficiently synthesized. The present catalytic protocol paved the way to obtain functionalized 1,2‐diazepines.