Efficient Synthesis of 1,4‐Diazepines via Tf2O Promoted [5+2] Annulation of Ynamides with Imidazolidines

Abstract A Tf 2 O‐promoted [5+2] annulation of imidazolidines with ynamides has been developed, providing an efficient and sustainable strategy for the synthesis of 1,4‐diazepines under the mild and metal‐free conditions. A diverse of 6‐aryl/alkyl substituted 5‐amino‐1,4‐diazepines were formed in moderate to excellent yields. This transformation features with broad substrate scope, operational simplicity, environmental compatibility, and atomic economy. This protocol provides a sustainable alternative pathway for the synthesis of N ‐heterocycles.