Efficient and Sustainable Strategy for the Synthesis of 1,4-Diazepines via [5 + 2] Annulation of Ynamides with Imidazolidines.

Abstract

A Tf₂O-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.