A four-component domino reaction for the synthesis of novel bridgehead nitrogen-containing pyrido[1,2-d][1,4]diazepines

An efficient one-pot four-component reaction for the synthesis of a new family of novel bridgehead nitrogen-containing pyrido[1,2-d][1,4]diazepines has been described and its mechanism has been proposed, which follows a ring-closure and ring-cleavage pathway. The protocol involved a cyclization through γ-selective C–C bond formation, an intramolecular Michael addition and a ring-opening of a pyranone ring under refluxing conditions with high to excellent yields. The advantages of this methodology, including the use of easily available raw materials and an inexpensive catalyst, an open-air reaction setup, wide functional group tolerance, and gram-scale synthesis, make the developed methodology a practical way to access novel pyrido[1,2-d][1,4]diazepines and functionalized tricyclic or polycyclic fused 1,4-diazepines as well as novel analogs of important biologically active molecules.