N‐Heterocyclic Carbene Catalyzed Switchable Reactions of Enals with Azoalkenes: Formal [4 + 3] and [4 + 1] Annulations for the Synthesis of 1,2‐Diazepines and Pyrazoles.

Various 1,2-diazepine derivatives are synthesized by regio- and enantioselective formal [4 + 3] annulation reaction between enals and in situ formed azoalkenes.