Tandem Condensation-Cycloaddition of Propargylic Amines with α-Azido Ketones and β-Alkoxy-γ-Azido Enones.

α-Azido ketones and their vinylogous relatives β-alkoxy-γ-azido enones are versatile building blocks for constructing diverse heterocyclic products, but are prone to azide decomposition. Here, we report their condensation with propargylic amines and investigate the fate of the intermediate azido-enamine condensation products, both experimentally and theoretically. Efficient intramolecular cycloaddition was observed for electron-poor azide substrates, and a range of diversely substituted [1,2,3]triazolo[1,5-]pyrazine products is reported.