A Copper‐Catalyzed Synthesis of Pyrroles through Photochemically Generated Acylazirines

A synthesis of highly substituted 2,4‐diacylpyrroles through a Cu‐catalyzed dimerization of acylazirines generated in situ by a photochemical valence isomerization is described. The shown methodology allows the use of simple precursors and a readily available copper(II)‐catalyst. Since the reaction is best performed at elevated temperatures, a method to adjust the temperature of the reaction mixture during this dual light and metal‐induced process was established. Additionally, mechanistic studies of the reaction were performed in order to provide a deeper understanding of the chemistry of 2‐acylazirines.