Gold-Catalyzed Stereoselective Synthesis of Azacyclic Compounds through a Redox/[2 + 2 + 1] Cycloaddition Cascade of Nitroalkyne Substrates

We report a new redox/cycloaddition cascade on readily available 1-alkynyl-2-nitrobenzenes that produces complex azacyclic compounds stereoselectively. The core structures of the resulting products are constructed through a formal [2 + 2 + 1] cycloaddition among α-carbonyl carbenoids, nitroso species, and external alkenes.