Photoredox/Iron Dual-Catalysis-Enabled [4 + 2] Cyclization of Acyl Nitrene with Alkynes

In this work, the annulation of acyl nitrene with alkynes is reported under photoredox/iron dual-catalysis for the synthesis of a series of isoquninalin-2-ones. The reaction is featured with a high reaction regioselectivity and good reaction generality. In particular, the resulting isoquinalin-2-ones could be structurally elaborated into several biologically interesting scaffolds. Mechanism investigation suggests that the reaction was ascribed to a formal [4 + 2] cyclization. It is believed that this reaction represents an initial example of preparing isoquinolin-1-ones from ferric peroxyl-catalyzed nitrene insertion.