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.