Visible‐Light‐Induced Cyclization of NHPI Esters With 1,7‐Enynes to Quinolinone‐Fused Carbocycles

This article describes a visible‐light photocatalytic method for the divergent cyclization of 1,7‐enynes using N‐hydroxyphthalimide (NHPI) esters as alkyl radical precursors. Employing fac ‐Ir(ppy) 3 as the photocatalyst together with Lewis acid activation, this strategy efficiently constructs a range of biologically relevant fused polycyclic quinolinones, including benzo[ j ]phenanthridines, indeno[1,2‐ c ]quinolinones, and spirocyclic quinolinones. The study reveals a pronounced substrate‐dependent reaction outcome: by fine‐tuning the character of the radical derived from the NHPI ester (methyl, cyclopropyl, or tertiary carbon radicals vs. other primary/secondary carbon radicals) and the substituents on the acrylamide scaffold, the cyclization pathway can be deliberately directed toward distinct product manifolds, enabling diversity‐oriented synthesis from common intermediates.