Visible‐Light Induced Single‐Atom‐Insertion of Indenes via Aerobic Ring Scission‐Condensation‐Rearomatization

Here we present a photocatalyzed single‐atom insertion of indenes, involving an aerobic ring scission into dicarbonyl intermediates, which subsequently undergo condensation and re‐aromatization to efficiently synthesize isoquinoline and naphthalene derivatives. The use of an inexpensive organic dye as the photocatalyst under aerobic conditions with cheap ammonium acetate (NH4OAc) as the nitrogen source makes this method very practical and environmentally friendly to access isoquinoline. Alternatively, an intramolecular carbon‐atom‐insertion process, involving the Aldol reaction of the dicarbonyl intermediates, affords the naphthalenamine and naphthalen‐2‐ol derivatives. Mechanistic studies support that the superoxide anion radical species mediates the C–C double bond scission of indenes rather than the singlet oxygen intermediate.