I2/O2‑Promoted Domino Reactions of Isatins or 3‑Hydroxyindolin-2-one Derivatives with Enaminones

I2-promoted domino reactions of isatins or 3-hydroxyindolin-2-one derivatives with enaminones under O2 conditions have been established. The reactions of isatins with enaminones afforded functionalized tetracyclic pyrrolo­[2,3,4-kl]­acridine derivatives in moderate to good yields through domino cyclization and C–H oxidation. The reactions of 3-hydroxyindolin-2-one derivatives with enaminones proceeded well to give functionalized pyrrolo­[2,3,4-kl]­acridine derivatives via tandem ring-opening/recyclization/methyl migration sequences with two C–C bonds cleaved.