Synthesis of Fused Tetracyclic Compounds via Oxidative Annulation: Access to Copper-Catalyzed Indolo[1,2‑a]quinolines and to Ruthenium-Catalyzed Isoquinolin-1[2H]‑ones

A facile double oxidative annulation of (en-3-yn-1-yl)­phenylbenzamides was developed allowing us to synthetize fused tetracyclic compounds. Under copper catalysis, the reaction proceeds with high efficiency and leads to new indolo­[1,2-a]­quinolines via a decarbonylative double oxidative annulation. On the other hand, under ruthenium catalysis, new isoquinolin-1­[2H]-ones were obtained via a double oxidative annulation.