Synthesis of 4‐(Iso)Quinolinyl‐3(2H)‐furanones from (Iso)Quinoline N‐oxides and 1,4‐Diyn‐3‐ones: A Comparison of Copper Catalysis and Metal‐free Reaction

A facile synthesis of (iso)quinolinyl‐3(2H)‐furanones from (iso)quinoline N‐oxides and 1,4‐diyn‐3‐ones in the presence of copper catalyst or under metal‐free conditions was developed. The resulting (iso)quinolinyl‐3(2H)‐furanones could be easily converted to (iso)quinolinyl‐isoxazoles, pyrazoles and polycyclic (iso)quinoline derivatives. In addition, the success in one‐pot, metal‐free synthesis of isoquinolinyl‐3(2H)‐furanone starts from isoquinoline shows the capacity of this method for the metal‐free derivatization of pyridine, quinoline and isoquinoline.