Metal-Free Synthesis of 3-(Iso)quinolinyl 4-Chromenones and 3-(Iso)quinolinyl 4-Quinolones from (Iso)quinoline N-Oxides and Ynones.

A general approach for the synthesis of 3-(iso)quinolinyl 4-chromenones and 3-(iso)quinolinyl 4-quinolones from (iso)quinoline N-oxides and ynones under metal-free conditions was developed. The reaction of (iso)quinoline N-oxide with the electron-deficient alkyne first generated an (iso)quinolinyl β-diketone intermediate, which then underwent an intramolecular dehydration, affording 3-(iso)quinolinyl 4-chromenones and 3-(iso)quinolinyl 4-quinolones.