Gold(I)-Catalyzed [4 + 2] Annulation between Arylynes and C,N-Diaryl Nitrones for Chemoselective Synthesis of Quinoline Scaffolds via Gold Acetylide Intermediates

Gold-catalyzed synthesis of quinoline derivatives via [4 + 2] annulation between terminal arylynes and nitrones is described. Our mechanistic analysis supports the participation of alkynylgold intermediates, instead of a typical gold–carbene species in recently reported gold catalysis. These nucleophilic alkynylgold species react with nitrones via Povarov-type reactions. Cheap, readily available materials and a broad substrate scope manifest the advantage of this method.