Transition-Metal-Free Catalyzed Dehydrative Coupling of Quinoline and Isoquinoline N-Oxides with Propargylic Alcohols

A novel, green, and transition-metal-free protocol for the facile modification of quinoline and isoquinoline derivatives is introduced, starting from readily available and environmentally benign quinoline and isoquinoline N-oxides with propargylic alcohols in the presence of Na₂S₂O₈ or K₂S₂O₈ at 100 °C. The one-pot transformation features the advantages of good functional group compatibility, short reaction time, operational simplicity, and highly efficient reaction system. This protocol, which produces water as the only byproduct, provides efficient and atom-economical access to a class of fascinating quinoline and isoquinoline products in satisfactory yields. The method is effective on the gram scale, thus highlighting the inherent practicality of this methodology.