Synthesis of 2-furanyl quinolines via zinc-catalyzed cascade cyclization of enynones with anthranils

A facile Zinc(II)-catalyzed cascade [4 + 2] cyclization of enynones with anthranils was developed to afford a series of 2-furanyl quinolines derivatives with various substituents in up to 91% yield via ring-opening/tandem cyclization. Mechanistic studies indicated that enaminone is an important intermediate, and furylcarbene was employed as a novel 2C synthon unit in this reaction. This protocol is characterized by high step economy, good functional group tolerance, simple operation, and a cheap zinc salt as the catalyst with low toxicity, and provides a new route for the synthesis of 2-furanyl quinolines with a variety of potential biomedical activities.