Construction of 4-Acyl-2-quinolones through Sc(OTf) 3 -Catalyzed Ring-Closing Alkyne-Carbonyl Metathesis.

An atom-economical protocol to construct densely substituted 4-acyl-2-quinolones from N -(2-alkynylphenyl)-α-ketoamides has been developed through Sc(OTf) 3 -catalyzed ring-closing alkyne-carbonyl metathesis. Mechanistic experimental studies support that coordinative interaction between Sc(OTf)) 3 and the substrate, the formation of an oxetene intermediate, and an electrocyclic ring-opening of the oxetene might be involved.