Carbocation-Catalyzed Intramolecular and Intermolecular Carbonyl-Alkyne Metathesis Reactions

The carbonyl-alkyne metathesis (CAM) reaction is a versatile, stereoselective, and atom-economical method to access a diverse range of alpha,beta-unsaturated carbonyl compounds, which are useful synthetic precursors and constitute an important structural motif in biologically active substances. In this work, we developed an efficient organic Lewis acid catalytic system to promote both the intramolecular and intermolecular CAM reactions. This type of versatile catalytic activity has been rarely demonstrated for other established CAM catalysts. Our metal-free protocol was applied to a broad range of substrates to produce a diverse family of useful organic structures.