Palladium-Catalyzed Reactions of Cyclohexadienones: Regioselective Cyclizations Triggered by Alkyne Acetoxylation

Regioselective cyclizations of alkyne-tethered cyclohexadienones can be accomplished under palladium catalysis. The cyclization involves an Initial Pd-mediated acetoxylation of the alkyne, followed by migratory insertion and protonolysis of the resulting palladium enolate. The predictable regloselectivity of these atom-economical and stereoselective reactions is influenced by developing steric interactions during migratory insertion of a vinyl palladium intermediate.