Palladium-Catalyzed Nucleophilic Reaction of Alkylidenecyclopropanes with β,γ-Unsaturated α-Ketoesters: Ligand-Controlled Divergent Synthesis.

A palladium-catalyzed ligand-controlled selective 1,4-addition and cycloaddition reaction of β,γ-unsaturated α-ketoesters with alkylidenecyclopropanes (ACPs) has been developed. Using ACPs and β,γ-unsaturated α-ketoesters as starting materials, γ-dienyl-α-ketoesters and dihydro-2 H -pyrans could be prepared selectively by modulating the ligand. A range of multisubstituted α-ketoesters and dihydro-2 H -pyrans were obtained in moderate to excellent yields with excellent regioselectivities.