Copper-Catalyzed Regio- and Stereoselective Three-Component Coupling of Allenyl Ethers with gem -Dichlorocyclobutenones and B 2 pin 2 .

The three-component coupling method for regio- and stereoselective difunctionalization of allenes with allenyl ethers, bis(pinacolato)diboron, and gem -dichlorocyclobutenones as electrophiles was reported, yielding a variety of highly functionalized cyclobutenone products tethering with an alkenylborate fragment. The polysubstituted cyclobutenone products also underwent diverse transformations.