Synthesis of Cross-Conjugated Polyenes via Palladium-Catalyzed Oxidative C–C Bond Forming Cascade Reactions of Allenes

An efficient palladium-catalyzed oxidative C–C bond forming cascade reaction of allenes involving a coupling between an enallene and an allenyne followed by a carbocyclization of the generated Pd-intermediate was developed. This cascade reaction afforded functionalized cross-conjugated polyenes. The enallene is initially activated by palladium and reacts with the allenyne to give the cross-conjugated polyenes.