α-Allenyl Ethers as Starting Materials for Palladium Catalyzed Suzuki–Miyaura Couplings of Allenylphosphine Oxides with Arylboronic Acids

Abstract

We disclose here the first palladium-catalyzed Suzuki-Miyaura couplings of aryl ethers functionalized allenylphosphine oxides with arylboronic acids. This new methodology with α-allenyl ethers as starting materials provides a novel approach to generate phosphinoyl 1,3-butadienes and derivatives with medium to excellent yields. The reaction tolerates a variety of functional groups to afford ranges of structurally diverse substituted phosphionyl 1,3-butadienes. For unsymmetrical allene substrates, high stereospecific additions to give E-isomers are usually observed. On the basis of the known palladium and allene chemistry, a mechanism is proposed.