Palladium(II)-Catalyzed Asymmetric Coupling of Allylic Alcohols and Vinyl Ethers: Insight into the Palladium and Copper Bimetallic Catalyst

[GRAPHICS] The use of PdX2, CuX2 (X = OAc, OCOCF3, or Cl), and catechol together with (S,S)-4,4'-bisbenzyl-2,2'-bioxazoline under O-2 induces the asymmetric coupling of cinnamyl alcohols and vinyl ethers to give (R)-(+)-2-alkoxy-4-benzylidenetetrahydrofurans in 40-53% ee (79% yield). The present study provides implications for the so-called Wacker catalyst of PdX2 and CuX2, in terms of that the anionic ligands (X) of Pd and Cu interchange between two metals.