Synthesis of Planar Chiral Phosphapalladacycles by N-Acyl Amino Acid Mediated Enantioselective Palladation

Reaction of 2-(dicyclohexylphosphino)phenylferrocene with sodium tetrachloropalladate in the presence of 1 equiv of (R)-N-acetylphenylalanine in MeOH/H2O/CH2Cl2 at pH 8 resulted in the formation of bis(μ-chloro)bis[2-(2-(dicyclohexylphosphino)phenyl)ferrocene-C 1 ,P]dipalladium(II) with a 59% enantiomeric excess of the p S planar chiral palladacycle. Similarly, (dimethylaminomethyl)ferrocene gave (p S)-bis(μ-chloro)bis[2-(dimethylaminomethyl)ferrocene-C 1 ,P]dipalladium(II) in 96% ee. An intramolecular isotope effect of 2.3 was observed for the palladation of 2-(diphenylphosphino)phenylferrocene under these conditions.