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

Reaction of 2-(dicyclohexcylphosphino)phenylferrocene with sodium tetrachloropalladate in the presence of 1 equiv of (R)-N-acetylphenylalamine in MeOH/H2O/CH2Cl2 at pH 8 resulted in the formation of bis(mu-chloro)bis-[2-(2-(dicyclohexylphosphino)phenyl)ferrocene-C-I, P]dipalladium(II) with a 59% enantiomeric excess of the S-p planar chiral palladacycle. Similarly, (dimethylamitionmethyl)ferrocene gave (S-p)-bis-(mu-chloro)bis[2-(dimethylaminomethyl)ferrocene-C-I, 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.