Nitrogen-Based Chirality Effects in Novel Mixed Phosphorus/Nitrogen Ligands Applied to Palladium-Catalyzed Allylic Substitutions

A novel series of chiral P,N-ligands was obtained by desymmetrization of the achiral meso-N,N'-dimethyl-1,2-diphenylethane-1,2-diamine backbone and resolution of the resulting adducts. This transformation was achieved by the selective introduction of a diphenylphosphine moiety on one of the two nitrogen centers. The resulting palladium complexes were used for the catalytic enantioselective allylic alkylation of 1,3-diphenyl-1-acetoxy-2-propene with dimethyl malonate. In some cases, high conversions (up to 98% after 1 h) along with good chiral inductions (up to 95% e.e.) were obtained, as a result of a control of the inversion of the stereogenic center formed at nitrogen upon coordination to palladium.