Synthesis, resolution, and reactivity of benzylmesitylphenylphosphine: a new p-chiral bulky ligand.

The synthesis of P,P'-dimesityl-P,P'-diphenyldiphosphine and benzylmesitylphenylphosphine is described as well as the resolution of the latter ligand by means of homochiral organometallic complexes. The absolute configuration of the phosphine is assigned by NMR spectra, using the homochiral palladacycle as a reference point. The configuration has been confirmed by single crystal X-ray diffraction. Molecular mechanics calculations were performed in [PdCl-(R)-(+)-C10H6CH(Me)NH2(PBnMesPh)], and showed that the rotation around the Pd-P bond is restricted in this complex. [Pd(eta3-2-MeC3H4)Cl(PBnMesPh)] was obtained and used as a precursor in the catalytic hydrovinylation of styrene. Benzylmesitylphenylphosphine has a strong tendency to form phosphapalladacycles by activation of one of the ortho-methyl groups. The formation of this metallacycle from cyclopalladated N-donor derivatives by a ligand-exchange reaction is also described.