General synthetic route to chiral flexible biphenylphosphine ligands: The use of a chiral additive enables the preparation and observation of metal complexes incorporating the enantiopure form

[GRAPHICS] The enantio- and diastereomerically pure metal complex of a chirally flexible BIPHEP ligand is obtained through enantiomer-selective coordination of a BIPHEP-RU complex with enantiopure 3,3'-dimethyldiaminobinaphthyl, DM-DBN, followed by epimerization of the remaining BIPHEP-RU enantiomer to complex with DM-DABN. Thus, an efficient and general synthetic route to a variety of substituted BIPHEP ligands from biphenol and observation of the enantiomerically pure BIPHEP ligands in their Ru(II) complexes are described.