Synthesis, Characterization, and Application of Segphos Derivative Having Diferrocenylphosphino-Donor Moieties

An axially chiral bisphosphine, Fc-Segphos (1), which possesses diferrocenylphosphino-donor moieties, was prepared as a racemate, and its optical resolution was achieved by the use of chiral HPLC. Ligand 1 coordinated to a palladium(II) cation in a bidentate fashion to construct a unique chiral environment at the palladium center due to the sterically demanding ferrocenyl groups. Ligand (R)-1 was applied in the palladium-catalyzed asymmetric synthesis of axially chiral allenes showing good enantioselectivity of up to 92% ee. In general, (R)-1 displayed better enantioselectivity than the parent Segphos in the palladium-catalyzed reaction, and the Pd/(R)-1 species showed up to 18% ee enhancement over the (R)-Segphos-derived palladium catalyst.