Asymmetric Synthesis\nof P‑Chirogenic Ferrocenyl\nBipheP<sub>Fc</sub>* Diphosphine by Ephedrine–Aryne Methods\nand Application in Rhodium-Catalyzed Hydrogenation

Chiral diphosphines with a biphenyl\nbridge and the chirality borne\nby the phosphorus atoms and not due to the atropoisomery of the biaryl\nbackbone have been scarcely studied. Herein, we report the asymmetric\nsynthesis of the (<i>S</i>,<i>S</i>)-2,2′-bis(ferrocenylphenylphosphino)biphenyl\n(BipheP<sub>Fc</sub>*) ligand and its application in Rh-catalyzed\nhydrogenation. The synthesis was based on the enantioselective preparation\nof P-chirogenic ferrocenyl(<i>o</i>-bromophenyl)phenylphosphine\nby the reaction of <i>sec</i>-phosphine-borane with 1,2-dibromobenzene\nand its homocoupling into BipheP<sub>Fc</sub>*. Hydrogenations catalyzed\nby the Rh/BipheP<sub>Fc</sub>* complex led to enantioselectivities\nof ≤96%.