Asymmetric Synthesis of P-Chirogenic Ferrocenyl BiphePFc* Diphosphine by Ephedrine–Aryne Methods and Application in Rhodium-Catalyzed Hydrogenation

Abstract

Chiral diphosphines with a biphenyl bridge and the chirality borne by the phosphorus atoms and not due to the atropoisomery of the biaryl backbone have been scarcely studied. Herein, we report the asymmetric synthesis of the (S,S)-2,2′-bis(ferrocenylphenylphosphino)biphenyl (BipheP_Fc*) ligand and its application in Rh-catalyzed hydrogenation. The synthesis was based on the enantioselective preparation of P-chirogenic ferrocenyl(o-bromophenyl)phenylphosphine by the reaction of sec-phosphine-borane with 1,2-dibromobenzene and its homocoupling into BipheP_Fc*. Hydrogenations catalyzed by the Rh/BipheP_Fc* complex led to enantioselectivities of ≤96%.