C1-Symmetric Binap Derivative Featuring Single Diferrocenylphosphino-Donor Moiety

Abstract

A C1-symmetric chiral bisphosphine, FcPh-Binap (1), which possesses a single diferrocenylphosphino moiety together with a conventional Ph2P-substituent, was prepared in enantiomerically pure forms. Ligand 1 is sterically less demanding than Fc-Segphos (A), which has two diferrocenylphosphino groups, and showed higher activity than A in the rhodium-catalyzed asymmetric conjugate addition of phenylboronic acid to 2-cyclohexenone. Ligand 1 was applied in the two palladium-catalyzed asymmetric reactions, namely the synthesis of axially chiral allenes and the intermolecular Heck reaction, and displayed higher enantioselectivity than parent Binap. The Pd/(R)-1 species showed up to 47% ee enhancement over the Pd/(R)-Binap catalyst in the former reaction and up to 39% ee enhancement in the latter.