C₁-Symmetric Binap Derivative Featuring Single Diferrocenylphosphino-Donor Moiety

Abstract

A C 1 -symmetric chiral bisphosphine, FcPh-Binap (1), which possesses a single diferrocenylphosphino moiety together with a conventional Ph 2 P-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 rhodiumcatalyzed 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.

Recent advances in the metal-catalyzed asymmetric synthesis of chiral allenes

“…Later in 2021, the same group further reported a novel C 1 -symmetric chiral bisphosphine L34 and employed it in the same reaction (Scheme 41B). 59 The newly prepared chiral bisphosphine promoted the reaction smoothly, leading to the corresponding allenes in good yields and exhibiting higher enantioselectivities than the parent BINAP.…”