Enantioselective Synthesis of Chiral Ferrocenyl Aminoalcohols: Simultaneous Induction of Multiple Types of Chirality by a Rhodium‐Catalyzed Asymmetric Ring‐Opening Strategy

Abstract

Chiral ferrocenyl aminoalcohols were enantioselectively synthesized via the rhodium‐catalyzed asymmetric aminative ring‐ opening of 1,4‐epoxy‐1,4‐dihydronaphthalenylferrocenes. A planar chiral phosphine‐olefin ligand consisting of a cyclopentadienyl (Cp) manganese scaffold provided excellent catalytic performance, furnishing the ring‐opening products in high yield and enantioselctivity (up to 99:1 enantiomeric ratio (e.r.)). The enantioselectivity could be further improved by changing the steric congestion in the cyclopentadienyl unit of the ferrocenyl fragment of the starting 1,4‐epoxy‐1,4‐dihydronaphthalenylferrocene. Density functional theory (DFT) calculations confirmed the high enantioselective induction in the ring‐opening reaction, estimating an e.r. of 99:1, which is in excellent agreement with the experimental results. The application of the thus obtained chiral ferrocenyl aminoalcohols as ligands in asymmetric reactions was also investigated.