Highly Enantioselective Epoxidation of α,β-Unsaturated Ketones Catalyzed by Rare-Earth Amides [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 with Phenoxy-Functionalized Chiral Prolinols

A simple and efficient catalytic enantioselective epoxidation of α,β-unsaturated ketones has been successfully developed, which was catalyzed by rare-earth metal amides [(Me3Si)2N]3RE­(μ-Cl)­Li­(THF)3 (RE = Yb (1), La (2), Sm (3), Y (4), Lu (5)) in the presence of phenoxy-functionalized chiral prolinols at room temperature using tert-butylhydroperoxide (TBHP) as the oxidant. The combination of an Yb-based amide 1 and a chiral proligand (S)-2,4-di-tert-butyl-6-((2-(hydroxy­diphenyl­methyl)­pyrrolidin-1-yl)­methyl)­phenol) performed very well, and both the yields and the enantiomeric excess of the chiral epoxides reached up to 99% and 99% ee.