博彩平台

Asymmetric Epoxidation of Unsaturated Ketones Catalyzed by Heterobimetallic Rare Earth–Lithium Complexes Bearing Phenoxy-Functionalized Chiral Diphenylprolinolate Ligand

Qinqin Qian^†,   Yufang Tan^†,   Bei Zhao^*†(赵蓓),   Tao Feng^†,   Qi Shen^†  and   Yingming Yao^*†(姚英明)

^† Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Dushu Lake Campus, Soochow University, Suzhou 215123, China

Org. Lett. 2014, 16, 4516-4519

Four novel heterobimetallic complexes [REL2]{[(THF)3Li]2(μ-Cl)} stabilized by chiral phenoxy-functionalized prolinolate (RE = Yb (1), Y (2), Sm (3), Nd (4), H2L = (S)-2,4-di-tert-butyl-6-[[2-(hydroxydiphenylmethyl)pyrrolidin-1-yl]methyl]phenol have been synthesized and characterized. These readily available complexes are highly active in catalyzing the epoxidation of α,β-unsaturated ketones, while the enantioselectivity varies according to the ionic radii of the rare earth center. A series of chalcone derivatives were converted to chiral epoxides in 80 → 99% ee at 0 °C using TBHP as the oxidant in the presence of 10 mol % of 1.

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