Asymmetric epoxidation of α,β-unsaturated ketones catalyzed by rare-earth metal amides RE[N(SiMe<sub>3</sub>)<sub>2</sub>]<sub>3</sub>with chiral TADDOL ligands
作者:Haiwen Shan、Chengrong Lu、Bei Zhao、Yingming Yao
DOI:10.1039/d0nj05228k
日期:——
The catalytic asymmetric epoxidation of α,β-unsaturated ketones by tert-butylhydroperoxide (TBHP) has been well established using rare-earth metal amides RE[N(SiMe3)2]3 (RE = La(1), Nd(2), Sm(3), Y(4), Yb(5)) with chiral TADDOL ligands. It was found that the combination of Yb[N(SiMe3)2]3 and chiral TADDOL ligand H2L2 ((4S,5S)-2,2-dimethyl-α,α,α′,α′-tetra-3,5-bis(trifluormethylphenyl)-1,3-dioxolane-4
α的催化不对称环氧化,通过β不饱和酮叔-butylhydroperoxide(TBHP)已经很好地使用稀土类金属酰胺建立RE [N(森达3)2 ] 3(RE = La(上1),钕(2) ,Sm(3),Y(4),Yb(5))和手性TADDOL配体。发现Yb [N(SiMe 3)2 ] 3和手性TADDOL配体H 2 L 2((4 S,5 S)摩尔比为1:1的)-2,2-二甲基-α,α,α',α'-tetra-3,5-双(三氟甲基苯基)-1,3-二氧戊环-4,5-二甲醇)最佳选择,使用DBU作为添加剂,可以以优异的收率(89–99%)和良好至高的对映选择性(57–94%ee)提供所需的环氧化物。各种底物被证明具有官能团耐受性。此外,还进行了克级实验和衍生化实验。