asymmetric Michael reaction between 5H‐oxazol‐4‐ones and α,β‐unsaturated acylimidazoles is reported. A novel 2‐benzo[b]thiophenyl‐modified chiral ProPhenol species is synthesized and used as a ligand, leading to good enantioselectivities in this asymmetric conjugate addition reaction. Furthermore, the introduction of phenol additives as achiral co‐ligands is found to improve the reaction’s chemical yields
据报道,5 H-恶唑-4-酮与α,β-不饱和酰基咪唑之间存在不对称迈克尔反应。合成了一种新型的2-苯并[ b ]硫代苯基修饰的手性脯酚,并用作配体,从而在该不对称共轭加成反应中产生了良好的对映选择性。此外,发现引入苯酚添加剂作为非手性配体可提高反应的化学收率,非对映选择性和对映选择性。
Zinc-Mediated Asymmetric Additions of Dialkylphosphine Oxides to α,β-Unsaturated Ketones and <i>N</i>-Sulfinylimines
作者:Depeng Zhao、Lijuan Mao、Dongxu Yang、Rui Wang
DOI:10.1021/jo1014917
日期:2010.10.15
A catalyst was synthesized on the basis of Trost's dinuclear catalyst characterized by working well without pyridine in the present phospha-Michael reaction Nevertheless, the presence of pyridine is still advantageous in the present system The substrate scope was successfully extended to enones employing diallyl phosphine oxide as a nucleophile Excellent yields and enantioselectivities (up to >99% ee) wine achieved for a wide scope of enones employing the catalyst under mild conditions The detailed reaction mechanism is also discussed hetein Finally. the unprecedented asymmetric additions of dialkylphosphine oxides to N-sulfinylumines were achieved by using Et2Zn as a base