Organocatalytic Enantioselective Michael Addition of Oxazolones to 2‐Enoylpyridine
<i>N</i>
‐Oxides for Assembling of Pyridine
<i>N</i>
‐Oxides Featuring Vicinal Oxygen‐Containing Tetrasubstituted Stereocenters
作者:Yipeng Luan、Anqi Huang、Yuyu Cheng、Xiaohong Liu、Pengfei Li、Wenjun Li
DOI:10.1002/adsc.201900684
日期:2019.9.17
enantioselective Michael addition of 5H‐oxazol‐4‐ones to 2‐enoylpyridine N‐oxides is described. Under mild conditions, a series of optically active pyridine N‐oxides inlaid with oxazolone motif were obtained in high yields (62–99%) with excellent stereoselectivities (84–>99% ee and >20:1 dr). Notably, the method offers a direct synthetic approach to enantioenriched pyridine N‐oxides featured by vicinal
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。
Asymmetric One-Pot Construction of Three Stereogenic Elements: Chiral Carbon Center, Stereoisomeric Alkenes, and Chirality of Axial Styrenes
作者:Anqi Huang、Lili Zhang、Dongmei Li、Yidong Liu、Hailong Yan、Wenjun Li
DOI:10.1021/acs.orglett.8b03492
日期:2019.1.4
An organocatalytic enantioselective method for the synthesis of multiple stereoisomers bearing E, Z configurations, stereogeniccarboncenters, and axially chiral styrenes is reported. The method enabled the rapid construction of a series of stereochemical complexity products with excellent E, Z selectivity, diastereoselectivity (>20:1 dr), and enantioselectivity (up to 96% ee). This method provides