在本报告中,我们首次展示了苯乙炔与手性外消旋氯酮的非对映选择性加成。添加量由氯酮的反应性控制,允许立体选择性反应在 -20 °C 下进行。反应中使用手性外消旋氯酮。通过仔细控制温度和反应时间,我们能够以中等产量和良好、简单和可预测的面部立体选择分离出相应的产品。我们的反应是在对映选择性炔基化反应中使用手性酮的罕见例子,并为手性四元立体中心的形成开辟了新的视角。
Catalytic Enantioselective Carbon Insertion into the β-Vinyl C–H Bond of Cyclic Enones
摘要:
Chiral oxazaborolidinium ion-catalyzed C-sp(2)-H functionalization of enones using diazoacetate has been developed. Various beta-substituted cyclic enones were synthesized in high yield (up to 99%) with high to excellent enantioselectivity (up to 99% ee). The synthetic utility of this reaction was demonstrated by the formal synthesis of (+)-epijuvabione.
Highly enantioselective catalytic 1,3-dipolar cycloadditions of α-alkyl diazoacetates: efficient synthesis of functionalized 2-pyrazolines
作者:Sung Il Lee、Ka Eun Kim、Geum-Sook Hwang、Do Hyun Ryu
DOI:10.1039/c4ob02372b
日期:——
Highly enantioselective 1,3-dipolar cycloaddition reactions of α-substituted diazoacetates are accomplished by catalysis of the chiral oxazaborolidinium ion. Functionalized 2-pyrazolines are synthesized in high to excellent enantiomeric ratios (up to >99 : 1). The syntheticutility of 2-pyrazoline was expanded via preparation of 2,4-diamino ester compounds bearing a chiral quaternary carbon center.
π-Coordinating Chiral Primary Amine/Palladium Synergistic Catalysis for Asymmetric Allylic Alkylation
作者:Yaning Wang、Junli Chai、Chang You、Jie Zhang、Xueling Mi、Long Zhang、Sanzhong Luo
DOI:10.1021/jacs.9b13026
日期:2020.2.12
synergistic catalysis for asymmetric allylic alkylation of α-branched β-ketocarbonyls. The use of arene-containing chiral primary amine catalyst led to not only enhanced reaction rate but also reversed chiral induction comparing with its sterically bulky derivative. Both enantiomers of the allylic adducts bearing acyclic all-carbon quaternary stereocenters could be obtained from the same configured chiral aminocatalyst
A Michael addition initiated cyclopropanation/[1,5]-hydrogen shift has been developed for the enantioselective synthesis of Rauhut–Currier products. The reaction of α-alkyl diazoesters and in situ generated o-quinone methides proceeds in the presence of chiral oxazaborolidinium ion, providing Z-stereocontrolled Rauhut–Currier products in high yields (up to 96%) with excellent Z/E selectivities (>20:1)
Catalytic Carbon Insertion into the β-Vinyl C–H Bond of Cyclic Enones with Alkyl Diazoacetates
作者:Sung Il Lee、Byung Chul Kang、Geum-Sook Hwang、Do Hyun Ryu
DOI:10.1021/ol4000026
日期:2013.4.5
The first example of the boron Lewis acid catalyzed C-SP2-H functionalization of cyclic enones was achieved using diazoacetates. The insertion of the carbon atom of diazoacetates utilizes BF3 center dot Et2O or a newly designed oxazaborolidinium ion as a catalyst to afford beta-functionalized cyclic enones from simple cyclic enones In a single step and high yields. The reaction mechanism was investigated with deuterium labeled 2-cyclohexen-1-one.