描述了瑞香内酯 B 的 ABCD 环系的不对称合成。该合成的特点是对高度官能化、对映体富集的硝基烯烃进行串联、双分子内[4+2]/[3+2]环加成,生成五环亚硝基缩醛。环加成建立了六个连续的立体中心,包括具有两个四元立体中心的关键 CD 环连接处。亚硝基缩醛氢解,然后进行酰胺还原和环化,得到AB环。在最后一步中,通过环外烯烃的氢化,A 环上的甲基取代基以正确的构型安装。
Highly Selective Hydrolytic Kinetic Resolution of Terminal Epoxides Catalyzed by Chiral (salen)Co<sup>III</sup> Complexes. Practical Synthesis of Enantioenriched Terminal Epoxides and 1,2-Diols
作者:Scott E. Schaus、Bridget D. Brandes、Jay F. Larrow、Makoto Tokunaga、Karl B. Hansen、Alexandra E. Gould、Michael E. Furrow、Eric N. Jacobsen
DOI:10.1021/ja016737l
日期:2002.2.1
The hydrolytickineticresolution (HKR) of terminal epoxides catalyzed by chiral (salen)Co(III) complex 1 x OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several
Here, we report the discovery of such a phenomenon in nickel/copper-co-catalyzed divergent allylic alkylation of vinyl epoxides and aziridines using alkynes. Under otherwise identical conditions, the use of either strong bisphosphine ligands or hemilabile P,N-ligands leads to bimolecular allylicalkynylation or trimolecular dienyne formation, respectively. DFT calculations provide key insights for
Insertions of Silylenes into Vinyl Epoxides: Diastereoselective Synthesis of Functionalized, Optically Active <i>trans</i>-Dioxasilacyclooctenes
作者:Michel Prévost、K. A. Woerpel
DOI:10.1021/ja906204a
日期:2009.10.14
communication describes a direct route to functionalized nonracemic trans-dioxasilacyclooctenes that involves stereoselective silylene insertions into vinyl epoxides to provide vinyl silaoxetane intermediates. These strained allylic silanes then undergo uncatalyzed allylation of aldehydes to afford trans-dioxasilacyclooctenes. Diastereoselective additions to these alkenes allow efficient transfer of planar
Catalytic Nucleophilic Allylation Driven by the Water–Gas Shift Reaction
作者:Scott E. Denmark、Zachery D. Matesich、Son T. Nguyen、Selena Milicevic Sephton
DOI:10.1021/acs.joc.7b02658
日期:2018.1.5
of this reactionfrom the initial serendipitous discovery to its general synthetic scope is detailed, highlighting the roles of water, CO, and amine in the generation of a more complete catalytic cycle. The use of unsymmetrical allylic pro-nucleophiles was shown to give preferential product formation through the modulation of reaction conditions. Both (E)-cinnamyl acetate and vinyl oxirane were efficiently
钌与烯丙基亲核试剂的醛催化烯丙基化已被证明是在温和条件下形成碳-碳键的有效方法。此反应从最初的偶然发现到其一般合成范围的演变过程都进行了详细介绍,突出了水,一氧化碳和胺在更完整的催化循环生成中的作用。结果表明,使用不对称的烯丙基亲核亲核试剂可以通过调节反应条件来优先形成产物。(E)-肉桂酸乙酸酯和乙烯基环氧乙烷均有效地用于形成抗支链产物(抗/ syn最高> 20:1 )和E-线性产物(最高> 20:1 E / s )Z)分别与芳香族,α,β-不饱和和脂肪族醛形成高选择性。强调了使反应对映选择性的尝试,包括对苯甲醛高达75:25的对映富集。
Structure−Activity Relationships of Antitubercular Nitroimidazoles. 1. Structural Features Associated with Aerobic and Anaerobic Activities of 4- and 5-Nitroimidazoles
作者:Pilho Kim、Liang Zhang、Ujjini H. Manjunatha、Ramandeep Singh、Sejal Patel、Jan Jiricek、Thomas H. Keller、Helena I. Boshoff、Clifton E. Barry、Cynthia S. Dowd
DOI:10.1021/jm801246z
日期:2009.3.12
lipophilic tail conveyed aerobicactivity. Incorporation of a 2-position oxygen atom into a rigid 5-nitroimidazooxazine provided the first 5-nitroimidazole with aerobicactivity. Across both series, anaerobic and aerobicactivities were not correlated and Mtb mutants lacking the deazaflavin-dependent nitroreductase (Ddn) retained anaerobic sensitivity to some compounds. Aerobicactivity appears to be correlated