发现一种新的MOP配体(1b)(R)-(+)-2-(双(3-三氟甲基苯基)膦基)-2'-甲氧基-1,1'-联萘基比其他MOP配体对映选择性更高用甲酸催化钯催化α,α-二取代的烯丙基酯的不对称还原。还原苯甲酸dl-2-(1-萘基)-3-丁烯-2-基酯得到90%ee的3-(1-萘基)-1-丁烯。的对映体选择性高1B是归因于快速顺-反通过氧化加成烯丙基酯与钯(0)物种形成π烯丙基钯中间体的异构化。的速率顺-反异构化是通过在磁化饱和转移测定11 H NMR。
发现一种新的MOP配体(1b)(R)-(+)-2-(双(3-三氟甲基苯基)膦基)-2'-甲氧基-1,1'-联萘基比其他MOP配体对映选择性更高用甲酸催化钯催化α,α-二取代的烯丙基酯的不对称还原。还原苯甲酸dl-2-(1-萘基)-3-丁烯-2-基酯得到90%ee的3-(1-萘基)-1-丁烯。的对映体选择性高1B是归因于快速顺-反通过氧化加成烯丙基酯与钯(0)物种形成π烯丙基钯中间体的异构化。的速率顺-反异构化是通过在磁化饱和转移测定11 H NMR。
Bidentate Hydroxyalkyl NHC Ligands for the Copper-Catalyzed Asymmetric Allylic Substitution of Allyl Phosphates with Grignard Reagents
作者:Magaly Magrez、Yann Le Guen、Olivier Baslé、Christophe Crévisy、Marc Mauduit
DOI:10.1002/chem.201203969
日期:2013.1.21
Demonstrating their potential: Bidentate alkoxy NHC ligands have been used in the copper‐catalyzed asymmetricallylic alkylation of allylphosphates with Grignard reagents (see scheme). The method provides access to tertiary and quaternary chiral centers with high regio‐ and enantioselectivity. The system is also applied to the synthesis of chiral E,E‐dienes, a key structural motif prevalent in natural
Stereogenic-at-Metal Zn- and Al-Based N-Heterocyclic Carbene (NHC) Complexes as Bifunctional Catalysts in Cu-Free Enantioselective Allylic Alkylations
作者:Yunmi Lee、Bo Li、Amir H. Hoveyda
DOI:10.1021/ja904654j
日期:2009.8.19
detailed herein demonstrate the ability of chiral bidentate N-heterocyclic carbenes to promote directly-without the need for a Cu salt-site- and enantioselective C-C bond forming reactions. Within this context, catalytic allylic alkylations of various allylic phosphates with dialkylzinc and trialkylaluminum reagents, performed with chiral bidentate imidazoliniumsalts and in the absence of a Cu salt, are
本文详述的研究证明了手性双齿 N-杂环卡宾直接促进的能力 - 无需 Cu 盐位 - 和对映选择性 CC 键形成反应。在此上下文中,描述了使用二烷基锌和三烷基铝试剂在手性双齿咪唑啉盐和不存在 Cu 盐的情况下进行的各种烯丙基磷酸酯的催化烯丙基烷基化。无铜转化提供带有三级或(全碳)四级立体中心的产品,具有特殊的位点 - (>98:<2 S(N)2':S(N)2) 和高对映选择性 [高达 97.5:2.5对映体比率(er)]。分离并充分表征了一种手性锌基 N-杂环卡宾 (NHC) 配合物,该配合物用作对映选择性烯丙基烷基化反应的催化剂。光谱和 X 射线晶体学研究表明,在 Zn 双齿复合物中的磺酸盐基团与 NHC 主链的近端苯基取代基同步(相对于最初预期的反)。对相关 NHC-Al 复合物的调查揭示了类似的结构属性。概述的研究提供了关于无铜烯丙基烷基化反应机制的合理原理,该反应涉及二烷基锌或三烷基
Improvements and Applications of the Transition Metal-Free Asymmetric Allylic Alkylation using Grignard Reagents and Magnesium Alanates
作者:David Grassi、Alexandre Alexakis
DOI:10.1002/adsc.201500495
日期:2015.10.12
Two new N-heterocyclic carbene (NHC) ligands have been synthesized and employed in the transition metal-free asymmetric allylic alkylation (AAA) mediated by Grignardreagents and magnesium alanates. The employment of these ligands showed high yields and improved regio- and enantioselectivity in the formation of tertiary and quaternary stereocenters. Moreover, the low catalyst loading (up to 0.3 mol%)
Cu-Catalyzed Asymmetric Allylic Alkylations of Aromatic and Aliphatic Phosphates with Alkylzinc Reagents. An Effective Method for Enantioselective Synthesis of Tertiary and Quaternary Carbons
作者:Monica A. Kacprzynski、Amir H. Hoveyda
DOI:10.1021/ja0478779
日期:2004.9.1
Efficient enantioselective Cu-catalyzed allylicalkylations of aromatic and aliphatic allylic phosphates bearing di- and trisubstituted olefins are disclosed. Enantioselective C-C bond forming reactions are promoted in the presence of 10 mol % readily available chiral amino acid-based ligand (5 steps, 40% overall yield synthesis) and 5 mol % (CuOTf)2 x C6H6. Reactions deliver tertiary and quaternary stereogenic
公开了带有二和三取代烯烃的芳族和脂族烯丙基磷酸酯的有效对映选择性Cu催化的烯丙基烷基化。在 10 mol% 容易获得的手性氨基酸基配体(5 步,40% 总产率合成)和 5 mol% (CuOTf)2 x C6H6 存在下,对映选择性 CC 键形成反应得到促进。反应区域选择性地以 78-96% ee 传递叔和四元立体碳中心。提供了有关配体结构变化对烷基化过程的效率和对映选择性的影响的数据,以及机械工作模型。建议的模型涉及手性 Cu 络合物的双重作用:Cu(I) 中心与烯烃的结合是通过配体羰基之间的两点结合来促进的
A Readily Available Chiral Ag-Based N-Heterocyclic Carbene Complex for Use in Efficient and Highly Enantioselective Ru-Catalyzed Olefin Metathesis and Cu-Catalyzed Allylic Alkylation Reactions
作者:Joshua J. Van Veldhuizen、John E. Campbell、Russell E. Giudici、Amir H. Hoveyda
DOI:10.1021/ja050179j
日期:2005.5.1
ligand does not require optically pure biaryl amino alcohols, its synthesis is significantly shorter and simpler than the related first generation ligands bearing a chiral binaphthyl-based amino alcohol. The chiral NHC ligand can be used in the preparation of highly effective Ru- and Cu-based complexes (prepared and used in situ from the Ag(I) carbene) that promote enantioselective olefin metathesis and