Asymmetric Catalysis with Silicon-Based Cuprates: Enantio- and Regioselective Allylic Substitution of Linear Precursors
作者:Alexander Hensel、Martin Oestreich
DOI:10.1002/chem.201501371
日期:2015.6.15
linear allylic phosphates that makes use of catalytically generated cuprate‐type siliconnucleophiles is reported. The method relies on soft bis(triorganosilyl) zincs as silicon pronucleophiles that are prepared in situ from the corresponding hard lithium reagents by transmetalation with ZnCl2. With a preformed chiral N‐heterocyclic carbene–copper(I) complex as catalyst, exceedingly high enantiomeric excesses
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
Asymmetric Synthesis of α-Chiral Allylic Silanes by Enantioconvergent γ-Selective Copper(I)-Catalyzed Allylic Silylation
作者:Lukas B. Delvos、Devendra J. Vyas、Martin Oestreich
DOI:10.1002/anie.201300648
日期:2013.4.22
way: Regio‐ and enantioselective allylic substitution with a silicon nucleophile generated by copper(I)‐catalyzed SiB bond activation provides direct access to α‐chiral allylicsilanes from linear acceptors. The enantioconvergent catalysis employing McQuade's six‐membered N‐heterocyclic‐carbene–copper(I) catalyst is applicable to aryl‐ and alkyl‐substituted allylic phosphates (see scheme).
The asymmetricallylicsubstitution of allylphosphates with aryl‐ and alkenylboronates catalyzed by a copper/N‐heterocyclic carbene complex was developed and the γ‐substitution products were obtained with high enantioselectivity (see scheme). To account for the observed influence of the reaction parameters a possible catalytic cycle for this process was proposed.