描述了基于咪唑并[1,5- a ]吡啶(ImPy)支架的手性双官能NHC配体的合成和表征。这些配体具有通量的联芳基轴和手性中心。研究了联芳基轴在其金(I)配合物中的构型稳定性。探索了这些轴向手性基于ImPy的AuCl配合物在一系列金催化中的应用,并观察到了不同程度的不对称诱导。在大多数情况下,配体(a S,R)-L8-H的环己基指向反应位点,因此发挥不对称空间影响在不对称诱导中更有效。
Asymmetric Au-catalyzed domino cyclization/nucleophile addition reactions of enynes in the presence of water, methanol and electron-rich aromatic derivatives
作者:Alexandre Pradal、Chung-Meng Chao、Maxime R. Vitale、Patrick Y. Toullec、Véronique Michelet
DOI:10.1016/j.tet.2011.03.071
日期:2011.6
system is described for the asymmetric domino cyclization/functionalization reactions of functionalized 1,6-enynes in the presence of an external nucleophile. The use of (R)-4-MeO-3,5-(t-Bu)2-MeOBIHEP ligand associated with gold led to clean rearrangements implying the formal addition of an oxygen or carbon nucleophile to an alkene followed by a cyclization process. The enantiomeric excesses were highly
The synthesis, optical resolution through derivatization, characterization and utilization of a new helical bisphosphinite–gold complex derived from HELIXOL are described.
precursors. When armed with a methylene phosphine oxide moiety on the stereogenic center adjacent to the nitrogenatom, the corresponding bifunctional carbene ligands give rise to highly enantioselective heterocyclizations. DFT calculations brought some rationalization and highlighted the critical roles played by the phosphine oxide group and the tosylate anion in the asymmetric cyclization of γ-allenols
Structure–enantioselectivity correlation in NHC–Au(I) catalysis for 1,6-enynecyclizations
作者:Benjamin W. Gung、Michael R. Holmes、Caleb A. Jones、Ruoyu Ma、Charles L. Barnes
DOI:10.1016/j.tetlet.2016.07.046
日期:2016.8
A direct correlation of the NHC ligandstructure and the induced enantioselectivity has been uncovered for a series of new chiral gold(I) complexes. The Au(I)Cl complexes were identified by 1H, 13C NMR spectroscopy, and X-ray structure analysis. The corresponding activated Au(I) catalysts with a phenyl nitrile dynamic ligand are prepared and used in the catalysis of 1,6-enyne cyclization reactions
对于一系列新的手性金(I)配合物,已经发现了NHC配体结构和诱导的对映选择性的直接相关性。通过1 H,13 C NMR光谱和X射线结构分析鉴定Au(I)Cl络合物。制备具有苯基腈动态配体的相应活化的Au(I)催化剂,并将其用于1,6-烯炔环化反应的催化中。用6%的手性NHC–Au(I)催化剂可获得高化学产率和良好的对映选择性。这些反应中的产物可达到75%ee。手性NHC配体的结构,其中邻-联苯基部分与氮原子相连,远端3,5-二烷基苯基在对映选择性中起决定性作用。
Towards asymmetric Au-catalyzed hydroxy- and alkoxycyclization of 1,6-enynes
作者:Chung-Meng Chao、Emilie Genin、Patrick Y. Toullec、Jean-Pierre Genêt、Véronique Michelet
DOI:10.1016/j.jorganchem.2008.08.008
日期:2009.2
The efficiency of a Au(III)/chiral ligand system has been studied. The association of several chiral mono- and bidentate phosphanes with gold has been tested in the formal addition of an oxygen nucleophile to an alkene followed by a cyclization process, namely the hydroxycyclization reaction of 1,6-enynes. The use of ( R)-4-MeO-3,5-(t-Bu)(2)-MeOBIPHEP ligand led to clean cycloisomerizations and afforded the highest enantiomeric excesses. The enantiomeric excesses were highly dependant on the substrate/nucleophile combination. A P-31 NMR study of the catalytic species tends to prove that Au( III) catalyst may be reduced to Au( I) intermediate in the presence of phosphanes. (C) 2008 Elsevier B.V. All rights reserved.