Design of Chiral Hydroxyalkyl‐ and Hydroxyarylazolinium Salts as New Chelating Diaminocarbene Ligand Precursors Devoted to Asymmetric Copper‐Catalyzed Conjugate Addition
作者:Diane Rix、Stéphane Labat、Loïc Toupet、Christophe Crévisy、Marc Mauduit
DOI:10.1002/ejic.200801243
日期:2009.5
The design and the synthesis of a set of new chiral hydroxyalkyl- and hydroxyaryl-chelating diaminocarbene ligands is reported. Comparative catalytic studies show the importance of the scaffold design around the NHC unit to obtain a high enantiocontrol in Cu-catalyzed asymmetric conjugate addition (ACA). Whereas low selectivities are observed when the stereogenic centre is placed within the N-heterocyclic
报道了一组新的手性羟烷基和羟芳基螯合二氨基卡宾配体的设计和合成。比较催化研究表明围绕 NHC 单元的支架设计对于在 Cu 催化的不对称共轭加成 (ACA) 中获得高对映控制的重要性。当立体中心位于 N-杂环内时观察到低选择性,当中心手性位于两条侧链内时可以观察到有趣的匹配效应,这使得催化反应中的 ee 达到 92%。 (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)