Oxidation and β-Alkylation of Alcohols Catalysed by Iridium(I) Complexes with Functionalised N-Heterocyclic Carbene Ligands
作者:M. Victoria Jiménez、Javier Fernández-Tornos、F. Javier Modrego、Jesús J. Pérez-Torrente、Luis A. Oro
DOI:10.1002/chem.201502910
日期:2015.12.1
for the use of alcohols as alkylating agents for CC bond forming processes offering significant environmental benefits over traditional approaches. Iridium(I)‐cyclooctadiene complexes having a NHC ligand with a O‐ or N‐functionalised wingtip efficiently catalysed the oxidation and β‐alkylation of secondary alcohols with primary alcohols in the presence of a base. The cationic complex [Ir(NCCH3)(cod)(MeIm(2‐
借用氢的方法学允许将醇用作CC键形成过程的烷基化剂,与传统方法相比具有显着的环境效益。在碱存在下,具有NHC配体和O-或N-官能化的翼尖的铱(I)-环辛二烯络合物可有效催化仲醇与伯醇的氧化和β-烷基化。具有刚性O-官能化翼尖的阳离子络合物[Ir(NCCH 3)(cod)(MeIm(2-甲氧基苄基))] [BF 4 ](cod = 1,5-环辛二烯,MeIm = 1-甲基咪唑基)显示苯甲醇在丙酮中脱氢的最佳催化剂性能,初始转换频率(TOF 0)为1283 h -1,以及2-丁醇与丁-1-醇的β-烷基化反应,在10小时内转化率为94%,对庚烷-2-醇的选择性为99%。我们已经通过DFT计算研究了完整的反应机理,包括脱氢,交叉羟醛缩合和氢化步骤。有趣的是,这些研究表明铱催化剂参与了导致形成新的CC键的关键步骤,该键涉及在碱性介质中生成的O-键烯醇与亲电子醛的反应。