Ruthenium(II)-Catalyzed Asymmetric Transfer Hydrogenation Using Unsymmetrical Vicinal Diamine-Based Ligands: Dramatic Substituent Effect on Catalyst Efficiency
作者:Bo Zhang、Hui Wang、Guo-Qiang Lin、Ming-Hua Xu
DOI:10.1002/ejoc.201100299
日期:2011.8
The use of unsymmetrical vicinal diamines as ligands for Ru-catalyzed asymmetric transfer hydrogenation is described. With a SmI(2)-mediated cross-coupling protocol, a series of enantiomerically pure unsymmetrical vicinal diamines were readily prepared and examined in the asymmetric transfer hydrogenation. It was found that an aromatic substituent on the carbon bearing the -NHTs group and a bulky alkyl
描述了使用不对称连二胺作为 Ru 催化的不对称转移氢化的配体。使用 SmI(2) 介导的交叉偶联方案,在不对称转移氢化中很容易制备和检查了一系列对映异构纯的不对称邻二胺。发现带有-NHTs 基团的碳上的芳族取代基和另一侧的庞大烷基取代基对于配体的有效性都非常重要,表明该取代基对催化剂效率具有显着影响。使用配体 8,实现了与 N-tosyl-1,2-diphenylethane-1,2-diamine (TsDPEN) 相当的出色对映选择性。结果为 Ru 催化的不对称转移氢化机理提供了一些有用的信息。