Ruthenium-Catalyzed Asymmetric Epoxidation of Olefins Using H2O2, Part II: Catalytic Activities and Mechanism
作者:Man Kin Tse、Santosh Bhor、Markus Klawonn、Gopinathan Anilkumar、Haijun Jiao、Anke Spannenberg、Christian Döbler、Wolfgang Mägerlein、Herbert Hugl、Matthias Beller
DOI:10.1002/chem.200501262
日期:2006.2.20
tetra-substituted aromatic olefins with versatile functional groups can be epoxidized with this type of catalyst in good to excellent yields (up to 100 %) with moderate to good enantioselectivies (up to 84 % ee). Additive and solvent effects as well as the relative rate of reaction with different catalysts have been established. It is shown that the presence of weak organic acids or an electron-withdrawing
在[Ru(pybox)(pydic)] 1和[Ru(pyboxazineazine)(pydic)] 2存在下,使用30%H2O2的烯烃进行不对称环氧化的过程已得到详细研究(pybox =吡啶-2,6-双恶唑啉,pyboxazine =吡啶-2,6-双恶嗪,pydic = 2,6-吡啶二甲酸)。已在环境无害的环氧化反应中测试了35个空间和电子不同取代基的钌配合物。具有通用官能团的单,1,1-二-,顺式和反式1,2-二,三和四取代的芳族烯烃可以用这种类型的催化剂以优异的收率(最高到100%),具有中等到良好的对映选择性(最高84%ee)。已经确定了添加剂和溶剂的作用以及与不同催化剂的相对反应速率。结果表明,催化剂上弱有机酸或吸电子基团的存在增加了反应活性。在密度泛函理论计算和实验的基础上,提出了钌催化环氧化反应中间体和反应途径的新见解。