Influence of the Conformation of Salen Complexes on the Stereochemistry of the Asymmetric Epoxidation of Olefins
作者:Andreas Scheurer、Harald Maid、Frank Hampel、Rolf W. Saalfrank、Loic Toupet、Paul Mosset、Ralph Puchta、Nico J. R. van Eikema Hommes
DOI:10.1002/ejoc.200500042
日期:2005.6
Compared with Katsuki’s or Jacobsen’s catalysts (R,R,R,R)-1 or (R,R)-2, the phenomenon of reversed asymmetric induction in the course of the epoxidation of unfunctionalised olefins in the presence of (salen)manganese complex (S,S)-3 is indirectly explained by means of quantumchemical calculations, as well as by 1H NMR spectra of salen ligand (S,S)-10 and diamagnetic low-spin nickel complex (S,S)-7
与Katsuki's或Jacobsen's催化剂(R,R,R,R)-1或(R,R)-2相比,在(salen)锰配合物存在下未官能化烯烃环氧化过程中出现反向不对称诱导现象(S,S)-3 是通过量子化学计算以及萨伦配体 (S,S)-10 和抗磁性低自旋镍配合物 (S,S)-7 的 1H NMR 光谱以及它的X 射线结构分析。而在 (R,R,R,R)-1 和 (R,R)-2 中,苯基和环己基取代基占据赤道位置,由锰催化剂 (S,S)-3 引起的反向对映选择的起源是基于在 (S,S)-3 的二亚胺骨架中无环杂烷基取代基的轴向位置上,如模型镍配合物 (S,S)-7 所示例性证实的那样。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)