Asymmetric Catalysis; 140: Tris(2-pyridyl)methane Derivatives with a Chiral Bridging Atom
作者:Henri Brunner、Reinhard Maier、Manfred Zabel
DOI:10.1055/s-2001-18716
日期:——
Two different series of C 1-symmetric tris(2-pyridyl)methane tripod ligands were synthesized with pyridin-2-yl, 6-phenylpyridin-2-yl and 6-methoxy- or 6-menthyloxypyridin-2-yl substitutents. The menthoxy devivatives were resolved with respect to the bridging carbon atom by chromatography. In reactions with CuCl2 and RhCl3 complexes were obtained which could be analyzed by X-ray crystallography. In the formation of the Rh complex an ortho-metallation of the 6-phenyl substituent occurred giving rise to a Î/Î-element of chirality. Whereas the chiral tripod ligand conferred a stable configuration to the Rh atom, a fast equilibration of the Î- and Î-isomers was observed.
两种不同系列的 C1-对称三(2-吡啶基)甲烷三足配体被合成,配体的取代基为吡啶-2-基、6-苯基吡啶-2-基、6-甲氧基或6-薄荷氧基吡啶-2-基。与桥接碳原子相关的薄荷氧衍生物通过色谱法进行分离。在与 CuCl2 和 RhCl3 的反应中获得了可以通过X射线晶体学进行分析的络合物。在 Rh 络合物的形成过程中,6-苯基取代基发生了邻位金属化,产生了 Δ/Λ 的手性元素。尽管手性三足配体赋予了 Rh 原子稳定的构型,但观察到 Δ-和 Λ-异构体之间存在快速平衡。