A powerful chiral counterion strategy for asymmetric transition metal catalysis
A powerful chiral counterion strategy for asymmetric transition metal catalysis
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DOI：
10.1126/science.1145229
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发表时间：
2007-07-27
期刊：
影响因子：
56.9
通讯作者：
Toste, F. Dean
中科院分区：
文献类型：
--
作者：
Hamilton, Gregory L.;Kang, Eun Joo;Toste, F. Dean
传统上，过渡金属催化的对映选择性转化依赖于与金属紧密结合的手性配体来诱导产物的不对称分布。在这里，我们报道了在金属催化反应中，手性反离子赋予的高对映体选择性。阳离子金(I)络合物催化的两种不同的转化反应在手性联萘酚衍生的磷酸阴离子的作用下生成了90~99%的对映体过量产物。此外，我们证明了手性反离子可以与手性配体加成结合，从而实现不对称转化，这是任何一种方法都不能实现的。这种通过离子对传递手性信息的概念应该适用于大量的金属中介过程。
Traditionally, transition metal-catalyzed enantioselective transformations rely on chiral ligands tightly bound to the metal to induce asymmetric product distributions. Here we report high enantioselectivities conferred by a chiral counterion in a metal-catalyzed reaction. Two different transformations catalyzed by cationic gold( I) complexes generated products in 90 to 99% enantiomeric excess with the use of chiral binaphthol-derived phosphate anions. Furthermore, we show that the chiral counterion can be combined additively with chiral ligands to enable an asymmetric transformation that cannot be achieved by either method alone. This concept of relaying chiral information via an ion pair should be applicable to a vast number of metal-mediated processes.