Asymmetric additions to dienes catalysed by a dithiophosphoric acid.
Asymmetric additions to dienes catalysed by a dithiophosphoric acid.
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DOI：
10.1038/nature09723
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发表时间：
2011-02-10
期刊：
影响因子：
64.8
通讯作者：
Toste, F. Dean
中科院分区：
文献类型：
--
作者：
Shapiro, Nathan D.;Rauniyar, Vivek;Hamilton, Gregory L.;Wu, Jeffrey;Toste, F. Dean
手性布朗斯台德酸已成为一种宝贵的工具，用于在催化条件下实现各种不对称化学转化，同时避免使用有毒和昂贵的金属。虽然迄今为止开发的催化剂在活化极化官能团方面非常有效，但化学家尚未能够使用有机布朗斯台德酸催化未活化的碳-碳多重键的高度对映选择性转化。尽管外消旋酸催化的烯烃的“马尔可夫尼科夫”加成是化学家工具箱的一个完善的部分，但这种缺陷仍然存在。在这里，我们表明，手性二硫代磷酸催化分子内氢胺化和氢芳基化的二烯和联烯生成杂环产物在特殊的产率和对映体过量。为了使这种催化体系的独特成功合理化，我们提出了一种机理假设，该假设涉及将酸催化剂添加到二烯中，然后将所得二硫代磷酸盐中间体SN 2 ′置换。质谱和氘标记的研究提出了支持拟议的机制。在这项研究中揭示的催化剂和概念应证明适用于其他不饱和系统的不对称官能化。
Chiral Brønsted acids have become an invaluable tool for achieving a variety of asymmetric chemical transformations under catalytic conditions while avoiding the use of toxic and expensive metals. While the catalysts developed so far are remarkably effective at activating polarized functional groups, chemists have not yet been able to use organic Brønsted acids to catalyze highly enantioselective transformations of unactivated carbon-carbon multiple bonds. This deficiency persists despite the fact that racemic acid-catalyzed “Markovnikov” additions to olefins are a well-established part of the chemist’s toolbox. Here we show that chiral dithiophosphoric acids catalyze the intramolecular hydroamination and hydroarylation of dienes and allenes to generate heterocyclic products in exceptional yield and enantiomeric excess. To help rationalize the unique success of this catalytic system, we present a mechanistic hypothesis that involves the addition of the acid catalyst to the diene followed by SN2′ displacement of the resulting dithiophosphate intermediate. Mass spectrometry and deuterium labelling studies are presented in support of the proposed mechanism. The catalysts and concepts revealed in this study should prove applicable to other asymmetric functionalizations of unsaturated systems.
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