Au(I)-Catalyzed Dimerization of Two Alkyne Units-Interplay between Butadienyl and Cyclopropenylmethyl Cation: Model Studies and Trapping Experiments.
Au(I)-Catalyzed Dimerization of Two Alkyne Units-Interplay between Butadienyl and Cyclopropenylmethyl Cation: Model Studies and Trapping Experiments.
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DOI：
10.1021/acs.joc.7b02843
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发表时间：
2017-11
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影响因子：
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通讯作者：
Mathis Kreuzahler;Sven Fabig;Gebhard Haberhauer;R. Gleiter
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文献类型：
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作者：
Mathis Kreuzahler;Sven Fabig;Gebhard Haberhauer;R. Gleiter
近年来，Au(I)催化反应被证明是一种有价值的工具，用于从炔烃开始通过环芳构化和环异构化合成取代环。尽管有无数Au(I)催化的炔烃反应，但单Au(I)催化的非共轭炔基二聚化反应尚未被量子化学计算所研究。本文通过量子化学计算，描述了单Au(I)催化的两个炔单元的二聚化反应以及非共轭双炔的跨环闭环反应。我们发现，根据不同的体系和方法，相应的环丙烯甲基阳离子或丁二烯基阳离子代表稳定的中间体。这种情况可以用不同的稳定效应来解释。此外，计算表明，与非催化的自由基变体相比，Au(I)催化的反应具有显著的（bbb1012倍）加速度。用取代的1,6-环十二炔在室温下以苯为溶剂进行的捕集实验以及用氘化溶剂进行的研究证实了计算结果。在这种情况下，我们还证明了阳离子中间体与苯的捕获不是通过弗里德尔-克拉夫特型反应进行的。
In recent years, Au(I)-catalyzed reactions proved to be a valuable tool for the synthesis of substituted cycles by cycloaromatization and cycloisomerization starting from alkynes. Despite the myriad of Au(I)-catalyzed reactions of alkynes, the mono Au(I)-catalyzed pendant to the radical dimerization of nonconjugated alkyne units has not been investigated by quantum chemical calculations. Herein, by means of quantum chemical calculations, we describe the mono Au(I)-catalyzed dimerization of two alkyne units as well as the transannular ring closure reaction of a nonconjugated diyne. We found that depending on the system and the method used either the corresponding cyclopropenylmethyl cation or the butadienyl cation represents the stable intermediate. This circumstance could be explained by different stabilizing effects. Moreover, the calculation reveals a dramatic (>1012-fold) acceleration of the Au(I)-catalyzed reaction compared to that of the noncatalyzed radical variant. Trapping experiments with a substituted 1,6-cyclodecadiyne using benzene as a solvent at room temperature as well as studies with deuterated solvents confirm the calculations. In this context, we also demonstrate that trapping of the cationic intermediate with benzene does not proceed via a Friedel-Crafts-type reaction.