Computational insight into a gold(I) N-heterocyclic carbene mediated alkyne hydroamination reaction.
Computational insight into a gold(I) N-heterocyclic carbene mediated alkyne hydroamination reaction.
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DOI：
10.1021/ic2024605
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发表时间：
2012-05
影响因子：
4.6
通讯作者：
M. Katari;M. N. Rao;G. Rajaraman;P. Ghosh
中科院分区：
文献类型：
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作者：
M. Katari;M. N. Rao;G. Rajaraman;P. Ghosh
使用密度泛函理论 (DFT) 研究对金 (I) N-杂环卡宾 (NHC) 络合物介导的炔烃氢胺化进行了建模。在这方面，我们研究了两种代表性底物（即MeC=CH和PhNH(2)）之间的加氢胺化反应的炔和胺配位途径，该反应由金（I）NHC基（NHC）AuCl型预催化剂（即[1,3-二甲基咪唑-2-亚基]氯化金）催化。胺配位途径表现出比炔配位途径更低的活化势垒。催化循环被认为是通过中间体 [(NHC)AuCH=CMeNH(2)Ph](+) (D) 和 [(NHC)Au(PhNHMeC=CH(2))](+) (E) 之间发生的关键质子转移步骤进行，发现其活化势垒通过任何外来 H(2)O 分子的存在或什至任何反应物的辅助的质子中继机制过程而显着降低。 PhNH(2) 底物。最终的加氢胺化烯胺产物 PhNHMeC=CH(2) 进一步稳定在其互变亚胺形式 PhN=CMe(2) 中。
A gold(I) N-heterocyclic carbene (NHC) complex mediated hydroamination of an alkyne has been modeled using density functional theory (DFT) study. In this regard, alkyne and amine coordination pathways have been investigated for the hydroamination reaction between two representative substrates, namely, MeC≡CH and PhNH(2), catalyzed by a gold(I) NHC based (NHC)AuCl-type precatalyst, namely, [1,3-dimethylimidazol-2-ylidene]gold chloride. The amine coordination pathway displayed a lower activation barrier than the alkyne coordination pathway. The catalytic cycle is proposed to proceed via a crucial proton-transfer step occurring between the intermediates [(NHC)AuCH═CMeNH(2)Ph](+) (D) and [(NHC)Au(PhNHMeC═CH(2))](+) (E), the activation barrier of which was found to be significantly reduced by a proton relay mechanism process assisted by the presence of any adventitious H(2)O molecule or even by any of the reacting PhNH(2) substrates. The final hydroaminated enamine product, PhNHMeC═CH(2), was further seen to be stabilized in its tautomeric imine form PhN═CMe(2).