Department of Chemistry Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
Inorg Chem. 2012 May 21;51(10):5593-604. doi: 10.1021/ic2024605. Epub 2012 May 7.
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).
采用密度泛函理论（DFT）研究了金（I）氮杂环卡宾（NHC）配合物介导的炔烃的氢胺化反应。在这方面，研究了金（I）基于 N-杂环卡宾（NHC）的（NHC）AuCl 型前催化剂催化下，两种代表性底物（即 MeC≡CH 和 PhNH（2））之间的氢胺化反应中炔烃和胺的配位途径。胺配位途径的活化能垒低于炔烃配位途径。提出的催化循环通过在中间体 [(NHC)AuCH═CMeNH（2）Ph]（+）（D）和 [(NHC)Au（PhNHMeC═CH（2）)]（+）（E）之间发生关键的质子转移步骤进行，其中该活化能垒通过质子传递机制显著降低，该机制由任何外加的 H（2）O 分子甚至任何反应的 PhNH（2）底物辅助。最终的氢胺化烯胺产物 PhNHMeC═CH（2）进一步以其互变异构亚胺形式 PhN═CMe（2）稳定。
