Department of Chemistry, Duke University, French Family Science Center, Durham, NC 27708-0346, USA.
Chemistry. 2021 Jul 16;27(40):10377-10386. doi: 10.1002/chem.202100741. Epub 2021 Jun 4.
The mechanism of the intermolecular hydroamination of 3-methylbuta-1,2-diene (1) with N-methylaniline (2) catalyzed by (IPr)AuOTf has been studied by employing a combination of kinetic analysis, deuterium labelling studies, and in situ spectral analysis of catalytically active mixtures. The results of these and additional experiments are consistent with a mechanism for hydroamination involving reversible, endergonic displacement of N-methylaniline from [(IPr)Au(NHMePh)] (4) by allene to form the cationic gold π-C1,C2-allene complex [(IPr)Au(η -H C=C=CMe )] (I), which is in rapid, endergonic equilibrium with the regioisomeric π-C2,C3-allene complex [(IPr)Au(η -Me C=C=CH )] (I'). Rapid and reversible outer-sphere addition of 2 to the terminal allene carbon atom of I' to form gold vinyl complex (IPr)Au[C(=CH )CMe NMePh] (II) is superimposed on the slower addition of 2 to the terminal allene carbon atom of I to form gold vinyl complex (IPr)Au[C(=CMe )CH NMePh] (III). Selective protodeauration of III releases N-methyl-N-(3-methylbut-2-en-1-yl)aniline (3 a) with regeneration of 4. At high conversion, gold vinyl complex II is competitively trapped by an (IPr)Au fragment to form the cationic bis(gold) vinyl complex {[(IPr)Au] [C(=CH )CMe NMePh]} (6).
[(IPr)AuOTf 催化 3-甲基-1,2-丁二烯（1）与 N-甲基苯胺（2）的分子间氢胺化反应的机理，通过动力学分析、氘标记研究以及催化活性混合物的原位光谱分析进行了研究。这些和其他实验的结果与氢胺化反应机理一致，涉及 [(IPr)Au(NHMePh)]（4）中 N-甲基苯胺的可逆、吸能取代，由丙二烯形成阳离子金π-C1，C2-丙二烯配合物 [(IPr)Au(η -H C=C=CMe )]（I），与区域异构的 π-C2，C3-丙二烯配合物 [(IPr)Au(η -Me C=C=CH )]（I'）处于快速、吸能平衡。2 快速可逆地与 I'的末端丙二烯碳原子进行外球加成，形成金乙烯配合物（IPr）Au[C(=CH )CMe NMePh]（II），同时 2 较慢地与 I 的末端丙二烯碳原子进行加成，形成金乙烯配合物（IPr）Au[C(=CMe )CH NMePh]（III）。III 的选择性原脱金释放出 N-甲基-N-（3-甲基-2-丁烯-1-基）苯胺（3a），同时再生 4。在高转化率下，金乙烯配合物 II 可被（IPr）Au 片段竞争性捕获，形成阳离子双（金）乙烯配合物{[(IPr)Au] [C(=CH )CMe NMePh]}（6）。
