The mechanism studies of catalytic chemoselective conjugate addition of amino alcohols to α,β-unsaturated ester
The mechanism studies of catalytic chemoselective conjugate addition of amino alcohols to α,β-unsaturated ester
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DOI：
10.1007/s00214-020-02711-y
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发表时间：
2021-01-01
影响因子：
1.7
通讯作者：
Liu，Chunhui
中科院分区：
文献类型：
--
作者：
Han，Peilin;Han，Huijuan;Liu，Chunhui
用密度泛函方法系统地研究了银/氨基锂催化的α，β不饱和酯与氨基醇氢化反应的竞争机理。在这里，氨基醇中较弱的亲核羟基的酸性明显高于NH2基团，因此很容易被Ag(HMDS)/dppe去质子化。然而，生成的Ag-O键比相应的Ag-N键更稳定。因此，在Lewis酸/Brnsted碱对催化剂存在下，OH基团表现出比NH2基团更高的反应活性。然后，将α，β-不饱和酯插入到相应的Ag-O键中，得到烷基银物种。烷基银可被双(三甲基硅基)胺质子化，得到氢功能化产物并再生银氨基活性化合物Ag(HMDS)/dppe。
The competing mechanisms of silver-/aminolithium-catalyzed hydrofunctionalization ofα,β-unsaturated ester with an amino alcohol have been systematically studied with the DFT methods. Here, the acidity of a weaker nucleophile OH group of an amino alcohol is significantly higher than that of NH2group, so it is easy to deprotonate by Ag(HMDS)/dppe. However, the generated Ag–O bond is more stable than the corresponding Ag–N bond. Therefore, the OH group shows higher reactivity than the NH2group in the presence of a Lewis acid/Brønsted base pair catalyst. Then,α,β-unsaturated esters can be inserted into corresponding Ag–O bonds to obtain alkyl silver species. Alkyl silver can be protonated by bis(trimethylsilyl)amines to obtain hydrogen functionalized products and regenerate silver amino active compounds Ag(HMDS)/dppe.