Aerobic Aliphatic Hydroxylation Reactions by Copper Complexes: A Simple Clip-and-Cleave Concept
Aerobic Aliphatic Hydroxylation Reactions by Copper Complexes: A Simple Clip-and-Cleave Concept
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DOI：
10.1002/chem.201802607
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发表时间：
2018-10-17
影响因子：
4.3
通讯作者：
Schindler, Siegfried
中科院分区：
文献类型：
--
作者：
Becker, Jonathan;Zhyhadlo, Yevheniia Y.;Schindler, Siegfried
开发了一种简单的亚胺剪切概念，用于通过铜络合物用双氧选择性羟基化脂肪醛中未活化的 CH 键。合成方案包括底物醛与 N,N-二乙基乙二胺反应生成相应的亚胺，亚胺用作双齿供体配体，与 [Cu(CH3CN)(4)][CF3SO3] 形成铜 (I) 络合物。将反应混合物暴露于双氧酸性裂解和水处理后，释放出相应的β-羟基化醛。研究了三甲基乙醛以及金刚烷和二金刚烷 1-甲醛的羟基化概念，并以高选择性获得了相应的 β-羟基醛。低温停流测量的结果表明形成了作为反应中间体的双(mu-氧化)二铜络合物。根据密度泛函理论（DFT，RI-BLYP-D3/def2-TZVP（SDD）/COSMO（CH2Cl2）//RI-PBE-D3/def2-TZVP（SDD））计算，适当地倾向于[Cu2O2]（2+）核心的CH键在具有特别低的活化势垒的协调步骤中经历羟基化，这解释了实验观察到的区域选择性。
A simple imine clip-and-cleave concept has been developed for the selective hydroxylation of non-activated CH bonds in aliphatic aldehydes with dioxygen through a copper complex. The synthetic protocol involves reaction of a substrate aldehyde with N,N-diethyl-ethylendiamine to give the corresponding imine, which is used as a bidentate donor ligand forming a copper(I) complex with [Cu(CH3CN)(4)][CF3SO3]. After exposure of the reaction mixture to dioxygen acidic cleavage and aqueous workup liberates the corresponding beta-hydroxylated aldehyde. The concept for the hydroxylation of trimethylacetaldehyde as well as adamantane and diamantane 1-carbaldehydes was investigated and the corresponding beta-hydroxy aldehydes were obtained with high selectivities. The results of low temperature stopped-flow measurements indicate the formation of a bis(mu-oxido)dicopper complex as reactive intermediate. According to density functional theory (DFT, RI-BLYP-D3/def2-TZVP(SDD)/COSMO(CH2Cl2)//RI-PBE-D3/def2-TZVP(SDD)) computations CH bonds suitably predisposed to the [Cu2O2](2+) core undergo hydroxylation in a concerted step with particularly low activation barriers, which explains the experimentally observed regioselectivities.