Aerobic oxidation of benzylic alcohols with bis(3,5-di-tert-butylsalicylaldimine) copper(II) complexes
Aerobic oxidation of benzylic alcohols with bis(3,5-di-tert-butylsalicylaldimine) copper(II) complexes
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DOI：
10.1016/j.apcata.2009.09.011
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发表时间：
2009-12-15
影响因子：
5.5
通讯作者：
Repo, Timo
中科院分区：
文献类型：
--
作者：
Ahmad, Jahir Uddin;Figiel, Pawel J.;Repo, Timo
合成了一系列双(3,5-二叔丁基水杨醛亚胺)铜(II)络合物，并将其用于以分子氧作为末端氧化剂的醇的催化氧化。这些络合物与 TEMPO 结合形成高效催化系统，用于在温和的反应条件下进行伯苄醇和烯丙醇的有氧氧化。例如，在 60 摄氏度和 1 bar 的 O-2 压力下，苯甲醇在 2 小时内以低催化剂负载量定量转化为苯甲醛。该催化体系的吸引人的特点包括分子氧的有效利用、高选择性、TEMPO（2 mol%）和铜催化剂（0.66 mol%）的低负载量以及温和的反应条件（大气氧和60℃温度）。此外，通过X射线衍射分析确定了配合物的晶体结构。该结构以单体扭曲的方形平面几何形状呈现铜离子，涉及不寻常且空间不利的顺式 N2O2 配位球。 (C) 2009 Elsevier B.V. 保留所有权利。
A series of bis(3,5-di-tert-butylsalicylaldimine)copper(II) complexes were synthesized and employed in the catalytic oxidation of alcohols using molecular oxygen as a terminal oxidant. These complexes, when combined with TEMPO form a highly efficient catalytic system for the aerobic oxidation of primary benzylic and allylic alcohols under mild reaction conditions. For example at 60 degrees C and 1 bar of O-2 pressure benzyl alcohol is quantitatively converted to benzyl aldehyde in 2 h with low catalyst loading. Attractive features of this catalytic system include the efficient use of molecular oxygen, high selectivity, low loading of both TEMPO (2 mol%) and copper catalyst (0.66 mol%) and mild reaction conditions (atmospheric oxygen and 60 degrees C temperature). In addition, the crystal structure of the complex was determined by X-ray diffraction analysis. The structure presents the Cu ion in a monomeric distorted square-planar geometry involving the unusual and sterically unfavorable cis-N2O2 coordination sphere. (C) 2009 Elsevier B.V. All rights reserved.