新型三芳基咪唑类有机电催化剂的创制及其电氧化活化C-H键和C-C键研究

The activation of C-H and C-C bonds has always been of foundmental interest in organic synthetic chemistry and the electrochemically oxidative activation is one of its main approach.Given the shortcoming of tribenzeneamines type of organic redox catalyst,such as low solubility in organic solvent and difficulty of synthesis, very recently, our research group found that triarylimidazoles can not only make up for the above-mentioned drawback, but also catalytically activate C-H bond.Unfortunately, it was found that the triarylimidazoles decomposed to an extend. Therefore, the present project will focus on three key scientific issues, naming the stability of radical cation, accessibility of wide range of redox potential and efficient electron transfer between catalyst and substrate. The answer to the above three issues will disclose the correlation between the structure of the catalyst and redox potential and chemical stability. On the basis of these understanding, we will develop a novel class of triarylimidazoles catalysts that are readily prepared,wide range of redox potential accessible, easily dissolved in organic solvent, chemical stable and high efficiency of electron transfer. Then, the class of catalyst will be applied to the oxidative activation of C-H bond-nucleophilic addition and C-C bond activation-cation radical cycloaddition reaction. Finally, the isolation and recovery of these catalysts will be investigated, along with the catalytic efficiency of the anode-supported catalyst.As far as we know, the above research work is not reported. The present project will benefit the development of organoelectrosynthetic chemistry and material chemistry. In addition, the project will promote the advance of organoelectrochemistry in China.

C-H键和C-C键的活化是有机合成化学的永恒主题和前沿课题，电化学方法是其有效途径之一。针对现有三苯胺类电催化剂不易合成、难溶的问题，本课题组前期发现三芳基咪唑化合物能弥补以上缺点，并能活化C-H键，但有一定程度的分解。为此，本项目将重点解决三芳基咪唑阳离子自由基的化学稳定性，氧化电位可调性及其与有机底物间的有效电子转移等关键科学问题，揭示有机电催化剂的结构与其氧化电位和化学稳定性的关系。在此基础上，创制出易于合成、可溶、电位可调、阳离子自由基稳定的基于三芳基咪唑骨架的新型有机电催化剂，并将其应用到C-H键电氧化活化-亲核加成和C-C键电氧化活化-阳离子自由基型环加成等串联反应中，同时考察电催化剂的分离回收及阳极负载后催化剂的催化效率。以上研究内容未见文献报道，本项目的实施，对有机电合成化学和材料科学的发展具有重要的科学意义和广泛的应用前景，也对我国有机电合成化学的进步具有明显的推动作用。

针对现有三苯胺类有机电催化剂所存在的问题，本项目首先设计合成了一类基于三芳基咪唑骨架的有机电催化剂，分析了该类化合物电化学性质。接着采用循环伏安法研究了该类有机电催化剂的电极反应动力学，并与传统的三苯胺类电催化剂进行了比较。在此基础上将其应用于C-H键的氧化活化、【4+2】环加成以及查尔酮环氧化合物的开环-傅克烷基化等反应中，最后考察了支持电解质和催化剂的回收利用。