导向基团辅助金属催化C-H键官能团化的理论研究

发布时间：2018-06-11 14:55

本文选题：过渡金属 + 含氮杂环化合物　；参考：《暨南大学》2016年硕士论文

【摘要】：过渡金属催化Csp~2-H键官能团化合成含氮杂环类化合物已被广泛研究,但是实现区域选择性的碳氢键活化还是一个重大的挑战。尽管不同的碳氢活化模式的催化反应均有报道,配位导向的碳氢活化反应是目前报道最多的方法之一。但是,其理论研究的发展稍显滞后,反应机理的很多细节问题尚不明确。在本文中,主要采用了密度泛函理论(DFT)对Pd/Rh过渡金属配合物催化C-H键选择性断裂及Cu催化C-H键胺化反应机理进行详细的理论研究。在第三章中,用密度泛函理论(DFT)B3LYP方法对1,2,3-三氮唑导向的Pd催化Csp~2-H键官能团化的反应机理进行了系统的理论研究。Pd(OAc)2催化Csp~2-H键活化反应的取代与环化机理的竞争反应。计算结果表明TAA和TAPy体系环化机理反应的步骤为:(1)Pd(II)通过CMD机理活化C-H键;(2)Pd(II)中间体被PhI(OAc)2氧化为Pd(III)的中间体;(3)Pd(III)下进行亚氨基去质子化;(4)C-N键还原消除。取代路径的机理为:(1)Pd(II)通过CMD机理活化C-H键;(2)Pd(II)中间体被PhI(OAc)2氧化为Pd(III)的中间体;(3)在Pd(III)下,通过5元环过渡态进行C-O键连接。当TAA作为定位基时,反应趋向于环化产物;恰恰相反,当TAPy作为定位基时,反应倾向于取代产物。对于TAPy体系倾向于形成取代产物的原因在于TAPy这一定位基中的吡啶作为一个配体与Pd作用,使得醋酸根一直是以单配的形式存在,比TAA作为定位基时,少一个键的断裂过程。在第四章中,采用密度泛函理论M06的计算方法对Rh(III)催化N-O取代的苯甲酰胺与1,6-烯炔环己二烯酮反应的机理进行了系统的理论研究。详细探讨了-OPiv和-OMe两种取代基进行芳基环化的不同机理。两种不同的取代基的反应路径中,最初的亚氨基去质子化、通过CMD机理实现C-H键活化和1,6-烯炔的插入是相同的,之后,由于不同取代基得到的7元环中间物的不同,导致随后的反应遵循不同的反应机理。当-OPiv作为取代基时,高稳定性的7元环中间物将有效的增高?-迈克尔加成路径的能垒,因此阻止其发生;当-OMe作为取代基时,不稳定的7元环中间物极易与环己二烯酮中的双键作用,而这利于?-迈克尔加成路径的发生。其中,?-迈克尔加成从7元环开始,会得到Rh(I)的中间物,如果先进行N-O键的断裂,即Rh(III)→Rh(V),不利于反应的进行。而?-迈克尔加成反应中Rh始终保持三价。在第五章中,用密度泛函方法(DFT)B3LYP方法研究Cu(II)催化合成吡啶并[1,2-a]苯并咪唑反应的机理。设计了5种可能的反应途径:(1)首先C-H键断裂,然后亚氨基去质子化,最后还原消除(路径a);(2)首先亚氨基去质子化,然后C-H键断裂,最后还原消除(路径b);(3)首先C-H键断裂,然后C-N键形成,最后亚氨基去质子化(路径c);(4)anti-imino-cupration机理(路径d);(5)傅-克烷基化反应机理(路径e)。计算表明路径a最可能发生,即首先发生C-H键活化,然后在三重态上亚氨基去质子化,最后还原消除。
[Abstract]:Transition metal catalytic synthesis of nitrogen-containing heterocyclic compounds by functionalization of Csp-2-H bonds has been extensively studied, but the realization of regioselective activation of carbon-hydrogen bonds is still a major challenge. Although catalytic reactions in different hydrocarbon activation modes have been reported, ligand oriented hydrocarbon activation is one of the most widely reported methods. However, the development of theoretical research is slightly lagging behind, and many details of the reaction mechanism are still unclear. In this paper, density functional theory (DFT) is used to study the mechanism of C-H bond selective fracture catalyzed by PD / Rh transition metal complexes and Cu catalyzed C-H bond amination reaction in detail. In chapter 3, the mechanism of the catalytic functionalization of Csp-2-H bond catalyzed by PD was systematically studied by using DFTFT-B3LYP method. The competitive reaction between the cyclization mechanism and the substitution of the Csp-2-H bond activation reaction catalyzed by PdN OAc2 was studied systematically by DFTFT-B3LYP method. The calculated results show that the cyclization mechanism of TAA and TAPy system is as follows: 1 / 1 / Pd2) the intermediate is activated by the CMD mechanism. The intermediate is oxidized by PhIOOAc2 to the intermediate of PdPy III) by deprotonation of the iminodium and the reduction of the C-N bond by deprotonation. The mechanism of the substitution path is that the C-H bond is activated by the CMD mechanism. The intermediate is oxidized by PhIOAc2 to PdOIII) and the C-O bond is connected by the transition state of the five-member ring. The reaction tends to cyclization product when TAA is the locus group, but on the contrary, when TAPy is the locus group, the reaction tends to replace the product. For the TAPy system, the reason for the formation of the substitution product is that the pyridine in the TAPy site acts as a ligand with PD, which makes the acetate radical always exist in the form of monozygosity, which is one less bond breaking process than that of the TAA system. In chapter 4, the mechanism of the reaction of N-O-substituted benzamide with 1-butene cyclohexadienone was systematically studied by density functional theory (DFT) M06. The different mechanisms of aryl cyclization of -OPiv and -OMe substituents are discussed in detail. In the reaction paths of two different substituents, the initial iminodization, the activation of C-H bond by CMD mechanism and the insertion of 1-hexene, are the same. After that, due to the different substituents, the intermediate of 7-member ring is different. The subsequent reactions follow different reaction mechanisms. When -OPiv acts as the substituent, the highly stable intermediate of the 7-member ring effectively increases the energy barrier of the Michael addition path, thus preventing it from occurring, and when -OMe is used as the substituent, The unstable 7-member ring intermediates are easy to interact with the double bonds in cyclohexadienone, which is conducive to the occurrence of the N-Michael addition path. The intermediate of Rhn I will be obtained from the addition of 7 element ring. If the N-O bond is broken first, that is, Rhn II I) RhN V _ (+), it will be unfavorable to the reaction. In addition, Rh remained trivalent in the addition reaction. In chapter 5, the mechanism of the synthesis of pyridino [1o 2-a] benzimidazole catalyzed by CuPII was studied by density functional method (DFT) and B3LYP method. Five possible reaction pathways were designed: first, C-H bond breaks, then iminamine-deprotonation, and finally reductive elimination (path A ~ (2) first, then C-H bond fracture, finally reductive elimination (path BX ~ (3) first C-H bond fracture. Then the C-N bond was formed, and finally the mechanism of Friedel-g alkylation (path eau) of the imino-cupration mechanism (path C ~ (4) ~ (4) ~ (-) anti-imino-cupration) was formed. The results show that path a is most likely to occur, that is, the activation of C-H bond first, then the deprotonation of iminodium on the triplet, and finally the reduction and elimination.
【学位授予单位】：暨南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O621.251

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