镍催化不饱和烃选择性插入C-C键反应机制的理论研究

发布时间：2018-05-04 15:33

本文选题：C-C键活化 + 过渡金属　；参考：《东北师范大学》2016年硕士论文

【摘要】：碳-碳(C-C)键的断裂是有机化学的基础问题,过渡金属催化C-C键活化是有效途径之一。其中科研工作者们发展了一系列的催化碳-碳键官能团化的反应体系,如钌、铑、钯、铁、钻、镍、铱、钨、铼、锇和金等过渡金属配合物。这些过渡金属配合物能够高效的催化不饱和烃(炔烃或烯烃)插入C-C键,从而实现官能团的转化或者扩环反应。新颖的协同催化策略包括有机-有机,金属-金属和有机-金属协同作用已经引起了人们的重视。而且,在C-C键活化领域,路易斯酸(LA)和过渡金属化合物结合有望成为一种高效有力的手段。在实验中,催化剂的设计与优化往往需要大量试验。通过计算机程序模拟催化过程是认识催化机理的重要手段。当掌握催化剂在催化反应中的作用机理时,通过比较不同催化剂对反应的影响,进而改善、设计新型催化剂。过渡金属催化机理的理论研究是目前催化剂设计与合成的重要指导支持。本论文首先采用密度泛函方法(DFT)详细探讨了过渡金属催化不饱和烃插入C-C键的反应机制,并与实验结果对照,为实验设计更为高效的催化剂提供理论依据。本文的研究结果如下：1.镍/路易斯酸协同催化炔烃选择性插入2,3,5,6-四氟苯甲腈C-CN键反应机制的理论研究。本文详细研究了零价Ni/BPh_3协同催化的2-丁炔插入2,3,5,6-四氟苯甲腈的反应机制。结果表明,此反应完整的催化循环包括Ni迁移,氧化加成,炔烃插入和还原消除。其中炔烃插入(ΔG°(?)=21.9kcal/mol)是决速步骤。通过对比有无助催化剂BPh_3参与的反应势能面表明,BPh_3的参与能够有效降低Ni迁移,氧化加成以及炔烃插入步骤的活化能垒,特别是Ni迁移步骤的反应能垒降低了3.4 kcal/mol,计算结果与实验事实一致。此外,本文成功解释了Ni0催化剂选择性活化C-CN键的原因,并预测单膦配体催化剂Ni(PPh_3)(AL)对此反应体系具有更好的催化活性,活化能AG°(?)=10.0 kcal/mol(炔烃插入),为实验合成提供了新的方向。2.镍催化1,3-二烯和3-氮杂环丁酮环加成反应机制的理论研究。本文利用DFT方法详细探讨了镍催化1-Boc-3-氮杂环丁酮和1,3-二烯的环加成反应的β-碳消除和氧化加成两种可能反应机制。结果表明,通过β-碳消除断裂C-C键的能垒高达48.0 kcal/mol,说明此反应机制并非经过传统的β-碳消除。氧化加成机制由氧化加成,烯烃插入和还原消除三个基元步骤组成,而且烯烃插入是决速步骤(AG°(?)=32.2 kcal/mol)。这表明这个反应是经过氧化加成的反应机制进行的。这有助于我们更好的理解此类反应的机制,从而为实验上设计更为高效的催化剂,有效的降低决速步骤的活化能提供理论依据。
[Abstract]:The fracture of C-C bond is a fundamental problem in organic chemistry, and the activation of C-C bond catalyzed by transition metal is one of the effective ways. Among them, researchers have developed a series of transition metal complexes such as ruthenium, rhodium, palladium, iron, drill, nickel, iridium, tungsten, rhenium, osmium and gold. These transition metal complexes can efficiently catalyze unsaturated hydrocarbons (alkynes or alkenes) into C-C bonds to achieve functional group conversion or ring expansion reaction. Novel synergistic catalysis strategies, including organic-organic, metal-metal and organic-metal synergistic effects, have attracted much attention. Furthermore, in the field of C-C bond activation, the binding of Lewis acid and transition metal compounds is expected to be an efficient and powerful means. In experiments, the design and optimization of catalysts often require a large number of tests. The simulation of catalytic process by computer program is an important means to understand the mechanism of catalysis. The new catalyst was designed by comparing the influence of different catalysts on the reaction and improving the mechanism of catalyst in the catalytic reaction. The theoretical study on the catalytic mechanism of transition metals is an important support for the design and synthesis of catalysts. In this paper, the mechanism of transition metal-catalyzed unsaturated hydrocarbon insertion into C-C bond is discussed in detail by using density functional method (DFT), and compared with the experimental results, it provides a theoretical basis for the design of more efficient catalysts. The results of this paper are as follows: 1: 1. A theoretical study on the Mechanism of selective insertion of alkynes by Nickel / Lewis Acid in the C-CN Bond reaction of Tetrafluorobenzonitrile (Tetrafluorobenzonitrile). In this paper, the mechanism of 2-butadiene-2-butadiene-6-tetrafluorobenzonitrile catalyzed by zero-valent Ni/BPh_3 has been studied in detail. The results show that the complete catalytic cycle includes Ni migration, oxidation addition, alkynes insertion and reduction elimination. The insertion of alkynes (螖 G 掳) is a critical step. By comparing the potential energy surface of the reaction with or without the co-catalyst BPh_3, it is shown that the participation of BPhS _ 3 can effectively reduce the activation energy barrier of Ni migration, oxidation addition and alkynes insertion steps. In particular, the reaction barrier of Ni transport step decreases by 3.4 kcal / mol, and the calculated results are in agreement with the experimental results. In addition, the reason for the selective activation of C-CN bond over Ni0 catalyst was successfully explained, and it was predicted that the single phosphine ligand nip PPh3AL had better catalytic activity for this reaction system. The activation energy AG 掳C / L was 10.0 kcal / mol (alkynes insertion), which provided a new direction for the experimental synthesis. A theoretical study on the mechanism of cycloaddition reaction of 1: 3-diene and 3-azacyclic butanone catalyzed by nickel. In this paper, the mechanism of 尾 -carbon elimination and oxidative addition of 1-Boc-3-azacyclobutanone and 1-oc-3-diene catalyzed by nickel was discussed in detail by DFT method. The results show that the barrier of C-C bond cleavage by 尾 -carbon is up to 48.0 kcal / mol, which indicates that this reaction mechanism is not eliminated by traditional 尾 -carbon elimination. The oxidation addition mechanism consists of three basic steps: oxidation addition, olefins insertion and reduction elimination, and olefin insertion is a critical step, which is 32.2 kcal / mol ~ (-1) 路mol ~ (-1). This indicates that the reaction is carried out by the mechanism of oxidation addition. This will help us to better understand the mechanism of such reactions, thus providing a theoretical basis for the experimental design of more efficient catalysts and the effective reduction of the activation energy of the critical step.
【学位授予单位】：东北师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O621.251

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