几类有机环化反应的密度泛函理论研究

发布时间：2018-06-23 06:23

本文选题：密度泛函理论 + 过渡金属　；参考：《云南师范大学》2017年硕士论文

【摘要】：由于过渡金属最外层具有未被电子填满的d轨道,因而它们常常呈现出不同的氧化态,且对不饱和化合物具有较强的亲和力。过渡金属可通过配位作用与很多化合物以σ-键或π-键形式构成配位体,从而达到稳定状态。反应过程中,过渡金属既可向反应底物提供电子,又可从反应底物中夺取电子,并通过改变自身氧化态及配位数来促进整个反应的进行。这种催化方式常被用于构建复杂的杂环分子,因而,过渡金属催化剂在有机合成领域一直扮演着很重要的角色。本论文中,我们针对金属镍、金属银和金属钯催化环化反应的三个体系展开了理论研究,采用密度泛函理论(DFT)对反应的可能机理进行了计算,对反应中涉及的所有反应物、产物、过渡态和中间体等在IDSCRF-B3LYP/DGDZVP计算水平上进行了全几何构型优化,并进行了频率计算。本论文中使用的能量值均是在实验溶剂中,矫正到相应的实验温度下的吉布斯自由能值。1.在金属镍催化乙烯基环丙烷和亚胺的[3+2]环加成反应体系中,在乙烯基环丙烷的开环过程中我们找到五条可能的反应路径,通过计算我们发现镍催化剂配位在乙烯基下方并诱导环丙烷开环的路径(Path I)是能量优势路径。而在后续的[3+2]环加成的过程中,反应分步进行,首先亚胺与开环后的乙烯基环丙烷形成C-C键,之后形成C-N键得到吡咯环,其中形成C-C键的步骤是整个反应的决速步。由于亚胺上的苯环空间取向不同,在环加成的过程中存在形成顺式(Cis)和反式(Trans)产物两种不同的反应路径,其中对应形成反式产物的决速步过渡态的能垒为26.9 kcal/mol,比形成顺式产物的决速步过渡态的能垒(25.2kcal/mol)高出1.7 kcal/mol,基本能解释主要形成顺式产物的实验事实。电子密度拓扑分析结果表明:对应形成顺式产物的决速步过渡态的空间位阻较小,因而更加稳定。将dmpe配体换成PMe2Ph并对相应的优势路径Path Ia进行计算发现,使用PMe2Ph配体时反应的立体选择性不及使用dmpe配体明显,并且在[3+2]环化中形成C-N键所需的能量也比使用dmpe配体高,说明换用PMe2Ph配体后反应性和反应的立体选择性都有所下降,与实验结果较好吻合。最后,我们对比了三种计算水平(IDSCRF-B3LYP/DGDZVP、IDSCRF-M062X/DGDZVP、IDSCRFB3LYP+D3/DGDZVP)对优势路径的计算结果,发现IDSCRF-B3LYP/DGDZVP计算水平上得到的计算结果最贴近实验事实。2.在金属银催化α-氨基磷酸盐和烯烃的[3+2]环加成反应体系中,我们通过优化找到了该反应的可能机理。第一步是质子迁移的过程,Ag(OTf)经过配体交换过程与二茂铁类配体形成催化剂,并帮助α-氨基磷酸盐迁氢,同时形成的H-HMDS从反应中脱落。第二步是[3+2]环加成的过程,由于烯烃上的乙酸酯基的空间取向不同,在环加成的过程中存在形成内式(Endo)和外式(Exo)产物两条不同的反应路径,其中形成内式产物的路径是一个分步成环的过程,而形成外式产物的路径则表现为协同成环。计算结果显示:形成内式产物的路径对应的过渡态能垒比相应的外式过渡态的能垒高出2.2 kcal/mol,即形成内式产物的路径在能量上占优势,其根本原因是烯烃上的乙酸酯基与金属银的配位作用能够稳定内式过渡态的构型,而在外式过渡态中不存在该配位作用。第三步是氢原子从H-HMDS上迁移回反应物、同时再生催化剂的过程。该步为整个反应的决速步,相应的外式过渡态和内式过渡态的能垒分别为25.4和21.5 kcal/mol,外式比内式高出3.9 kcal/mol,能够较好解释内式产物为优势产物。另外,我们还通过对铜(I)催化甲亚胺叶立德与丙烯酸酯的[3+2]环加成反应的关键过程进行计算,发现由于配体与丙烯酸酯之间位阻较大,内式过渡态中C=O基团与金属铜之间不能形成配位键,从而导致外式产物成为优势产物,与相应的实验事实基本吻合。3.在金属钯催化环丁酮衍生物与炔烃的偶联环化反应体系中,我们通过优化找到了反应的可能机理。首先是2-(2-溴苯亚甲基)环丁酮上的溴原子迁移到钯上的过程,其次是取代环丁酮与第二个反应物2-炔基苯酚偶联、生成C-C键的过程。之后由于六元环成环和环丁酮开环顺序的不同,存在Path A(六元环优先成环后环丁酮再开环)和Path C(环丁酮开环后六元环再成环)两条可能的反应路径,其中Path A为能量优势路径,其决速步对应六元环成环形成螺环中间体的过程,能垒为33.0 kcal/mol。对Path A和Path C两条路径上关键驻点的几何构型参数和成键性质的分析结果同样印证了优先形成六元环的路径(Path A)比优先打开环丁酮的路径(Path C)更加容易。
[Abstract]:As the outer layer of the transition metal has an unfilled D orbit, they often exhibit different oxidation states and have a strong affinity for unsaturated compounds. Transition metals can form coordination bodies with many compounds in the form of sigma bonds or pion bonds, thus achieving a stable state. During the reaction process, transition gold. Genera can not only provide electrons to the reaction substrates, but also take electrons from the reaction substrates and promote the whole reaction by changing their own oxidation states and coordination numbers. This catalysis is often used in the construction of complex heterocyclic molecules. Therefore, the transition metal catalysts have been playing an important role in the field of organic synthesis. We have carried out a theoretical study of three systems for the catalytic cyclization of metal nickel, metal silver and metal palladium. The possible mechanism of the reaction was calculated by the density functional theory (DFT). All the reactants, products, transition states and intermediates involved in the reaction were fully geometrically constructed at the IDSCRF-B3LYP/DGDZVP Computing Level. The energy values used in this paper are all in the experimental solvent, and the Gibbs free energy value.1. is corrected to the corresponding experimental temperature. In the [3+2] ring addition reaction system of nickel catalyzed vinyl cyclopropane and imide, we found five possible reactions in the opening process of vinyl cyclopropane. According to the path, we find that the path of the nickel catalyst coordination position under the vinyl group and induced cyclopropane opening ring (Path I) is the energy dominant path. In the subsequent [3+2] ring addition process, the reaction is carried out step by step. First, the imide and the open ring vinyl cyclopropane form the C-C bond, and then form the C-N bond to get the pyrrole ring, which forms the C. The step of the -C bond is the quick step of the whole reaction. Due to the different spatial orientation of the benzene ring on the imide, there are two different reaction paths to form the CIS (Cis) and the trans (Trans) products in the process of the cycloaddition, in which the energy barrier of the fast step transition state corresponding to the formation of the trans product is 26.9 kcal/mol, which is faster than the quick step of forming the CIS product. The state energy barrier (25.2kcal/mol) is 1.7 kcal/mol high, which can basically explain the experimental fact that mainly forms the CIS product. The electronic density topology analysis shows that the spatial resistance of the fast step transition state corresponding to the formation of the CIS product is smaller and thus more stable. The DMPE ligand is changed to PMe2Ph and the corresponding dominant path Path Ia is calculated. Now, the stereoselectivity of the reaction with PMe2Ph ligands is less obvious than the use of the DMPE ligand, and the energy required to form a C-N bond in the [3+2] cyclization is also higher than the use of the DMPE ligand. It shows that the stereoselectivity of the reactivity and reaction of the PMe2Ph ligand is decreased and the experimental results are better anastomosed. Finally, we compared three kinds of calculation water. The calculation results of IDSCRF-B3LYP/DGDZVP, IDSCRF-M062X/DGDZVP, IDSCRFB3LYP+D3/DGDZVP on the dominant path have been found. It is found that the results obtained at the IDSCRF-B3LYP/DGDZVP computing level are closest to the experimental fact that.2. is in the [3+2] ring addition reaction system of metallic silver catalyzed alpha aminophosphate and olefin, and we found the reaction by optimization. The first step is the process of proton transfer. Ag (OTf) forms a catalyst with two ferrocene ligands through the ligand exchange process, and helps the alpha aminophosphate to be removed from the reaction. The second step is the process of addition of the [3+2] ring, and the process of the cycloaddition of the alkyl group on the olefin is in the process of addition. There are two different reaction paths for the formation of internal (Endo) and external (Exo) products, in which the path of the internal product is a step forming the ring, while the path of the formation of the external product is a cooperative ring. The results show that the transition state energy barrier of the path corresponding to the internal product is more than the corresponding transition state. The base of the barrier is 2.2 kcal/mol, that is, the path of forming the internal product is dominated by the energy. The fundamental reason is that the coordination of the alkenes on the alkene and the metal silver can stabilize the internal transition state, but there is no coordination in the external transition state. The third step is to migrate the reactant from the H-HMDS and regenerate the catalyst. This step is the quick step of the whole reaction, the corresponding transition state and the internal transition state are 25.4 and 21.5 kcal/mol respectively, and the external internal formula is 3.9 kcal/mol higher, which can better explain the internal product as the dominant product. In addition, we also add the [3+2] ring of copper (I) to the methimide leaves and the [3+2] ring of the acrylate. The critical process is calculated. It is found that the coordination between the C=O group and metal copper in the inner transition state can not form a coordination bond in the internal transition state, which leads to the external product becoming the dominant product. The coupling cyclization reaction of.3. in metal palladium catalyzed ring butanone derivatives and alkynes is basically consistent with the corresponding experimental facts. In the system, we find the possible mechanism by optimizing the reaction. First, the process of migration of bromine atoms on 2- (2- bromine Ya Jiaji) ring butanone to palladium, followed by the coupling of cyclic butanone with second reactants, 2- alkynyl phenol, and the process of generating C-C bonds. After that, there is a Path A due to the difference in the ring opening sequence of the six membered ring and the ring butanone. Two possible reaction paths (six membered ring precedence ring to ring butanone ring) and Path C (ring ring reformed ring after ring opening ring), in which Path A is an energy dominant path, and its speed step corresponds to a six membered ring forming a spiral intermediate process and can be built into a geometric structure of the key point on the Path A and Path C two paths by 33 kcal/mol.. The analysis results of type parameters and bonding properties also confirm that the path of preferential formation of six membered rings (Path A) is easier than that of the route of Path (C).
【学位授予单位】：云南师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O621.256.9

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