【作者】 王岩；

【导师】 刘建标；

【作者基本信息】 山东师范大学 ， 物理化学， 2025， 硕士

【摘要】 过渡金属催化的烯烃氢官能团化反应能够在C=C键上同时引入氢原子和官能团,是构建C-C和C-X键的重要策略,在药物合成及材料化学领域中具有重要作用。近年来,镍和钴催化体系因其独特的反应活性而受到广泛关注。通过调控配体结构和不同链长烯烃底物性质,可有效控制氢烷基化反应和氢胺化反应的区域选择性,从而制备具有不同结构的氢烷基化/氢胺化产物。尽管近年来基于过渡金属催化的烯烃官能团化反应已经取得显著进展,但具体的催化循环机理以及反应选择性的调控规律仍需进一步探究。本论文采用密度泛函理论方法探讨了配体调控的Ni-H催化非活化烯烃区域选择性氢烷基化反应的机理。基于反应路径的动力学和热力学行为差异,明确了优势活性催化剂并讨论了配体对于区域选择性的调控机制。计算结果表明,相比于Ni^Ⅰ-H物质,Ni^Ⅱ-HI催化的氢烷基化反应在动力学上更有利,为优势活性催化剂。上述两种物质催化反应过程中,烯烃迁移插入步骤的活化能垒存在显著差异。对于Ni^Ⅱ-HI,虽然烯烃插入过渡态中底物烯烃双键与Ni^Ⅱ-HI的立体排斥较强,但其静电和轨道相互作用更为显著,进而导致活化能降低。基于优势活性催化剂进一步研究了配体性质差异对区域选择性具有重要影响。菲啰啉配体（L₁）和双恶唑啉配体（L₂）分别得到α-选择性和β-选择性烷基化产物。计算结果表明,α-烷基化反应路径中的β-H消除与β-烷基化反应路径中的自由基加成步骤的能垒差异直接决定该反应的区域选择性。非共价相互作用分析表明,在双恶唑啉配体涉及的自由基加成过渡态中,底物与配体取代基间的分子内弱相互作用更强,构型更稳定,从而促进β-选择性产物的生成。本论文还研究了Co（Ⅱ）催化烯烃氢胺化反应的机理及不同链长烯烃底物的反应性差异。Co（Ⅱ）催化短链烯烃氢胺化反应机理包括N-H去质子化、σ键复分解、烯烃迁移插入、氧化加成、还原消除和质子化等基元步骤,最终生成马氏支链型产物,其中氧化加成为整个反应的速率决定步骤。Co-H中间体发生的1,2-烯烃插入和2,1-烯烃插入将分别得到支链型和直链型产物。形变-相互作用分析表明,短链烯烃涉及的2,1-烯烃插入过渡态中具有较低的烯烃底物片段的形变能进而有效地降低了活化能垒,最终在动力学上更有利,促进了马氏支链型产物的产生。此外,我们还探讨了高价钴中间体产生过程中所涉及的四种竞争性反应机理,即内层和外层单电子转移、氧化加成以及Co-C键均裂。计算结果表明,氧化加成过程因为具有较强放热特性与较低的活化能垒,在动力学和热力学上较为有利。本论文通过系统的理论研究明确了双氮配体在调控镍催化非活化烯烃氢烷基化反应中的关键作用,阐明了其对反应机制和区域选择性的影响规律。本论文所建立的烯烃氢官能团化反应的催化循环机理,有助于理解配体的空间效应以及金属中心的电子结构性质对反应选择性的内在调控机制。所取得的研究成果加深了对3d后过渡金属的独特的催化性质的理解,为进一步设计廉价过渡金属催化的高效和高选择性氢官能团化反应提供了理论指导。更多还原

【Abstract】 Transition metal-catalyzed hydrofunctionalization of alkenes enables the simultaneous introduction of hydrogen atoms and functional groups across the C=C bond,representing an important strategy for constructing C-C and C-X bonds.This method plays a crucial role in drug synthesis and materials chemistry.In recent years,nickel and cobalt catalytic systems have garnered significant attention due to their unique reactivity.By modulating ligand structures and the properties of alkenes substrates with different chain lengths,the regioselectivity of hydroalkylation and hydroamination reactions can be effectively controlled,allowing the synthesis of hydroalkylation/hydroamination products with diverse structures.Despite significant progress in transition metal-catalyzed alkenes functionalization in recent years,the specific catalytic cycle mechanisms and the principles governing reaction selectivity still require further investigation.This dissertation explores the mechanism of ligand-controlled Ni-H-catalyzed regioselective hydroalkylation of unactivated alkenes using density functional theory（DFT）methods.By analyzing the kinetic and thermodynamic behaviors along the reaction pathways,the dominant active catalyst was identified,and the role of ligands in regulating regioselectivity was discussed.Computational results indicate that Ni^Ⅱ-HI is kinetically more favorable than Ni ^Ⅰ-H as the dominant active catalyst.Significant differences in the activation energy barriers for the alkenes migratory insertion step were observed between the catalytic cycles of these two species.For Ni^Ⅱ-HI,although the substrate alkenes double bond experiences stronger steric repulsion in the insertion transition state,the stronger electrostatic and orbital interactions lead to a reduced activation energy.Further studies based on the dominant active catalyst revealed that differences in ligand properties significantly influence regioselectivity.Neocuproine（L₁）and bisoxazoline-based ligands（L₂）lead toα-selective andβ-selective alkylation products,respectively.Computational results show that the energy barrier difference betweenβ-H elimination in theα-alkylation pathway and the radical addition step in theβ-alkylation pathway directly determines the regioselectivity of the reaction.Non-covalent interaction analysis indicates that in the radical addition transition state involving bisoxazoline-based ligands,the intramolecular weak interactions between the substrate and ligand substituents are stronger,stabilizing the transition state and promoting the formation ofβ-selective products.This dissertation also investigates the mechanism of Co（Ⅱ）-catalyzed alkenes hydroamination and the reactivity differences of alkenes substrates with varying chain lengths.The Co（Ⅱ）-catalyzed hydroamination mechanism for short-chain alkenes involves elementary steps including N-H deprotonation,σ-bond metathesis,alkenes migratory insertion,oxidative addition,reductive elimination,and protonation,ultimately yielding Markovnikov branched products.Among these steps,oxidative addition is the rate-determining step.The 1,2-alkenes insertion and 2,1-alkenes insertion of Co-H intermediates lead to branched and linear products,respectively.Deformation-interaction analysis reveals that the transition state for 2,1-alkenes insertion involving short-chain alkenes has lower deformation energy for the alkenes substrate fragment,effectively reducing the activation energy barrier and making it kinetically more favorable,thereby promoting the formation of Markovnikov branched products.Additionally,four competitive reaction mechanisms involved in the formation of high-valent cobalt intermediates inner-sphere and outer-sphere single-electron transfer,oxidative addition,and Co-C bond homolysis were explored.Computational results indicate that the oxidative addition process is kinetically and thermodynamically favorable due to its strongly exothermic nature and low activation energy barrier.Through systematic theoretical calculations,this dissertation clarifies the critical role of bidentate nitrogen ligands in regulating nickel-catalyzed hydroalkylation of unactivated alkenes and elucidates their influence on reaction mechanisms and regioselectivity.The catalytic cycle mechanism of alkenes hydrofunctionalization established in this study enhances the understanding of how ligand steric effects and the electronic structure of the metal center intrinsically control reaction selectivity.The research findings deepen the understanding of the unique catalytic properties of late 3d transition metals and provide theoretical guidance for designing efficient and selective hydrofunctionalization reactions catalyzed by low-cost transition metals.更多还原