京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19726号 / 工博第4181号 / 新制||工||1645(附属図書館) / 32762 / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 松原 誠二郎, 教授 吉田 潤一, 教授 中尾 佳亮 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20391号 / 工博第4328号 / 新制||工||1671(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 中村 正治, 教授 辻 康之, 教授 小澤 文幸 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21115号 / 工博第4479号 / 新制||工||1696(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 辻 康之, 教授 近藤 輝幸, 教授 中村 正治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

This thesis focuses on the study of nickel boride as a catalyst in various coupling reactions. The nickel boride catalyst was investigated in three different coupling reactions, the experiments aimed at understanding the activity and catalytic properties of nickel boride. We successfully synthetized the nickel boride catalyst, alongside with the cobalt and iron boride. Different methods of preparation were compared and we concluded, that the differences in the preparation, such as solvent and atmosphere, influence the activity of the catalyst in coupling reactions. We found that the most suitable solvent for preparing nickel boride is anhydrous methanol, thus we proceeded our research with this catalyst. In the case of the Sonogashira cross-coupling we found that the homocoupling of the acetylene starting material is a side reaction we could not exclude. However, with the proper solvent it is possible to shift the reaction towards homocoupling, without the formation of the heterocoupling product. Thus, we decided to investigate the Glaser homocoupling between acetylenes. In the case of the Sonogashira coupling only TLC was used to examine the reaction mixture. However, in the case of Glaser coupling, after pre-investigations we developed a gas chromatography method for analyzing the reaction mixtures. We learned, that the homocoupling only results in trace amounts (2-4%) of product. Previous investigations in our research group showed, that the nickel boride could catalyze Suzuki-Miyaura-type couplings. Examining this reaction all three metal borides were tested; however, the reactions only led to the desired product with nickel boride. Analyzing the reaction with gas chromatography we learned that the choice of solvent influences the stability of the starting materials and the formation of side products. Reactions with different starting materials, in different solvents, with different bases were analyzed. The effect of microwave irradiation was also examined. Based on the results we concluded, that with nickel boride it is not possible to achieve high yields in coupling reactions.

<p>Advances in nanomaterials research have stoked interests in the design of dispersible catalysts for specific organic transformations, with higher reaction efficiency or lower burden in post-reaction waste processing. Multicomponent heterogeneous catalysts generally offer higher catalytic performance than single-component catalysts, with metal–substrate interactions (MSI) playing a key role in their performance. This thesis focuses on silver–iron-oxide particles as heterogeneous catalysts, starting with a literature survey (Chapter 1) followed by the synthesis and catalytic properties of two novel types of Ag–Fe₃O₄ particles that show strong potential for mediating C(sp²)–H arylation reactions (Chapters 2 and 3). Silver and especially iron oxide are much less expensive than other types of metals, and the magnetic properties of the Fe₃O₄ support transferability and reuse of the active catalytic species which enables us to reduce the ratio of catalyst to reactant. These features address multiple goals outlined by the principles of green chemistry. The arylation of heterocyclic compounds is frequently used in the preparation of organic dyes, polymers, and pharmaceutical intermediates, and is a useful benchmark reaction for comparing our cross-coupling catalyst with those from prior reports. </p> <p>In Chapter 2, we describe the synthesis of colloidal silver–iron-oxide (SIO) and investigate its conversion into an efficient catalyst for C(sp²)–H arylation using novel modes of activation. This includes electrochemical activation using mild cathodic potentials, and photoactivation using a white light source. Both methods dramatically improve the efficacy of colloidal SIO as a catalyst for the cross coupling of diazonium salts with heteroaromatic rings at room temperature. High-resolution transmission electron microscopy analysis reveals that the SIO particles are primarily composed of colloidal Ag that are coated with nanosized islands of Fe₃O₄. The SIO catalysts are magnetically responsive and can be collected and reused multiple times, without requiring reactivation. The SIO is susceptible to acid degradation but can be preserved with neutralization by added base during reaction cycling. </p> <p>In Chapter 3, we describe a second-generation catalyst in which Fe₃O₄ microspheres serves as the supporting substrate for Ag islands, with synthetic control over Ag size distribution. This material does not require any activation for cross-coupling catalysis, which can be attributed to better charge transfer between the Ag islands and Fe₃O₄ substrate. A comparison of Ag–Fe₃O₄ microspheres with different Ag/Fe ratios suggests that catalytic activity correlates with smaller particle sizes, where the strongest charge-transfer interactions are likely to occur. The role of MSI between Ag and Fe₃O₄ was further explored using X-ray absorption spectroscopy. The second-generation Ag–Fe₃O₄ catalysts are far more robust than the previous version and are better able to withstand acidic degradation, with less mass loss after multiple reaction cycles and no loss in catalytic function. Lastly, we have found that Ag–Fe₃O₄ microspheres can also be an efficient catalyst for the reduction of nitro groups into amines, and describe progress toward the one-pot conversion of  nitroarenes into  cross-coupling products.  </p>

No description available.

Constructing C-C and C-heteroatom bonds is of the utmost importance in organic chemistry. Cross-coupling is a reaction where a transition metal catalyst facilitates the formation of a C-C or C-heteroatom bond between two coupling partners. Cross-coupling reactions are often very robust and reliable and thus have established themselves as one of the most powerful and versatile tools for the modern synthetic organic chemist. A great area of modern cross-coupling research has been the expansion of electrophiles that can participate in cross-coupling reactions. By expanding the scope of available electrophiles, one can access a greater variety of products from simpler starting materials. Esters are relatively robust scaffolds and are difficult to engage in cross-coupling reactions due to the substantial double-bond character of the C(acyl)-O bond. Developing methods to functionalize esters via cross-coupling reactions would be highly beneficial as esters are ubiquitous and readily available. The cross-coupling of phenyl esters has been relatively well established throughout the past decade. The cross-coupling of simple methyl esters largely remains elusive in the primary literature. Chapter 1 of this thesis provides a detailed literature background on the field of carboxylic acid derivative cross-coupling, with a primary focus on esters. Chapter 2 describes our efforts in discovering new methodologies for methyl ester cross-coupling reactions. We invoked the use of high throughput experimentation (HTE) studies to facilitate our search for novel methyl ester cross-coupling reactivity. Chapter 3 describes our efforts in developing an additive free, Ni-catalyzed transesterification reaction of methyl esters. The use of alcohols as nucleophilic coupling partners for methyl esters has yet to be reported. We obtained a scope of 20 isolated examples and were able to identify scaffolds that could not be tolerated under our reaction conditions. Lastly, we began preliminary reaction kinetics studies in order to gain useful mechanistic insights for methyl ester cross-coupling reactions.

Thesis advisor: Jeffery A. Byers / This dissertation will discuss the development of Suzuki-Miyaura cross-coupling reactions catalyzed by iron-based complexes with an emphasis on addressing limitations to their practical application in industrial contexts. Chapter 1 will provide an overview of the development of the palladium-catalyzed Suzuki-Miyaura cross-coupling reaction and key factors which have enabled its prevalent use in various industries, with a comparison to how those factors have limited similar development of iron-catalyzed analogues. Chapter 2 will discuss the initial discovery and subsequent development of a series of iron-based precatalysts for the cross-coupling reaction of unactivated aryl boronic esters and alkyl halides. Chapter 3 will discuss the development and validation of a bench-stable iron(III)-based complex capable of catalyzing the Suzuki-Miyaura cross-coupling reaction between unactivated aryl boronic esters and alkyl halides. To conclude, Chapter 4 will discuss the ability of iron-based complexes to participate in the Suzuki-Miyaura cross-coupling reaction with alkyl tosylate electrophiles and its implications for harnessing the ability of iron catalysis to operate under different mechanistic manifolds. / Thesis (PhD) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

No description available.

Contemporary challenges in synthetic organic chemistry require innovative solutions. The discovery of highly-effective and readily accessible scaffolds drives the ever expanding scope of catalytic transformations. This dissertation outlines the repurposing of 1,5-Diaza-3,7-diphosphacyclooctanes (P₂N₂) ligands, commonly employed in inorganic or coordination chemistry, towards organic cross-coupling reactions. Despite their prominence in energy-storage applications, P₂N₂ ligands have been underexplored in catalytic C-C bond formation reactions. Chapter 1 provides a detailed introduction to late transition metal catalysis and the history of P₂N₂ ligands. Chapter 2 outlines the discovery of P^(Cy)₂N^(ArCF3)₂ as a powerful P₂N₂ ligand for the Ni-catalyzed reductive cross-coupling of aryl iodides with aldehydes. Chapter 3 details the extrapolation of the Ni/P^(Cy)₂N^(ArCF3)₂ catalyst system to the related, but less established, redox-neutral α-arylation of primary alcohols. Chapter 4 highlights the applicability of P₂N₂ ligands towards Ni- and Pd-catalyzed Mizoroki-Heck reactions. High-throughput experimentation (HTE) indicated a range of hits with P₂N₂ ligands compared to established ligands in Heck-type couplings. We discovered that absolute site selectivity of C-C bond formation could be controlled by simply altering the phosphorus substituent on the P₂N₂ ligand for the coupling of aryl triflates with styrenes. Notably, this degree of selectivity was not observed with conventional ligands. Chapter 5 focuses on the preparation of the P₂N₂ ligands. Finally, chapter 6 offers a perspective on future developments of P₂N₂ ligands and the prospective directions of their application in transition metal-catalyzed transformations.