京都大学 / 0048 / 新制・課程博士 / 博士(薬科学) / 甲第21346号 / 薬科博第96号 / 新制||薬科||10(附属図書館) / 京都大学大学院薬学研究科薬科学専攻 / (主査)教授 川端 猛夫, 教授 高須 清誠, 教授 大野 浩章 / 学位規則第4条第1項該当 / Doctor of Pharmaceutical Sciences / Kyoto University / DFAM

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The first project in this dissertation presents a simplified and efficient protocol for synthesizing pyrrolines through 5-exo iminyl radical cyclizations. The microwave irradiation of O-Phenyloximes tethered to alkenes causes N-O homolysis resulting in iminyl radical generation, which subsequently undergoes 5-exo-trig cyclizations furnishing pyrrolines. This eliminates the need for toxic radical initiators (AIBN, benzoyl peroxide), propagating agents (Bu3SnH, (Me3Si)3SiH), and expensive catalysts or single-electron transfer (SET) cycles. We explored the scope of diverse traps and substrates for iminyl radical cyclizations. The iminyl radical cyclizations formed versatile pyrrolines with moderate to excellent yields. The diastereoselectivity also ranged from low to high. Moreover, these versatile pyrrolines were further transformed via various reactions, such as hydrogenation, allylation, dihydroxylation, and cross-metathesis. The second part of this project extends the scope of the non-redox iminyl-radical based approach to γ-C(sp3)−H ketone activation. The sequence of N-O homolysis triggered by microwave irradiation of O-phenyloximes, 1,5-hydrogen atom transfer (HAT), trapping of the radical intermediate, and in situ imine hydrolysis, ultimately leads to the formal γ-C–H functionalization of ketones. We achieved both C-O and C-C bond formation by using diverse O-phenyloxime substrates. This work's notable achievement was accomplishing γ-C–H activation of 1o carbon atoms, a feat that has not been attained using SET-based iminyl radical chemistry. The third part of this dissertation focuses on the influence that dehydroamino acids have on secondary structures. This project describes the synthesis of incipient 310 helical tetrapeptides containing dehydroamino acids. A bulky dehydroethylnorvaline-containing tetrapeptide was synthesized. Based on our published data, we speculated that dehydroethylnorvaline might increase peptide proteolytic stability.

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This dissertation describes the synthesis, antimicrobial properties, and catalytic activity of a variety of eta5-ligand rhodium and iridium complexes. Cp*RM(beta-diketonato)Cl (Cp*R = R-substituted tetramethylcyclopentadienyl ligand) complexes were found to have selective activity against Mycobacterium smegmatis, with activity highly dependent upon the substituents on the Cp*R ligand as well as on the beta-diketonato ligand. These complexes were synthesized in good yield from the reaction of the chloro bridged dimers ([Cp*RMCl2]2) with the desired beta-diketonato ligand under basic conditions. All complexes were fully characterized by 1H and 13C NMR. Twenty single crystal X-ray structures were solved. The success of these syntheses led to investigation of another beta-diketonato ligand: 1,1,1,5,5,5-hexafluoroacetylacetonate (hfac). Though many metal complexes of this ligand are known, reaction with [Cp*MCl2]2 did not yield the desired Cp*M(hfac)Cl complexes. Instead, a variety of products were obtained, three of which were characterized crystallographically. The most interesting structure featured a non-coordinating trifluoroacetate (TFA) anion and a [Cp*Ir]3Na1O4 cubane structure, which is an unprecedented and highly unusual arrangement for iridium. Attempts to synthesize this cluster rationally through reactions of [Cp*IrCl2]2 with TFA yielded instead a chloro bridged [Cp*IrCl(TFA)] dimer. Reaction of [Cp*MCl2]2 with 1,1,1-trifluoroacetylacetonate (tfac) yielded the expected Cp*M(tfac)Cl complex, indicating that the problem lies with using hfac as a ligand for Cp*M(III) complexes. Finally, the indenyl effect was investigated for the oxidative annulation of 2-phenylimidazole with 1-phenyl-1-propyne catalyzed by a series of methyl-substituted [(indenyl)RhCl2] dimers. [(Ind*)RhCl2]2 was found to have significantly greater activity than [Cp*RhCl2]2 (100% vs. 51%). Two plausible catalytic cycles were proposed, one of which invokes a ring slip transition state. Though it is unclear if the "indenyl effect" is responsible for this differing activity, it is certainly apparent that using an indenyl ligand has a notable effect in this catalytic reaction. Cyclometalation was also investigated stoichiometrically for 2-phenyl-1H-imidazole and 1-phenylpyrazole and found to proceed readily for [(Ind*)RhCl2]2. Additionally, the crystallographic structure of a Rh+ /Rh– ionic pair was solved. Ionic pairs such as this are rarely found in the literature. / Doctor of Philosophy / This dissertation deals with the uses of a series of unusual compounds containing the metals rhodium and iridium. Though these are rare and expensive metals, the uses and benefits described in this dissertation far outweigh the costs. Overall, the compounds described in this dissertation are colorfully characterized as “piano stool” compounds because of their overall shape and appearance. The metal, either rhodium or iridium, occupies a central point in the complex. On top of the metal is a “flat” organic group that gives the appearance of the seat of the piano stool. Below the metal, there are three other groups that look like the legs of the piano stool. By appropriate choice of the metals and the surrounding groups, special properties can be designed into these “piano stool” complexes. Chapter 2 describes the synthesis of a series of complexes where the “flat” group is a variant of a five-membered carbon ring compound known as cyclopentadienyl, the metal is rhodium or iridium, and two of the three legs come from a family of compounds known as acetylacetonates (acac). This series of piano stool compounds display antimicrobial activity against a class of pathogens known as mycobacteria, an example of which causes the disease tuberculosis. Changing the cyclopentadienyl group and the acac group allows for this antimicrobial activity to be tuned. In the following chapter, attempts to make the same type of compound described in the paragraph above with fluorine-substituted acacs gave some very unexpected results. The most surprising result was a very unusual cube-shaped structure containing 3 iridium atoms, 1 sodium atom, and 4 oxygen atoms, which is an unprecedented arrangement for iridium. Finally, there is a specific example of a flat group for the piano stool known as indenyl. Indenyl is intriguing because it can change shape from a flat group to a bent group. In doing this, it provides more space around the metal for other molecules to bind. The result of this work shows that piano stool compounds created with this indenyl group are more active and selective for carrying out a catalytic reaction to make new ring systems that could have potential use in the synthesis of new flavorings, fragrances, and even pharmaceuticals.

Au cours de cette thèse, nous nous sommes intéressés à l'activation de liaisons C-H catalysée par des catalyseurs au palladium pour la préparation de biaryles portant un groupement SO₂R. De très nombreux composés biologiques possèdent une fonction SO₂R. Nous avons donc choisi d'étudier activation de liaisons C-H de ce type de substrat. L'activation de liaisons C-H est considérée comme attractive pour l'environnement par rapport à d'autres types de couplages tels que Suzuki, Stille, ou Negishi. D'abord, nous avons démontré qu'il est possible d'appliquer la méthode d'activation de liaisons C-H pour l'arylation directe de thiophènes portant un substituant SO₂R. Nous avons ensuite établi un système catalysé au palladium pour l'arylation sélective en C2 de dérivés N-tosylpyrrole. Nous avons constaté que le N-tosylpyrrole est plus réactif comparé au pyrrole non protégé. Nous avons également étudié l'arylation directe d'hétéroarènes par des bromobenzènes possédant un substituant SO₂R soit en C2 ou C4 par catalyse au palladium. Cette méthode fournit un accès simple à des dérivés de ArSO₂R. Enfin, nous avons développé la première méthode de déshydrogénation de liaisons sp³ C-H catalysée au palladium de N-alkyl-benzènesulfonamides pour produire des N-alcényle benzènesulfonamides. / During this Ph.D. period, we were interested in the C-H bonds activation catalysed by palladium catalysts for the preparation of biaryls units bearing SO₂R group. Many biological compounds present a SO₂R function and thus we chose to activate this family of substrates. This method is considered as cost effective and environmentally attractive compared to other types of couplings such as Suzuki, Stille, or Negishi. First, we demonstrated that it is possible to apply C-H bond activation method for the direct arylation of thiophene derivatives bearing a SO₂R substituent. We then established palladium-catalysed system for the selective C2 arylation of N-tosylpyrrole derivatives. We found that N-tosylpyrrole is more reactive than free NH-pyrrole. We also studied the direct arylation of heteroarenes using bromobenzenes bearing SO₂R substituents either at C2 or C4 via palladium-catalysed C-H activation. This method provides a simpler access to substituted SO₂R derivatives. Finally we developed the first palladium-catalysed dehydrogenative sp³ C-H bond functionalization/activation of N-alkyl-benzenesulfonamides to produce N-alkenyl-benzenesulfonamides. The reaction proceeds with easily accessible ligand-free Pd(OAc)₂ catalyst for aryl bromides bearing electron-withdrawing groups or PdCl(C₃H₅)(dppb) catalyst for aryl bromides with electron-donating substituents. We found that the reaction tolerates a variety of substituents both on nitrogen and on the bromobenzene moiety.

The thesis presents an experimental investigation of combustion performance and emissions of waste cooking oil (WCO) based biodiesel. To evaluate the comparative performance of biodiesel and diesel, combustions tests were conducted using Continuous Combustion rig (CCR) and Land Rover VM diesel engine. Firstly, physical properties of WCO biodiesel and diesel samples were measured in the laboratory. Elemental analysis of WCO biodiesel showed that there are differences between the functional groups in diesel and biodiesel which lead to major differences in the combustion characteristics of the two fuel types. It was found that biodiesel had 10% lower carbon content, almost no sulphur content for biodiesel and up to 12% more oxygen content compared with diesel. This explains the lower caloric value for WCO biodiesel (up to l8 %) compared with diesel. However, higher oxygen content and double bounds in WCO biodiesel increase its susceptibility to oxidation. The CCR test results showed an increase in combustion gas temperature with the increases in biodiesel blend ratio in diesel. This was due to a faster reaction rate for biodiesel than that of diesel leading to a faster brakeage of the hydrocarbon chain to release more heat. The engine tests were performed to measure the torque and emissions for different engine speeds and loads. In general a decrease in engine torque with up to 9% for biodiesel was observed, which was due to the lower calorific value of biodiesel compared with that of diesel. The brake specific fuel consumption (BSFC) increased as the biodiesel blend ratio in diesel increases due a greater mass of fuel being injected at a given injection pressure, compared with diesel. Using WCO blends ratio up to 75% in diesel showed a reduction in exhaust emission compared with diesel, however, at the cost of increased fuel consumption. A common conclusion can be drawn in favour of the WCO biodiesel as being a greener alternative to petro-diesel when used in blend with diesel. However, due to large variations in the biomass used for biodiesel production could lead to variations in physical and chemical properties between biodiesel produced from different biomass. Therefore more stringent standards need to be imposed for biodiesel quality in order to diminish the effect of variation in physicochemical properties on engine performance and emissions. The future work in developing standard test procedures for establishing fuel properties and limits/targets would be beneficial in using a large amount of waste cooking oil in the production of biodiesel, thus contributing to reduction in CO2 and waste minimisation.

The functionalisation of C-H bonds has been widely studied in organic synthesis. This work presents the results of investigation into two areas of current research, copper-catalysed aromatic C-H functionalisation and rhodium-catalysed hydroacylation. Chapter 1 presents the development of palladium- and copper-catalysed aromatic C-H functionalisation with particular attention paid to regiocontrol. Chapter 2 describes the development of copper-catalysed cross-coupling of perfluorinated arenes and alkenyl halides along with efforts to expand this methodology to a more general reaction. In Chapter 3 the development of chelation-controlled rhodium-catalysed hydroacylation is discussed. Chapter 4 outlines the utilisation of amino acid derived N-methylthiomethyl aldehydes in rhodium-catalysed hydroacylation methodology.

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