21 |
Ruthenium(II) arene complexes for asymmetric catalysisZhu, Zhenyu 09 August 2019 (has links)
Within the last few years, a significant contribution to the discovery of sp2C−H activation processes and useful applications for cross-coupling C−C bond formation has been achieved by the use of ruthenium(II) arene catalysts. The aim of this thesis is to describe a modular approach for the synthesis of several ruthenium(II) arene complexes with the potential for C−H activation. Another cutting-edge field, catalytic enantioselective functionalization of C−H bonds by transitional metal catalysts, has also been realized within the last few years. It represents a highly atom- and step-economic approach toward the generation of structural complexity. However, the majority of current methodologies rely on the usage of late third- row transition metals such as pallidum, iridium and rhodium. There is a need that motivates the search for cheaper, relative earth abundant metals that could have similar catalytic ability. Herein is also represented a preliminary study of a ruthenium(II)-catalyzed enantioselective access to chromane moiety enabled by chiral transient directing group.
|
22 |
Synthesis of CCC-NHC pincer Re and Mn complexes: Air stable catalysts for borrowing hydrogen and dehydrogenative/oxidative cyclization reactionsPham, Huy Hoang 13 August 2024 (has links) (PDF)
The application of N-heterocyclic carbenes (NHCs) in organic and organometallic chemistry has been well-established. The utilization of Zr(NMe2)4 for transmetallation has facilitated the synthesis of CCC-NHC pincer transition metal complexes since 2005 by our group, including Fe, Co, Rh, Ir, Ni, and Pt. However, there have been no reports on the synthesis, characterization, and application of CCC-NHC pincer complexes involving Re and Mn to date. This dissertation aims to address this gap by discussing the synthesis and catalytic activities of CCC-NHC pincer Re and Mn complexes in crossed-coupling reactions. Chapter II will focus on the synthesis of the CCC-NHC pincer Re complex. The synthesis involved transmetallation with CCC-NHC pincer Zr complex using Re(CO)5Cl. The Re complex was characterized by 1H and 13C NMR spectroscopy, mass spectroscopy and its structure was determined by X-ray crystallographic methods. Catalytic activities of Re complex were demonstrated through borrowing hydrogen reactions for the crossed-coupling between ketones and primary alcohols, yielding α-alkylated ketones with water as the only by-product. The borrowing hydrogen reaction improved the economic efficiency when it did not require the good leaving group that conversed from primary alcohols. A wide range of substrates yielded yields ranging from 53% to 92%. Chapter III willdiscuss the expanded application of the Re complex, including borrowing hydrogen reactions for coupling between primary and secondary alcohols, as well as one-pot synthesis of quinolines via dehydrogenative/oxidative cyclization reactions. Control experiments support the proposed catalytic cycle of borrowing hydrogen reactions by the Re complex. In Chapter IV, the synthesis and catalytic activities of CCC-NHC pincer Mn complex are examined. The proposed structure of the Mn complex was supported by NMR spectroscopy, mass spectroscopy, and single X-ray diffraction. The Mn complex demonstrates catalytic activities through borrowing hydrogen and dehydrogenative cyclization, yielding α-alkylated ketones, 2-oxindole derivatives, and quinolines. The control experiments were set up and the proposed mechanism of Mn complex for borrowing hydrogen reaction were consistent with Re complex.
|
23 |
Synthesis of Organoboron Compounds via Reductive Carbon-Carbon Bond Cleavage by Means of Electron Injection / 電子注入による還元的炭素-炭素結合切断を利用した有機ホウ素化合物の合成Fukazawa, Mizuki 25 March 2024 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第25138号 / 理博第5045号 / 新制||理||1719(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 依光 英樹, 教授 畠山 琢次, 教授 松永 茂樹 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM
|
24 |
Unconventional Carbene-Donor Ligands for the Development of new CatalystsReichmann, Sven Ole 13 October 2016 (has links)
No description available.
|
25 |
Préparation de tensioactifs par aldolisation de cétoses non protégés / Aldolisation of unprotected ketoses to surfactantsZhu, Biwen 20 September 2018 (has links)
Dans ce manuscrit, une voie atome économique d'un robuste amphiphile polyols à base de alkyle chaîne liée à liaison C-C ont été développés, ce qui est plus stable pour des applications plus larges. Ce processus implique l'utilisation de matières premières renouvelables et relativement peu coûteuses. Des cétoses tels que la 1,3-dihydroxyacétone et le D-fructose ont été utilisés comme substrats avec des aldéhydes comme agents d'alkylation sans aucune étape de protection-déprotection. La synthèse a été divisée en deux étapes, dans la première étape, les cétoses déprotonées réagissent avec les électrophiles aldéhydes pour former les intermédiaires hydroxycétones. Ensuite, une seconde étape d'hydrogénation avec un catalyseur du ruthénium sur alumine sous pression d'hydrogène a donné accès aux polyols alkylés. Le rendement global de ce procédé en deux étapes est modéré compte tenu de la difficulté de faire réagir une partie fortement hydrophobe avec une partie fortement hydrophile. Ensuite, ces adduits de tétraols obtenus avec la 1,3-dihydroxyacétone ont également été évalués en tant que tensioactifs en effectuant des tests physico-chimiques (CMC, point Krafft et Phase Inverse Temperature). Les résultats ont montré que ces nouveaux agents tensioactifs liés à la liaison C-C sont aussi efficaces que d'autres agents tensioactifs disponibles dans le commerce en diminuant la tension de surface, ce qui est une propriété très attrayante pour des applications potentielles / In this manuscript, an atom economic route of C-C bond based surfactants has been developed. They are more stable for broader applications. This process involves the use of renewable and relatively low cost raw materials. Ketoses such as 1,3-dihydroxyacetone and D-fructose were used as substrates with aldehydes as alkylation agents without any protection-deprotection step. The synthesis has been divided into two steps, in the first step the deprotonated ketoses react with the aldehydes electrophiles to form the hydroxyketone intermediates. Then, a second step of hydrogenation with Ruthenium on alumina catalyst under hydrogen pressure gave access to the alkylated polyols. The overall yield of this two-step process is moderate considering the difficulty of reacting a highly hydrophobic part with a highly hydrophilic part. Then these tetraols adducts obtained with 1,3-dihydrdoxyacetone were also evaluated as surfactants by making physico-chemical tests (CMC, Krafft point and Phase Inverse Temperature). Results have exhibited this novel C-C bond connected surfactants perform as efficient as other commercially available surfactants in decreasing the surface tension which is a very attractive property for potential applications
|
26 |
Visualisering av datastrukturer : Utveckling av ett tolkningsverktygAdborn, Mats January 2013 (has links)
Tolking och tillgodogörande av datastrukturer, organiserad information ochprogramkodsfiler förekommer frekvent i arbete med mjukvaruutveckling. Dennainformation är lagrad i textbaserad form och dess förståelse kräver stornoggrannhet och tidsinvestering från utvecklarens sida. I syfte att försöka förenklaprocessen beskriver detta examensarbete utvecklingen av en prototyp till ettverktygsprogram, vilket automatiserar tolkning av XML-data och källkodsfiler förprogrammeringsspråken C och C++. Programmet skapar och presenterar sedanen visuell graf av den undersökta strukturen. Algoritmen klarar av att presenteragodtyckligt stora XML-filer samt ett begränsat antal samtidigt inlästakällkodsfiler. Effekterna på tolkningens tidsåtgång och dess tillförlitlighet harutvärderats i en undersökning bland studenter inom mjukvaruutveckling.Resultatet visade på en viss mätbar ökning i antalet korrekta slutsatser somanvändaren drog efter att ha studerat datasammanhanget grafiskt jämfört meddess ursprungliga textform. Tidsåtgången mättes inte mer noggrant än subjektivthos användarna, av vilka en övervägande andel ansåg att tiden förkortades medden grafiska representationen till deras hjälp. Examensarbetet visar attanvändandet av detta eller motsvarande verktyg kan öka tillgodogörandet avdatastrukturer genom att både höja graden av tillförlitligheten hos dennainformation och samtidigt minska tidsåtgången. Däremot är den kvantifierbaravinsten av dessa resultat inte statistiskt säkerställd till en högre grad. / Interpretation and assimilation of data structures, organized information andsource code files are frequently occuring during software development. This kindof information is stored in text-based form and its understanding requires greatthoroughness and investment in time from the developer's part. This thesisdescribes the development of a utility program prototype, which automates theparsing of XML data and source code files from the programming languages Cand C++, in purpose of trying to simplify the interpretation process. The programcreates and presents a visual graph of the structure found, using an algorithmwhich can present arbitrary large XML files as well as a limited number ofconcurrent source code files. The effects on the interpretation time and itsreliablity has been evaluated in a survey among software development students.The result showed a certain increase in the number of correct conclusions fromthe participants' side after studying the visual representation compared to itsorignial text-based form. The amount of time used was not measured other thansubjectively by the users themselves, of which a predominant proportionconsidered a reduction in needed time when using the graphical representation.The thesis shows that the use of this or an equivalent utility can enhance theassimilation of data structures by increasing the rate of reliabilty whilesimultaneously decreasing the needed amount of time. Still, the quantifyable gainsof these results remains statistically largely uncertain.
|
27 |
Palladiové katalyzátory deponované na nových silikátových materiálech / Palladium catalysts deposited over novel siliceous supportsKřečková, Pavlína January 2013 (has links)
Title: Palladium catalysts deposited over novel siliceous supports Author: Pavlína Křečková Department: Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague Supervisor: prof. RNDr. Petr Štěpnička, Ph.D. Supervisor's e-mail address: stepnic@natur.cuni.cz Advisor: prof. Ing. Jiří Čejka, DrSc. Advisor's e-mail address: jiri.cejka@jh-inst.cas.cz Abstract Keywords: palladium; deposited catalysts; siliceous supports; C-C coupling reaction. The aim of this work was to prepare a deposited palladium catalyst from Pd2+ and twodimensional zeolite ITQ-2 bearing ≡SiCH2CH2CH2NHCH2CH2NEt2 groups at the surface. This catalys has been evaluated in the Heck reaction between n-butyl-acrylate and brombenzene to give n-butyl-cinnamate. Influence of the reaction temperature, the solvent, base and hydrate water on the progress of the Heck reaction was investigated. This work also deals with the possibility of recycling the catalyst and, due to its nature, with the quantity of leached palladium into the reaction mixture. Furthermore, the work describes differences in morphology between the fresh and a recycled catalyst.
|
28 |
PROTECTION OPTIMIZATION OF CARBON-CARBON COMPOSITES AGAINST AIR OXIDATION BY COATING WITH ANTI-OXIDANTSOues, Adnan Khalil 01 May 2017 (has links)
AN ABSTRACT OF THE DISSERTATION OF TITLE: (OPTIMIZATION PROTECTION OF CARBOB-CARBON COMPOSITES DISC-BRAKES MATERIAL BY COATING WITH ANTI-OXIDANTS) Developing glass enhancer mixture solutions (Ki’s), which promote the formation of a stable glass layer, homogenous clear liquid solution, and low viscosity liquid form, are easy to apply, and penetrating. They are compatible with ceramic liquid glass based anti-oxidants for treating surfaces of carbon/carbon composites material, and significantly increase the rate of protection against oxidation. Ki’s’ are comprised of mixing chemical compositions at standard temperature and pressure conditions from group one and two such as Na, K, Ca, Mg, etc. of 5 to 25 wt. %, deionized water from 95 to 75 % by weight, and adding up to 1 % by weight of surfactants such as DF-16, DF-20, and CF-10 with specific proportions, and followed by thorough stirring to produce a homogeneous blend of mixture solution. The glass enhancers, which are aqueous mixture solutions, are applied to the surfaces of carbon/carbon (C/C) composites by dipping, brushing, spraying, or other painting application techniques, followed by annealing, or a heat-treating range of 80 to 110 ℃ for a minimum of 8 hours, and allowing cooling time of the coated C/C composites of a minimum of 12 hours to room temperature. Preferential compatibility of the glass enhancer mixture solutions (Ki's) is with liquid glass former's, anti-oxidants comprised mostly of borate and phosphate glasses. The glass enhancer solution mixtures (Ki’s) are supplemental additions to ceramics’ liquid anti-oxidants coatings used for carbon-carbon composites protection against oxidation, and it will increase the rate of protection against oxidation for low, and moderate temperature’s range from 400 to 900 ℃. The glass enhancer Ki’s mixture solutions should be used with liquid glass former's’ anti-oxidants, such as SiO₂, GeO₂, B₂O₃, and P₂O₅. A series of glass enhancer’s Ki’s, heat treatment cycle (char-cycle) ranged between 700 to 900 ℃, and application methods, were developed and tested experimentally. Two arbitrary isothermal temperatures of 650 ℃, and 871 ℃ were selected for thermal oxidation testing, and a temperature of 650 ℃ was selected, and tested against catalytic thermal oxidation. Additions of glass enhancer Ki’s improved protection of C/C composites disc-brakes against oxidation by double, and triple amount of time in hours versus the use of anti-oxidant coatings alone.
|
29 |
Síntesi, estructura i reactivitat de nous complexos de Cu, Ag i Ni contenint lligands triazamacrocíclics. Aplicacions en l'activació d'enllaçosXifra Garcia, Raül 28 January 2005 (has links)
· S'ha preparat i caracteritzat una família de complexos de Cu(III) contenint lligands triazamacrocíclics, estudiant-se les seves propietats estructurals, espectroscòpiques i redox. Aquesta àmplia família de complexos tenen un gran interès perquè permeten descriure les propietats dels complexos de Cu en un estat d'oxidació poc habitual i a més ens han permès mesurar de manera quantitativa l'efecte Meyerstein.· Una nova família de complexos de Cu(I) amb els lligands triazamacrocíclics es sintetitzada i caracteritzada per tècniques espectroscòpiques i estructurals, demostrant que aquests complexos presenten diferents estructures a l'estat sòlid i en dissolució. Així doncs, mentre que en dissolució es demostra per RMN que es tracta d'una espècie monomèrica, la determinació estructural per difracció de raigs X d'aquests complexos de Cu(I), ens confirma la formació d'espècies polimèriques. Per altra banda, s'ha estudiat la seva reactivitat; a) la seva implicació en la formació de lligands deuterats mitjançant l'intercanvi H/D en condicions suaus i b) la formació de complexos bisfenoxo a partir de la reactivitat entre els corresponents complexos de Cu(I) i oxigen molecular. De la mateixa manera, s'ha preparat el corresponent anàleg de Ag(I) en estat sòlid, obtenint la formació d'un polímer de Ag(I), el qual presenta a l'estat sòlid una estructura en forma de ziga-zaga, diferent a l'estructura del polímer de Cu(I), que és lineal.· S'ha determinat i proposat el mecanisme que té lloc en l'activació de l'enllaç C-H i posterior reacció de transferència per tal d'estabilitzar els productes finals mitjançant una reacció de desproporció. El seguiment de la reacció té lloc mitjançant tècniques espectroscòpiques com UV-vis. Dit seguiment, ens permet determinar les diferents influències electròniques sobre la reacció de formació dels complexos organometàl·lics de Cu(III). A més a més, el seguiment de la reacció a baixa temperatura ens permet determinar espectroscòpica i teòricament la formació d'un intermedi de Cu(II), i mitjançant la determinació dels paràmetres cinètics i termodinàmics es proposa un mecanisme de reacció. Posteriorment, s'ha assajat la reactivitat d'una sal de Cu(II) amb un lligand macrocíclic que conté un grup metil en el carboni orientat cap al centre del macrocicle, implicant la formació d'un intermedi agòstic. De la determinació estructural d'aquest intermedi de CuII i del lligand protonat, s'extreuen una sèrie de conclusions molt interessants, com són la demostració estructural de l'activació de l'enllaç C-C en la primera etapa de formació i de manera anàloga poder comparar-ho amb els sistemes macrocíclics HL2-HL6, demostrant la possible formació d'un intermedi agòstic, on es produeix l'activació de l'enllaç C-H. Aquesta similitud estaria d'acord amb els sistemes HL2-HL6, els quals espectroscòpica i teòricament s'havia detectat la presència d'un intermedi de característiques similars. Degut a l'acidesa d'aquest protó, i gràcies a la presència d'una base com és el propi lligand, aquest podia ésser extret donant lloc a la formació dels corresponents organometàl·lics de Cu(III). Dita estructura també representa un dels pocs exemples d'un organometàl·lic de CuII, un estat d'oxidació poc conegut dins d'aquest camp.· S'ha descrit la reactivitat dels nous complexos organometàl·lics de Cu(III), els quals sota medi pròtic i en condicions àcides o neutres són espècies totalment estables, però en condicions bàsiques o reductores aquestes espècies reaccionen donant lloc a la formació de noves espècies de tipus bisfenoxo, on el Cu es troba en estat d'oxidació +2. S'han caracteritzat mitjançant difracció de RX, on es s'observa l'entorn químic del Cu, la geometria del complex bisfenoxo i l'hidroxilació de l'anell aromàtic.· Finalment, s'ha descrit per primera vegada la síntesi i caracterització d'uns nous complexos organometàl·lics de Ni. Aquests són sintetitzats en base als càlculs teòrics realitzats sobre els nostres sistemes macrocíclics. Per aquests complexos hem investigat l'efecte del metall, canviant el coure per altres metalls de la primera sèrie de transició (Mn, Fe, Co, Ni, Cu, Zn) i de la segona sèrie de transició (Ru, Rh, Pd, Ag). Els resultats demostren que el Ni(II), és el metall que presenta una major capacitat de l'activació de l'enllaç C-H en aquests sistemes aromàtics. Aquests compostos s'oxiden lentament cap a complexos de Ni(III). Per altra banda, l'addició d'una sal de clor sobre una solució d'un complex de Ni(II) permet aïllar el corresponent complex de Ni(III), caracteritzat per ressonància de spin electrònic / · A family of Cu(III) complexes containing triaza macrocyclic ligands has been described and their structural, spectroscopic and redox properties thoroughly investigated. This family is of interest because it allows studying the properties of Cu complexes in the very unusual oxidation state III and furthermore it allows measuring the so called Meyerstein effect in a quantitative manner.· A new family of Cu(I) complexes containing triaza macrocyclic ligands has been synthesized and characterized both in the solid state and in solution by spectroscopic and structural techniques. NMR spectroscopy demonstrates that the complexes adopt monomeric structures in solution. However, X-ray diffraction analyses demonstrate a polymeric nature in the solid state. On the other hand, the reactivity of these complexes in H/D exchange reactions has been studied, demonstrating that these systems are capable of activating the C-H bond of the aromatic ring in deuterated acetone. On the other hand, the Cu(I) complexes are capable of activating O2, leading to intramolecular aromatic hydroxylation, thus generates complexes with the general formula [(CuII2(m-OLi)2]2+. Finally, we have prepared the corresponding Ag(I) compound. X ray analysis shows that the complex adopts a lineal zigzag polymeric structure.· We propose the mechanism for the activation C-H bond by a Cu(II) complex, coupled to a disproportionation reaction. The monitoring of this reaction has been performed at room and at low temperatures, determinating the different electronic influences of the ligand on the organometallic Cu(III) formation reaction. The monitoring at low temperatures allows to observe and spectroscopically characterize a Cu(II) intermediate. Determination of the kinetic and thermodynamic parameters leads us to propose a mechanism for the reaction. By replacing the H with a Me group, we have crystallography characterized the first example of a Cu(II) C-C agostic intermediate. This specie bears spectroscopic resemblance with the Cu(II) species formed in the aromatic C-H bond activation, and thus we propose it to be the analogous Cu(II) intermediate.Both Cu(I) and Cu(III) complexes are known in organocopper chemistry, but a stable Cu(II) complex is seldom reported. Furthermore, this specie constitutes the second example of a Cu(II) organometallic compound reported in the literature.· We have studied the reactivity of organocopper(III) complexes under different conditions to synthesize new bisphenoxo Cu(II) complexes. These bisphenoxo complexes have been characterized by X-ray diffraction.· A new family of Ni(II) complexes containing triaza macrocyclic ligands have been described and their structural and spectroscopic properties thoroughly investigated. In this case, the C-H bond activation is proposed to occur via acid-base reaction. Moreover, a theoretical study of the activation of the C-H bond in aromatic systems by several transition metals has been carried out. For these specific ligands we have investigated the effect of the metal, changing the copper ion by other first (Mn, Fe, Co, Ni, Cu, Zn) and second transition series metals (Ru, Rh, Pd, Ag). The results demonstrate that the Ni(II) is the ion that presents the highest capacity for activating the C-H bond in the aromatic system of the ligand. On the other hand, the addition of a chloride salt to the Ni(II) complex solution allows the formation of a new and extremely rare organometallic Ni(III) complex.
|
30 |
Réactivités de N-Tosylhydrazones : application à la Synthèse d’Analogues de l’isoCombrétastatine A-4 / N-Tosylhydrazones : towards the synthesis of isocombretastatin A-4 analoguesAziz, Jessy 24 November 2014 (has links)
Les travaux rapportés dans ce mémoire concernent le développement de la réactivité de N-tosylhydrazones dans la création de liaisons carbone-carbone et carbone-azote ainsi que leurs applications à la synthèse des analogues de l’isocombrétastatine A-4 (isoCA-4), aux propriétés antivasculaires.Au cours de ce travail, des molécules de type 1,1-diaryléthylène furent synthétisées par un couplage pallado-catalysé entre des N-tosylhydrazones et des aryles halogénés. Ainsi, des oléfines polysubstituées avec un motif alcoxyle, analogues de l’isoCA-4, ont présenté des activités biologiques intéressantes. De même, les N-tosylhydrazones constituent des intermédiaires pour la synthèse de 1,5-énynes aromatiques. La cyclisation de ces derniers a pu être contrôlée selon la nature du catalyseur utilisé. En effet, en présence de l’or comme catalyseur, une cyclisation 6-endo-dig majoritaire est obtenue alors qu’en présence du palladium, une cyclisation 5-exo-dig exclusive est observée. Cette méthode permettrait de synthétiser des analogues contraints de l’isoCA-4. Le couplage réducteur, catalysé au cuivre, entre des N-tosylhydrazones et des amines et conduisant à des motifs arylalkylamines fut développé. Enfin, un processus cascade entre des 2’-halogéno-biaryl- N-tosylhydrazones et des amines fournit des dérivés du fluorène par la création d’une liaison CN et d’une liaison CC sur le même atome carbénique. / This manuscript reports the development of new metal-catalyzed reactions using N-tosylhydrazones as coupling partners for the creation of carbon-carbon and carbon-nitrogen bonds. These reactions are applied in the synthesis of analogues of isocombretastatine A-4 (isoCA-4), a vascular disrupting agent.First, a palladium-catalyzed cross-coupling reaction between N-tosylhydrazones and aryl halides was developed. By this means, polysubstituted olefins with an alkoxy motif were synthesized and presented good biological activities. Then, aromatic 1,5-enynes were synthesized by a multi-step approach using N-tosylhydrazones as intermediates. The regioselectivity of the cyclisation of these enynes was controlled depending on the reaction conditions. Under gold catalysis, a major 6-endo-dig cyclisation pattern leads to naphthalene derivatives while under palladium catalysis; an exclusive 5-exo-dig cyclisation furnishes benzofulvène derivatives. Conformationnally restricted isoCA-4 analogues could be synthesized by applying this method. A copper-catalyzed reductive coupling between N-tosylhydrazones and amines leading to -branched amine derivatives was also developed. Finally, a cascade reaction between 2’-halo-biaryl-N-tosylhydrazones and amines furnished fluoren scaffold by the formation of CC and CN bonds on the same carbenic atom.
|
Page generated in 0.0365 seconds