Dissertations / Theses on the topic 'C-C bond catalysis'
To see the other types of publications on this topic, follow the link: C-C bond catalysis.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'C-C bond catalysis.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Rousseaux, Sophie. "Palladium-Catalyzed C(sp2)-C(sp3) Bond Formation." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23058.
Full textAbstract:
Palladium-catalyzed reactions for carbon-carbon bond formation have had a significant impact on the field of organic chemistry in recent decades. Illustrative is the 2010 Nobel Prize, awarded for “palladium-catalyzed cross couplings in organic synthesis”, and the numerous applications of these transformations in industrial settings. This thesis describes recent developments in C(sp2)-C(sp3) bond formation, focusing on alkane arylation reactions and arylative dearomatization transformations. In the first part, our contributions to the development of intramolecular C(sp3)-H arylation reactions from aryl chlorides are described (Chapter 2). The use of catalytic quantities of pivalic acid was found to be crucial to observe the desired reactivity. The reactions are highly chemoselective for arylation at primary aliphatic C-H bonds. Theoretical calculations revealed that C-H bond cleavage is facilitated by the formation of an agostic interaction between the palladium centre and a geminal C-H bond. In the following section, the development of an alkane arylation reaction adjacent to amides and sulfonamides is presented (Chapter 3). The mechanism of C(sp3)-H bond cleavage in alkane arylation reactions is also addressed through an in-depth experimental and theoretical mechanistic study. The isolation and characterization of an intermediate in the catalytic cycle, the evaluation of the roles of both carbonate and pivalate bases in reaction mechanism as well as kinetic studies are reported. Our serendipitous discovery of an arylation reaction at cyclopropane methylene C-H bonds is discussed in Chapter 4. Reaction conditions for the conversion of cyclopropylanilines to quinolines/tetrahydroquinolines via one-pot palladium(0)-catalyzed C(sp3)-H arylation with subsequent oxidation/reduction are described. Initial studies are also presented, which suggest that this transformation is mechanistically unique from other Pd catalyzed cyclopropane ring-opening reactions. Preliminary investigations towards the development of an asymmetric alkane arylation reaction are highlighted in Chapter 5. Both chiral carboxylic acid additives and phosphine ligands have been examined in this context. While high yields and enantiomeric excesses were never observed, encouraging results have been obtained and are supported by recent reports from other research groups. Finally, in part two, the use of Pd(0)-catalysis for the intramolecular arylative dearomatization of phenols is presented (Chapter 7). These reactions generate spirocyclohexadienones bearing all-carbon quaternary centres in good to excellent yields. The nature of the base, although not well understood, appears to be crucial for this transformation. Preliminary results in the development of an enantioselective variant of this transformation demonstrate the influence of catalyst activation on levels of enantiomeric excess.
2
Lomas, Sarah. "C-C bond forming catalysis with alkaline earth acetylides." Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604644.
Full textAbstract:
After spending so many years in the shadow of magnesium chemistry the chemical abilities of the heavier alkaline earth metals, calcium, strontium and barium are beginning to emerge. This thesis is concerned with the development of a catalytic reactivity for the heavier alkaline earth metals. By taking inspiration from lanthanide metal catalysis, this thesis will begin by describing the hydroamination and hydrophosphination of unsaturated molecules catalysed by lanthanide and group 2 metals before extending this work to the group 2 catalysed hydroacetylation of terminal acetylenes (chapter 2), and the insertion of unsaturated bonds of carbodiimides (chapter 4), and organic isocyanates (chapter 5) into the polarised M-C bonds of group 2 acetylides. The third chapter of this thesis will describe the observation of the first acetylide coupling with a group 2 metal complex and extension of this reactivity to a catalytic process.
3
Fossey, John Stephen. "Group 10 NCN pincer complexes for C-C bond forming catalysis." Thesis, Queen Mary, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409665.
Full text
4
Szymaniak, Adam Anthony. "Nonracemic Organoboronates by Transition Metal-Catalyzed C-C and C-Si Bond Forming Reactions." Thesis, Boston College, 2018. http://hdl.handle.net/2345/bc-ir:108119.
Full textAbstract:
Thesis advisor: James P. MorkenThis dissertation will describe the development of three transition metal-catalyzed syntheses of nonracemic organoboronates. The first chapter explains the development of a palladium-catalyzed enantiotopic-group-selective cross-coupling of geminal bis(boronates) with alkenyl electrophiles. This process enables the synthesis of highly valuable nonracemic disubstituted allylic boronates. Chapter two describes a palladium-induced 1,2-metallate rearrangement of vinylboron “ate” complexes. The newly developed process incorporates an alternative route for the transmetallation step of Suzuki-Miyaura cross-couplings. Lastly, an enantioselective platinum-catalyzed hydrosilylation of alkenyl boronates is disclosed. This reaction enables the synthesis of nonracemic geminal silylboronates for the divergent synthesis of functionalized
Thesis (PhD) — Boston College, 2018
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
5
Wilkinson, Matthew. "Bulky arylphosphines and arylarsines for catalysis of C-C bond-forming reactions." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274605.
Full text
6
Truscott, Fiona Rosemary. "Transition metal catalysed C-C bond formation via C-H functionalisation." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:6a1ef296-8d63-470d-96bd-3e01a887c81f.
Full textAbstract:
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.
7
Zárate, Sáez Cayetana. "C-heteroatom bond-formation via ni-catalyzed c-o bond cleavage." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/401555.
Full textAbstract:
Tot i que el camp de l'acoblament creuat ha desenvolupat increïbles avenços, la gran majoria de processos encara es basen en l'ús d'halurs d'aril. No obstant, aquest tipus d’electròfils presenten una toxicitat intrínseca i, al mateix temps, la seva síntesis resulta tediosa, especialment quan es tracta d'halurs d'aril altament funcionalitzats. A causa d'això, la comunitat sintètica s'ha bolcat en la recerca d'alternatives a l'ús d'halurs d'aril en química d'acoblament creuat. Grans esforços s'han desenvolupat en la última dècada per implementar els derivats del fenol en aquest tipus de transformacions a causa de l'abundància natural i comercial d'aquests compostos i a la seva baixa toxicitat en comparació amb els organohalurs. No obstant, l'alta energia d'activació necessària per trencar els enllaços C-O ha limitat considerablement l'ús de derivats de fenol en reaccions d’acoblament creuat, sobretot si es tracta d'éters de metil. Actualment la gran majoria de mètodes basats en aquesta família d’electròfils s'utilitzen en la formació d'enllaços C-C. Altrament, gairebé no existeixen tècniques per obtenir enllaços Cheteroàtom probablement a causa de la baixa reactivitat dels nucleòfils, on la densitat de càrrega negativa resideix en un heteroàtom. La present tesi doctoral s'ha centrat en el desenvolupament de noves metodologies per a la creació d'enllaços de tipus C-heteroàtom mitjançant l’activació catalítica d'enllaços C-O amb complexes de Ni. S'han descrit nous mètodes de sililació i borilació d'ésters i metil éters
d’aril i benzil. Aquests mètodes suposen una via alternativa per a la síntesis de silans i boronats, els quals són intermedis de gran utilitat en
síntesis orgànica. A més, el descobriment d'unes condicions totalment inusuals per activar enllaços de tipus C-OMe ha obert noves
perspectives sobre la reactivitat d'aquest tipus d'enllaços i, alhora, ha suggerit l'existència de nous mecanismes d'activació.A pesar de que el campo del acoplamiento cruzado ha desarrollado increíbles avances, la gran mayoría de procesos todavía se basa en el uso de halogenuros de arilo. Sin embargo, este tipo de electrófilos presentan una toxicidad intrínseca y, a su vez, su síntesis resulta tediosa, especialmente cuando se trata de halogenuros de arilo altamente funcionalizados. Debido a ello, la comunidad sintética se ha volcado en la búsqueda de alternativas al uso de halogenuros de arilo en química de acoplamiento cruzado. Un gran esfuerzo se ha desarrollado en la última década para implementar los derivados del fenol en este tipo de transformacions debido a la abundancia natural y comercial de dichos compuestos y a su baja toxicidad en comparación con los organohalogenuros. Sin embargo, la alta energía de activación necesaría para romper los enlaces C-O ha limitado considerablemenete el uso de derivados del fenol en reacciones de acomplamineto cruzado, sobre todo si se trata de éteres de metilo. Actualmente la gran mayoría de métodos basados en esta familia de electrófilos se utilizan en la formación de enlaces C-C. De lo contrario, apenas existen técnicas para obtener enlaces C-heteroátomo probablemente debido a la baja reactividad de los nucleófilos donde la densidad de carga negativa reside en un heteroátomo. La presente tesis docotoral se ha centrado en el desarrollo de nuevas metodologías para la creación de enlaces de tipo C-heteroatomo mediante la activción catalítica de enlaces C-O con complejos de Ni. Se han descrito novedosos métodos de sililación y borilación de ésteres y metil éteres de arilo y bencilo. Dichos métodos suponen una via alternativa para la síntesis de silanos y boronatos, los cuales son intermedios de gran utilidad en síntesis orgánica. Además, el descubrimiento de unas condiciones totalmente inusuales para activar enlaces de tipo C-OMe ha abierto nuevas perspectivas sobre la reactividad de este tipo de enlaces y, a la vez, ha sugerido la existencia de nuevos mecanismos de activación.
While the field of cross-coupling has reached remarkable levels of sophistication, the vast majority of processes are still being conducted with organic halide counterparts. Drawbacks associated to their toxicity and the limited accessibility of densely functionalized aryl halides have prompted chemists to develop powerful, yet practical, alternatives. Among these, the utilization of phenol derivatives as coupling partners via C-O bond cleavage would be particularly rewarding due to their readily availability and benign nature. However, the high activation energy required for effecting C–O bond cleavage has become a daunting challenge when devising catalytic techniques using phenol derivatives, specially always-elusive aryl methyl ethers. At present, the vast majority of cross-coupling reactions using phenol derivatives remains confined to C–C bond formation, whereas the formation of C-heteroatom bonds has been poorly studied, likely due to the less reactivity of heteroatom-based nucleophiles. This doctoral thesis has focused on the development of new methodologies for forging C-heteroatom bonds via Ni-catalyzed C-O bond cleavage. It has been described new protocols for the silylation and borylation of aryl and benzyl esters and methyl ethers. These methodologies can be used as useful alternatives towards the synthesis of aryl and benzyl silanes and boronates, incredible important intermediates in organic synthesis. Furthermore, the discovery of unusual, yet surprising, conditions for the cleavage of C-OMe bonds have opened up new vistas towards the reactivity of aryl and benzyl methyls ethers while suggesting new activation pathways.
8
Bartoszewicz, Agnieszka. "Transition metal-catalysed hydrogen transfer processes for C-C and C-N bond formation : Synthetic studies and mechanistic investigations." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-81596.
Full textAbstract:
This thesis focusses on synthetic studies and mechanistic investigations into reactions involving hydrogen-transfer processes. In the first part, the development of an efficient method for the synthesis of β-hydroxy ketones (aldols) and β-amino ketones (Mannich products) from allylic alcohols and aldehydes is described. These reactions use Ru(η5-C5Ph5)(CO)2Cl as the catalyst. The reaction parameters were optimised in order to suppress the formation of undesired by-products. Neutral and mild reaction conditions enabled the synthesis of a variety of aldol products in up to 99% yield, with a good syn/anti ratio. The influence of the stereoelectronic properties of the catalyst on the reaction outcome was also studied. Based on the results obtained, a plausible reaction mechanism has been proposed, involving as the key steps the 1,4-addition of hydride to α,β-unsaturated ketones and the formation of ruthenium (Z)-enolates. In the second part of this thesis, a ruthenium-catalysed tandem isomerisation/C-H activation reaction is presented. A number of ruthenium complexes, phosphine ligands, and additives were evaluated in order to establish the optimal reaction conditions. It was found that the use of a stable ruthenium catalyst, Ru(PPh3)3Cl2, together with PtBu3 and HCO2Na resulted in an efficient tandem transformation. Using this procedure, a variety of ortho-alkylated ketones were obtained in excellent yields. Moreover, homoallylic alcohols could also be used as starting materials for the reaction, which further expands the substrate scope. Mechanistic investigations into the isomerisation part of the process were carried out. The last project described in the thesis deals with the design and preparation of novel bifunctional iridium complexes containing an N-(2-hydroxy-isobutyl)-N-Heterocyclic carbene ligand. These complexes were used as catalysts to alkylate amines using alcohols as latent electrophiles. The catalytic system developed here was found to be one of the most active systems reported to date, allowing the reaction to be performed at temperatures as low as 50 °C for the first time. A broad substrate scope was examined. Combined experimental and theoretical studies into the reaction mechanism are consistent with a metal-ligand bifunctional activity of the new catalyst.
9
Mazzarella, Daniele. "C-C and C-B Bond Forming Strategies Driven by the Photoexcitation of Organocatalytic Intermediates." Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/669808.
Full textAbstract:
El principal objectiu científic dels meus estudis de doctorat va ser demostrar que la reactivitat en estat excitat dels intermedis organocatalítics són capaços de proporcionar noves oportunitats per desenvolupar noves reaccions catalítiques mitjançant radicals per a la formació d'enllaços C-C i C-B. La fotoexcitació d'intermedis organocatalítics van proporcionar radicals mitjançant transferència d'un sol electró o homòlisis.
En el capítol II, analitzo el desenvolupament d'una funcionalització asimètrica organocatalítica fotoquímica de C-H del toluè i derivats. El nostre sistema aprofita les propietats oxidatives millorades dels ions d’imini quirals excitats amb llum visible i el caràcter bàsic dels seus contraanions per activar, a través d'una transferència d'electrons acoblada a protons multilloc, derivats de toluè. El radical resultant és atrapat més tard per l'intermedi organocatalític quiral amb alt estereocontrol.
A la segona part dels meus estudis de doctorat, em vaig concentrar en la generació catalítica de compostos fotó làbils basats en tiocarbonil per promoure la formació d'enllaços C-B i C-C. Com es detalla en el capítol III, utilitzem un organocatalitzador nucleofílic d'anió ditiocarbonil per activar electròfils d’alquil a través d'una via SN2. El producte intermedi resultant que absorbeix fotons, després de l'absorció de llum visible, genera radicals a través de l'escissió homolític de l'enllaç C-S feble. El radical generat és llavors interceptat per bis(catecolat)diboro per proporcionar productes d'èster alquilborònic. El capítol IV destaca com aquest enfocament fotolític es va expandir a l'activació dels clorurs d'acil i carbamoil a través d'una via de substitució d'acil nucleofílica. Els radicals acil i carbamoil generats fotoquímicament s'han utilitzat en reaccions de tipus Giese amb olefines pobres en electrons per formar nous enllaços C-C. Una investigació mecanística detallada, basada en anàlisis espectroscòpics i electroquímics juntament amb la caracterització d'intermedis clau, va identificar una varietat d'equilibris fora del cicle que cooperen per controlar les concentracions generals dels radicals, contribuint a l'eficiència del procés.El principal objetivo científico de mis estudios de doctorado fue demostrar que la reactividad en estado excitado de los intermedios organocatalíticos son capaces de proporcionar nuevas oportunidades para desarrollar nuevas reacciones catalíticas mediante radicales para la formación de enlaces C-C y C-B. La fotoexcitación de intermedios organocatalíticos proporcionaron radicales mediante transferencia de un solo electrón u homólisis. En el Capítulo II, analizo el desarrollo de una funcionalización asimétrica organocatalítica fotoquímica de C-H del tolueno y derivados. Nuestro sistema aprovecha las propiedades oxidativas mejoradas de los iones de iminio quirales excitados con luz visible y el carácter básico de sus contraaniones para activar, a través de una transferencia de electrones acoplada a protones multisitio, derivados de tolueno. El radical resultante es atrapado más tarde por el intermedio organocatalítico quiral con alto estereocontrol. En la segunda parte de mis estudios de doctorado, me concentré en la generación catalítica de compuestos fotolábiles basados en tiocarbonilo para promover la formación de enlaces C-B y C-C. Como se detalla en el Capítulo III, empleamos un organocatalizador nucleofílico de anión ditiocarbonilo para activar electrófilos de alquilo a través de una vía SN2. El producto intermedio resultante que absorbe fotones, tras la absorción de luz visible, genera radicales a través de la escisión homolítica del enlace C-S débil. El radical generado es entonces interceptado por bis(catecolato)diboro para proporcionar productos de éster alquilborónico. El Capítulo IV destaca cómo este enfoque fotolítico se expandió a la activación de los cloruros de acilo y carbamoilo a través de una vía de sustitución de acilo nucleofílica. Los radicales acilo y carbamoilo generados fotoquímicamente se han utilizado en reacciones de tipo Giese con olefinas pobres en electrones para formar nuevos enlaces C-C. Una investigación mecanística detallada, basada en análisis espectroscópicos y electroquímicos junto con la caracterización de intermedios clave, identificó una variedad de equilibrios fuera del ciclo que cooperan para controlar las concentraciones generales de los radicales, contribuyendo a la eficiencia del proceso.
The main scientific objective of my doctoral studies was to demonstrate that the excited-state reactivity of organocatalytic intermediates could provide new opportunities to develop novel catalytic radical C-C and C-B forming reactions. The photoexcitation of organocatalytic intermediates afforded radicals through either single-electron transfer or homolysis. In Chapter II, I discuss the development of an asymmetric organocatalytic photochemical C-H functionalization of toluene and derivatives. Our system harnesses the enhanced oxidative properties of visible-light excited chiral iminium ions and the basic character of their counteranions to activate, through a multisite proton coupled electron transfer, toluene derivatives. The ensuing radical is later trapped by the chiral organocatalytic intermediate with high stereocontrol. In the second part of my doctoral studies, I focused on the catalytic generation of photolabile thiocarbonyl-based compounds to promote the formation of C-B and C-C bonds. As detailed in Chapter III, we employed a nucleophilic dithiocarbonyl anion organocatalyst to activate alkyl electrophiles through an SN2 pathway. The ensuing photon-absorbing intermediate, upon visible light absorption, generates radicals through homolytic cleavage of the weak C-S bond. The generated radical is then intercepted by bis(catecholato)diboron to afford alkyl boronic ester products. Chapter IV highlights how this photolytic approach was expanded to the activation of acyl and carbamoyl chlorides through a nucleophilic acyl substitution pathway. The photochemically generated acyl and carbamoyl radicals have been used in Giese-type reactions with electron-poor olefins to form new C-C bonds. A detailed mechanistic investigation, based on spectroscopic and electrochemical analyses along with the characterization of key intermediates, identified a variety of off-the-cycle equilibriums that cooperate to control the overall concentrations of the radicals, contributing to the efficiency of the process.
10
Zhang, Qi. "Transition-metal-catalyzed C-F bond formation." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/3228.
Full textAbstract:
Fluorine atom plays a very important role in pharmaceuticals, agricultural chemicals, and medical imaging and it has become one of the most popular area in organic chemistry. For example, in modern medicinal chemistry introducing fluorine atom could potentially improve absorption, metabolism and potency of drug candidates. As a result, methods that allow the selective and efficient formation of the carbon-fluorine bond are highly desirable. An evolving approach is the utilization of transition-metals to catalyze the nucleophilic substitution of fluoride ion. This thesis described several novel and efficient methods to generate allylic and benzylic C-F bonds using rhodium/iridium catalyst.
11
Harkness, Gavin J. "Sequential processes using catalytic C-O bond activation." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/12809.
Full textAbstract:
This thesis is centred around sequential C-C bond forming processes using oxygenated electrophiles. A major part of this research focuses on the constructive deoxygenation of 2-methoxyphenol (guaiacol), a major breakdown product of the renewable feedstock, lignin. 1,2-dielectrophiles are known to be challenging substrates for catalysis if both leaving groups are of similar reactivity, however high selectivity was observed in the palladium- catalysed Grignard cross-coupling of 2-methoxyphenyl-1H-imidazole-1-sulfonate. The previously untested Grignard cross-coupling catalyst, [PdCl₂(Xylyl-Phanephos)], was found to be highly active. A 2-benzoxazolyl functionality was shown to be an excellent directing group for the chelation-controlled nucleophilic aromatic substitution of aryl methyl ethers. However, this modified Meyers reaction is limited to aryl ethers containing an ortho-chelating group. To expand the ether scope, nickel-catalysed Grignard cross-coupling was studied. [NiCl₂(PⁿBu₃)2] showed increased activity in the Grignard cross-coupling of challenging ortho-substituted anisoles compared to the well-renowned [NiCl₂(PCy₃)2] and several Ni0 -NHC systems, with a ligand steric effect demonstrated. The success of [NiCl₂(PⁿBu₃)2] was extended to more activated methoxynaphthalene substrates, in which the lowest reported catalyst loadings (0.1-0.25 mol%) were reported. Induction periods at 0.1 mol% suggested the requirement of inorganic Lewis-acidic magnesium salts to be formed in situ before any considerable activity was observed. Further work is required to increase reaction and ether scope, but this work provides a basis for exploiting lignin- derived phenols as a framework in the synthesis of functionalised chemicals of higher value. The final results chapter concerns an alternative sequential C-C bond forming process using another oxygenated electrophile. [PdCl₂((S)-Xylyl-Phanephos)] was used to accomplish a Grignard cross-coupling of vinyl tosylate, with the product then subjected to a highly enantioselective methoxycarbonylation using the same catalyst. This lead to a concise synthesis of (S)-Flurbiprofen.
12
Godwin, Christopher. "Oxovanadium Complex-Catalyzed Aerobic C-C Bond Cleavage of Biomass-derived Scaffolds." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39567.
Full textAbstract:
The non-sustainable nature of fossil fuels as feedstocks for valuable chemicals, combined with the environmental damage caused by their extraction and combustion, increases the need for the development of a bio-based economy. While industry and public opinion are slowly shifting towards acceptance of this change, efficient technologies for the depolymerization and subsequent separation of lignocellulosic biomass fall short of the ever-increasing demand. In particular, there are currently no efficient, sustainable mass scale methods to convert lignin, the most abundant source of aromatic molecules on Earth. The use of oxovanadium(V) catalyst complexes to aerobically cleave C‒C bonds has been demonstrated previously and remains an attractive option for incorporation into a sustainable bio-based economy.
Two new triphenoxyamine oxovanadium(V) catalysts with reduced steric bulk and electron density at the metal center (vs. previously reported complexes) have been synthesized for aerobic oxidative diol C‒C bond cleavage. These complexes were found to cleave less activated and more complex substrates than previous generations, including cyclic diols and polyalcohols. Several insights into the reaction pathways of this class of complex were elucidated through a series of kinetic studies. Experimentally, the rate of C‒C bond cleavage of both pinacol and hydrobenzoin was determined to be unaffected by substitution of the O‒H bonds with deuterium, suggesting that currently proposed mechanisms need to be revised. Multiple catalytic regimes were observed during anaerobic reaction, which were not altered significantly by the brief addition of O2. A series of density functional theory calculations revealed a plausible mechanism for the trialkoxy complex that did not involve a proton transfer in the rate determining step, instead suggesting that ligand-arm dissociation-reassociation play a significant role in the reaction.
In a second project, new bisphenoxyamine-N-appended base ligand with less steric hindrance and electron density at the metal center, has been synthesized utilizing similar design principles gained from work with triphenoxyamine catalysts. When reacting with lignin model compound 1,2-diphenyl-2-methoxyethanol, this new complex displays a higher selectivity towards aldehydes and esters (relative to previous bisphenoxyamine-N-appended ligands), leading to a higher rate of C‒C bond cleavage. Investigations into the mechanism of bisphenoxy complexes, as well as the role of the N-appended base in reactivity, were performed using substrate pre-complexed bisphenoxy compounds. Thermolysis at 60 and 100 °C produced almost exclusively oxidative C‒H bond cleavage product benzyl methyl ether, with evidence for overoxidation product benzoic acid observed. Thermolysis of labelled substrate pre-complexed revealed that N-appended base may impede C‒C cleavage of 1,2-diphenyl-2-methoxyethanol by forcing the methyl ether away from the oxovanadium(V) center.
Through the use of these multidentate phenoxyamine ligands, advances have been made towards sustainable oxovanadium catalysis in the pursuit of efficient and selective lignocellulosic disassembly for a sustainable bio-based economy.
13
Reich, Blair Jesse Ellyn. "Cyanide-catalyzed C-C bond formation: synthesis of novel compounds, materials and ligands for homogeneous catalysis." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4987.
Full textAbstract:
Cyanide-catalyzed aldimine coupling was employed to synthesize compounds
with 1,2-ene-diamine and ñ-imine-amine structural motifs: 1,2,N,N'-
tetraphenyletheylene-1,2-diamine (13) and (+/-)-2,3-di-(2-hydroxyphenyl)-1,2-
dihydroquinoxaline (17), respectively. Single crystal X-ray diffraction provided solidstate
structures and density functional theory calculations were used to probe isomeric
preferences within this and the related hydroxy-ketone/ene-diol system. The enediamine
and imine-amine core structures were calculated to be essentially identical in
energy. However, additional effects-such as ÃÂ conjugation-in 13 render an enediamine
structure that is slightly more stable than the imine-amine tautomer (14). In
contrast, the intramolecular hydrogen bonding present in 17 significantly favors the
imine-amine isomer over the ene-diamine tautomer (18).
Aldimine coupling (AIC) is the nitrogen analogue of the benzoin condensation
and has been applied to dialdimines, providing the first examples of cyclizations effected
by cyanide-catalyzed AIC. Sodium cyanide promoted the facile, intramolecular
cyclization of several dialdimines in N,N-dimethylformamide, methanol, or
dichloromethane/water (phase-transfer conditions) yielding a variety of six-membered
heterocycles. Under aerobic conditions, an oxidative cyclization occurs to provide the
diimine heterocycle.
Cyanide-catalyzed aldimine coupling was employed as a new synthetic method
for oligomerization. Nine rigidly spaced dialdimines were oxidatively coupled under
aerobic conditions to yield conjugated oligoketimines and polyketimines with
unprecedented structure and molecular weight (DP = 2 - 23, ~700 -8200 g/mol). The ñ- diimine linkage was established based on IR spectroscopy, NMR spectroscopy, size
exclusion chromatography, and X-ray crystallographic characterization of the model
oxidized dimer of N-benzylidene-(p-phenoxy)-aniline. Cyclic voltammetry indicates ptype
electrical conductivity, suggesting they are promising candidates for plastic
electronic devices.
The cyanide-catalyzed benzoin condensation reaction of 4-substituted
benzaldehydes followed by oxidation to the diketone, and the Schiff Base condensation
of two equivalents of o-aminophenol provides 2,3-(4-X-phenyl)2-1,4-(2-
hydroxyphenyl)2-1,4-diazabutadiene. The ligand is given the moniker X-dabphol.
These ligands are readily metallated to form M-X-dabphol complexes. The copper
complexes catalytically fix CO2 with propylene oxide to yield propylene carbonate. DFT
studies along with a comparison with Hammet parameters help validate and elaborate on
the catalytic cycle and the catalytic results obtained. The nickel complex is competent
for olefin epoxidation. Synthesis, characterization, X-ray structure, DFT analysis, and
catalytic activity of the parent nickel dabphol complex are reported.
14
Bayless, Michael Bruce. "New redox-active ligands on iron and cobalt for C-C bond forming reactions." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52286.
Full textAbstract:
Redox-active ligands deliver redox equivalents to impart multi-electron functionality at 3d metals that typically undergo to one electron redox events. It was proposed that 3d metals with redox-active ligands could form unusually well-defined catalysts for C-C bond forming reactions to mimic palladium-type reactivity. Therefore, several new complexes containing an iron or cobalt with redox-active ligands were synthesized and tested for their ability to form new C-C bonds. A bis(iminosemiquinone) iron (III) complex was able to homocouple aryl Grignards using dioxygen as the terminal oxidant. However, ligand redistribution prevented detailed mechanistic study of the C-C bond forming reaction and led to catalyst degradation. To address the challenges seen in the iron catalyst a new cobalt electron transfer (ET) series containing a pincer-type bis(phenolate) N-heterocyclic carbene ligand (CoNHC) was synthesized. Studies indicate the CoNHC ET series spans multiple-electrons by corporative metal and ligand redox. These complexes were evaluated for cross-coupling of alkyl halides and aryl Grignards. Mechanistic studies imply that the low cross-coupling yields were due to ligand degradation. However, CoNHC catalytically activate cross-couples ether nitriles and aryl Grignards via a novel C-O bond activation leading to a new C-C bond. Findings concerning redox-active ligands on iron and cobalt for C-C bond forming reactions and implications for future research are discussed.
15
Wang, Lianhui. "Carboxylate-Assisted Ruthenium-Catalyzed Direct C-H Bond Functionalizations." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-5E47-2.
Full text
16
Pearson, Stephen. "High oxidation state carbene complexes for C-H bond activation catalysis." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/7570.
Full textAbstract:
Chapter one is an introduction to the less common coordination and oxidation chemistry of palladium; complexes containing Pd-OR, Pd-NR2 and those in the oxidation states of +IV. An outline of PdII/IV catalysed ligand-directed oxidative functionalisation is also included. Chapter two covers the design and synthesis of a range of tethered N-heterocyclic carbene (NHC) complexes of Pd. In addition, the syntheses of a number of new tethered NHC ligands are described. The use of Density Functional Theory (DFT) to model the complexes in this thesis was explored. Chapter three describes the synthesis and characterisation of PdIV halide complexes. The relevance of these compounds to PdII/IV catalysed ligand-directed oxidative functionalisation is explored. DFT was used to probe the reaction pathway for N-bromosuccinimide and iodobenzene dichloride. Chapter four examines reactions with oxidants used to form C-O and C-C bonds. The reaction pathway for iodobenzene diacetate was investigated using DFT. Chapter five contains experimental details and characterising data for the compounds reported.
17
Kossen, Hanno. "Exploration of Brønsted base catalysis for formal C–H bond activations." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/23598.
Full textAbstract:
This PhD project investigates the use of (Lewis or Brønsted) bases in catalysis. While the first chapter explores the use of main group metal amides in C–H bond activation reactions, the second chapter focusses on metal-free organocatalysis using so-called carbones. In the first chapter, formal allylic C(sp3)–H bond activations of unfuctionalised alkenes for C–C bond formations with imines were investigated. Alkali metal amides were used as catalysts for these transformations, giving homoallylic amine products. The investigations showed the unique reactivity of the Na-amide catalyst compared to other metal base complexes. The reaction scope and robustness was explored and initial insights into the reaction mechanism were obtained. A related K-amide catalyst was then developed for the isomerisation of allyl benzenes, as well as functionalised olefins such as allylic silanes, boronic esters, phosphines, amines, ethers, and thioethers. This part explored the use of ligands to increase the catalyst’s selectivity. Finally, the metal- or functional group-substituted classes of reagents were used in the functionalised allylation of imines, giving highly complex molecules with a diverse range of applications. Here, unprecedented reactivities were observed for the use of allyl–M reagents, as the allylation involved the activation of C–H bonds rather than C–X bonds. Furthermore, new catalytic formations of heteroatom-substituted homoallylic amines were described. The following chapter focussed on the use of carbodiphosphoranes (CDPs) in catalysis. These C(0) bases, or carbones, represent a class of heteroallene compounds that exhibit a high electron density on a P(V)-flanked carbon centre. Their potential as either a Lewis or Brønsted base was examined. Different CDPs were synthesised and reacted stoichiometrically with CO2, boron Lewis acids and metal salts. The generated intermediates were then studied in their reaction behaviour, taking advantage of a potentially available second pair of electrons. The results of these reactions were compared to other carbon bases, such as carbenes or other carbones. Finally, the Brønsted basicity of the CDP was examined in reactions with acidic pro-nucleophiles. The conjugate addition of alkylnitriles to α,β- unsaturated amides was developed using a catalytic amount of CDP. To the best of our knowledge, the first catalytic use of a CDP, as well as the first C–H bond activation of acetonitrile in Michael additions was reported.
18
Nagendiran, Anuja. "Catalytic reactions with palladium supported on mesocellular foam : Applications in hydrogenation, isomerization, and C-C bond forming reactions." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-122061.
Full textAbstract:
The major part of this thesis concerns the development of catalytic methodologies based on palladium nanoparticles immobilized on aminopropyl-functionalized siliceous mesocellular foam (Pd0-AmP-MCF). The catalytic activity of the precursor to the nanocatalyst, PdII-AmP-MCF is also covered by this work. In the first part the application of Pd0-AmP-MCF in Suzuki-Miyaura cross-coupling reactions and transfer hydrogenation of alkenes under microwave irradiation is described. Excellent reactivity was observed and a broad range of substrates were tolerated for both transformations. The Pd0-AmP-MCF exhibited high recyclability as well as low metal leaching in both cases. The aim of the second part was to evaluate the catalytic efficiency of the closely related PdII-AmP-MCF for cycloisomerization of various acetylenic acids. The catalyst was able to promote formation of lactones under mild conditions using catalyst loadings of 0.3 - 0.5 mol% at temperatures of up to 50 oC in the presence of Et3N. By adding 1,4-benzoquinone to the reaction, the catalyst could be recycled four times without any observable decrease in the activity. The selective arylation of indoles at the C-2 position using Pd-AmP-MCF and symmetric diaryliodonium salts is presented in the third part. These studies revealed that Pd0-AmP-MCF was more effective than PdII-AmP-MCF for this transformation. Variously substituted indoles as well as diaryliodonium salts were tolerated, giving arylated indoles in high yields within 15 h at 20 - 50 oC in H2O. Only very small amounts of Pd leaching were observed and in this case the catalyst exhibited moderate recyclability. The final part of the thesis describes the selective hydrogenation of the C=C in different α,β-unsaturated systems. The double bond was efficiently hydrogenated in high yields both under batch and continuous-flow conditions. High recyclability and low metal leaching were observed in both cases.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Submitted.
19
Snell, Robert Henry. "Development and application of asymmetric C-N bond formation." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:512e617a-2b01-45f3-86ae-c0cf4b874149.
Full textAbstract:
A synthetic investigation on the chemistry of cyclotryptamine derived natural products, with a particular focus on the synthesis of the trimeric-alkaloid, hodgkinsine. Methodology has been developed to tackle this complex natural product which utilises a desymmetrization approach; this strategy hinges on the development and applications of asymmetric C-N bond forming reactions. Chapter one examines elements of symmetry in natural products, looking in particular at the synthesis of compounds which contain cyclotryptamine functionality. Chapter two contains a brief review of enantioselective desymmetrization paying attention, if possible, on its application in the synthesis of natural products. In the remaining chapters we discuss our own progress and results in our pursuit of an efficient enantioselective total synthesis of hodgkinsine.
20
Mateo, Martínez Ana. "Computational studies of C-B bond formation reactions." Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668479.
Full textAbstract:
La gran quantitat de fluorocarbons a la natura i la seva estabilitat a animat a la comunitat científica a trobar noves metodologies per trencar l'enllaç C-F d'aquest compostos. D'aquesta manera, aquest flurorocarbons poden ser utilitzats com a reactius a la síntesi orgànica. L'estabilitat dels fluorurs d'aril es dona per la força de l'enllaç C-F, que és l'enllaç simple més fort de la natura. Aquesta és la seva principal característica i la raó de la seva poca reactivitat. Per aquest motiu, es desafiant per la comunitat científica trobar la manera per trencar l'enllaç C-F. De la mateixa manera l'enllaç C-O te característiques molt similars a les del C-F i per això, s'ha utilitzat com a alternativa per evitar residus fluorats. Aquesta Tesi tracta de l'estudi computacional del trencament d'enllaços C-F y C-O mitjançat borilacions i catalitzades per un catalitzador de níquel. Concretament, s'ha estudiat tres reaccions diferents, les hem comparades i trobat els punts en comú de les tres reaccions.La gran cantidad de fluorocarbonos en la naturaleza y su estabilidad a animado a la comunidad científica a buscar nuevas metodologías para la rotura del enlace C-F de estos compuestos. De esta manera, estos fluorocarbonos pueden ser utilizados como reactivos en la síntesis orgánica. La estabilidad de los fluoruros de arilo se da por la fuerza del enlace C-F, que es el enlace simple más fuerte de la naturaleza. Ésta es su principal característica y la razón de su poca reactividad. Por este motivo, es desafiante para la comunidad científica encontrar la manera de romper el enlace C-F. De la misma forma el enlace C-O tiene características muy similares a las del C-F y por esto, se ha utilizado como alternativa para evitar residuos fluorados. Esta Tesis trata del estudio computacional de la ruptura de los enlaces C-F y C-O mediante borilaciones y catalizadas por un catalizador de níquel. Concretamente, se ha estudiado tres reacciones diferentes y las hemos comparado y buscado sus puntos en común.
The large presence of fluorocarbons in nature and its great stability encourage science community to found new methods to break the C-F bond of this compounds, because it could be used as a starting reactant in organic synthesis. The stability of aryl fluorides is given because its C-F bond is the strongest single bond in the nature. That is its principal characteristic and the reason of it lack of reactivity. For this reason, it is challenging for scientists found the manner for C-F cleavage. As the same wise, C-O becomes an alternative of C-F to avoid the fluoride waste. This Thesis is about the computational study of the C-F and C-O cleavage through the borylation catalysed by nickel catalyst. Concretely, we have studied three borylation of C-F and C-O bonds and we compared it and show what have in common the three reactions.
21
Li, Bin. "Ruthenium(II) catalyzed C-H bond functionalization and hydrosilylation reactions." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S114.
Full textAbstract:
Dans ce travail de recherche, la synthèse de complexes de ruthénium cyclometallés a été effectuée à partir d'imines, 2-phénylpyridine, 2-phényloxazoline, phénylpyrazole, et benzo[h]quinoline par réaction avec [RuCl2(p-cymène)]2 et KOAc via une activation de liaison sp2 C-H. Le système [RuCl2(p-cymène)]2/KOAc/PPh3 est un catalyseur efficace pour réaliser la diarylation d'imines et de 2-phénylpyridine dans l'eau, solvant qui donne de meilleures activités que les solvants organiques. Des amines encombrées ont été préparées par une séquence catalytique activation C-H/arylation/ hydrosilylation d'imines catalysée par [RuCl2(p-cymène)]2. La monoarylation sélective de 2-pyridyl arylcétones, via la formation d'un intermédiaire ruthénacycle à 6 chainons plus difficile à former, est catalysée par l'espèce Ru(O2CC6H4CF3)2(p-cymène) formée in situ. L'alcénylation déhydrogénative oxydante directe d'aryloxazoline par du styrène et des acrylates est catalysée par le système [RuCl2(p-cymène)]2/BNPAH (1,1′-binaphthyl-2,2′- diylhydrogénophosphate) en présence de Cu(OAc)2.H2O utilisé comme oxydant sous air. La réaction tandem oxydation des 2-pyridylméthanols / mono- ou di-α-alkylation sélective de liaisons sp3 C-H de 2-pyridylcétones avec des alcènes fonctionnalisés a été catalysée par le complexe de [RuCl2(p-cymène)]2 en présence de Cu(OAc)2.H2O dans le DCE ou le toluène. Dans la deuxième partie de ce travail, le complexe [RuCl2(p-cymène)]2 a été utilisé efficacement en hydrosilylation catalytique d'imines et d'amides primaires. Nombreuses aldimines et cétimines ont été réduites chémosélectivement en amines correspondantes en utilisant le PMHS comme silane « vert » dans l'éthanol à température ambiante. De plus les amides primaires ont été sélectivement transformés en amines secondaires dans une réaction sans solvantIn this research doctoral thesis, we have shown that imines, 2-phenylpyridine, 2-phenyloxazoline, phenylpyrazole, benzo[h]quinoline led to cyclometallated ruthenium(II) complexes from [RuCl2(p-cymene)]2 and KOAc via sp2 C-H bond activation. [RuCl2(p-cymene)]2 /KOAc/PPh3 is an efficient catalytic system for diarylation of imines and 2-phenyloxazolines in water, which gave higher activity than in organic solvents. Bulky amines were then synthesized through sequential catalytic C-H arylation and hydrosilylation of imines using [RuCl2(p-cymene)]2 catalyst. Challenging selective mono arylation of 2-pyridyl arylketones, leading to six-membered ruthenacycle intermediate, difficult to perform, was achieved with in situ generated Ru(O2CC6H4CF3)2(p-cymene) catalyst. The direct dehydrogenative oxidative alkenylation of aryloxazolines with styrenes and acrylates was catalyzed by [RuCl2(p-cymene)]2/BNPAH (1,1′-binaphthyl-2,2′- diylhydrogenophosphate) catalytic system in the presence of Cu(OAc)2.H2O as an oxidant in air. Tandem catalytic oxidation of 2-pyridylmethanols and selective sp3 C-H (mono or di) α-alkylation of 2-pyridyl ketones with functional alkenes was performed by using [RuCl2(p-cymene)]2 complex in the presence of Cu(OAc)2.H2O in DCE or toluene. In the second part, it is shown that, [RuCl2(p-cymene)]2 is a very efficient catalyst for the hydrosilylation of imines and primary amides. A wide range of aldimines and ketimines were successfully reduced to corresponding amines in high chemoselectivity by using PMHS as greener silane in ethanol at RT. Moreover, challengingly, primary amides could be selectively converted by hydrosilylation to the secondary amines under solvent free conditions
22
Afewerki, Samson. "Development of catalytic enantioselective C-C bond-forming and cascade transformations by merging homogeneous or heterogeneous transition metal catalysis with asymmetric aminocatalysis." Doctoral thesis, Mittuniversitetet, Avdelningen för naturvetenskap, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-23605.
Full textAbstract:
Chiral molecules play a central role in our daily life and in nature, for instance the different enantiomers or diastereomers of a chiral molecule may show completely different biological activity. For this reason, it is a vital goal for synthetic chemists to design selective and efficient methodologies that allow the synthesis of the desired enantiomer. In this context, it is highly important that the concept of green chemistry is considered while designing new approaches that eventually will provide more environmental and sustainable chemical synthesis.The aim of this thesis is to develop the concept of combining transition metal catalysis and aminocatalysis in one process (dual catalysis). This strategy would give access to powerful tools to promote reactions that were not successful with either transition metal catalyst or the organocatalyst alone. The protocols presented in this thesis based on organocatalytic transformations via enamine or iminium intermediates or both, in combination with transition metal catalysis, describes new enantioselective organocatalytic procedures that afford valuable compounds with high chemo- and enantioselectivity from inexpensive commercial available starting materials. In paper I, we present a successful example of dual catalysis: the combination of transition metal activation of an electrophile and aminocatalyst activation of a nucleophile via enamine intermediate. In paper II, the opposite scenario is presented, here the transition metal activates the nucleophile and the aminocatalyst activates the electrophile via an iminium intermediate. In paper III,we present a domino Michael/carbocyclisation reaction that is catalysed by a chiral amine (via iminium/enamine activation) in combination with a transition metal catalysts activation of an electrophile. In paper IV, the concept of dual catalysis was further extended and applied for the highly enantioselective synthesis of valuable structural scaffolds, namely poly-substituted spirocyclic oxindoles. Finally, in paper V the concept of dual catalysis was expanded, by investigating more challenging and environmentally benign processes, such as the successful combination of a heterogeneous palladium and amine catalysts for the highly enantioselective synthesis of functionalised cyclopentenes, containing an all carbonquaternary stereocenter, dihydrofurans and dihydropyrrolidines.
23
Vuong, Khuong Quoc Chemistry Faculty of Science UNSW. "Metal complex catalysed C-X (X = S, O and N) bond formation." Awarded by:University of New South Wales. Chemistry, 2006. http://handle.unsw.edu.au/1959.4/23015.
Full textAbstract:
This thesis describes the catalysed addition of X-H bonds (X = S, O and N) to alkynes using a range of novel rhodium(I) and iridium(I) complexes containing hybrid bidentate phosphine-pyrazolyl, phosphine-imidazolyl and phosphine-N heterocyclic carbene (NHC) donor ligands. The synthesis of novel bidentate phosphine-pyrazolyl, phosphine-imidazolyl (P-N) and phosphine-NHC (PC) donor ligands and their cationic and neutral rhodium(I) and iridium(I) complexes [M(P N)(COD)]BPh4, [M(PC)(COD)]BPh4, [Ir(P-N)(CO)2]BPh4 and [M(P-N)(CO)Cl] were successfully performed. An unusual five coordinate iridium complex with phosphine-NHC ligands [Ir(PC)(COD)(CO)]BPh4 was also obtained. Seventeen single crystal X-ray structures of these new complexes were determined. A range of these novel rhodium and iridium complexes were effective as catalysts for the addition of thiophenol to a variety of alkynes. Iridium complexes were more effective than rhodium analogues. Cationic complexes were more effective than neutral complexes. Complexes with hybrid phosphine-nitrogen donor were more effective than complexes containing bidentate nitrogen donor ligands. An atom-economical, efficient method for the synthesis of cyclic acetals and bicyclic O,O-acetals was successfully developed based on the catalysed hydroalkoxylation. Readily prepared terminal and non-terminal alkyne diols were cyclised into bicyclic O,O-acetals in quantitative conversions in most cases. The efficiency of a range of rhodium and iridium complexes containing bidentate P-N and PC donor ligands as catalysts for the cyclisation of 4-pentyn-1-amine to 2-methyl-1-pyrroline varied significantly. The cationic iridium complexes with the bidentate phosphine-pyrazolyl ligands, [Ir(R2PyP)(COD)]BPh4 (2.39-2.42) were extremely efficient as catalysts for this transformation. Increasing the size of the substituent on or adjacent to the donor led to improvement in catalytic activity of the corresponding metal complexes. The mechanism of the catalysed hydroalkoxylation was proposed to proceed by the initial activation of the alkyne via ?? coordination to the metal centre. The ?? binding of both aliphatic and aromatic alkynes to [Ir(PyP)(CO)2]BPh4 (2.44) was observed by low temperature NMR and no reaction between 2.44 and alcohols was observed. In contrast, the facility in which thiol and amine oxidatively added to 2.44 led the proposal that in the hydrothiolation and hydroamination reaction, the catalytic cycle commences with the activation of the X-H bond (X = S, N) by an oxidative addition process.
24
Cai, Yingxiao. "Cobalt-catalyzed carbon-carbon bond formation by activation of carbon-halogen or carbon-hydrogen bonds." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX039/document.
Full textAbstract:
Ce travail de thèse présente le développement de nouvelles réactions de formation de liaisons carbone-carbone. Le premier chapitre décrit la cyanation d’arylzinciques par catalyse au cobalt à partir d’une source non toxique et bénigne, le N-cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS), et conduit à de bons rendements en benzonitriles correspondants. Dans cette réaction, le cobalt sert de catalyseur non seulement pour la formation des arylzinciques mais aussi pour la formation de liaisons C-CN. Les groupements fonctionnels, cétone et nitrile, sont permis lorsque le complexe de cobalt associé au ligand bipyridine est utilisé. Le deuxième chapitre porte sur l’homocouplage Csp3-Csp3. Un simple halogénure de cobalt permet de catalyser la dimérisation des halogénures d’alkyles et des acétates d’allyles avec de bons à d’excellents rendements. L’ajout d’iodure de sodium permet d’étendre cette réaction aux chlorures et tosylates d’alkyles. Le couplage croisé entre 2 halogénures d’alkyle différents a également été testé mais les conditions doivent être optimisées. Dans le troisième chapitre, le couplage croisé catalysé au cobalt entre des bromures vinyliques et des chlorures benzyliques est présenté. Des halogénures de vinyles et de benzyles porteurs de groupements electrodonneurs ou electroattrateurs peuvent ainsi être couplés efficacement avec rétention de la configuration de la double liaison. Un mécanisme radicalaire semble être impliqué. Enfin, le dernier chapitre décrit l’arylation d’une 2-phenylpyridine avec un arylzincique par catalyse au cobalt par activation d’une liaison C-H et conduit à de premiers résultats encourageantsThis thesis presents the development of cobalt-catalyzed carbon-carbon bonds formation. The first chapter describes a novel cobalt-catalyzed electrophilic cyanation of arylzinc species, employing benign and non-toxic N-cyano-N-phenyl-p-methylbenzenesulfonamide (NCTS) as the cyano source. In this reaction, cobalt catalyzes both the formation of arylzinc species and the cyanation reaction. Various benzonitriles are synthesized affording good to excellent yields. Using cobalt-bipyridine complexes instead of CoBr2, ketone and nitrile groups can be tolerated. The second chapter reports cobalt-catalyzed Csp3-Csp3 homocoupling reaction. A simple catalytic system could deliver dimers of a number of alkyl halides/pseudohalides and allylic acetates. Sodium iodide is crucial for the homocoupling of unactivated alkyl chlorides and tosylates. This method is extended to alkyl-alkyl cross-coupling; however, the conditions still need to be optimized. The third chapter describes a cobalt-catalyzed vinyl-benzyl cross-coupling. A variety of functionalized vinyl bromides and benzyl chlorides are efficiently coupled under mild conditions in good to excellent yields, with retention of Z/E configuration. A few mechanistic experiments indicate a single electron transfer involved. The last chapter discusses the progress on the cobalt-catalyzed arylation of 2-phenylpyridine with an arylzinc species by C-H activation and promising results are obtained
25
Diers, Emelyne. "Ruthenium-Catalyzed Synthesis of Biaryls through C–H Bond Functionalizations." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://hdl.handle.net/11858/00-1735-0000-0001-BC4E-F.
Full text
26
Lapointe, David. "Part A: Palladium-Catalyzed C–H Bond Functionalization Part B: Studies Toward the Synthesis of Ginkgolide C using Gold(I) Catalysis." Thesis, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20642.
Full textAbstract:
The field of metal-catalyzed C–H bond functionalizations is an incredibly vibrant and spans beyond the formations of biaryl motifs. The introduction chapter will cover the mechanistic aspects of the C–H bond functionalization with metal-carboxylate complexes. The mechanistic facets of this reaction will be the main conducting line between the different sections and chapters of the first part of this thesis. In the second chapter, will be described additives that can readily promoted C–H bond arylation of poorly reactive substrates. More specifically, we will revisit the intramolecular direct arylation reaction we will demonstrate the effect of pivalic acid as a co-catalyst by developing milder reaction conditions. In the third chapter we be described experimental and computational studies which suggested that the a single pathway might be involved in the palladium-catalyzed C–H bond functionalization of a wide range of (hetero)arene. Following this we will describe a general set of conditions for the direct arylation of wide range of heteroarenes. Also, we will present two different strategies to selectively and predictably arylate substrates containing multiple functionalizable C–H bonds. In the fourth chapter will be presented our efforts toward the development of new C–H bond functionalization methods in which we could apply our knowledge on the C–H bond cleavage and apply it to the formation of new scaffolds. The development of two new palladium-catalyzed methods were also described. In the fifth chapter, our effort toward the development of ligands to specifically promoted C–H bond cleavage will be presented. In the sixth chapter will be presented the latest results on the study of the mechanism of the C–H bond cleavage combining experimental and computational studies. In part B of this thesis will be presented our strategy toward the total synthesis of ginkgolide C that included two gold(I)-catalyzed reactions as key steps in the preparation of the spiro[4.4]nonane core of this natural product. The first studies on the feasibility of the key steps of the synthesis will be described.
27
Bruneau, Alexandre. "Développement de nouvelles réactions métallo-catalysées pour la création de liaisons C-C et C-hétéroatomes : Application à la synthèse d’inhibiteurs de la Hsp90 et aux ligands de la lectine A." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS138.
Full textAbstract:
Les travaux rapportés dans ce mémoire concernent le développement de nouvelles réactions métallo-catalysées pour la création de liaison carbone-hétéroatome et carbone-carbone ainsi que leurs applications à la synthèse de produits biologiquement actifs. La première partie de ce manuscrit est consacrée à l'étude de la réactivité des sucres dans les couplages organométalliques. Des conditions ont été développées pour la création de la liaison C-S entre glycosyl thiols et partenaires arylés. De plus, la création de la liaison carbone azote de glycosyl amines avec des acides boroniques a été étudiée. Les produits synthétisés dans cette première partie ont été évalués pour leur potentiel d'inhibition de la Lectine A chez Pseudomonas aeruginosa, impliquée dans de sévères infections pulmonaires.La seconde partie de ce travail est dédiée à la création d'une série inédite d'analogues du 6BrCaQ, inhibiteurs de la Hsp90 ainsi que leur évaluation biologique. Cette nouvelle série est obtenue grâce à une nouvelle méthodologie de synthèse basée sur l'activation C-H entre un hétérocycle halogéné et son partenaire C-H activable. L'activité antiproliférative et l'inhibition de la Hsp90 ont été évaluées et seront présentées dans ce manuscritThe work reported in this dissertation concerns the development of new metal-catalyzed reactions for the creation of carbon-heteroatom and carbon-carbon bonds as well as their applications to the synthesis of biologically active products.The first part of this manuscript is devoted to the study of the reactivity of sugars as nucleophiles in organometallic couplings. Conditions were developed for the creation of the C-S bond between glycosyl thiols and aryl partners. Moreover, the creation of the nitrogen carbon bond of glycosyl amine with boronic acids was studied. The products synthesized in this first part have been evaluated for their potential to inhibit the lectin A, in Pseudomonas aeruginosa related lung infections.The second part of this work is dedicated to the creation of a new series of 6BrCaQ analogues as Hsp90 inhibitors and their biological evaluation. This new series was synthetized through a new CH activation methodology. The antitumoral potential was evaluated and will be presented in this manuscript
28
Zhao, Liqin. "Palladium-catalyzed direct arylation via sp² and sp³ C-H activation of hetero(aromatics) and hydrocarbons for C-C bond formation." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S038/document.
Full textAbstract:
Au cours de cette thèse, nous nous sommes intéressés à l'activation de liaisons sp² et sp³ C-H catalysée par le palladium pour la préparation d'(hétéro)aryl-aryles et de biaryles. Cette méthode est considérée comme attractive pour l'environnement par rapport aux méthodes classiques, tels que Suzuki, Heck, ou Negishi. Tout d'abord, nous avons décrit que la C2-arylation directe de benzothiophènes peut être effectuée par un catalyseur du palladium en l'absence de ligand phosphine avec une grande sélectivité. Nous avons également démontré qu'il est possible d'activer les positions C2 et C5 de pyrroles pour accéder en une seule étape a des 2,5-diarylpyrroles. Des 2,5-diarylpyrroles non-symétriques ont été formés par arylation séquentielle en C2 suivie par une arylation en C5. Nous avons également étudié la réactivité de polychlorobenzenes pour l'activation de liaisons C-H catalysé au palladium. Nous avons finalement étudié l'activation sp² et sp³ sélective catalysé au palladium de liaisons C-H du guaiazulene. La sélectivité de la réaction dépend du solvant et de la base : C2-arylation (KOAc en éthylbenzène), C3-arylation (KOAc dans le DMAc) et C4-Me arylation (CsOAc/K₂CO₃ dans le DMAc). Grâce à cette méthode, une liaison sp³ C-H peu réactive a été activéeDuring this thesis, we were interested in the sp² and sp³ C-H bond activation catalyzed by palladium catalysts for the preparation of (hetero)aryl-aryls and biaryls. This method is considered as cost effective and environmentally attractive compared to the classical couplings such as Suzuki, Heck, or Negishi. First we described the palladium-catalyzed direct C2-arylation of benzothiophene in the absence of phosphine ligand with high selectivity. We also demonstrated that it is possible to active both C2 and C5 C-H bonds for access to 2,5-diarylated compounds in one step, and also to non-symmetrically substituted 2,5-diarylpyrroles via sequential C2 arylation followed by C5 arylation. We also studied the reactivity of polychlorobenzenes via palladium-catalyzed C-H activation. We finally examined the palladium-catalysed selective sp² and sp³ C-H bond activation of guaiazulene. The selectivity depends on the solvent and base: sp² C2-arylation (KOAc in ethylbenzene), sp² C3-arylation (KOAc in DMAc) and sp³ C4-Me arylation (CsOAc/K₂CO₃ in DMAc). Through this method, a challenging sp³ C-H bond was activated
29
Liu, Cong. "Transition Metal Mediated C-o Bond Cleavage: From Co2 Activation to Lignin Degradation." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc283790/.
Full textAbstract:
CO2 activation and conversion mediated by transition metal (TM) catalysts were investigated. Homogeneous catalysis of the reverse water gas shift reaction CO2+H2→H2O+CO was studied as a means to reduce CO2. β-diketiminato metal models L'MI ( L' =C3N2H5-; M = first-row TMs) were considered as potential catalysts. The thermodynamics of prototypical reaction pathways were simulated using B3LYP/aug-cc-pVTZ. Results show that middle series metal complexes result in more thermodynamically favorable properties; therefore, more detailed thermodynamic and kinetic studies were carried out for Mn, Fe, and Co complexes. On the other hand, heterogeneous catalysis of the reduction of CO2 to CO was carried out on Fe, Co, Ni, and Cu surfaces, using the PBE functional. Reaction barriers were calculated using the climbing image nudged elastic band method. Late 3d and 4d transition metal ion (Fe, Co, Ni, Cu, Ru, Rh, Pd, and Ag) mediated activation of dimethyl ether was studied to investigate the intrinsic catalytic properties of metals for C-O bond cleavage. A set of density functional theory (DFT) methods (BLYP, B3LYP, M06, M06-L, B97-1, B97-D, TPSS, and PBE) with aug-cc-pVTZ basis sets was calibrated with CCSD(T)/CBS calculations on reaction energies and barriers.
30
Borràs, Noguera Carlota. "Sustainable and cost-effective development of chiral metal-catalysts for C-H and C-X bond forming reactions." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/664741.
Full textAbstract:
L’obtenció de compostos enantiomèricament purs ha esdevingut una necessitat que ha conduit a un important progrés en la catàlisi asimètrica, principalment usant compostos organometàl•lics quirals. Entre les diferents estratègies en l’optimització dels catal•litzadors per aconseguir elevades selectivitats i activitats, el disseny i correcta selecció de lligands quirals, modificant-ne les seves propietats és fonamental i la més utilitzada. Que un lligand sigui fàcil de sintetitzar a partir de compostos de partida accessibles i que aquests lligands siguin estables i fàcils de manipular, tenen un elevat interès en la industria.
En aquest context, el principal objectiu d’aquesta tesi és la síntesi de diferents famílies de lligands quirals, acomplint els requisits prèviament esmentats, i la seva posterior aplicació a diverses reaccions asimètriques d’elevat interès industrial: hidrogenació d’olefines funcionalitzades i no funcionalitzades catalitzada per Rh i Ir, hidrogenació de cetones catalitzada per Ir, reaccions de substitució al•lílica catalitzades per Pd i reaccions de substitució propargílica catalitzada per Cu. S’han sintetitzat diverses famílies fosfit/fosfinit-tioèter/selenoèter, carbè-tioèter, amino-fosfit/fosfinit/fosfina, i varies famílies de lligands tridentats.La obtención de compuestos enantioméricamente puros se ha convertido una necesidad que ha conducido a un importante progreso en la catálisis asimétrica, principalmente usando compuestos organometalicos quirales. Entre las diferentes estrategias en la optimización de los catalizadores para conseguir elevadas selectividades y actividades, el diseño y la correcta selección de ligandos quirales, modificando sus propiedades es fundamental y la más utilizada. Que un ligando sea fácil de sintetizar a partir de compuestos de partida accesibles y que estos ligandos sean estables y fáciles de manipular, tienen un elevado interés en la industria. En este contexto, el principal objetivo de esta tesis es la síntesis de distintas familias de ligandos quirales, cumpliendo con los requisitos previamente mencionados, y su posterior aplicación en distintas reacciones asimétricas de alto interés industrial: hidrogenación de alquenos funcionalizados y no funcionalizados catalizados por Rh y Ir, hidrogenación de cetonas catalizada por Ir, reacciones de substitución alílica catalizada por Pd y reacciones de substitución propargílica catalizada por Cu. Se han sintetizado diferentes familias de ligandos Fosfito/fosfinito-tioéter/selenoéter, carbeno-tioéter, amino-fosfito/fosfinito/fosfina, y varias familias de ligandos tridentados.
The obtaining of enantiomerically pure compounds has become a need that led to an important progress in asymmetric catalysis, mainly using organometallic chiral compounds. Among different strategies to optimize catalysts in order to obtain high selectivities and activities, the design and the correct selection of chiral ligands, modifying their properties, is fundamental and the most used strategy. Ligands easy to synthesize from readily accessible starting material and stable and easy to manipulate ligands, have a high interest in the industry. In this context, the main objective of this thesis is the synthesis of different chiral ligand families, according to the previously mentioned requirements, and their application in different asymmetric reactions with high industrial interest: Rh- and Ir-catalyzed hydrogenation of functionalized and minimally functionalized olefins; Ir-catalyzed hydrogenation of simple ketones; Pd-catalyzed asymmetric substitution of allylic acetates and Cu-catalyzed propargylic substitution. There have been synthesized different phosphite/phosphinite-thioether/selenoether, carbene-thioether, amino-phosphite/phosphinite/phosphine and various tridentated ligand families.
31
Bosnidou, Alexandra Eleni. "New Methodology for C-N Bond Formation within Iodine Redox Manifolds." Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668478.
Full textAbstract:
Els últims desenvolupaments en el camp de la construcció d’enllaços carboni-nitrogen es mostren en aquesta tesi doctoral. En aquesta, es revelen alternatives més verdes a les metodologies sintètiques comunes, amb l’ús de reactius de iode hipervalent i iode molecular com a principals promotors.
Inicialment, es presenta l’ús de reactius de iode hipervalent definits que promouen l’aminació C-H selectiva i directa del nucli indol de diferents tipus de triptamines. Començant per l’aminació general, transformacions posteriors, com la iodació, fluoració, etc. es van realitzar per tal de rendir productes més funcionalitzats, amb una quimioselectivitat remarcablement alta. Per tant, s’ha fet disponible un major grau de diversificació estructural per als derivats triptamínics, proveint blocs de construcció (building blocks) que obren espai químic per a més exploració.
Seguidament, es discuteix l’aminació catalítica fotoquímica d’arens. La reacció es dóna en catàlisi de iode i presència de llum visible com a iniciador, i permet l’accés a un ventall d’aril amines substituïdes. L’ampli abast de la reacció es va poder expandir encara més a derivats bloquejats amb grups silil, que experimenten una aminació intramolecular per tal de donar lloc a heterocicles de set membres. L’escissió del grup silil permet l’accés a les corresponents anilines 3-substituïdes.
L’aminació directa d’enllaços C-H alifàtics ha estat una de les transformacions més desafiants en la química orgànica. En la última part de la tesi, reportem l’esmunyedissa aminació C(sp3)-H sota un sistema catalític únic, basat en la recentment desenvolupada aminació intramolecular. Aquesta estratègia sintètica pràctica permet l’accés a blocs de construcció aminats. És presentada també una extensió que fomenta múltiples aminacions C-H per a aconseguir heterocicles aminats. La utilitat sintètica de la metodologia és demostrada per la síntesi de quatre productes farmacèutics rellevants.En esta Tesis Doctoral se describen los últimos avances en el campo de la construcción de enlaces carbono-nitrógeno. En ella se discuten alternativas más verdes, comparadas con las metodologías más comunes, mediante el uso de reactivos hipervalentes de yodo y yodo molecular como principales promotores. En la primera sección se presenta el uso de reactivos hipervalentes de yodo que promueven la aminacion C-H directa y selectiva del grupo indol en varios derivados de triptamina. A partir de esta aminación general, otras transformaciones, tales como iodinación, fluorinación, etc. fueron llevadas a cabo, obteniendo productos altamente funcionalizados con una remarcable alta quimioselectividad. De este modo, una alta diversificación estructural de derivados de triptamina están disponibles, proveyendo diferentes componentes que permiten futuras exploraciones en este área. En la siguiente sección, se describe la aminación fotoquímica y catalítica de arenos. Esta reacción funciona mediante catálisis de yodo molecular en presencia de luz visible como iniciador, dando acceso a un amplio rango de arilaminas con diferentes patrones de substitución. Esta metodología es muy general y puede expandirse a derivados con silicio que dan lugar a heterociclos de siete miembros. La ruptura de este enlace silicio-carbono da acceso a las correspondientes anilinas meta-subtituidas. La aminación directa de enlaces C-H alifáticos es una de las transformaciones más dificiles de conseguir en química orgánica. En la última parte de esta Tesis se describe la aminación intermolecular de C(sp3)-H basada en la recientemente desarrollada versión intramolecular. Esta estrategia sintética permite el acceso a diferentes estructuras aminadas de importancia. También se presenta la extensión de esta metodología hacia la aminacion de multiples C-H, obteniendo aza-heterociclos. La utilidad práctica de esta metodología esta demostrada mediante la síntesis de cuatro compuestos de interés farmacéutico
The latest developments in the field of oxidative carbon-nitrogen bond construction are represented in this Doctoral Thesis. Greener alternatives to established synthetic methodologies have been disclosed with the use of hypervalent iodine reagents and molecular iodine as main promoters. Initially, the use of defined hypervalent iodine reagents that promote the selective direct C-H-amination at the indole core of various tryptamines is presented. Starting from the general amination, subsequent transformations, such as iodination, fluorination etc. were performed to afford higher-functionalized products with a noteworthy chemoselectivity. Consequently, a higher degree of structural diversification has become available for tryptamine derivatives, providing building blocks that open chemical space for further exploration. Subsequently, a photochemical catalytic amination of arenes is discussed. The reaction proceeds under benign iodine catalysis in the presence of visible light as the initiator and provides access to a range of differently substituted arylamines. The broad scope of the reaction could further be expanded to silyl-tethered derivatives, which undergo intramolecular amination to give rise to seven-membered heterocycles. Cleavage of the silicon tether provides access to the corresponding 3-substitued anilines. The direct amination of aliphatic C-H bonds has remained one of the most challenging transformations in organic chemistry. In the last part of this thesis, the elusive intermolecular C(sp3)-H amination based on a unique homogeneous iodine catalyst system is reported. This practical synthetic strategy allows the access to aminated building blocks. An extension that fosters innovative multiple C-H amination toward aminated heterocycles is also presented. The synthetic utility of the methodology is demonstrated by the synthesis of four relevant pharmaceuticals.
32
Olsson, Vilhelm. "Development of New Synthetic Routes to Organoboronates by Catalytic Allylic Substitution and C-H bond Functionalization." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-27753.
Full textAbstract:
This thesis describes the development of new catalytic methods for the synthesis and application of organometallic reagents, mainly focusing on allylboronic acid derivatives. Thus, palladium pincer-complex catalysis has been applied for extending the scope of palladiumcatalyzed borylation reactions in the synthesis of regio- and stereodefined functionalized allylboronic acid derivatives. These novel allylboronic acids were also employed as substrates in palladium catalyzed regioselective coupling reactions with iodobenzenes. We have also developed a new one-pot sequence based on preparation of allyl- and vinylboronates via catalytic carbon-hydrogen bond activation/borylation reactions. The synthetic scope of the reaction as well as mechanistic studies on the borylation process are presented. Finally, the synthesis of new chiral palladium pincer-complexes is described. These species were employed as catalysts in asymmetric electrophilic allyation of imines.
33
Balzarek, Christoph. "Reactivity and mechanisms in aqueous organometallic chemistry : C-H bond activation in water catalyzed by molybdocenes /." [Eugene, Or. : University of Oregon Library System], 2000. http://libweb.uoregon.edu/UOTheses/2000/balzarekc00.pdf.
Full text
34
Balzarek, Christoph 1972. "Reactivity and mechanisms in aqueous organometallic chemistry: C-H bond activation in water catalyzed by molybdocenes." Thesis, University of Oregon, 2000. http://hdl.handle.net/1794/142.
Full textAbstract:
Adviser: Kenneth M. Doxsee.
xvii, 167 p.A print copy of this title is available through the UO Libraries under the call number: SCIENCE QD412.M7 B35 2000
The chemistry of three organometallic systems in water was studied with the goal of understanding more fully the reactivity of organometallic complexes in aqueous environments. Molybdocene complexes were found to catalyze C-H bond activation reactions in water. The catalytically active solutions were prepared from the molybdocene dimer [Cp
35
Hofmann, Nora. "Carboxylate-Assisted Ruthenium-Catalyzed C-H Bond meta-Alkylations and Oxidative Annulations." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2013. http://hdl.handle.net/11858/00-1735-0000-0014-D4A4-1.
Full text
36
Ziadi, Asraa. "Metal-catalyzed functionalization of c-c bonds in four-membered rings." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/320185.
Full textAbstract:
En els darrers anys, la funcionalització catalítica d´enllaços C-C ha suscitat un gran interés, essent una de les disciplines amb més potencial en química organometàlica. Aquesta tesi doctoral es basa en el repte de dissenyar nous mètodes catalítics de functionalitazió d´enllaços C-C en anells de cuatre baules. Específicament, s´ha demostrat la viabilitat per preparar cetones γ-arilades via rotura d´enllaços C-C catalitzada per Pd en anells de tert-ciclobutanol utilitzant clorur d´aril i tosilats (Capítol 2). La transformació presenta una gran generalitat amb càrregues de catalitzador molt baixes. Tanmateix, s´ha trobat que fosfines riques en electrons i impedides estèricament permeten evitar processos destructius de β-eliminació d´hidrògen.
Amb els precedents del capítol 2, s´ha extés satisfactòriament la generalitat de la reacció de rotura d´enllaços C-C d´anells de tert-ciclobutanol mitjançant l´acoplament amb haloacetilens per donar lloc a cetones amb grups alquins en posició γ (Capítol 3). Curiosament, els substituents del grup alquí tenen una gran influencia en la reacció. És certament remarkable l´interés potencial de la metodologia ja que els productes finals poden ser transformats fàcilment en productes d´alt valor afegit mitjançant reaccions d´acoplament creuat. Al Capítol 4, s´ha pogut extendre les metodologies de trencament d´enllaços C-C en anells de cuatre baules mitjançant el desenvolupament d´una metodologia catalitzada per Ni entre benzociclobutanones i diens per donar lloc a cicloadicions [4+4]. El mètode va mostrar una preferència específica per la formació d´anells de vuit baules respecte la formació d´anells de sis baules.
Aquesta tesi doctoral també ha estudiat el disseny de metodologies de fixació de CO2 i formació d´enllaços C-F mitjançant activació catalítica d´enllaços C-C (Capítol 5). Tot i que no s´han trobat condicions de reacció òptimes, el nostre grup de recerca està actualment involucrat en el disseny de metodologies semblants i s´espera que aquesta recerca permeti el disseny de processos de fixació de CO2 i formació d´enllaços C-F mitjançant trencament C-C en un futur no molt llunyà.Recientemente la funcionalización catalítica de enlaces C-C ha suscitado un gran interés en la comunidad científica a pesar de los retos que conlleva. Esta tesis doctoral se ha basado en diseñar nuevos procesos catalíticos para la funcionalización de enlaces C-C en anillos de cuatro miembros. Específicamente, se ha demostrado la viabilidad de preparar cetonas con grupos arilo en posición γ usando precatalizadores de Pd para promover la rotura de enlaces C-C en anillos de tert-ciclobutanol utilizando cloruros de arilo y tosilatos como agentes arilantes (Capítulo 2). La transformación se caracteriza por su amplia generalidad y baja carga de catalizador. La selectividad de la reacción puede ser fácilmente controlada por la naturaleza del ligando, en la que fosfinas con grupos ricos en electrones y voluminosos dan los mejores resultados, evitando la β-eliminación de hidrógeno de las especies organometálicas intermedias. Considerando los precedentes del Capítulo 2, se ha extendido esta metodología al acoplamiento con haloacetilenos para preparar cetonas con grupos alquino en posición γ (Capítulo 3). Curiosamente, los substituyentes del grupo alquino juegan un papel fundamental en la reactividad, pudiéndose controlar mediante la utilización de un cierto ligando. En el Capítulo 4, se ha desarrollado una nueva transformación basada en una reacción catalizada por compuestos de Ni para efectuar la síntesis de anillos de ocho eslabones mediante una reacción formal de cicloadición [4+4] de benzociclobutanonas y dienos simples. Curiosamente, dicho método muestra una especial preferencia para formar anillos de ocho eslabones sobre los, a priori, anillos de 6 eslabones que son más estables termodinámicamente. En la presente tesis doctoral se ha estudiado también la viabilidad de llevar a cabo una fijación catalítica de CO2 y la formación de enlaces C-F mediante una rotura de enlaces C-C (Capítulo 5) aunque no se han encontrado las condiciones óptimas para llevar a cabo tales transformaciones.
The means to promote catalytic C-C bond-functionalization has gained a considerable attention in recent years and probably can be considered one of the most challenging and vibrant subjects in organometallic chemistry. This PhD thesis deals with the design of new metal-catalyzed functionalization of C-C bonds in four-membered ring frameworks. Specifically, we have demonstrated the viability of preparing γ-arylated ketones via Pd-catalyzed cleavage of C-C bonds in tert-cyclobutanol using aryl chloride or tosylate counterparts (Chapter 2). The transformation possesses a wide substrate scope and remarkable low catalyst loadings. Selectivity was controlled by the ligand in which electron-rich and sterically-hindered phosphine ligands provided a unique reaction outcome that avoided the proclivity of alkyl metal species towards destructive β−hydride elimination. Prompted by the precedents in Chapter 2, we successfully extended the scope of the metal-catalyzed C-C bond-cleavage of tert-cyclobutanols by using halo acetylene counterparts giving γ-alkynylated ketones (Chapter 3). Interestingly, substituents on the alkyne motif showed a remarkable influence on reactivity. Of particular interest is the application profile of such methodology since γ-alkynylated ketones could promote consecutive metal-catalyzed transformations into valuable synthetic intermediates. In Chapter 4, we extended the interest for C-C bond-cleavage beyond the use of tert-cycñobutanols. Specifically, we developed a Ni-catalyzed C-C bond-cleavage event in benzocyclobutenones for preparing eight-membered rings via formal [4+4]-cycloaddition with dienes (Chapter 4). The method shows a specific preference for eight-membered rings over thermodynamically more stable six-membered rings. This PhD thesis has also studied the development of catalytic CO2 fixation and C-F bond-formation via C-C bond-cleavage (Chapter 5). While we have not found reaction conditions to effect the desired transformations, our research group is actively involved in related catalytic endeavors and it is expected that such research will shed light into the targeted CO2 fixation or C-F bond-forming reactions via C-C bond-cleavage.
37
Barde, Etienne. "Catalyse au cobalt : applications en couplages croisés et en activation/fonctionnalisation de liaison C-H." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLET019.
Full textAbstract:
De grands progrès ont été réalisés ces cinquante dernières années en synthèse organique grâce au développement de la catalyse métallique. Parmi les différents métaux généralement utilisés, le cobalt se distingue car il est abondant, peu coûteux, peu toxique et car il offre une réactivité unique.Dans ce contexte, deux types de réaction faisant appel à une catalyse au cobalt ont été plus particulièrement étudiés durant cette thèse, les couplages croisés et l’activation de liaison C—H.Grâce à un sel de cobalt commercialement disponible et un ligand diphosphine, la fonctionnalisation d’amides α-halogénés par des réactifs de Grignard a été réalisée. Cette méthode, facile à mettre en place, s’est montrée générale car elle a permis de synthétiser une grande diversité d’amides α-fonctionnalisés par l’ajout de réactifs de Grignard de différentes natures (aromatiques, vinyliques et acétyléniques) en utilisant le même système catalytique.Ensuite, un autre sel de cobalt a été impliqué dans l’activation de liaison C—H de benzamides pour réaliser l’aminoarylation d’alkylidènes cyclopropanes. Cette méthode, qui utilise des conditions douces, a permis d’accéder à des molécules polycycliques de structure originale.Ces résultats obtenus dans deux domaines distincts de la catalyse ont pu montrer le potentiel de réactivité des sels de cobaltOrganic synthesis has been making outstanding recent progress because of the use of transition-metal catalysis into laboratory routine. Among different metals involved in catalysis, cobalt is interesting because of its low cost and toxicity but also because of its unique reactivity.During this thesis, cross-coupling and C—H bond activation reactions using cobalt complexes as catalysts were investigated.A simple catalytic system composed of diphosphine ligand and a cost-effective cobalt salt allowed us to functionnalize α-haloamides using Grignard reagents. A large variety of amides and Grignard reagents (aryl-, vinyl-, alkynyl-) were successfully tested, generating an interesting library of α-functionnalized amides.Moreover, simple cobalt salts were engaged in the activation of the C—H bond of benzamides for the aminoarylation of alkylidene cyclopropanes. Under mild conditions, original and polycyclic molecules were obtained in a single step.These results obtained in two different domains treated in this thesis demonstrate the high potential of simple cobalt salt in catalysis
38
Bheeter, Charles Beromeo. "Palladium-catalysed C-H bond activation for simpler access to ArSO₂R derivatives." Thesis, Rennes 1, 2013. http://www.theses.fr/2013REN1S171.
Full textAbstract:
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 benzènesulfonamidesDuring 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
39
Närhi, Katja. "Studies on Palladium-Catalyzed Carbocyclizations of Allene-Substituted Olefins and 1,3-Dienes." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-794.
Full textAbstract:
This thesis describes the development and mechanistic studies of carbocyclization reactions of allene-substituted olefins and 1,3-dienes, catalyzed by palladium(0) and palladium(II). These reactions results in the formation of [n,3,0] bicyclic systems (n = 3-5) with high stereoselectivity and in good to excellent yields. The first carbocyclization presented is a novel palladium(0)-catalyzed cyclo- isomerization of allene-substituted olefins. Secondly an efficient aerobic biomimetic system has been developed for a Pd(II)-catalyzed allylic oxidative carbocyclization of allene-substituted olefins. Additionally, during the studies of palladium-catalyzed carbocyclizations of allene-substituted olefins, it was found that in the absence of palladium a mild thermal ene-reaction occurs. In this manner stereodefined, functionalized bicyclic compounds are obtained with good regioselectivity and in high yields. The third and fourth carbocyclization developed are a palladium(II)-catalyzed oxidation and a palladium(0)-catalyzed intramolecular telomerization of allene-substituted 1,3-dienes. A mechanistic study of the palladium(II)-catalyzed oxidation of allene-substituted 1,3-dienes was made, and reaction intermediates could be isolated. The stereochemistry of the reaction intermediates was assigned, and this made it possible to suggest a mechanism for the reaction. The presented mechanism is a trans carbopalladation of the 1,3-diene, where the allene act as the carbon nucleophile. Due to different stereochemical outcomes of the stoichiometric and catalytic reactions, this mechanism could only explain the stoichiometric reaction. Another mechanism for the catalytic reaction was suggested, which rationalizes both the regio- and stereochemistry of the products.
40
Li, Haoran. "Pd-catalyzed C-H bond functionalizations of (hetero)arenes and alkenes : A one step access to poly(hetero)aromatics and styrene derivatives." Thesis, Rennes, Ecole nationale supérieure de chimie, 2020. http://www.theses.fr/2020ENCR0068.
Full textAbstract:
Afin d'expliquer le contexte de mon travail de recherche, j'ai résumé dans le premier chapitre des informations mécanistiques générales sur l'arylation des liaisons C-H catalysée par le palladium et j'ai détaillé certains travaux sur l'arylation directe en relation avec mes travaux. Mes objectifs étaient d'étudier la réactivité de nouvelles unités synthétiques permettant l'accès direct à des composés bi-(hétéro)aryls ou à des dérivés du styrène. Ensuite, dans les chapitres 2 à 6, j'ai résumé mes travaux de recherche. J'ai étudié l’arylation directes en C2 du Methoxsalen par des chlorures de benzènesulfonyle, ainsi que la diarylation en C2,C3 en utilisant des bromures d'aryle catalysée par le palladium. Ces résultats sont résumés dans le chapitre 2. Ensuite, j'ai montré que la réaction d'arylation directe catalysée par le palladium permet d'accéder facilement à des dérivés de la Ticlopidine arylés en position C5 du cycle thiényle en une seule étape. Ces résultats sont décrits dans le chapitre 3. Dans le chapitre 4, nous avons étudié la réactivité du Diflufénican qui contient un cycle 1,3- difluorobenzène et une unité pyridine en utilisant la catalyse au ruthénium et au palladium. Dans des conditions appropriées, deux liaisons C-H différentes du Diflufénican peuvent être arylées. Dans le chapitre 5, j'ai utilisé différentes sources d’aryle pour fonctionnaliser les positions C10 et C11 des dibenzo[b,f]azépines. Grâce à ces réactions, une grande diversité de groupes fonctionnels a été introduite sur les dérivés de dibenzo[b,f]azépines. Enfin, dans le chapitre 6, j’ai décrit la première méthode permettant de préparer des dérivés de la Cyproheptadine C10-arylésIn order to explain the background of my research work, in the first chapter, I summarized general mechanistic information on palladium-catalyzed C-H bond arylation and detailed some literature on direct arylation related to my research work. My objectives were to study the reactivity of new synthetic units allowing the straightforward access to bi-(hetero)aryls compounds or styrene derivatives using aryl halides or benzenesulfonyl chloride derivatives as the aryl-sources. Then, in the chapters 2-6, I summarized my research work. I studied the regiocontrolled palladium-catalyzed direct C2-arylations of Methoxsalen using benzenesulfonyl chlorides and C2,C3-diarylations using aryl bromides as the aryl sources. These results are summarized in the chapter 2. Then, I found that Pd-catalyzed direct arylation reaction allows the easy access to Ticlopidine derivatives arylated at the C5-position of the thienyl ring in one step. These results are reported in the chapter 3. In the chapter 4, we studied the reactivity of Diflufenican which contains a 1,3-difluorobenzene ring and a pyridine unit using Ru and Pd catalysis. Under appropriate conditions, two different C-H bonds of Diflufenican could be arylated. In the chapter 5, I employed different aryl sources to functionalize the C10- and C11-positions of dibenzo[b,f]azepines, and obtained asymmetric products. Through these reactions, a wide diversity of functional group were introduced on the dibenzo[b,f]azepine derivatives. Finally, in the Chapter 6, I report the first method allowing to prepare C10-arylated Cyproheptadine derivatives
41
Kornhaaß, Christoph Frank. "Sustainable Syntheses of Substituted Heterocycles through Ruthenium- and Palladium-Catalyzed Direct C−H Bond Functionalizations." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2014. http://hdl.handle.net/11858/00-1735-0000-0023-9911-5.
Full text
42
Platon, Mélanie. "Propriétés et performances de phosphines ferrocéniques dans le couplage C-O, C-S et C-N : nouvelles méthodologies de synthèse au palladium." Phd thesis, Université de Bourgogne, 2012. http://tel.archives-ouvertes.fr/tel-00818998.
Full textAbstract:
Les ligands multidentes montrent généralement de très bonnes activités dans la catalyse organométallique au palladium à faibles charges. Parmi ces ligands, l'utilisation des ligands polyphosphines ferrocéniques mènent à des résultats intéressants. Des systèmes catalytiques palladium/triphosphine ferrocénique robustes ont permis d'obtenir d'une part des diarylamines et d'autre part des éthers d'aryle et d'hétéroaryle avec de faibles charges catalytiques. Des calculs théoriques de DFT sur le cycle catalytique lors de la formation d'éthers d'aryle et d'hétéroaryle ont été réalisés. La présence d'un troisième groupement phosphino permettrait de stabiliser les états de transition et accélèrerait l'élimination réductrice. Les triarylamines ont pu être obtenues à l'aide d'une diphosphine ferrocénique avec une charge de 2 mol% de palladium. Des résultats modérés à excellents ont été obtenus. Enfin, les thioéthers d'aryle et d'hétéroaryle ont été obtenus avec d'excellents résultats à l'aide d'une tétraphosphine ferrocénique en présence de 0,2 mol% de palladium
43
Sofack-Kreutzer, Julien. "Synthèses de carbocycles et d'hétérocycles à cinq chaînons par activation de liaisons c(sp3)-h non activées." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00744243.
Full textAbstract:
La fonctionnalisation de liaisons C-H réputées peu réactives ouvre de nouvelles perspectives en synthèse organique. La catalyse par un métal de transition comme le palladium représente une solution particulièrement efficace à ce problème. Les travaux de thèse présentés dans ce mémoire s'inscrivent dans ce contexte. Dans un premier temps, la réaction étudiée, catalysée par le palladium, a visé à étendre une méthodologie mise au point au laboratoire pour la synthèse de carbocycles et d'hétérocycles à cinq chaînons par activation intramoléculaire de liaisons C(sp3)-H à partir de chlorures d'aryles. Ces derniers sont en effet plus disponibles et moins onéreux que les bromures d'aryle correspondants. Des études d'optimisation ont été effectuées pour la mise au point d'une réaction diastéréosélective et régiosélective. Plusieurs substrats ont été synthétisés pour être ensuite placés dans les conditions optimales de la réaction d'activation C(sp3)-H, et ont conduit à une grande diversité de cycles à cinq chaînons fusionnés. Dans un deuxième temps, nos travaux ont consisté à étendre l'activation C(sp3)-H pallado-catalysée à des précurseurs non aromatiques cycliques ou acycliques. Pour des raisons d'accessibilité, nos études se sont alors portées sur la préparation de bromures vinyliques azotés pouvant conduire après activation C-H à des motifs hexahydroindoles ou pyrrolidines. De nouvelles conditions d'activation CH ont alors été trouvées pour cette famille de substrats, et ont conduit aux hétérocycles cibles de manière diastéréosélective et régiosélective. Après extension de la réaction à divers précurseurs, nous nous sommes intéressés à la synthèse d'un intermédiaire poly-fonctionnalisé permettant d'accéder aux aéruginosines, famille de produits naturels bioactifs.
44
Hu, Yimin. "Intramolecular C-C bond formation via ruthenium and palladium catalysis : application of ruthenium catalyzed [5+2] cycloaddition for the synthesis of frondosin A and palladium catalyzed cyclizations with carbon nucleophiles /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Full text
45
Guyonnet, Mathieu. "Synthèse totale d’alcaloïdes de type dibenzopyrrocoline par arylation C(sp3)-H intramoléculaire." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10143.
Full textAbstract:
La fonctionnalisation de liaisons carbone – hydrogène réputées peu réactives ouvre de nouvelles perspectives en synthèse organique. Une stratégie efficace consiste en l'utilisation de métaux de transition comme le palladium. L'activation C-H organométallique a fait l'objet de nombreux développements méthodologiques au cours des dernières décennies, toutefois peu d'applications de ces travaux en synthèse multi-étapes ou totale sont reportées dans la littérature. Les travaux de recherche décrits dans ce mémoire s'inscrivent dans ce contexte. Nous nous sommes intéressés à la famille des alcaloïdes de type dibenzopyrrocoline, une famille de produits naturels structurellement originaux. Au vu des travaux précédemment reportés dans la littérature, l'analyse rétrosynthétique de ces produits nous a conduits à développer dans un premier temps une séquence N-arylation / bromation / arylation C(sp3)-H intramoléculaire de lactames et analogues qui nous a permis d'accéder à diverses indolines tricycliques fusionnées. Dans un deuxième temps, la synthèse du squelette dibenzopyrrocoline a été entreprise à l'aide de la méthodologie séquentielle développée et la difficulté d'accès au précurseur d'arylation C(sp3)-H intramoléculaire a nécessité l'exploration de différentes voies synthétiques, potentiellement prometteuses. Enfin les différents travaux méthodologiques effectués ont mis à jour la faisabilité de l'arylation C(sp3)-H intramoléculaire d'anilines tertiaires, jamais reportée dans la littératureThe direct functionalization of unactivated C-H bonds represents an atom- and stepeconomical alternative to more traditional synthetic methods based on functional group interconversion. Transition-metal catalysis has recently emerged as a powerful tool to functionalize otherwise unreactive C-H bonds. Whereas a lot of methodological studies have been developed in the past decade, few applications of these methodologies in multi-step or total synthesis have been reported in the literature. In this context, we envisioned the total synthesis of dibenzopyrrocoline alkaloids, a family of structurally original natural products, by using intramolecular C(sp3)-H arylation as a key step. This work led us to first develop a N-arylation / bromination / intramolecular C(sp3)-H arylation sequence which allowed us to access diverse fused tricyclic indolines. We next investigated the application of this strategy to the synthesis of the dibenzopyrrocoline motif. The difficulty to access the C(sp3)-H arylation precursor required an exploration of different synthetic pathways, which proved to be potentially promising. Finally the different performed methodological studies showed the feasibility of the intramolecular C(sp3)-H arylation of tertiary anilines, which was never described in the literature
46
Reina, Tapia Antonio. "Metal nanoparticles stabilized by alkaloids in glycerol : from design to catalytic applications." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30160.
Full textAbstract:
Les nanoparticules métalliques (MNPs) ont un grand succès dans les dernières décennies dû à la variété d'applications dans différents domaines (microélectronique, matériaux, catalyse). Mis à part les solvants organiques, les liquides ioniques, l'eau, le CO2 supercritique et les polyols, en particulier le glycérol, ont démontré leur capacité à stabiliser et immobiliser les nanoparticules métalliques. Ces milieux évitent l'agglomération des MNPs et facilitent leur recyclage. Des nanoparticules de Pd(0) et Ni(0) dans le glycérol, sphériques, petites en taille et bien dispersées, ont été synthétisées avec succès à partir d'une méthodologie simple sous pression d'hydrogène, en présence de différents stabilisants (alkaloïdes, phosphine, polymer). La caractérisation complète de ces matériaux en solution et à l'état solide, ainsi que la possibilité de faire des synthèses à grande échelle et de stocker les solutions catalytiques longtemps, montrent la grande stabilité de ces solutions colloïdales. Les nanoparticules dans le glycérol ont été impliquées dans une large variété de transformations : hydrogénations, hydrodéhalogénations, couplages de Hiyama, additions conjuguées et hydrosilylations. De plus, nous avons étudié l'effet du stabilisant sur la réactivité catalytique, nous permettant de contrôler l'état de surface des nanoparticules et moduler ainsi leur réactivité. Nous avons montré, de même, la capacité du glycérol pour immobiliser les catalyseurs, ce qui s'est traduit par la possibilité de recycler la phase catalytique entre 4 et 10 fois sans perte de metal. En parallèle, nous avons évalué le comportement du Ni(OAc)2 libre de ligands dans le glycérol, en tant que catalyseur alternatif pour des couplages C-C et C-hétéroélément. Nous présentons aussi une étude en flux continu, en collaboration avec la Maison Européenne des Procédés Innovants (MEPI), pour l'hydrogénation de différents groupes fonctionnels, en utilisant les PdNPs dans le glycérol synthétisées préalablementMetal nanoparticles (MNPs) have been largely studied in the last decades due to their interesting properties which found applications in several fields (microelectronics, materials and catalysis, among others). In contrast to common organic solvents, ionic liquids, water, supercritical CO2, polyols such as glycerol, represent innovative solvents for the immobilization of MNPs, avoiding their agglomeration and facilitating their recycling. Small, spherical, and well-dispersed Pd(0) and Ni(0) nanoparticles were synthesized under hydrogen pressure in glycerol, in the presence of different kinds of stabilizers (cinchona-based alkaloids, phosphine, polymer). The high stability of these colloidal solutions permitted the full characterization both in solution and at solid state, large-scale synthesis, and stocking the solutions for months. These colloidal catalysts were applied in a large variety of transformations including hydrogenations, hydrodehalogenations, Hiyama C-C couplings, hydrosilylation reactions, and Michael conjugate additions. Furthermore, we conducted a comparative study exhibiting the differences in catalytic reactivity by effect of the stabilizer, allowing us tuning the surface-state of the nanoparticles. Moreover, we showed the ability of glycerol to immobilize metal nanoparticles permitting the recycle of the catalytic phase between 4 and 10 times, without metal leaching. Additionally, we studied the behavior of ligand-free Ni(OAc)2 in glycerol as an alternative catalyst for C-C and C-heteroatom couplings. Also, we developped a continuous flow study, in collaboration with the Maison Européenne des Procédés Innovants (MEPI), for the hydrogenation of different functional groups, using PdNPs in glycerol
47
Aspin, Samuel. "Arylation migratoire C(sp3)-H d'énolates d'esters." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10298.
Full textAbstract:
La fonctionnalisation C(sp3)-H catalysée par des métaux de transitions, ouvre de nombreuses perspectives en synthèse organique, permettant des voies d'accès plus économes en atomes, et en étapes à des molécules à forte valeur ajoutée. Dans cette optique, une méthode efficace permettant l'arylation des liaisons C(sp3)-H en position α d'un groupement attracteur, plus communément appelée α -arylation a récemment fait l'objet d'une attention toute particulière de la part de la communauté scientifique. Le travail détaillé dans ce manuscrit décrit les dernières avancées de cette méthodologie, ainsi qu'une variante «β-arylation » développée au laboratoire qui constitue une évolution significative dans le domaine de l'arylation regiosélective des liaisons C(sp3)-H non activées. Dans le cadre de ce projet de thèse nous nous sommes efforcés de développer cette nouvelle réaction que nous avons pu optimiser pour l'étendre à une famille plus étendue de substrats de type amino-esters. Dans la continuité de ce travail nous avons réalisé la première réaction d'arylation migratoire sélective d'amino-esters pouvant aller jusqu'à la position η d'une chaîne alkyle linéaire. Enfin, dans le but d'accéder à de nouvelles molécules à plus haute valeur ajoutée, nous avons pu appliquer notre méthodologie aux acetals de cétènes silylés permettant de dépasser certaines limitations du système existant. Dans ce cas précis, des conditions plus douces (sans base forte) ont permis l'arylation de substrats dits sensibles et par extension la synthèse de lactones fonctionnaliséesThe transition metal catalysed functionalization of C(sp3)-H bonds unlocks numerous perspectives within organic synthesis in terms of atom economical access routes to otherwise difficult to synthesise molecules. One efficient method to exact such transformations involves the exploitation of an activated C-H bond situated adjacent to an activating electron withdrawing group, allowing facile insertion of a transition metal catalyst species and subsequent functionalization with a new species (normally an aryl group). This strategy is generally termed ‘α-functionalization’. The work detailed within this manuscript describes a diversion from the classic, and well documented α-functionalization reaction, in which rearrangement steps within the catalytic cycle give rise to β- and more remote substrate functionalization. The first new methodology to be described involves a fundamental extension to the in-house developed β-arylation reaction, in which, through careful substrate and ligand choice, this methodology could be applied to achieve the functionalization of simple ester enolates in remote γ- to η - positions. The developed strategy allowed the synthesis of a small range of interesting homophenylalanine analogues, and higher homologues. The second methodology to be described involves a necessary modified protocol for the β-arylation reaction, in which silyl ketene acetals were exploited as mild metal-enolate surrogates, allowing the coupling of base-sensitive substrates. The previously described reaction scope has been extended in terms of both the electrophile and nucleophile coupling partners through the development of mild reaction conditions, which subsequently allowed application of several products towards the synthesis of lactones
48
Biosca, Brull Maria. "Fitting the catalysts for effective enantioselective C-X bond forming reactions. Theoretically guided ligand design and mechanistic investigations." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/665121.
Full textAbstract:
La creixent demanda de compostos enantiomèricament purs, ha incrementat l’interès pel desenvolupament de metodologies per l’obtenció d'aquests compostos. Entre elles, la catàlisi asimètrica és la tècnica més emprada. En aquesta metodologia, l'elecció lligand quiral és clau per l'obtenció de elevades activitats i enantioselectivitats. En aquest context, aquesta tesis és centra en la síntesis de diferents famílies de lligands quirals altament modulars a partir de productes de partida d'elevada disponibilitat. Més concretament, s’han sintetitzat diverses famílies de lligands heterodadors P-oxazolina (P= fosfina, fosfinit, fosfit, fosforamidit), P-altres grups N-dadors (P= fosfit, fosforamidit, fosfonit i N= tiazol, sulfoximina, hidrazona, amina, piridina), P-tioèter (P= fosfina, fosfinit, fosfit) i una família de lligands fosfina quiral-fosfit. Aquests lligands s'han aplicat en la reacció d’hidrogenació d’olefines funcionalitzades i mínimament funcionalitzades catalitzada per Rh i Ir, la reacció de substitució al·lílica i la reacció de protonació descarboxilativa d’oxindoles ambdues catalitzades per Pd. A més a més, en alguns casos, s'han dut a terme estudis computacionals en combinació amb assajos experimentals per estudiar l'origen de les enantioselectivitats obtingudes o bé per guiar l'optimització dels lligand.La creciente demanda de compuestos enantioméricamente puros, ha incrementado el interés por el desarrollo de metodologías para la obtención de dichos compuestos. Entre ellas, la catálisis asimétrica es la técnica mas utilizada. En dicha metodología, la elección del ligando quiral es clave para la obtención de elevada actividades i enantioselectividades. En este contexto, esta tesis se centra en la síntesis de diferentes familias de ligandos quirales altamente modulares a partir de productos de partida de elevada disponibilidad. Más concretamente, se ha trabajado en la síntesis de ligandos heterodadores P-oxazoline (P= fosfina, fosfinito, fosfito, fosforamidito), P-otros grupos N-dadores (P= fosfito, fosforamidito, fosfonito y N= tiazol, sulfoximina, hidrazona, amina, piridina), P-tioéter (P= fosfina, fosfinito, fosfito) i una familia de ligandos fosfina quiral-fosfito. Estos ligandos se han aplicado en la reacción de hidrogenación de olefinas funcionalitzadas i mínimamente funcionalitzadas catalizada por Rh i Ir, la reacción de substitución alílica y la reacción de protonación descarboxilativa de oxindolas ambas catalizadas por Pd. Además, en algunos casos, se han realizado cálculos computacionales en combinación con ensayos experimentales para estudiar el origen de las enantioselectividades obtenidas o bien para guiar la optimización de los ligandos.
The growing demand on enantiomerically pure compounds has stimulated the interest for the development of methodologies to obtain these compounds. Among them, asymmetric catalysis is one of the most employed tools. In this technic, the choice of the chiral ligand is fundamental to obtain high levels of activity and enantioselectivity. In this context, this thesis is focused on the synthesis of several families of highly modular chiral ligands from readily available starting materials. Particularly, we worked on the synthesis of P-oxazoline (P= phosphine, phosphinite, phosphite, phosphoroamidite), P-other N-donor groups (P= phosphite, phosphoroamidite, phosphonite and N= thiazole, sulfoximine, hydrazone, amine, pyridine), P-thioether (P= phosphine, phosphinite, phosphite) and a family of P*-stereogenic phosphine-phosphite ligands. These ligands have been applied in the Rh- and Ir-catalyzed hydrogenation of functionalized and minimally functionalized olefins, Pd-catalyzed allylic substitution reaction and Pd-catalyzed decarboxylative protonation. Furthermore, in some cases, DFT studies in combination with experimental ones have been performed to better understand the origin of the obtained enantioselectivities or in order to guide the ligand optimization.
49
Rovira, Coll Mireia. "Reaction mechanisms involved in cross coupling processes catalysed by copper and nickel." Doctoral thesis, Universitat de Girona, 2017. http://hdl.handle.net/10803/403434.
Full textAbstract:
Organometallic aryl-CuIII species have been proposed as key intermediates in Ullmann-type reactions. However, such species have long remained elusive and mechanistic investigations of a plausible catalytic cycle remained ambiguous and speculative. The first part of this thesis deals with the reactivity of well-defined aryl-CuIII macrocyclic complex in presence of activated methylenes (Hurtley-type coupling) and terminal acetylenes (Stephens-Castro-type coupling). The subsequent part deals with the synthesis and fully characterization of well-defined aryl-NiII complex, which is analogous to aryl-CuIII complex. The strength of the Ni-C bond precludes their direct reactivity with nucleophiles via reductive elimination. Nevertheless, we have proved their reactivity in the presence of a 2 e- redox oxidant as an electrophilic CF3+ source. In the last part, we turned our attention to the standard Cu-catalyzed Ullmann-type reactions by studying the effect of the ligand choice on the chemoselectivity of a multiple combinations of amides, amines and phenols in competitive reactionsLes espècies aril-CuIII han estat proposades com les espècies a través de les quals operen els acoblaments tipus Ullmann. No obstant, aquestes espècies són molt reactives i difícilment detectables en els processos fonamentals que governen aquests acoblaments. La primera part d’aquesta tesi es centra en l’estudi de la reactivitat de complexes ben definits aril-CuIII davant de metilens actius (Reacció de Hurtley) i acetilens terminals (Reacció de Stepens-Castro). La següent part es centra en la síntesi i caracterització de complexes ben definits aril-NiII, anàlegs als de coure. La curta distància de l’enllaç Ni-C dissenteix la seva reactivitat davant diversos nucleòfils via eliminació reductiva. Per contra, aquestes espècies són reactives en presència de fonts electrofíliques de CF3+. En l’última part, ens centrem en l’estudi de les propietats estèriques dels lligands auxiliars coordinats al centre de coure i la selectivitat que presenten envers diferents nucleòfils en els sistemes estàndards de tipus Ullmann
50
Margalef, Pallarès Jèssica. "Screening of modular and readily available ligand libraries for C-X (X=H, C, N and O) bond forming reactions. The use of DFT studies for catalysts optimization." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/386578.
Full textAbstract:
El creixent interès per a l’obtenció de compostos enantiomèricament purs, ha conduït a un important desenvolupament de la catàlisi asimètrica. En aquest context, aquesta tesis és centra en la síntesis de vàries famílies de lligands quirals altament modulars a partir de compostos de fàcil disponibilitat. Concretament, s'ha treballat en la síntesis de lligands fosfit-tioèter, fosfit-piridina, fosfit-triazola i lligands hidroaximida i tioamida. Tots ells tenen en comú que són sòlids, estables i per tant de fàcil manipulació. Aquests lligands s'han aplicat en la hidrogenació d’olefines funcionalitzades i no funcionalitzades catalitzada per Rh i Ir, en la reducció de cetones mitjançant transferència d’hidrogen catalitzada per Rh i Ru, en reaccions de substitució alílica catalitzada per Pd i en l'addició d'organoaluminats a aldehids catalitzada per Ni. A més a més, en alguns casos s'han realitzat estudis DFT per tal d'agilitzar el procés d'optimització dels lligands. Així doncs, s'ha aconseguit l'obtenció de diferents compostos químics quirals d'alt interès sintètic (alcohols, alcans funcionalitzats i no funcionalitzats, al·lils substituits) en grans enantioselectivitats i en el millor dels casos s'han aconseguit els productes en la seva forma enantiomèricament pura (>99% ee).El creciente interés para la obtención de compuestos enantioméricamente puros para la obtención de compuestos enantioméricamente puros, ha conducido a un importante desarrollo de la catálisis asimétrica. En este contexto, esta tesis se centra en la síntesis de varias familias de ligandos quirales altamente modulares a partir de compuestos de fácil disponibilidad. Concretamente, se ha trabajado en la síntesis de ligandos fosfito-tioéter, fosfito-piridina, fosfito-triazoles y ligandos hidroaximida y tioamida. Todos ellos tienen en común que son sólidos, estables y por lo tanto de fácil manipulación. Estos ligandos se han aplicado en la hidrogenación de olefinas funcionalizadas y no funcionalizadas catalizada por Rh e Ir, en la reducción de cetonas mediante transferencia de hidrógeno catalizada por Rh y Ru, en reacciones de sustitución alílica catalizada por Pd y en el adición de organoaluminiatos a aldehídos catalizada por Ni. Además, en algunos casos se han realizado estudios DFT para agilizar el proceso de optimización de los ligandos. Así pues, se ha logrado la obtención de diferentes compuestos químicos quirales de alto interés sintético (ej. alcoholes, alcanos funcionalizados y no funcionalizados, alilos sustituidos) en grandes enantioselectividades y en el mejor de los casos se han conseguido los productos en su forma enantioméricamente pura (> 99% ee).
The growing interest in obtaining enantiomerically pure compounds in obtaining enantiomerically pure compounds has led to a significant development in the field of asymmetric catalysis. In this context, this thesis is focused on the synthesis of several families of highly modular chiral ligands from readily available compounds. Specifically, we worked on the synthesis of thioether-phosphite ligands, phosphite-pyridine, phosphite-triazole and hidroaximide and thioamide ligands. They all have in common that are solid, stable and therefore easy to handle. These ligands have been applied in the Rh- and Ir-catalyzed hydrogenation of functionalized and unfunctionalized olefins, in the Ru- and Rh-catalyzed asymmetric transfer hydrogenation of ketones, in Pd-catalyzed allylic substitution reactions and in the Ni-catalyzed addition of organoalumininum to aldehydes. Moreover, in some cases DFT studies have been performed to speed up the optimization of ligands. Hence, a variety of chiral chemical compounds of high synthetic interest (i. e. alcohols, functionalized and non-functionalized alkanes, substituted allyl) lhigh enantioselectivities were achieved and in some cases the products were obtained in their enantiomerically pure form(> 99% ee).