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Das, Pralay. "New reactions and methodology : studies on transition metal catalyzed organic transformations." Thesis, University of North Bengal, 2005. http://hdl.handle.net/123456789/775.
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Ganguly, Bhaskar. "Transition-metal catalyzed organic transformations and application towards the synthesis of heterocyclic compounds." Thesis, University of North Bengal, 2017. http://ir.nbu.ac.in/handle/123456789/2650.
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Gandolfo, Eugenio. "Light-driven Metal-catalyzed Asymmetric Transformations." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/672439.
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Resum
Una molècula en el seu estat excitat ofereix una reactivitat completament diferent de la del seu estat fonamental. Pot comportar-se tant com a millor oxidant com a millor reductor, permetent així noves transformacions a causa de la capacitat de generar radicals intermedis en condicions suaus.
El principal objectiu científic d'aquesta tesi doctoral va ser investigar l'excitació directa de substrats i intermedis de reacció per desbloquejar noves vies de reacció, permetent transformacions asimètriques catalitzades per metalls les quals serien inviables sota el domini tèrmic. Amb aquesta finalitat, vaig investigar la química de les 4-alquil-1,4-dihidropiridines (4-alquil-DHP) com a font d'electrons i precursors de radicals tant en el seu estat excitat com en el seu estat fonamental.
En el primer projecte, vaig aprofitar les propietats dels 4-alquil-DHP en el seu estat excitat, actuant com forts fotorreductors i font de radicals, per permetre l'acoblament creuat asimètric d'acil catalitzat amb níquel i així, accedir a cetones α, α- disubstituïdes altament enantioenriquides.
En el segon projecte, vaig estudiar com, mitjançant l'excitació de la llum, era possible desviar la reactivitat establerta en l'estat fonamental d'un complex quiral d’organoiridi, permetent processos mecanístics originals inabastables en el domini tèrmic. En particular, vam provar un complex particular de η3-aliliridio (III) quiral per al qual estimem un potencial d'oxidació de ̴ +1.24 V en l'estat excitat. Aquesta nova funció catalítica adquirida després de l'excitació a través de la llum es va aprofitar per desenvolupar un acoblament enantioselectiu creuat alquil-alquil entre alcohols benzil al·lílics i radicals α-amino, derivats de 4-alquil-DHP que serveixen com a fonts de radicals en estat fonamental.Resumen Una molécula en su estado excitado ofrece una reactividad completamente diferente a la de su estado fundamental. Puede comportarse tanto como mejor oxidante como mejor reductor, lo que permite nuevas transformaciones debido a la capacidad de generar radicales intermedios en condiciones suaves. El principal objetivo científico de esta tesis doctoral fue investigar la excitación directa de sustratos e intermedios de reacción para desbloquear nuevas formas de reacción, permitiendo transformaciones asimétricas catalizadas por metales las cuales serían inviables bajo el dominio térmico. Con este fin, investigué la química de las 4-alquil-1,4-dihidropiridinas (4-alquil-DHP) como fuente de electrones y precursores de radicales tanto en su estado excitado como en su estado fundamental. En el primer proyecto, aproveché las propiedades de los 4-alquil-DHP en su estado excitado, actuando como fuertes fotorreductores y fuente de radicales, para permitir el acoplamiento cruzado asimétrico de acilo catalizado con níquel y así, acceder a cetonas α, α-disustituidas altamente enantioenriquecidas. En el segundo proyecto, estudié cómo, mediante la excitación de la luz, era posible desviar la reactividad establecida en el estado fundamental de un complejo quiral de organoiridio, permitiendo procesos mecanísticos originales inalcanzables en el dominio térmico. En particular, probamos un complejo particular de η3-aliliridio (III) quiral para el cual estimamos un potencial de oxidación de ̴ +1.24 V en el estado excitado. Esta nueva función catalítica adquirida tras su excitación con la luz se aprovechó para desarrollar un acoplamiento cruzado enantioselectivo alquil-alquilo entre alcoholes bencil alílicos y radicales α-amino, derivados de 4-alquil-DHP que sirven como fuentes de radicales en estado fundamental.
Abstract An excited-state molecule offers a completely different reactivity than in its ground state. It can be both a better oxidant and a better reductant, thus enabling novel transformations due to the ability to generate radical intermediates under mild conditions. The main scientific objective of this doctoral thesis was to investigate the direct excitation of substrates and intermediates to unlock novel reactivity manifolds, enabling asymmetric metal-catalyzed transformations unfeasible under the thermal domain. To this end, I exploited the chemistry of 4-alkyl-1,4-dihydropyridines (4-alkyl-DHPs) in either their excited- and ground-state as sources of electrons and radical precursors. In the first project, I exploited the excited-state properties of 4-alkyl-DHPs, serving as strong photoreductant and radicals source, to enable an asymmetric nickel-catalyzed acyl cross-coupling to access highly enantioenriched α,α-disubstituted ketones. In the second project, I studied how, by means of light-excitation, it was possible to divert the established ground-state reactivity of an organoiridium chiral complex, enabling mechanistically original processes unattainable in the thermal domain. In particular, we probed a particular chiral η3-allyliridium(III) complex for which we estimated an oxidation potential of ̴ +1.24 V in the excited state. This novel catalytic function acquired upon light excitation was exploited to develop an enantioselective alkyl-alkyl cross-coupling between benzyl allylic alcohols and α-amino radicals, derived from 4-alkyl-DHPs serving as ground-state radical sources.
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Nimmagadda, Sri Krishna. "Asymmetric Transformations Catalyzed By Chiral BINOL Alkaline Earth Metal Phosphate Complexes." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6554.
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Small molecule hydrogen bond donors have emerged as versatile catalysts in asymmetric synthesis. Within this class, chiral BINOL phosphoric acid is regarded as one of the pioneer catalysts used in several asymmetric transformations. The ability of the catalyst to activate the substrates could be controlled in two different ways. (1) Dual activation/bifunctional activation of substrate by hydrogen bond interactions or ion pairing with phosphoric acid or (2) By forming chiral BINOL phosphate metal complex that could significantly alter the interactions in chiral space. In particular, chiral alkaline earth metal phosphate complexes have unique advantages as catalysts owing to the ubiquitous availability of alkaline earth metals, strong Brønsted basicity of their counterions, mild but significant Lewis acidity of the metal and their ability to coordinate at multiple reactive sites due to large ionic radius.
Chapter 1 summarizes the recent development of alkaline earth metal complexes in asymmetric catalysis. My thesis dissertation is focused on the application of chiral alkaline earth metal phosphate complexes in novel asymmetric reactions.
In Chapter 2, we disclosed an efficient asymmetric one-pot synthesis of chiral 1,3-oxazolidines and chiral 1,3-oxazinanes. Chiral oxazolidines and oxazinanes are widely used as auxiliaries in asymmetric transition metal catalysis and also key structural motifs in natural products with biological activities. We developed a new synthetic method for chiral 1,3-oxazolidines which follows the enantioselective addition of alcohols to imines catalyzed by chiral 3,3’-(triisopropylphenyl)-derived BINOL magnesium phosphate to form hemiaminal intermediate, which then undergoes mild base mediated intramolecular nucleophilic substitution to afford highly enantioselective 1,3-oxazolidines and 1,3-oxazinanes in good yields.
In Chapter 3, we developed the first catalytic enantioselective desymmetrization process for the synthesis of novel axially chiral cyclohexylidene oxime ethers. Even though these molecules were found to be optically active in 1910, methods to synthesize these molecules are scarce. We have developed an efficient desymmetrization process of 4-phenyl cyclohexanones with phenoxyamines catalyzed by chiral BINOL strontium phosphate complex to afford highly enantioselective products. We then extended this methodology to the dynamic kinetic resolution of 2-substituted cyclohexanones to form chiral 2-substituted cyclohexyl oximes in good enantioselectivities, as demonstrated in Chapter 4. We further demonstrated the utility of these compounds by converting them to chiral 2-aryl cyclohexylamines which are important synthetic intermediates.
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Tan, Peng Wen. "Transition metal catalyzed reactions and functionalized group transformations." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:336947d0-c3c7-4c45-9849-d3231c53ab42.
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The overall objective of this thesis is to develop contemporary transition-metal-catalyzed strategies and applications to access various biologically and chemically relevant compounds in a direct and elegant fashion.
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Song, Xuejing. "Studies of transition metal catalyzed propylene polymerization." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308611.
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Zweni, Pumza P. "Dendrimer-transition metal catalyzed oxidation and reduction reactions." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/10529.
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This project was launched with the aim of developing dendrimer catalysts for oxidation and reduction reactions. Poly(amidoamine) (PAMAM) and poly(propyleneimine) (PPI) dendrimers were of interest because of their well-established synthesis. Chapter 1 describes the fundamentals of dendrimers and provides a brief insight of their application in catalysis. In particular, examples of dendritic catalysts that have been previously employed as oxidation and reduction catalysts are presented. Chapter 2 presents the synthesis and characterization of silica-supported PAMAM dendrimers, their phosphomethylation with Ph2 PCH2OH, and their complexation to palladium complexes. Chapter 3 reports the application of the silica-supported PAMAM-Pd complexes to the oxidation of alkenes to methyl ketones under Wacker-type conditions as well as the use of tBuOOH as the oxidant in these reactions. Chapter 4 discusses the use of the above-mentioned complexes to catalyze the selective hydrogenation of dienes to monoolefins in the presence of H2 under mild reaction conditions. Chapter 5 presents our efforts in modifying PPI dendrimers with the salen moiety to give ligands that are coordinated to the metals Ti and V. Attempts at using the former complexes to promote the epoxidation of alkenes and the latter complexes to catalyze the epoxidation of olefinic alcohols are discussed.
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Trono, Corazon. "Transition metal catalyzed synthesis of glycoclusters from sugar alkynes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58515.pdf.
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Tatsumi, Kenta. "Transition Metal-Catalyzed Novel Transformations of Acid Chlorides and Acid Anhydrides." Kyoto University, 2019. http://hdl.handle.net/2433/242519.
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Duvvuri, Krishnaja. "Transition Metal Catalyzed Enantioselective Hydroboration and Hydrovinylation of Alkenes." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524049349604356.
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Shen, Di. "Transition metal catalyzed alkylation and synthesis of biotin derivatives." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1467ba98-846c-46e6-9620-e4639ed07e43.
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Transition Metal Catalyzed Alkylation We have reported methodology for the use of methanol as an alkylation reagent using catalytic rhodium or iridium species for the formation of branched products from methyl ketones. The synthetic utility of the dialkylated products was enhanced by performing a regioselective Baeyer-Villiger oxidation which allowed access to ester products. A range of different phosphine ligands were screened, and sterically hindered and electron rich phosphine ligands were found to favour the formation of enone and methoxy adducts under an O2 atmosphere. This interrupted hydrogen borrowing reaction enabled the in situ addition of a nucleophile to give more complex products. A range of tetrasubsitituted pyridines were then synthesized from 1, 5-dicarbonyl compounds formed in the methylenation/conjugate addition sequence. Finally, deuteration experiments suggest that the reaction proceeds via a monohydride mechanism, and the possibilities for the beneficial effect of O2 were discussed. Synthesis of biotin derivatives The streptavidin-biotin system was chosen for the studies of protein/ligand interactions at molecular level. A series of modified biotin ligands were designed and synthesized to introduce repulsive interations with streptavidin. The protein/ligand complexes were analyzed at high resolution by X-ray crystallography.
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Perego, Luca Alessandro. "Transition metal-catalyzed reactions : mechanistic studies and methodology developments." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE003/document.
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Dans cette thèse les mécanismes de trois réactions catalysées par des complexes de palladium et de cuivre ont été étudiés en utilisant des méthodes expérimentales et théoriques. La première réaction est la synthèse d’amides à partir d’halogénoarènes, d’isonitriles et d’eau, qui est un exemple de couplage catalysé par le palladium impliquant l’insertion d’un isonitrile. Cette dernière molécule sert à la fois de ligand et de substrat, et son influence sur chaque étape du cycle catalytique a été mise en évidence. La deuxième réaction est l’ouverture des benzofuranes conduisant à des dérivés indoliques catalysée par des sels de palladium. Les conditions opératoires ont été optimisées et les étapes clés du mécanisme ont été élucidées.La dernière réaction étudiée, qui est le sujet principal de cette thèse, est l’addition d’amines sur des allènes catalysée par des sels de cuivre (hydroamination). La caractérisation des espèces catalytiques de cuivre(I) et l’étude théorique du mécanisme ont permis d’étendre cette réaction à différents substrats (allénamides, N-allénylazoles, N-allénylsulfamides) dans des conditions particulièrement douces et efficacesIn this thesis, the mechanism of three organic reactions catalyzed by palladium and copper complexes has been elucidated by the use of both experimental and theoretical methods. The first reaction is the synthesis of amides from haloarenes, isocyanides and water as an example of the broad family of palladium-catalyzed imidoylative couplings. Multiple roles of the isocyanide as both a ligand and a substrate in the different steps of the catalytic cycle have been disclosed. The second transformation is the palladium-catalyzed ring opening of benzofurans leading to indoles. Optimal conditions for this transformation have been found and the key aspects of its mechanism clarified. The last reaction, which is the main topic of this thesis, is the addition of amines to allenes catalyzed by copper salts (hydroamination). A characterization of the catalytically active copper(I) species and insight from theoretical calculations suggested how to extend this reaction to other substrates (allenamides, N-allenylazoles, N-allenylsulfonamides) under mild and efficient conditions
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Meyer, Tjark Hannes [Verfasser]. "Merging Electrosynthesis with 3d Transition Metal-Catalyzed C–H Transformations / Tjark Hannes Meyer." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://d-nb.info/123763346X/34.
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Midya, S. P. "Transition metal catalyzed (de) hydrogenative C-C and C-N bond formation." Thesis(Ph.D.), CSIR-National Chemical laboratory, Pune, 2018. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4568.
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Oshima, Kazuyuki. "Organic Synthesis Based on Transition-Metal-Catalyzed Addition Reactions of Boron Reagents." 京都大学 (Kyoto University), 2012. http://hdl.handle.net/2433/157539.
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Zanini, Margherita. "Transition metal-catalyzed reactions of heteroatom-substituted alkynes." Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/670898.
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La catàlisi homogènia d'or(I) és una eina per a la construcció de complexitat molecular mitjançant l'activació selectiva
d'enllaços múltiples C-C. El nostre grup ha desenvolupat una sèrie de reaccions d'alquins amb alquens catalitzades
per or(I) tant en forma intramolecular com intermolecular. Aquestes reaccions s’inicien amb l'atac nucleofílic del doble
enllaç a l'alquí per formar un intermedi tipus ciclopropil carbé d'or(I) que evoluciona per donar diferents productes. En
aquesta tesi doctoral es descriu una sèrie de noves reaccions intermoleculars de alquens amb alquins substituïts amb
heteroàtoms catalitzades per or(I). A més, es presenten els estudis mecanístics corresponents, realitzats mitjançant
experiments i càlculs DFT.
En les reaccions entre bromolaquins i alquens catalitzades per or(I), inicialment es genera un 1-brom ciclopropil carbé
d'or(I) que evoluciona a través d'un catió bromoni ciclic per formar un vinilidè d'or(I) o en un catió vinilidilareni
estabilitzat per or. Els càlculs DFT demostren que aquests dos intermedis són confòrmers de la mateixa espècie però
tenen diferent reactivitat. D'una banda, el vinilidè d'or(I) pot participar en reaciones d'activació C-H o de hidroarilació,
mentre que el catió vinilidilareni participa en transposicions 1,2 de l'areni per a formar un triple enllaç.
A més, els alquinil èters terminals participen en cicloaddicions [2 + 2] amb alquens per formar ciclobutens que poden
convertir-se fàcilment en les corresponents ciclobutanones.La catálisis homogénea de oro(I) es una poderosa herramienta para la construcción de complejidad molecular en condiciones suaves mediante la activación selectiva de enlaces múltiples C-C. Nuestro grupo ha desarrollado una serie de reacciones de alquinos con alquenos catalizadas por oro(I), tanto de forma intramolecular como intermolecular. Estas reacciones comienzan con el ataque nucleofílico del doble enlace al alquino para formar un intermedio tipo ciclopropil carbeno de oro(I), que evoluciona para dar lugar a diferentes productos. En esta Tesis Doctoral se describen una serie de nuevas reacciones intermoleculares entre alquenos y alquinos sustituidos con heteroátomos catalizadas por oro(I). Además, se presentan los estudios mecanísticos correspondientes, realizados mediante experimentos y cálculos DFT. En las reacciones entre bromoalquinos y alquenos catalizadas por oro(I), inicialmente se genera un 1-bromo ciclopropil carbeno de oro(I) que evoluciona a través de un catión bromonio cíclico para formar un vinilideno de oro(I) o un catión vinilidilarenio estabilizado por oro. Los cálculos DFT demuestran que estos dos intermedios son confórmeros de la misma especie pero tienen diferente reactividad. Los vinilidenos de oro(I) pueden participar en reacciones de activacion C-H o de hidroarilación, mientras que los cationes vinilidilarenio participan en transposiciones 1,2 del areno para formar enlaces triples.
Homogeneous gold(I) catalysis is a powerful tool for the construction of molecular complexity under mild conditions by mean of the selective activation of C-C multiple bonds. Our group developed a series of gold(I)-catalyzed reactions of alkynes with alkenes both in intramolecular and intermolecular settings. These reactions start with the nucleophilic attack of the double bond on the alkyne to form a cyclopropyl gold(I) carbene intermediate that than rearranges into a variety of products. In this Doctoral Thesis we present a series of new gold(I)-catalyzed intermolecular reactions of heteroatom-substituted alkynes with alkenes and the mechanistic investigation we performed by means of experimental work and DFT calculations. In the gold(I) catalyzed reactions of bromoalkynes with alkenes, the 1-bromo-cyclopropyl gold(I) carbene initially formed rearranges into gold(I) vinylidenes and vinylidenephenonium gold(I) cations passing through a cyclic bromonium intermediate. DFT calculations demonstrated that these two reactive intermediates are conformers of the same species but have different reactivity. On one side gold(I)-vinylidenes can undergo hydroarylation or C-H insertion, while vinylidenephenonium gold(I) cations easily undergo 1,2-aryl shift forming a triple bond. Moreover, we found that terminal alkynyl ethers are undergoing efficiently [2+2] cycloaddition with alkenes to form cyclobutene derivatives that can be easily transformed into the corresponding cyclobutanones.
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Lihammar, Richard. "Enzyme- and Transition Metal-Catalyzed Asymmetric Transformations : Application of Enzymatic (D)KR in Enantioselective Synthesis." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-108351.
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Dynamic kinetic resolution (DKR) is a powerful method for obtaining compounds with high optical purity. The process relies on the combination of a kinetic resolution with an in situ racemization. In this thesis, a combination of an immobilized hydrolase and a transition metal-based racemization catalyst was employed in DKR to transform racemic alcohols and amines into enantioenriched esters and amides, respectively. In the first part the DKR of 1,2-amino alcohols with different rings sizes and N-protecting groups is described. We showed that the immobilization method used to support the lipase strongly influenced the stereoselectivity of the reaction. The second part deals with the DKR of C3-functionalized cyclic allylic alcohols affording the corresponding allylic esters in high yields and high ee’s. The protocol was also extended to include carbohydrate derivatives, leading to inversion of a hydroxyl substituted chiral center on the carbohydrate. The third part focuses on an improved method for obtaining benzylic primary amines. By using a novel, recyclable catalyst composed of Pd nanoparticles on amino-functionalized mesocellular foam, DKR could be performed at 50 °C. Moreover, Lipase PS was for the first time employed in the DKR of amines. In the fourth part DKR was applied in the total synthesis of Duloxetine, a compound used in the treatment of major depressive disorder. By performing a six-step synthesis, utilizing DKR in the enantiodetermining step, Duloxetine could be isolated in an overall yield of 37% and an ee >96%. In the final part we investigated how the enantioselectivty of reactions catalyzed by Candida Antarctica lipase B for δ-substituted alkan-2-ols are influenced by water. The results showed that the enzyme displays much higher enantioselectivity in water than in anhydrous toluene. The effect was rationalized by the creation of a water mediated hydrogen bond in the active site that helps the enzyme form enantiodiscriminating binding modes.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.
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Zhou, Zhe. "Fe(II)-catalyzed transformation of ferrihydrite associated with natural organic matter." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6670.
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The association between natural organic matter (NOM) and iron (Fe) minerals was widely found in soil and sediments and has been shown to impact the fate of Fe minerals and NOM. Ferrihydrite, a ubiquitous Fe mineral, serves as important sink for NOM and rapidly transforms to secondary Fe minerals in the presence of Fe(II). The associated NOM has been found to influence the Fe(II)-catalyzed ferrihydrite transformation pathway, but it remains unclear how various NOM affects this transformation and the implication. This study specifically investigates how different species of NOM affect Fe(II)-catalyzed ferrihydrite transformation under different C/Fe ratios. A series of Fe isotope tracer experiments were conducted to measure Fe atom exchange and electron transfer between aqueous Fe(II) and ferrihydrite in the presence of diverse NOM species. The fate of Ni during Fe(II)-catalyzed transformation of NOM-Fh coprecipitate was also investigated.
Ferrihydrite was found less susceptible to Fe(II)-catalyzed transformation with increasing C/Fe ratio and fulvic acids and Suwannee River NOM (SRNOM) in the coprecipitates need lower C/Fe ratio than humic acids to completely inhibit formation of secondary Fe minerals. At C/Fe ratios where ferrihydrite transformed to secondary minerals, goethite was dominant in ferrihydrite coprecipitated with humic acids, whereas lepidocrocite was favored in ferrihydrite coprecipitated with fulvic acids and SRNOM. Adsorbed SRNOM may be more inhibitive than coprecipitated SRNOM on Fe(II)-catalyzed ferrihydrite transformation under similar C/Fe ratios. Despite no secondary mineral transformation at high C/Fe ratios, Mössbauer spectra indicated electron transfer still occurred between Fe(II) and ferrihydrite coprecipitated with fulvic acid and SRNOM. In addition, isotope tracer experiments revealed that a significant fraction of structural Fe(III) in the ferrihydrite mixed with the aqueous phase Fe(II) (~85%). After reaction with Fe(II), Mössbauer spectroscopy indicated some subtle changes in the crystallinity, particle size or particle interactions in the coprecipitate.
The effect of coprecipitated SRNOM on Ni(II) distribution during Fe(II)-catalyzed ferrihydrite transformation was investigated with adsorbed Ni(II) and coprecipitated Ni(II). Ni(II) adsorbed on ferrihydrite was more resistant to acid extraction after Fe(II)-catalyzed transformation and suggested that structural incorporation of Ni into secondary Fe minerals occurred. With coprecipitated SRNOM, ferrihydrite did not transform to secondary minerals in the presence of Fe(II) but extensive Fe atom exchange between aqueous Fe(II) and structural Fe(III) still occurred. Limited change in Ni stability was observed, suggesting there was only small portion of Ni redistributed in the presence of Fe(II). Pre-incorporated Ni(II) in Ni-SRNOM-Fh coprecipitate was partially released (6-8 %) in the presence of Fe(II), but the distribution of remaining Ni(II) in the solid did not change measurably. Our observation suggests that the presence of SRNOM limited the redistribution of Ni most likely because of limited transformation of ferrihydrite to secondary minerals.
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Nahra, Joe. "Synthesis of low-valency neoglycoconjugates using transition metal-catalyzed reactions and synthesis of phenylethanoid glycosides." Thesis, University of Ottawa (Canada), 2002. http://hdl.handle.net/10393/6166.
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In the first part of this thesis, a series of rigid glycodimers were synthesized from sugar alkenes and alkynes, using transition metal catalyzed reactions. The synthesis of these dimers depended on the formation of a new carbon-carbon bond between their monomeric units. Sugars containing terminal alkenes were homodimerized using the olefin metathesis reaction, catalyzed by Grubbs' ruthenium catalyst. Terminal alkene carbohydrate derivatives were also coupled with aryl halide carbohydrates by the Heck coupling reaction, using Pd (0) catalyst, to form homo- and hetero-carbohydrate dimers selectively. Glycodimers were also obtained from sugar alkynes, using the Sonogashira coupling reaction. The dimerization of aryl halide carbohydrate derivatives using Pd (0) catalyst, and the cyclotrimerization of alkyne carbohydrates, using Grubbs' catalyst, were also attempted but were not successful. In the second part of this thesis, phenylethanoid glycosides were synthesized by glycosidation reactions. This family of compounds was shown to have numerous biological activities. A multi-step synthesis of Echinacoside, a phenylethanoid glycoside, was attempted.
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Giguère-Bisson, Maxime. "Investigation of transition metal-catalyzed oxidative amidation of aldehydes and aldehyde-alkyne-amine coupling reactions." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103659.
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This thesis describes the investigation of various amino acids derivatives as reagents for copper-catalyzed, silver-catalyzed and iron-catalyzed reactions and the investigation of an enantioselective cobalt-catalyzed aldehyde-alkyne-amine (A3) coupling reaction. The first part focuses on the large-scale optimization of the oxidative amidation of aldehydes in the presence of amine hydrochloride salts as well as our effort to enhance the reaction scope by the use of amino acids derivatives and short peptides. This is then followed by the development of an enantioselective cobalt-catalyzed A3-coupling using binaphthol ligands as a source of chirality. Finally, the last part involves silver-catalyzed alkyne addition to iminoesters as well as silver-catalyzed A3-coupling.La présente thèse a pour but de présenter l'utilisation de divers dérivés d'acides aminés comme substrats pour plusieurs réactions catalysées par des sels de cuivre, d'argent et de fer, de même que du développement d'une réaction de couplage énantiosélective entre aldéhyde, alcyne et amine (A3) catalysée par des sels de cobalt. La première partie met l'emphase sur l'optimisation à grande échelle d'un procédé d'amidation oxydative d'aldéhydes en présence de sels d'amine ainsi que nos efforts pour adapter cette méthode à des substrats tels que courts peptides et dérivés d'acides aminés. Cela est suivi par le développement d'une réaction de couplage énantiosélective entre aldehyde, alcyne et amine (A3) catalysée par des sels de cobalt misant sur l'utilisation de binaphtols comme ligands chiraux. La dernière partie porte sur l'addition d'alcyne à des iminoesters catalysés par des sels d'argent ainsi que sur des réactions de couplage A3, elles aussi catalysées par des sels d'argent.
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Shuai, Qi. "Transition-metal-catalyzed functionalization of aryl C-H bonds via a cross-dehydrogenative-coupling process." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104709.
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This thesis is an investigation on the functionalization of aryl C-H bonds in the presence of transition-metal catalysts and oxidants.In the first part of this thesis, an oxidative amidation of 2-arylpyridine derivatives and 1-methylindoles with a variety of amides is described. Copper(I) bromide is used as catalyst and tert-butyl peroxide (TBP) is employed as oxidant. High regioselectivity of this amidation process is achieved through chelation-assisted aryl C-H activation. In the second part of this thesis, a new concept is described for aryl-aryl coupling that involves oxidative decarbonylative coupling of aryl C-H bonds and readily available aldehydes and forms the aryl-aryl union with complete control of reaction sites. This process is catalyzed by (CO)2Rh(acac), along with TBP as an oxidant.The third and final part of this thesis describes a novel ruthenium- and copper-catalyzed domino reaction between alkynols and aldehydes, which affords 5-olefinated 3,4-dihydropyran derivatives efficiently with only water as the byproduct.Ce manuscrit de thèse présente l'étude de la fonctionnalisation de liaisons C-H aryliques catalysée par des complexes de métaux de transition en présence d'un oxydant. Dans une première partie est décrite la réaction d'amidation oxydante de dérivés de 2 arylpyridine et de 1-méthylindole par une variété d'amides. Le bromure de cuivre(I) est utilisé comme catalyseur et le peroxyde de tert-butyle (TBP) comme oxydant. Dans ces conditions, une excellente régiosélectivité est obtenue pour cette transformation grâce à la présence d'un groupe directeur qui permet l'assistance par chélation de l'activation de la liaison C-H. Au cours de la deuxième partie est abordé un nouveau concept pour la synthèse de motifs aryl-aryl, impliquant une séquence décarbonylation/couplage oxydant. Cette réaction permet la formation d'un composé biaryle à partir d'arènes et d'aldehydes aromatiques aisément accessibles avec un contrôle total des sites réactionnels. Elle est catalysée par le complexe (CO)2Rh(acac) en présence de TBP comme oxydant. La troisième et dernière partie de cette thèse présente une nouvelle réaction domino catalysée par des complexes de ruthénium et de cuivre qui permet l'obtention de 3,4 dihydropyranes substitués en position 5 à partir d'aldéhydes et d'hydroxyalcynes avec la formation d'eau comme unique sous-produit.
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Chen, Haoguo, and 陳浩國. "Silver catalyzed enyne cyclization reactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B42841409.
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Chen, Haoguo. "Silver catalyzed enyne cyclization reactions." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B42841409.
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Albert-Soriano, María. "Towards sustainability in organic transformations catalysed by 1,3-bis(carboxymethyl)imidazole-based systems." Doctoral thesis, Universidad de Alicante, 2020. http://hdl.handle.net/10045/115117.
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Esta tesis doctoral describe la síntesis y aplicación como catalizadores de varios sistemas basados en el zwitterion 1,3-bis(carboximetil)imidazol. En el Capítulo 1 se describe la síntesis del compuesto 1,3-bis( carboximetil)imidazol, así como de tres sales de imidazolio derivadas (cloruro, bromuro y yoduro) y cinco estructuras metal-orgánicas conteniendo este compuesto como ligando (cobre, calcio/cloro, calcio/bromo, bario/cloro y bario/bromo). En todas las metodologías seguidas se utilizan materiales de partida fácilmente disponibles, tienen una preparación sencilla y son eficientes y reproducibles. En el Capítulo 2 se describe la síntesis de amidas a partir de ácidos carboxílicos y formamidas mediante acoplamiento oxidativo, usando la estructura metal-orgánica conteniendo cobre. Se ha obtenido una gran variedad de amidas combinando distintos ácidos y formamidas. Además, esta metodología se ha aplicado a la síntesis de dos compuestos interesantes en escala preparativa. En el Capítulo 3 se describe la síntesis de quinolinas mediante la reacción de Friedlander usando todas las estructuras metal-orgánicas preparadas. Estos sistemas son complementarios, esto es, la formación de las quinolinas a partir de cada sustrato depende del sistema utilizado, pero esto permite tener accesos a una gran variedad de quinolinas, partiendo de 2- aminobenzaldehídos o 2-aminoaril cetonas. En el Capítulo 4 se describe la síntesis de quinolinas mediante la reacción de Friedliinder utilizando solo el cloruro de 1,3-bis(carboximetil)imidazolio. A partir de diferentes 2-aminobenzaldehídos y 2-aminoaril cetonas, se ha preparado una gran cantidad de quinolinas diferentes. Dos de ellas se han podido preparar en escala preparativa. En el Capítulo 5 se describe la síntesis de N-alilanilinas, 2-alilanilinas y 4-alilanilinas mediante sustitución de alcoholes alílicos con anilinas. La regioselectividad de la reacción depende de los diferentes contraiones de la sal de 1,3-bis(carboximetil)imidazolio usada: cloruro, bromuro o yoduro. Se han preparado dos alilanilinas en escala de multigrano, demostrando la efectividad de los catalizadores. Todos los sistemas catalíticos preparados en esta tesis se han usado durante varios ciclos, y todos los procesos se han llevado a cabo sin añadir disolventes.
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Thu, Hung-yat. "Catalytic C-H bond functionalization reactions catalyzed by rhodium(III) porphyrin, palladium(II) and platinum(II) acetate complexes." View the Table of Contents & Abstract, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38027872.
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Lin, Xufeng. "Density functional theory studies of selected transition metals catalyzed C-C and C-N bond formation reactions." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39359645.
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Prina, Cerai Gabriele [Verfasser], Bill [Gutachter] Morandi, and Lukas J. [Gutachter] Gooßen. "First row transition metal catalyzed radical transformations / Gabriele Prina Cerai ; Gutachter: Bill Morandi, Lukas J. Gooßen ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2018. http://d-nb.info/1161942025/34.
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Lin, Xufeng, and 林旭鋒. "Density functional theory studies of selected transition metals catalyzed C-C and C-N bond formation reactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39359645.
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Ghosh, Sujit. "Greener approach towards arganic tranformation: application of transition metal catalysts and eco friendly reaction media." Thesis, University of North Bengal, 2016. http://ir.nbu.ac.in/handle/123456789/2481.
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Enquist, Per-Anders. "Novel Metal-Mediated Organic Transformations : Focusing on Microwave Acceleration and the Oxidative Heck Reaction." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7117.
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Bonfield, Eric. "Application of transition metal catalyzed aldehyde-alkyne-amine coupling reactions to tandem reaction sequences: a greener approach to the preparation of useful organic compounds." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40800.
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Tandem reactions are multiple reactions occurring simultaneously in one-pot, where the product of each reaction is the substrate for the next. The hallmark of tandem reactions is a considerable increase in molecular complexity resulting from a single synthetic step. As this represents a substantial gain in efficiency and step-economy, all tandem reaction methodology represents a more sustainable, “Greener,” approach to preparing more complex organic molecules from simple precursors. The aim of this study was to expand the two-step tandem reaction, aldehyde-alkyne-amine coupling, to include two to three additional intermolecular steps. The goal of green chemistry is for the means to justify the end, but for a proof a principle the end should also justify the means. We chose dipropargyl amines and isoindolines due to their well documented importance as synthetic precursors and biologically active compounds. We outline the development of methodology for the preparation of dipropargyl amines (Chapter 2) and isoindolines (Chapter 3) starting from simple amines, alkynes, and aldehydes in one-pot and a single synthetic operation.Les réactions tandem sont des réactions multiples qui se produisent de façon consécutive dans un seul milieu réactionnel. Le produit de chaque réaction est en fait un réactif pour la réaction suivante. Par le biais des réactions tandem, il est possible d'accéder à des molécules complexes en une seule étape synthétique. Comme elle représente un gain significatif en termes d'efficacité et d'économie synthétique, ce type de réaction représente une approche environnementalement durable pour la préparation de molécules complexes à partir de simples précurseurs.Le but de cette thèse consiste à augmenter la complexité de la réaction tandem entre les aldéhydes, les alcynes et les amines et d'y ajouter d'autres réactifs pour augmenter le nombre d'étapes synthétiques. Le but ultime de la chimie pour le développement durable est pour les moyens de justifier la fin. Par contre, comme preuve de principe, la fin doit aussi justifier les moyens. Nous avons choisi de synthétiser des amines dipropargyliques et des isoindolines en raison de leur importance bien documentée comme précurseurs synthétiques et comme composés biologiquement actifs. La méthodologie pour la préparation des amines dipropargyliques est développée dans le Chapitre 2 alors que la synthèse des isoindolines à partir d'aldéhydes, d'alcynes et d'amines simples (dans un seul milieu réactionnel et en une étape synthétique) est développée dans le Chapitre 3.
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Thu, Hung-yat, and 杜鴻溢. "Catalytic C-H bond functionalization reactions catalyzed by rhodium(III) porphyrin, palladium(II) and platinum(II) acetatecomplexes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B38798268.
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Guven, Sinem. "Construction Of Pyrrolo[1,2-a]pyrazine Structure By Metal Catalyzed Cyclization Of N-propargyl Substituted Pyrroles." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615582/index.pdf.
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Pyrrolo[1,2-a]pyrazine is one of the isomers of pyrolodiazine family. Pyrrolo[1,2-a]pyrazine possesses a bicyclic heteroaromatic structure that have 10 electrons. It has various biological importances in synthetic chemistrytherefore, many different approaches to generate this skeleton have been developed so far. In this study, our prior aim was to develop a new synthetic methodology for the formation of pyrrolo[1,2-a]pyrazine moiety. In the first part of this focus, the starting compound, methyl 2-(2-methoxy-2-oxoethyl)-1-(prop-2-yn-1-yl)-1H-pyrrole-3-carboxylate was successfully synthesized, then the conversion of the ester group at the lower arm to the amine group was carried out. Heteroatom cyclization catalyzed by CuI afforded the desired substituted pyrrolo[1,2-a]pyrazine structure. In the second part, it was aimed to synthesize new compounds with unusual structures which are not described in the literature
namely, as pyrrolo[1,2-a]pyrazine N-oxide. In this direction, first pyrrole was submitted to Vilsmeier-Haack reaction to attach a formyl group at C-2. Substitution reaction then effectively gave 1-(prop-2-yn-1-yl)-1H-pyrrole-2-carbaldehyde, which was a key molecule to synthesize the aldoxime. AuCl3 catalyzed cyclization of the corresponding oxime afforded pyrrolo[1,2-a]pyrazine N-oxide. In the next step, Sonogashira coupling reactions were carried out to obtain terminal alkynes (RC&equiv
CR'
) starting from 1-(prop-2-yn-1-yl)-1H-pyrrole-2-carbaldehyde. The aim of this part was to study the effect of aryl groups to the activated alkyl functional group by a metal catalyst. In this case, unexpected oxime-oxime transformation was observed, which is unprecedented in the literature
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Amenta, Arianna. "Palladium, ruthenium and iron in intramolecular transition metal-catalyzed carbene functionalization reactions of amino-tethered α-diazoesters." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/671148.
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Transition metal-catalyzed intramolecular C–H insertions of diazo compounds represent one of the most elegant and versatile methods in organic synthesis for the construction of carbocyclic and heterocyclic frameworks. In these reactions a C–C bond is formed with high atom economy, with N2 gas being the only subproduct.
In the last years, in the context of a research program aimed at developing efficient methodologies for the synthesis of nitrogen heterocycles, our research group has been studying the transition metal-catalyzed decomposition of amino-tethered α - diazo carbonyl compounds. Specifically, we have reported that palladium catalysts are able to promote the intramolecular carbene C–H insertions to produce pyrrolidines from α-diazoesters, and oxindoles as well as β-lactams from α -diazo- α - (methoxycarbonyl)acetamides.
As a continuation of these studies, in this Thesis we first explored the use of Pd, Rh(II) and Ru(II)-based catalysts for the intramolecular carbene C(sp3)–H insertion of γ - amino-α-diazoesters leading to pyrrolidines. Our comparative study allowed us to identify differences in the reactivities and selectivities between the different transition metals. The results obtained in these annulation reactions show that, although the chemoselectivity of the process is highly substrate-dependent, it can be controlled by adequate catalyst selection.
Taking this work as a reference, we then investigated the use of some structurally diverse Ru(II)-complexes to promote the C(sp3)–H insertion of γ-amino-α-diazoesters to form pyrrolidines. In this context, we have described the first examples of an unprecedented non-metathetic chemistry of Grubbs complexes, which were applied to achieve this target. Moreover, in our preliminary attempts to develop an enantioselective version of this carbene C(sp3)–H insertion reaction, we focused our attention on the use of different chiral Ru(II)-catalysts.
We also investigated the synthesis of tetrahydroquinolines by transition metal- catalyzed intramolecular aromatic CAr(sp2)-H functionalization of γ -anilino α-diazoesters. Both palladium(0)- and Grubbs catalysts were explored for this purpose.
Finally, we broadened our investigation on the transition metal-catalyzed decomposition of amino-tethered diazoesters by exploring the reactions of δ−amino and β-amino α-diazoesters. Some diverse palladium and ruthenium complexes as well as different iron salts were studied.Las reacciones de inserción intramolecular de diazocompuestos en enlaces C–H catalizadas por metales de transición se han convertido en una metodología extraordinariamente versátil para la construcción de sistemas carbocíclicos y heterocíclicos. En estas reacciones, la formación del enlace C–C tiene lugar con una economía atómica considerable ya que se genera N2 gas como único subproducto. Durante los últimos años, como parte de un ambicioso proyecto de investigación enfocado al desarrollo de metodologías más eficientes para la síntesis de heterociclos nitrogenados, en nuestro grupo de investigación se ha estudiado la inserción de carbenos metálicos derivados de compuestos α-diazocarbonilicos en enlaces C–H. En este contexto, se ha demostrado que los catalizadores de paladio pueden promover la inserción intramolecular de carbenos generados a partir de diferentes compuestos α- diazocarbonilicos. En concreto, se ha descrito su utilización en la síntesis de pirrolidinas a partir de α-diazoésteres, y de oxindoles y β-lactamas a partir de α-diazo-α- (metoxycarbonil)acetamidas. Como continuación de estos estudios y con el objetivo de desarrollar una metodología más eficiente para la síntesis de pirrolidinas, en la primera parte de la presente tesis doctoral nos propusimos explorar la viabilidad de diversos complejos de Pd, Rh(II) y Ru(II)como catalizadores en la reacción de inserción en enlaces C(sp3)–H a partir de γ - amino-α-diazoésteres. Este estudio comparativo ha permitido identificar las diferencias de reactividad y selectividad entre los distintos metales de transición. Los resultados obtenidos han puesto de manifiesto que la quimioselectividad de la reacción, aunque es altamente dependiente de la estructura del substrato, puede controlarse mediante una adecuada selección del catalizador. Seguidamente, decidimos explorar la utilización de otros complejos de Ru(II), escogidos en base a su considerable diversidad estructural, como catalizadores de la inserción en enlaces C(sp3)–H a partir de γ -amino-α-diazoésteres. En este contexto, hemos demostrado que los complejos de Grubbs también pueden emplearse para promover la inserción de carbenos en enlaces C(sp3)–H para preparar pirrolidinas. Este trabajo constituye el primer ejemplo de la utilización de este tipo de catalizadores en reacciones de inserción, una transformación química muy distinta de su aplicación clásica en las reacciones de metátesis. En este mismo contexto, hemos realizado también un estudio preliminar encaminado al desarrollo de una versión enantioselectiva de la reacción de inserción, utilizando distintos catalizadores de Ru(II) quirales. Por otro lado, hemos desarrollado un procedimiento para la síntesis de tetrahidroquinolinas mediante la inserción intramolecular de carbenos generados a partir de γ -anilino-α-diazoésteres en enlaces C(sp2)–H aromáticos. Para esta reacción se han explorado tanto los catalizadores de Pd(0) como los complejos de Grubbs. Finalmente, hemos ampliado nuestra investigación acerca de la utilización de distintos metales de transición para promover la descomposición de compuestos α- diazocarbonilicos con el estudio de la reacción a partir de δ-amino- y β-amino-α- diazoésteres. Para ello hemos explorado la utilización de distintos complejos de paladio y rutenio, así como de sales de hierro.
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González, Miera Greco. "Homogeneous and heterogeneous Cp*Ir(III) catalytic systems : Mechanistic studies of redox processes catalyzed by bifunctional iridium complexes, and synthesis of iridium-functionalized MOFs." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-143343.
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The purpose of this doctoral thesis is to investigate and develop catalytic processes mediated by iridium(III) complexes. By understanding the mechanisms, the weaknesses of the designed catalysts can be identified and be overcome in the following generation. The thesis is composed of two general sections dedicated to the synthesis and applications of homogeneous catalysts and to the preparation of heterogeneous catalysts based on metal-organic frameworks (MOFs). After a general introduction (Chapter 1), the first part of the thesis (Chapters 2-4, and Appendix 1) covers the use of several homogeneous bifunctional [Cp*Ir(III)] catalysts in a variety of chemical transformations, as well as mechanistic studies. Chapter 2 summarizes the studies on the N-alkylation of anilines with benzyl alcohols catalyzed by bifunctional Ir(III) complexes. Mechanistic investigations when the reactions were catalyzed by Ir(III) complexes with a hydroxy-functionalized N-heterocyclic carbene (NHC) ligand are discussed, followed by the design of a new generation of catalysts. The chapter finishes presenting the improved catalytic performance of these new complexes. A family of these NHC-iridium complexes was evaluated in the acceptorless dehydrogenation of alcohols, as shown in Chapter 3. The beneficial effect of a co-solvent was investigated too. Under these base-free conditions, a wide scope of alcohols was efficiently dehydrogenated in excellent yields. The unexpected higher activity of the hydroxy-containing bifunctional NHC-Ir(III) catalysts, in comparison to that of the amino-functionalized one, was investigated experimentally. In the fourth chapter, the catalytic process presented in Chapter 3 was further explored on 1,4- and 1,5-diols, which were transformed into their corresponding tetrahydrofurans and dihydropyrans, respectively. Mechanistic investigations are also discussed. In the second part of the thesis (Chapter 5), a Cp*Ir(III) complex was immobilized into a MOF. The heterogenization of the metal complex was achieved efficiently, reaching high ratios of functionalization. However, a change in the topology of the MOF was observed. In this chapter, the use of advanced characterization techniques such as X-ray absorption spectroscopy (XAS) and pair distribution function (PDF) analyses enabled to study a phase transformation in these materials.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Submitted.
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Börger, Carsten, Micha P. Krahl, Margit Gruner, Olga Kataeva, and Hans-Joachim Knölker. "First total synthesis of the biscarbazole alkaloid oxydimurrayafoline." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-139201.
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We report the first total synthesis of oxydimurrayafoline via nucleophilic substitution at the benzylic position at C-3 of the carbazole frameworkDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Börger, Carsten, Micha P. Krahl, Margit Gruner, Olga Kataeva, and Hans-Joachim Knölker. "First total synthesis of the biscarbazole alkaloid oxydimurrayafoline." Royal Society of Chemistry, 2012. https://tud.qucosa.de/id/qucosa%3A27812.
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We report the first total synthesis of oxydimurrayafoline via nucleophilic substitution at the benzylic position at C-3 of the carbazole framework.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Börger, Carsten, Olga Kataeva, and Hans-Joachim Knölker. "Novel approach to biscarbazole alkaloids via Ullmann coupling – synthesis of murrastifoline-A and bismurrayafoline-A." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-139195.
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Unprecedented Ullmann couplings of murrayafoline-A with either 6-bromo- or 4-bromocarbazole derivatives provide highly efficient synthetic routes to the biscarbazole alkaloids murrastifoline-A (6 steps, 66% overall yield) and bismurrayafoline-A (6 steps, 28% overall yield)Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Börger, Carsten, Olga Kataeva, and Hans-Joachim Knölker. "Novel approach to biscarbazole alkaloids via Ullmann coupling – synthesis of murrastifoline-A and bismurrayafoline-A." Royal Society of Chemistry, 2012. https://tud.qucosa.de/id/qucosa%3A27811.
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Unprecedented Ullmann couplings of murrayafoline-A with either 6-bromo- or 4-bromocarbazole derivatives provide highly efficient synthetic routes to the biscarbazole alkaloids murrastifoline-A (6 steps, 66% overall yield) and bismurrayafoline-A (6 steps, 28% overall yield).Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Hong, Xiang. "Nouveaux catalyseurs hétérogènes chiraux pour le dédoublement cinétique hydrolytique des époxydesTERMINAUX." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00770302.
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L'objectif de ce travail étaient le développement de catalyseurs hétérogènes efficaces pour promouvoir des réactions asymétriques, en utilisant la polymérisation oxydante ou la formation de polymères de coordination. De nouveaux complexes de salen Co(III) chiraux modifiés par des groupements aromatiques sur les position 5, 5' ont été préparés et testés dans le dédoublement cinétique hydrolytique (HKR) des époxydes terminaux en conditions homogènes. Ces complexes ont été ensuite engagés dans les polymérisations oxydantes électrochimiques ou chimiques, et une stratégie de copolymérisation a fourni des polymères chiraux très efficaces et stables pour catalyser l'HKR dans des conditions hétérogènes. Nous avons alors cherché à préparer un catalyseur capable de catalyser deux réactions en cascade, en copolymérisant deux complexes de salen portant des métaux différents. Pendant ces études, les complexes de salen Mn ont révélé leur participation active à la réaction d'HKR des époxydes terminaux catalysée par les complexes de salen Co(III), en augmentant l'excès énantiomérique du produit de façon significative. Les études mécanistiques ont été ensuite réalisées pour tenter de comprendre le rôle des complexes de Mn dans cette réaction. De plus, des complexes de salen fonctionnalisés par le groupement pyridine ou le groupement de type acide isophtalique ont été synthétisés. Ces complexes ont été utilisés pour préparer de nouveaux réseaux de polymères de coordination poreux chiraux (collaboration avec l'équipe LCI de l'ICMMO et l'Institut Lavoisier à Versailles), qui sont ensuite testés comme catalyseurs hétérogènes dans la réaction de Henry asymétrique et la réaction d'HKR.
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Kisan, Kawade Rahul, and 羅湖. "Transition Metal Catalyzed Transformations for Synthesis of Complex Organic Molecules." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/90562548330619458153.
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博士國立清華大學
化學系
103
This dissertation describes development of new synthetic organic transformations by using gold or copper metal salts. The use of these metals enables mild, selective and efficient oxidative transformations of readily available substrates to wide range of synthetically useful nitrogen, oxygen and sulfur containing complex organic molecules. For better understanding the thesis is divided into four chapters. The first chapter deals with the Gold-catalyzed oxidative cyclization of 4-allenyl-1-ynes with 8-methylquinoline oxide. The catalytic reaction produces diverse products bearing N and O heterocycles depending on the allenyl substituents. This reaction comprises initial formation of α-oxo gold carbenes that are attacked by allene to form allyl cation intermediates which either undergoes elimination or nucleophilic addition to afford diverse cyclic products. The results obtained here manifested that the intermediate α-oxo-gold carbenes has carbocation character. The second chapter deals with the Cu-catalyzed aerobic oxidative Mannich reactions with a skeletal rearrangement of N-hydroxyl propargylamines. These aerobic oxidations of readily available 3-N-hydroxyaminopro-1-ynes with water, alcohols, or thiols afford diverse 3-substituted 3-amino-2-en-1-ones. We developed cascade or sequential reactions of allylic alcohols, alkynols, and allenols, to involve a Claisen rearrangement or gold catalyzed cyclizations, providing new products with molecular complexity. The third chapter describes the Cu-catalyzed oxidative Povarov reactions between N,N-dialkylanilines and saturated oxa- or thiacycles with tert-butyl hydroperoxide (TBHP) to form tetrahydroisoquinoline derivatives. The use of cheap alkane based substances as four- and two-atom building units is of mechanistic and practical interest, this work also represents the first achievement of catalytic [4+2]-cycloaddition using neither [4p]- nor [2p]-motifs initially. The fourth chapter presents gold-catalyzed syntheses of 2,3-disubstituted indole derivatives from N-hydroxyanilines and allenes; with benzaldehyde as an additive to generate nitrones in situ. This synthetic method is compatible with reasonable range of allenes and N-hydroxyanilines, thus further highlighting its synthetic utility.
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Mokar, Bhanudas Dattatray, and 帕努達. "Transition Metal Catalyzed New Transformations for the Synthesis of Highly Functionalized Organic Frameworks." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/kr9an3.
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博士國立清華大學
化學系
105
This dissertation describes development of new synthetic organic transformations by using gold, platinum or copper metal salts. The use of these metals enables mild, selective and efficient oxidative transformations of readily available substrates to wide range of synthetically useful nitrogen, oxygen and sulfur containing complex organic molecules. For better understanding the thesis is divided into four chapters. The first chapter deals with the regiocontrolled hydrations of 1-aryl-3-en-1-ynes with suitable Au(I) and Pt(II), giving 3-en-1-ones and 2-en-1-ones selectively. Herein, we also develop one-pot synthesis of allylic and homoallylic alcohols from these 3-en-1-ynes, through in situ reductions of two ketone products. Our experimental data indicates that the sizes of catalysts play an important role. The second chapter deals with the gold-catalyzed reactions of 1,6-enynes with N-hydroxyanilines to generate kinetically unstable trisubstituted nitrones. Such transient species are efficiently trapped with tethered alkenes to achieve stereospecific cycloadditions. Notably, these annulations involve an atypical N-attack of hydoxyamines at gold--alkynes. Our data reveal that most propargyl ethers show the O-attack selectivity, whereas allyl propargyl ether proceeds exclusively through the N-attack selectivity. This alkene-directed chemoselectivity is postulated to accelerate the protodeauration by an alkene coordination to gold. The third chapter describes an atypical pathway in the gold-catalyzed intermolecular oxidations of ketonylalkynes with N-hydroxyanilines; this oxidation initially involves formation of an oxonium species that is subsequently attacked by N-hydroxyaniline, further leading to oxoamination products. This path is strongly supported by 18O-labeling experiments. In one control experiment, our resulting 2-aminoindenones were alternatively produced from the same ketonylalkynes, 8-methylquiniline oxide and aniline, but the efficiency was low. The fourth chapter presents copper-catalyzed oxidative coupling reactions of tetrahydroisoquinolines with cyclic ethers. These reactions are initiated by SET from a tertiary amine to form an iminium ion which is coupled with alkyl radical to form C1-etherized tetrahydroisoquinoline. This method could open the possibility to design coupling reactions with substrates of low nucleophilicity but reactivity toward carbon radicals.
43
傑德. "Metal Catalyzed Organic Transformations for Synthesis of Highly Functionalized Heterocycles." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/75921378176849813571.
Full text
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GHORPADE, SATISH MADHAV, and 沙提斯. "Transition Metals Catalyzed Organic Transformations, Oxidative Cycloadditions, Cyclizations and Dimeric Cyclizations on Diverse Enynes." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/10262012132558338430.
Full textAbstract:
博士國立清華大學
化學系
103
ABSTRACT This dissertation describes development of new synthetic organic transformations by using gold and copper salts. The use of these soft alkynophilic metals enables mild, diastereoselective and efficient transformations of a variety of readily available substrates to wide range of synthetically useful and biologically important N, O containing heterocyclic and carbocyclic products. For better understanding the thesis is divided into four chapters. The first chapter deals with the Gold-catalyzed oxidative cyclizations of cis-3-En-1-ynes to form cyclopentenone derivatives. The title reaction for synthesizing cyclopentenone derivatives utilizes a gold complex and 8-methylquinoline oxide as the catalyst system. The value of such reactions is reflected by their applicability to a broad range of benzene- and nonbenzene-derived substrates, thus giving various indanone and cyclopentenone derivatives, respectively. Such products are not attainable using diazocarbonyl reagents, as the gold carbenoids tend to react with C-H bonds. The second chapter deals with the gold-catalyzed oxidative cyclizations of 1,4-enynes were used to study the γ-effect on the Wagner–Meerwein rearrangement. Both experimental and theoretical work disclose that a gold substituent in the γ-position can direct a stereospecific 1,2 shift of the anti-β-substituent regardless of its intrinsic properties. The third chapter describes gold-catalyzed reactions of 3,5- and 3,6-dienynes with 8-alkyl- quinoline oxides results in an oxidative cycloaddition with high stereospecificity, this process involves a catalytic activation of a quinoline framework. The reaction mechanism involves the intermediacy of α-carbonyl pyridinium ylides (I) in a concerted [3+2]-cycloaddition with a tethered alkene. The fourth chapter presents the work aim at one-step construction of complex and important molecular frameworks via Cu-catalyzed oxidations of cheap tertiary amines. Cu-catalyzed aerobic oxidations of N-hydroxyaminopropenes to form C2-symmetric N- and O-functionalized cyclohexanes.
45
薩加. "The Transition Metal Catalyzed New Organic Transformation of Enynes for Synthesis of Highly Functionalized Carbocyclic & Heterocyclic Systems." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/73839021793932674798.
Full textAbstract:
博士國立清華大學
化學系
102
This dissertation describes the development of new synthetic organic transformation by using gold and zinc salts. Transition metal-catalyzed organic transformations such as Oxidative Cyclization, Di-stereo and Enatioselective [2+2+3] cycloaddition, 1,4-Dioxo Functionalizations, 1,4-Metathesis Reactions of appropriately functionalized organic molecules are described in this dissertation. For sake of convenience and better understanding, the thesis is divided into four chapters. The first chapter deals with the Gold-Catalyzed Oxidative Cyclization of 1,5-Enynes Using External Oxidants (8-Methylquinoline N-Oxide) to deliver indanone frameworks. Such indanone core is one of the most commonly encountering skeletons in nature. The core structure of the resulting products are construct through a formal reactions proceed through prior oxidations of alkyne to form α-carbonyl intermediates, followed by intramolecular carbocyclizations. The second chapter deals with the Gold-catalyzed diastereo- and enantioselective [2+2+3]-cycloaddition reactions of 1,6-enynes with nitrones. The utility of such reactions is manifested by a wide substrate scopes of 1,6-enynes and nitrones. This Gold-catalyzed diastereo- and enantioselective [2+2+3]-cycloaddition reactions of 1,6-enynes with nitrones deliver 1,2-Oxazepane core which has wide aplication in structural and biological importance. The third chapter describes new 1,4-oxo functionalizations of 3-en-1-ynes based on a hydrative oxidation approach. The one-pot dioxo reactions were applicable to various 3-en-1-ynes including unactivated 3-aryl-3-en-1-ynes, giving Z- or E-configured 2-en-1,4-dicarbonyl compounds selectively. In this chapter, mechanistic analysis supported an initial formation of furan intermediates, generated from carbonyl-assisted alkenyl fluorinations of hydration intermediates. This work reports the first success for 1,4-oxo functionations of readily available 3-en-1-ynes to offer highly functionalized alkenes. The fourth chapter presents Catalyst-dependent metathesis reactions between 3-en-1-ynamides and nitrosoarenes are described. Particularly notable are the unprecedented 1,4-metathesis reactions catalyzed by Ag(I) or Zn(II) to give 3-imidoylalkynes and benzaldehyde. With 3-en-1-ynamides bearing a cycloalkenyl group, 1,4-oxoimination products were produced efficiently without molecular fragmentation. We have developed metathesis/alkynation cascades for terminal 3-imidoylalkynes and benzaldehyde species generated in situ, to manifest 1,4-hydroxyimination reactions of 3-en-1-ynes.
46
Lamani, Manjunath. "Design And Development Of Synthetic Methods Using Metal-Mediated And Metal Free Redox Reactions : Novel C-H Activations, Reductions And Oxidative Transformations." Thesis, 2012. https://etd.iisc.ac.in/handle/2005/2501.
Full textAbstract:
The thesis entitled “Design and Development of Synthetic Methods using Metal-mediated and Metal-free Redox Reactions: Novel C-H Activations, Reductions and Oxidative Transformations” is presented in 4 chapters
Chapter 1; Iodine catalyzed amination of benzoxazoles: efficient metal free route to 2-aminobenzoxazoles under mild conditions.
The Chapter 1 of this thesis describes iodine catalyzed C-H activation of benzoxazole with primary and secondary amines to form oxidative aminated products. Selective C-H oxidation is a frontline area of modern chemical research as it offers the opportunities to new avenues and more direct synthetic strategies for the synthesis of complex organic molecules.1 In this context, transition metals such as palladium copper, nickel etc, are used extensively for the functional group directed C-H activation, and thus provides new, rapid, low-cost, and environmentally benign protocols for the construction of new chemical bonds.2 During the past two decades iodine and hypervalent iodine have been focus of great attention as they provide mild, chemoselective and environmentally benign strategies in contrast to toxic metal oxidants.3 In this chapter, a facile metal-free route of oxidative amination of benzoxazole with secondary or primary amines in the presence of catalytic amount of iodine (5 mol%) in aq tert-butyl hydroperoxide (1equiv) and AcOH (1.1 equiv) at ambient temperature, under the solvent-free reaction condition is presented. This user-friendly method to form C-N bonds produces tert-butanol and water as the by-products, which are environmentally benign. A wide range of benzoxazole derivatives containing electron-donating and electron-withdrawing groups were coupled with both primary and secondary amines (Scheme 1).
Application of this methodology is demonstrated by synthesizing therapeutically active benzoxazoles by reacting 5-chloro-7-methylbenzoxazole with N-methylpiperazine and N-ethylhomopiperazine to obtain corresponding N-aminatedbenzaxozoles, which exhibit antidiarrhetic activity (Scheme 2).4
Scheme 2
Chapter 2: NIS catalyzed reactions. amidation of acetophenones and oxidative amination of propiophenones
Chapter 2 is divided in to 2 parts. Part 1 describes the synthesis of α-ketoamides by using acetophenone and secondary amine in the presence of N-iodosuccinamide and TBHP in acetonitrile at room temperature, whereas Part 2 reveals the synthesis of 2-aminoketones by reacting aryl alkyl ketones and suitable secondary amine in the presence of NIS and TBHP.
Part 1: Oxidative amidation, synthesis of α-ketoamide:
Alpha α-ketoamides are important intermediates in organic synthesis that are present in a variety of natural products, and pharmaceutically active compounds. Herein, a mild and efficient conversion of acetophenones to α-ketoamide is documented by using aq.TBHP and N-iodosuccinamide (NIS) as a catalyst, at ambient temperature. This amidation reaction was found to be versatile as several aetophenone derivitives containing electron-withdrawing and electron-donating substituents underwent a facile amidation. It was also found that acetyl derivatives of heterocylic compounds could be easily converted to their corresponding ketoamides (few examples are shown in Scheme 3).5 Scheme3
Part 2 of Chapter 2 narrates a novel amination of propiophenone and its derivatives catalysed by NIS in the presence of TBHP to furnish their corresponding 2-aminoketone derivatives (Scheme 4). These derivatives are ubiquitous scaffolds that are present in a wide variety of therapeutic agents. Some of these compounds are used in the treatment of depression, smoking cessation, as monoamine uptake inhibitors, rugs for cancer. They are photoinitiators, precursors to β-aminoalcohols, such as pseudoephedrine analogues. 2-Aminoacetophenone analogues are also important intermediates for the formation of several heterocyclic compounds and are active moieties in several important drugs such as ifenprodil,
Scheme 4.
Chapter 3: Efficient oxidation of primary azides to nitriles
This Chapter is divided in to 2 parts, which presents the oxidation of primary azides to their corresponding nitriles.
Part 1: An Efficient oxidation of primary azides catalyzed by copper iodide: a convenient method for the synthesis of nitriles
In Part 1, an efficient oxidation of primary azides catalyzed by copper iodide to their corresponding nitriles is reported. Herein, the oxidation of primary azide to nitrile is performed using catalytic amount of copper iodide, and aq TBHP in water at 100 ° C. This methodology is compatible with a wide range of primary benzylic azides that contain electron-donating and electron-withdrawing functional groups. The oxidation was found to be selective and a number of oxidizable functional groups were well-tolerated during the reaction conditions (few examples are shown in Scheme 5).6
Scheme 6
Furthermore, oxidation of secondary azides furnished the corresponding ketones in excellent yields (Scheme 6).6
In the Part 2 of Chapter 3, a non-metal catalysed oxidation of primary azides to nitriles at ambient temperature is reported. This part reveals the oxidation of primary azides to nitriles by employing catalytic amounts of KI (25 mol%), DABCO (25 mol%) and aq. TBHP (3 equiv., 70% solution in water). This reaction provides a good selectivity, as double and triple bonds were not oxidized under the reaction conditions. Additionally, chemoselective oxidation of benzylicazides against aliphatic azides increases the potential application of the present method (Scheme 7).7
Chapter 4: Chemoeselective reduction of olefins
Part 1: Iron chloride catalysed aerobic reduction of olefins using aqueous hydrazine at ambient temperature
Chapter 4 describes the reduction olefins and acetylenes, which is presented in two Parts. Part 1 documents utility of hydrazine (1.5 equiv) for the chemoselective reduction of nonpolarised carbon-carbon bond using iron catalysts. In this part, a chemoselective reduction of alkenes and alkynes in the presence of a variety of reducible functional groups is demonstrated (Scheme 8). The highlight of the present method is that the reduction proceeds well at room temperature and requires only 1.5 equiv of hydrazine hydrate. The olefin reduction by hydrazine depends upon the controlled release of diimide during the reduction. Generally, metal catalyzed reduction of olefins employ a large excess of hydrazine (10-20 equiv), which might be attributed to uncontrolled release of diimide during the reduction.8
Scheme 8
Part 2: Guanidine catalyzed aerobic reduction: a selective aerobic hydrogenation of olefins using aqueous hydrazine
In Chapter 4, part 2, organocatalytic generation of diimide and its utility to reduce the double bonds is presented. Generation of diimide in situ by using organo catalysts and its use for the reduction of carbon-carbon double bond is one of the interesting topics in organic chemistry. It has been shown in this part of the thesis that the reduction of olefin at room temperature can be efficiently performed by using 10 mol% of guanidine nitrate, 2 equiv of aqueous hydrazine in oxygen atmosphere. This method tolerates a variety of reducible functional groups such as nitro, azido, and bromo and protective groups such as methyl ethers, benzyl ethers, and Cbz groups. It is also shown that terminal olefin can be selectively reduced in the presence of internal olefin (Scheme 9). Unlike other methods that employ diimide strategy, the present method is shown to be efficient in reducing substrates those contain internal double bonds such as cinnamyl alcohol and its derivatives
47
Lamani, Manjunath. "Design And Development Of Synthetic Methods Using Metal-Mediated And Metal Free Redox Reactions : Novel C-H Activations, Reductions And Oxidative Transformations." Thesis, 2012. http://hdl.handle.net/2005/2501.
Full textAbstract:
The thesis entitled “Design and Development of Synthetic Methods using Metal-mediated and Metal-free Redox Reactions: Novel C-H Activations, Reductions and Oxidative Transformations” is presented in 4 chapters
Chapter 1; Iodine catalyzed amination of benzoxazoles: efficient metal free route to 2-aminobenzoxazoles under mild conditions.
The Chapter 1 of this thesis describes iodine catalyzed C-H activation of benzoxazole with primary and secondary amines to form oxidative aminated products. Selective C-H oxidation is a frontline area of modern chemical research as it offers the opportunities to new avenues and more direct synthetic strategies for the synthesis of complex organic molecules.1 In this context, transition metals such as palladium copper, nickel etc, are used extensively for the functional group directed C-H activation, and thus provides new, rapid, low-cost, and environmentally benign protocols for the construction of new chemical bonds.2 During the past two decades iodine and hypervalent iodine have been focus of great attention as they provide mild, chemoselective and environmentally benign strategies in contrast to toxic metal oxidants.3 In this chapter, a facile metal-free route of oxidative amination of benzoxazole with secondary or primary amines in the presence of catalytic amount of iodine (5 mol%) in aq tert-butyl hydroperoxide (1equiv) and AcOH (1.1 equiv) at ambient temperature, under the solvent-free reaction condition is presented. This user-friendly method to form C-N bonds produces tert-butanol and water as the by-products, which are environmentally benign. A wide range of benzoxazole derivatives containing electron-donating and electron-withdrawing groups were coupled with both primary and secondary amines (Scheme 1).
Application of this methodology is demonstrated by synthesizing therapeutically active benzoxazoles by reacting 5-chloro-7-methylbenzoxazole with N-methylpiperazine and N-ethylhomopiperazine to obtain corresponding N-aminatedbenzaxozoles, which exhibit antidiarrhetic activity (Scheme 2).4
Scheme 2
Chapter 2: NIS catalyzed reactions. amidation of acetophenones and oxidative amination of propiophenones
Chapter 2 is divided in to 2 parts. Part 1 describes the synthesis of α-ketoamides by using acetophenone and secondary amine in the presence of N-iodosuccinamide and TBHP in acetonitrile at room temperature, whereas Part 2 reveals the synthesis of 2-aminoketones by reacting aryl alkyl ketones and suitable secondary amine in the presence of NIS and TBHP.
Part 1: Oxidative amidation, synthesis of α-ketoamide:
Alpha α-ketoamides are important intermediates in organic synthesis that are present in a variety of natural products, and pharmaceutically active compounds. Herein, a mild and efficient conversion of acetophenones to α-ketoamide is documented by using aq.TBHP and N-iodosuccinamide (NIS) as a catalyst, at ambient temperature. This amidation reaction was found to be versatile as several aetophenone derivitives containing electron-withdrawing and electron-donating substituents underwent a facile amidation. It was also found that acetyl derivatives of heterocylic compounds could be easily converted to their corresponding ketoamides (few examples are shown in Scheme 3).5 Scheme3
Part 2 of Chapter 2 narrates a novel amination of propiophenone and its derivatives catalysed by NIS in the presence of TBHP to furnish their corresponding 2-aminoketone derivatives (Scheme 4). These derivatives are ubiquitous scaffolds that are present in a wide variety of therapeutic agents. Some of these compounds are used in the treatment of depression, smoking cessation, as monoamine uptake inhibitors, rugs for cancer. They are photoinitiators, precursors to β-aminoalcohols, such as pseudoephedrine analogues. 2-Aminoacetophenone analogues are also important intermediates for the formation of several heterocyclic compounds and are active moieties in several important drugs such as ifenprodil,
Scheme 4.
Chapter 3: Efficient oxidation of primary azides to nitriles
This Chapter is divided in to 2 parts, which presents the oxidation of primary azides to their corresponding nitriles.
Part 1: An Efficient oxidation of primary azides catalyzed by copper iodide: a convenient method for the synthesis of nitriles
In Part 1, an efficient oxidation of primary azides catalyzed by copper iodide to their corresponding nitriles is reported. Herein, the oxidation of primary azide to nitrile is performed using catalytic amount of copper iodide, and aq TBHP in water at 100 ° C. This methodology is compatible with a wide range of primary benzylic azides that contain electron-donating and electron-withdrawing functional groups. The oxidation was found to be selective and a number of oxidizable functional groups were well-tolerated during the reaction conditions (few examples are shown in Scheme 5).6
Scheme 6
Furthermore, oxidation of secondary azides furnished the corresponding ketones in excellent yields (Scheme 6).6
In the Part 2 of Chapter 3, a non-metal catalysed oxidation of primary azides to nitriles at ambient temperature is reported. This part reveals the oxidation of primary azides to nitriles by employing catalytic amounts of KI (25 mol%), DABCO (25 mol%) and aq. TBHP (3 equiv., 70% solution in water). This reaction provides a good selectivity, as double and triple bonds were not oxidized under the reaction conditions. Additionally, chemoselective oxidation of benzylicazides against aliphatic azides increases the potential application of the present method (Scheme 7).7
Chapter 4: Chemoeselective reduction of olefins
Part 1: Iron chloride catalysed aerobic reduction of olefins using aqueous hydrazine at ambient temperature
Chapter 4 describes the reduction olefins and acetylenes, which is presented in two Parts. Part 1 documents utility of hydrazine (1.5 equiv) for the chemoselective reduction of nonpolarised carbon-carbon bond using iron catalysts. In this part, a chemoselective reduction of alkenes and alkynes in the presence of a variety of reducible functional groups is demonstrated (Scheme 8). The highlight of the present method is that the reduction proceeds well at room temperature and requires only 1.5 equiv of hydrazine hydrate. The olefin reduction by hydrazine depends upon the controlled release of diimide during the reduction. Generally, metal catalyzed reduction of olefins employ a large excess of hydrazine (10-20 equiv), which might be attributed to uncontrolled release of diimide during the reduction.8
Scheme 8
Part 2: Guanidine catalyzed aerobic reduction: a selective aerobic hydrogenation of olefins using aqueous hydrazine
In Chapter 4, part 2, organocatalytic generation of diimide and its utility to reduce the double bonds is presented. Generation of diimide in situ by using organo catalysts and its use for the reduction of carbon-carbon double bond is one of the interesting topics in organic chemistry. It has been shown in this part of the thesis that the reduction of olefin at room temperature can be efficiently performed by using 10 mol% of guanidine nitrate, 2 equiv of aqueous hydrazine in oxygen atmosphere. This method tolerates a variety of reducible functional groups such as nitro, azido, and bromo and protective groups such as methyl ethers, benzyl ethers, and Cbz groups. It is also shown that terminal olefin can be selectively reduced in the presence of internal olefin (Scheme 9). Unlike other methods that employ diimide strategy, the present method is shown to be efficient in reducing substrates those contain internal double bonds such as cinnamyl alcohol and its derivatives
48
Shaibu, Balagopal Shainamma, and 雪布. "PtII and RuII Catalyzed Regio-Controlled Synthesis of Ethylene-Bridged para-Phenylene Oligomers, Their Photophysical and Redox properties & Gold Catalyzed / Metal free Organic Transformations." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/01092102341825586951.
Full textAbstract:
博士國立清華大學
化學系
100
本篇論文可分為四個章節，第一章節為合成一系列線形多苯環化合物且於分子之頭尾兩端接上二苯胺分子，並進一步測量以及探討其特殊的光物理以及電化學性質。第二以及第三章節主要利用金金屬錯合物催化 ynamides 分子進行[2+2+2] 環化加成反應以及利用碳烯分子進行交叉耦合反應合成一系列二烯類化合物。最後第四章節利用苯炔化合物、氧化胺以及炔分子進行多化合物組成反應合成一系列苯基吡啶化合物。 第一章節我們利用了不同的金屬錯合物催化具有高度位向選擇性之環化反應，將線型對苯化合物以乙烯分子橋接起來，並於兩端引入了二苯胺分子合成了一系列不同長度的線形多苯環分子。經由測量其HOMO、LUMO、UV吸收光譜、 螢光放射光譜 以及量子產率，實驗中發現此系列分子具有特殊的光物理以及電化學性質。 第二章節中我們開發了新型的金金屬錯合物催化芳酰胺分子以及烯醚化合物進行[2+2+2] 環化加成反應，值得注意的是此類新型反應並沒有觀察到任何分子內反應發生，可以利用於合成一系列的環己烷化合物。 第三章節我們發展了利用炔酯類分子進行重排反應以及重氮烷基碳烯產生乙烯基碳烯再經由金金屬錯合物催化交叉耦合反應。 最後一個章節我們利用了苯炔化合物、氧化胺以及炔分子進行多化合物組成反應合成一系列苯基吡啶化合物。
49
van, der Donk Wilfred A. "Transition metal-catalyzed hydroboration." Thesis, 1994. http://hdl.handle.net/1911/16784.
Full textAbstract:
Model studies on rhodium catalyzed hydroborations of sterically unbiased alkenes with catecholborane provided evidence for the role of d$\pi$-p$\pi$ bonding in these transformations. Catalyzed hydroborations of 5-substituted-2-methylene adamantanes occurred predominantly from the face opposite the most electron withdrawing group, while uncatalyzed hydroborations gave the reversed selectivities.
Deuterium labeling studies on rhodium catalyzed hydroborations of allylic silyl ethers revealed some new mechanistic features. Vinylboronate esters were produced in these transformations in addition to the expected alkylboronate esters. The formation of such dehydrogenative borylation products can be explained by alkene insertion into the rhodium-boron bond of a metal complex produced from oxidative addition of catecholborane to the catalyst. Oxidation of the catalyst can have a pronounced effect on the product distributions. Catalyzed hydroboration of phenylethene produced 1-phenylethanol with freshly prepared Wilkinson's catalyst, but 2-phenylethanol was the predominant product if the catalyst had been in contact with oxygen.
Enantioselective hydroborations of prochiral alkenes in the presence of chiral phosphine ligands produced optically active alcohol products. The best results were obtained with DIOP or BDPP ligands. Asymmetric amplification was not observed in these reactions.
Bis(cyclopentadienyl) (tetrahydroborato(1-)) titanium promotes the addition of borohydride to alkenes. In the reaction of phenylethene the predominant products were tetraalkylborates. 1-Decene and $\beta$-pinene gave organoboron products that are involved in a dynamic equilibrium with borohydride. A mechanism is proposed which explains the observed experimental characteristics of this reaction.
(o-Aminophenyl)diphenylphosphine was prepared from aniline in two steps. Optically pure (S) N-(tert-butoxycarbonyl)-2-amino-3-diphenylphosphinoboranepropyl (p-nitrophenyl)carbonate was prepared from scL-serine.
50
Lawton, Michelle Claire. "Metal triflate catalysed organic transformations." Thesis, 2010. http://hdl.handle.net/10210/3456.
Full textAbstract:
Ph.D.The research described in this thesis was directed at advancing the application of metal triflates, Al(OTf)3 in particular, in organic synthesis, on the one hand and to contribute to the understanding of the underlying basis for their catalytic activity. The study was undertaken against the background and on the bases of a detailed literature study of metal triflates, their chemical and catalytic properties and applications thereof. Amongst others, it deals with the possible role of metal-bound water that give rise to Brønsted type acidity and that this induced Brønsted acidity may be responsible for the catalytic activity that is observed. The study was prompted by the realisation that Al(OTf)3 was largely neglected as a potential reusable catalyst. This is in marked contrast to the attention paid to other metal triflates, the rare earth metals in particular. Earlier work in this laboratory has shown that Al(OTf)3 is stable in water from which it can be recovered easily for reuse. In addition it showed promise as a Lewis acid catalyst and is relatively soluble in several organic solvents. New applications for the use of Al(OTf)3 have now been demonstrated. These include the efficient formation of acetals from aldehydes and ketones. The conversions can be carried out in an alcohol/orthoester mixture or preferably in neat orthoester. Other metal triflates, notably Sc(OTf)3 and In(OTf)3, are useful alternative catalysts. Al(OTf)3 can be easily recycled without loss of activity. This methodology also can be applied to aldehydes and ketones containing TBDMS groups without effecting deprotection of the ethers. In view of the sensitivity of the TBDMS groups to hydrolysis in the presence of triflic acid the results suggest little hydrolysis (or alcoholysis) of the metal triflates in the protic solvents used, which would generate trifluoromethanesulfonic acid as a consequence of such metal based hydrolysis. Al(OTf)3 was also found to be a good catalyst for the formation of THP ethers. It proved to be excellent for Friedel Crafts reactions using alkynes as substrates. Al(OTf)3 together with other triflates offers a mild alternative to the more traditional water sensitive Lewis acids, e.g. BF3, AlCl3 and TiCl4, which are difficult to recover and require the use of extremely dry solvents.