Dissertations / Theses on the topic 'Heteroatom Bond'
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1
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.
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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.
2
van, Rooy Sara Emily. "Reactivity of rhodium-heteroatom bonds: from catalytic bond activation to new strategies for olefin functionalization." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/444.
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Rhodium complexes bearing multidentate nitrogen donor ligands were investigated for their ability to promote alkyne and olefin functionalization reactions. This thesis work is comprised of two projects in which rhodium-heteroatom reactivity is investigated: P-H bond activation reactions and olefin functionalizations via rhodaoxetane intermediates.
[Tp*Rh(PPh3)2] [Tp* = hydrotris(3,5-dimethylpyrazolyl)borate] and
[Tp*Rh(cod)]2 (cod = cyclooctadiene) were evaluated for their activity in alkyne hydrophosphinylation in comparison to known catalysts for this reaction. [Tp*Rh(PPh3)2]and [Tp*Rh(cod)]2 were both shown to effect hydrophosphinylation of 1-octyne with diphenylphosphine oxide with high regioselectivity but moderate yields in comparison with Wilkinson's catalyst [C1Rh(PPh3)3]. [Tp*Rh(PPh3)2] was further shown to effect hydrophosphinylation of a range of aromatic and aliphatic alkynes with diphenylphosphine oxide, in each case exclusively providing the E-linear vinylphosphineoxide product. 1H and 31P NMR spectroscopy provided evidence that alkyne hydrophosphinylation in the presence of pyrazolylborate rhodium complexes follows an analogous mechanism to that proposed for this reaction catalyzed by [C1Rh(PPh3)3] or[C1Rh(cod)]2.
The 2-rhodaoxetane [(TPA)Rhmec2_,-4u, 0-2-oxyethypr BPh4- (TPA = tris[(2-pyridal)methyl]amine) was investigated for its potential as an intermediate in proposed functionalization reactions of olefins. RTPA)Rh111(K2-C,0-2-oxyethyl)]+ BPh4- was prepared by two published methods with limited success. A third method involved the use of nitrous oxide to oxygenate [(12-ethene)(K4-TPA)Rh1]+ to RTPA)Rh1110(-2-C,0-2-oxyethyDr. Only a trace amount of [(TPA)Rhmoc2 -C,0-2-oxyethypr was observed in the 1I-1 NMR spectrum of this reaction mixture. Initial test reactions of [(TPA)Rhilioc2_C,0-2-oxyethypr combined with substrates (aniline, toluenesulfonamide, phenylboronic acid, or benzaldehyde) were inconclusive since the results were obscured by the impurity of the samples.
3
Niljianskul, Nootaree. "New Pd and Cu-based catalysts for carbon-heteroatom bond formation." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98784.
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Thesis: Ph. D. in Organic Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references.
The research presented in this dissertation is aimed at the development of novel methodologies for carbon-heteroatom cross-coupling reactions catalyzed by late-transition metals. Both palladium and copper are central to the field of transition metal-catalysis and are integral to the catalyst systems developed as part of our continual advancement in cross-coupling reactions. The first part of this thesis focuses on the use of palladium catalysts to form carbon-sulfur bonds directed towards aryl sulfonamide synthesis. The second part of the thesis describes the recent development in the copper(!) hydride mediated formation of carbon-nitrogen bonds via hydroamination of olefins. Part I. Chapter 1. Palladium-Catalyzed Chlorosulfonylation of Arylboronic Acids Using a biaryl phosphine ligand platform, the first palladium-catalyzed cross-coupling reaction of phenyl chlorosulfate with arylboronic acids was achieved. In this context, the arylsulfonyl chloride products serve as useful precursors to a variety of sulfonyl functional groups, such as aryl sulfonamides, aryl sulfones, and arenesulfonate esters. In particular, this method allows for the preparation of a number of arylsulfonyl chlorides that are not accessible via electrophilic aromatic substitution pathways and under mild reaction conditions. Additionally, this methodology points to an unprecedented selectivity for the phenylchlorosulfate electrophiles used in the cross-coupling reactions. Part II. Chapter 2. Enantio- and Regioselective Copper-Catalyzed Hydroamination of Styrenes and the Extension of the Methodology towards Anti-Markovnikov Hydroamination of Terminal Aliphatic Alkenes The development of a copper-mediated strategy towards the hydroamination of styrene derivatives is reported. In this system, the reaction proceeds regioselectively and enantioselectively to generate [alpha]-branched amines. The system can transform a wide variety of substituted styrenes, including trans-, cis-, and [beta]-disubstituted styrenes. In addition, our extension to copper-catalyzed hydroamination reactions of unactivated aliphatic olefins is reported. Using terminal aliphatic alkenes, the copper-catalyzed hydroamination reactions proceed with anti-Markovnikov regioselectivity. Preliminary results point to the application of this methodology towards [beta]-chiral amine synthesis via the hydroamination of I, 1-disubstituted alkenes. Chapter 3. [alpha]-Aminosilane Synthesis via Copper-Catalyzed Hydroamination of Vinylsilanes The copper-catalyzed hydroamination of vinylsilanes is described. This regioselective reaction generates a-chiral aminosilanes in high yields and enantioselectivities. The method is compatible with differentially substituted vinylsilanes and allows access to many valuable chiral organosilicon compounds. Chapter 4. Synthesis of [gamma]-Chiral Amines via Copper-Catalyzed Hydroamination of 3,3- Disubstituted Allylic Alcohols and 3,3-Disubstituted Allylic Benzoates An investigation into the copper-catalyzed hydroamination of allylic alcohols and allylic benzoates is reported. The reaction proceeds via a [beta]-alkoxy elimination, setting a stereogenic center at the 3-postion to generate [gamma]-chiral amine products. The reaction is more efficient using allylic benzoates. This method is completely regioselective and is applicable to aliphatic allylic benzoates as well as aromatic allylic benzoates. Additionally, we demonstrated that this strategy is applicable towards an allylic epoxide substrate to generate [delta]-chiral amine.
by Nootaree Niljianskul.
Ph. D. in Organic Chemistry
4
Ly, Tuan Q. "New heteroatom ligands and metalla-heterocycles via P-N bond formation." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/32271.
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The reaction of K[N{P(S)Ph2}2] (R = Ph or iPr) with [Mo(N3S2)Cl3] in dichloromethane gives [Mo(N3S2){(ph2(O)PNP(S)P2}2] 1 and [Mo(N3S2){iPr2(O)PNP(S)iPr2}2] 2. X-ray crystallography revealed in both compounds the chelates are co-ordinated to octahedral metal centres. The oxygen atoms are located in the trans position to the nitrogen of the triazene ring. The absence of a chloride counter ion indicates that the metal centre has been reduced from Mo(VI) to Mo(V), and electron paramagnetic resonance spectroscopy confIrmed the reduction of the molybdenum centres. The friction reducing study of compound 1 and [Mo(N3S2)(DTBC)2]Na (DTBC = 3,5–di–tert–butylcatechol) has shown that both compounds exhibit low friction coefficient values.
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Oliver, Thomas Albert Anthony. "Exploring photoinduced heteroatom-H bond fission in the gas and solution phases." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.541647.
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De, Fusco Claudia. "Stereoselective carbon-carbon and carbon-heteroatom bond formation mediated by bifunctional organocatalysts." Doctoral thesis, Universita degli studi di Salerno, 2013. http://hdl.handle.net/10556/1323.
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2011 - 2012This PhD work describes the development of different Michael and Michael type processes employing different bifunctional organocatalysts. All the processes studied involved a non-covalent activation of the substrates provided by the organic promoters. An asymmetric epoxidation of electron-poor trisubstituted olefins has been developed by employing the commercially available diphenyl prolinol which afforded the epoxides in high yield, complete diastereocontrol and good enantioselectivity. Diaryl prolinols were found to promote a Michael addition of -ketoesters to nitroalkenes. An unexpected high efficiency and stereocontrol was observed with hexafluorobenzene as unconventional solvent, but also employed as an additive. A convenient tandem double Michael addition process was developed to access symmetrically and unsymmetrically 3,5-diaryl substituted cyclohexanones by using quinine as catalyst. An aziridination reaction of terminal electron-poor olefins has been disclosed by using a commercially available aminothiourea catalyst. The desired aziridines, bearing a quaternary stereocenter, were isolated in good yield and enantiocontrol. These compounds, were regioselectively ring-opened to access valuable ,-disubstituted -amino ester derivatives. Finally an asymmetric Fischer indolization to produce helical molecules was investigated employing a chiral phosphoric acid as promoter and an ion-exchange polymer as ammonia scavenger. [edited by author]
XI n.s.
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Maluenda, Borderas Irene. "(N-heterocyclic carbene) : metal catalysed carbon-carbon and carbon-heteroatom bond-forming reactions." Thesis, University of Sussex, 2018. http://sro.sussex.ac.uk/id/eprint/76274/.
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Tsang, Melanie Wing-Sze. "Pd-catalysed carbon-heteroatom bond formation and urea synthesis in supercritical carbon dioxide." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614105.
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Casitas, Montero Alícia. "Reactivity of well-defined organometallic copper(III) complexes in carbon-heteroatom bond forming reactions." Doctoral thesis, Universitat de Girona, 2012. http://hdl.handle.net/10803/81985.
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This thesis is focused on the unexplored field of organometallic copper(III) chemistry. Arylcopper(III) complexes have been proposed as key intermediates in Ullmann condensation reactions that consist in the coupling of aryl halides and heteroatom nucleophiles catalyzed by copper. The study of the reactivity of well-defined arylcopper(III) complexes may provide a better understanding of the mechanism of Ullmann condensation reactions, which is still under intense debate. In this doctoral dissertation we study the feasibility of well-defined arylcopper(III) complexes, which are stabilized within macrocyclic ligands, to participate in C-heteroatom bond forming reactions. We develop copper-catalyzed C-N and C-O bond forming reactions, as well halide exchange reactions, including fluorinations, based on Cu(I)/Cu(III) catalytic cycle within model aryl halide substrates. We uncover the fundamental understanding of the two-electron redox steps, oxidative addition and reductive elimination, at copper.Aquesta tesi es centra en el camp de la química organometàl•lica del coure(III) que roman sense explorar. Els complexos arilcoure(III) s'han proposat com a intermedis clau en les reaccions de condensació Ullmann que consisteixen en l'acoblament d'halurs d'arils i nucleòfils basats en heteroàtoms catalitzades amb coure. L'estudi de la reactivitat de complexos arilcoure(III) ben definits pot proporcionar una millor comprensió del mecanisme de les reaccions de condensació Ullmann, el qual es troba sota un intens debat. En aquesta tesi doctoral s'estudia la viabilitat del complexos arilcoure(III), estabilitzats en lligands macrocíclics, de participar en reaccions de formació d'enllaç carboni-heteroàtom. S'han desenvolupat reaccions de formació d'enllaç C-N i C-O així com reaccions d'intercanvi d'halurs, on s'inclouen fluoracions, catalitzades amb coure i basades en un cicle catalític Cu(I)/Cu(III) utilitzant substrats models d'halur d'aril. S'ha obtingut una comprensió fonamental de les etapes redox a dos electrons, addició oxidant i eliminació reductiva, en coure.
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Reding, Matthew Todd. "The development and synthetic application of titanium-mediated carbon-heteroatom double bond hydrosilylation methodologies." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42643.
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Altman, Ryan A. (Ryan Alan). "Recent advances in copper- and palladium-catalyzed carbon-heteroatom and carbon-carbon bond-formation." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/43779.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.Vita.
Includes bibliographical references.
Metal-catalyzed nucleophilic substitution reactions of aryl halides have become one of the most valuable and useful classes of reactions developed in the last 30 years. Foremost among these processes are the classes of palladium- and copper-catalyzed reactions, which employ heteroatom-based nucleophiles. Herein, newly designed catalyst systems are presented for the palladium- and/or copper-catalyzed nucleophilic substitution reactions of aryl halides with a variety of nucleophiles, including (benz)imidazoles, oxindoles, 2-, 3- and 4-hydroxypyridines, anilines, and aliphatic, benzylic, allylic and propargylic alcohols. In many cases, catalyst optimization and ligand structure are discussed and evaluated. Where applicable, the palladiumand copper-based catalyst systems are contrasted to demonstrate the complementary relationships between the employment of these two metals. Chapter One Chapter Two Chapter Three Chapter Four Chapter Five. Palladium- and Copper-catalyzed Reactions of Imidazoles and Benzimidazoles with Aryl Halides. Orthogonal Selectivity in Copper- and Palladium-catalyzed Reactions of Aryl Halides with Oxindoles. Copper-catalyzed Reactions of Hydroxypyridines and Related Compounds with Aryl Halides. Pyrrole-2-carboxylic Acid as a Ligand for the Copper-catalyzed Reactions of Primary Anilines with Aryl Halides. An Improved Copper-based Catalyst System for the Reactions of Aryl Halides with Aliphatic Alcohols.
y Ryan A. Altman.
Ph.D.
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Ichikawa, Saki. "Copper-catalyzed carbon-heteroatom bond formations : asymmetric hydroamination and continuous-flow aromatic Finkelstein reaction." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122852.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references.
The studies presented in this dissertation are regarding the development of new methods for copper-catalyzed carbon-heteroatom bond formations, including asymmetric hydroamination and continuous-flow aromatic Finkelstein reaction. The first part of this dissertation focuses on the development of copper-catalyzed asymmetric hydroamination reactions to access various classes of enantioenriched amines. This includes the development of a broadly applicable hydroamination protocol for the synthesis of enantioenriched N-arylamines (Chapter 1) and 1,2- diamines (Chapter 2). The second part of this dissertation describes the development of copper-catalyzed aromatic Finkelstein reaction under continuous-flow conditions (Chapter 3). Part I. Chapter 1.
A Modified System for the Synthesis of Enantioenriched N-Arylamines through Copper-Catalyzed Hydroamination Despite significant recent progress in copper-catalyzed enantioselective hydroamination chemistry, the synthesis of chiral N-arylamines, which are frequently found in natural products and pharmaceuticals, has not been realized. Initial experiments with N-arylhydroxylamine ester electrophiles were unsuccessful and instead, their reduction, in the presence of copper hydride (CuH) catalysts, was observed. We detail key modifications of our previously reported hydroamination protocols that led to broadly applicable conditions for the enantioselective net addition of secondary anilines across the double bond of styrenes, 1,1 -disubstituted alkenes, and terminal alkenes. NMR studies suggest that suppression of the undesired reduction pathway is the basis for the dramatic improvements in yield under this new protocol. Chapter 2.
Regio- and Enantioselective Synthesis of 1,2-Diamine Derivatives by Copper- Catalyzed Hydroamination A highly regio- and enantioselective synthesis of 1,2-diamines using [gamma]-substituted allylic pivalamides via copper-catalyzed hydroamination is reported. The N-pivaloyl group is essential, both in facilitating the hydrocupration step and in suppressing the unproductive [beta]-elimination from the alkylcopper intermediate. This synthetic approach enables an efficient construction of chiral, differentially protected, vicinal diamines under mild conditions with broad functional group tolerance. Part II. Chapter 3. Rapid and Efficient Copper-Catalyzed Finkelstein Reaction of (Hetero)Aromatics under Continuous-Flow Conditions A general, rapid, and efficient method for the copper-catalyzed Finkelstein reaction of (hetero)aromatics has been developed using continuous flow to generate a variety of aryl iodides.
The described method can tolerate a broad range of functional groups, including N-H and O-H groups. Additionally, in lieu of isolation, the aryl iodide products in solution can be directly used in two distinct multistep continuous-flow processes (amidation or Mg-I exchange/nucleophilic addition) to demonstrate the flexibility of this method.
by Saki Ichikawa.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemistry
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Gu, Yiting. "C-H & C-O Functionalization by Silicon-Heteroatom Interelement Linkage." Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668961.
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La química sintètica és gairebé inimaginable sense tres elements principals del grup, a saber, boro, silici i estany. Quan s'uneixen a un àtom de carboni de qualsevol hibridació, aquests grups funcionals serveixen de linchpins excepcionalment versàtils en síntesi, transformant-se selectivament en una enorme amplitud d'enllaços C-C i C-X, per tant, descobrir nous mètodes per forjar el valor afegit C-Si, Els enllaços C-B i C-Sn sempre tenen una gran demanda.
D'acord amb l'interès de la investigació en el grup de Martín per activar enllaços o molècules inerts, aquesta tesi doctoral se centra en el desenvolupament de noves tècniques per fer ús de l'enllaç d'interrelació de silici-heteroatoma per funcionalitzar l'enllaç C-O i C-H inerts mitjançant una catàlisi de níquel o sistema lliure de transició de metalls.
Hem desenvolupat tres nous mètodes per a la funcionalització d’enllaços C-O i C-H inerts mitjançant l’ús d’enllaços d’interrelació basats en silici. Totes les transformacions anteriors presenten un excel·lent perfil de quimioselectivitat en condicions suaus. Es duen a terme estudis i debats sobre mecanismes previs per entendre com i per què van continuar aquestes reaccions. Les transformacions realitzades contribueixen a la comprensió de l’ús més prolífic d’enllaços químics inerts en els compostos de valor afegit de síntesi. Creiem que aquests protocols contribuirienLa química sintética es casi inimaginable sin tres elementos principales del grupo, a saber, boro, silicio y estaño. Cuando se unen a un átomo de carbono de cualquier hibridación, estos grupos funcionales sirven como linchpins excepcionalmente versátiles en síntesis, transformándose selectivamente en una enorme variedad de enlaces C-C y C-X, por lo tanto, descubren nuevos métodos para forjar el valor agregado C-Si, Los bonos C-B y C-Sn siempre tienen una gran demanda. En línea con el interés de la investigación en el grupo de Martín de la activación de enlaces o moléculas inertes, esta tesis doctoral se centra en el desarrollo de nuevas técnicas para hacer uso del enlace de interelemento de silicio-heteroátomo para funcionalizar el enlace inerte C-O & C-H a través de catálisis de níquel o sistema sin transición de metal. Hemos desarrollado tres nuevos métodos para la funcionalización de enlaces inertes C-O y C-H mediante el uso de enlaces de interelemento basados en silicio. Todas las transformaciones anteriores muestran un excelente perfil de quimioselectividad en condiciones suaves. Se realizan estudios y debates mecanicistas preliminares para comprender cómo y por qué se produjeron estas reacciones. Las transformaciones realizadas contribuyen a la comprensión del uso más prolífico de enlaces químicos inertes a los compuestos de valor agregado de síntesis.
Synthetic chemistry is almost unimaginable without three main group elements, namely, boron, silicon, and tin. When attached to a carbon atom of any hybridization, these functional groups serve as exceptionally versatile linchpins in synthesis, selectively transforming into an enormous breadth of C-C and C-X bonds, thus, discover new methods to forge value added C-Si, C-B and C-Sn bonds are always in highly demand. In line with the research interest in Martín’s group of activating inert bonds or molecules, this doctoral thesis focuses on the development of novel techniques to make use of silicon-heteroatom interelement linkage to functionalize inert C-O & C-H bond via either nickel catalysis or transition metal free system. We have developed three new methods towards the functionalization of inert C-O & C-H bonds by using silicon-based interelement linkages. All the above transformations display excellent chemoselectivity profile under mild conditions. Preliminary mechanistic studies and discusses are carried out to understand how and why these reactions proceeded. The transformations realized contribute to the understanding of more prolific use of inert chemical bonds to the synthesis value added compounds. We believe these protocols would definitely contribute to a systematic utilization of silicon-heteroatom reagent in the arena of inert chemical bond functionalization.
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Cazin, Catherine Suzanne Julienne. "Catalysis of carbon-carbon and carbon-heteroatom bond-forming reactions : the importance of the palladium source." Thesis, University of Exeter, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248165.
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Graßl, Simon [Verfasser], and Paul [Akademischer Betreuer] Knochel. "Elaboration of electrophilic carbon heteroatom bond forming reactions using organozinc reagents / Simon Graßl ; Betreuer: Paul Knochel." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2020. http://d-nb.info/1210424398/34.
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Ekoue-Kovi, Kekeli Adjoa Sika. "Palladium-phosphinous acid-catalyzed carbon-carbon and carbon-heteroatom bond formation and synthesis of new antimalarial drugs." Connect to Electronic Thesis (CONTENTdm), 2008. http://worldcat.org/oclc/458487914/viewonline.
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PROPERZI, ROBERTA. "Synthesis of Pharmaceutically Active Heterocycles and Lipid Targets: Novel Rearrangements and Methods for Carbon-Heteroatom Bond Formation." Doctoral thesis, Università degli Studi di Camerino, 2014. http://hdl.handle.net/11581/401829.
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The pharmaceutical industry faces considerable challenges, not only from an R and D standpoint, but also politically and fiscally. Politically, governments around the world are trying to contain costs, and these costs are constantly the subject of intense scrutiny, with the real risk that the public health is suffering the consequences. Therefore, as scientists, we are called to innovate processes and help with witty and affordable solutions. In particular, as synthetic organic chemists, we are called to use imagination and expertise to bring new attractive organic transformations or bright improvements of existing processes, in order to maintain active and alive the real engine of innovation: research. Both from an academic and industrial point of view, new approaches for the achievement of synthetic fragments, moieties or targets are constantly required in a straightforward but brilliant fashion. For our part, we decided to investigate some of the most recurrent topics in organic chemistry and provide new synthetic ideas. This work has been divided into three main chapters, which incorporate topics such as the synthesis of biologically interesting lipid targets and pharmaceutically relevant heterocyclic structures. Therefore we put in place the search for new methods aimed at the formation of new carbon-carbon and carbon-heteroatom bonds. We addressed concerns about the quest for selectivity in the formation of these bonds, providing stereo-, chemo- and regioselective synthetic solutions. Specifically, the work described in Chapters 1 and 2 was carried out from January 2011 to January 2013 in the laboratories of Prof. Marcantoni at the University of Camerino, and focuses on the formation of new C-C and C-heteroatom bonds for the construction of more complex heterocyclic and lipid structures, mainly involving cerium (III) salts as Lewis acids and organometallic compounds. The results presented in the third chapter were achieved from February 2013 to December 2013 under the guidance of Dr. Jeremy T. Starr at Pfizer's Worldwide Research and Development Center in Groton, Connecticut, USA. Chapter 3 was dedicated to the study and the development of new applications of a novel thermal rearrangement of propargyl amine N-oxides, powerful acyclic precursors for the achievement of more interesting heterocyclic structure. As a proof of the validity of the method, and given the particular interest of heterocycles in medicinal chemistry, synthesis of Celebrex®, a drug commercialized by Pfizer, was carried out. The author wishes to thank Prof. Enrico Marcantoni, for his guidance and for the valuable expertise continuously provided. All the people who have been part of the group over the years, for friendship and helpful discussions. Dr. Jeremy T. Starr for extraordinarily mentoring the author and for the warm welcome in his great and highly qualified group. My family and my dad for making me the person I am.
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朱煒章 and Wai-cheung Chu. "Syntheses and reactions of copper and manganese complexes of tetradentate polyanionic chelating ligands and their applications incarbon-heteroatom bond formation reactions." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31236789.
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Chu, Wai-cheung. "Syntheses and reactions of copper and manganese complexes of tetradentate polyanionic chelating ligands and their applications in carbon-heteroatom bond formation reactions /." Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19324893.
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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.
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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
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Buquoi, John Q. III. "Multicomponent Radical Reactions Incorporating Heteroatom-Carbon Bonds Via Polarity-Reversal Cascades." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574348050305556.
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Hoppe, Martin Louis. "Characterization of the electronic structure of complexes containing metal-heteroatom multiple bonds." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184616.
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The electronic structure of a variety of metal-heteroatom multiply bonded complexes, including some active alkyne metathesis catalysts, have been investigated using He(I) and He(II) ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS) and Fenske-Hall molecular orbital calculations. Utilizing this electronic structure information, confirmation of the proposed mechanism for the alkyne metathesis reaction which involves formation of a metallacyclobutdienyl intermediate was ascertained. Also, the important relationships between metallatetrahedral and metallacyclobutadienyl complexes, both of which have been mentioned as possible intermediates in the alkyne metathesis reaction and for which examples have been prepared and isolated, are discussed in significant detail. In the final chapters the electronic structure of some corresponding metal-nitrogen triply bonded complexes are discussed as well as the results probing the charge distribution in metal-heteroatom multiply bonded systems as determined by the XPS experiment.
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Reina, Tapia Antonio. "Metal nanoparticles stabilized by alkaloids in glycerol : from design to catalytic applications." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30160.
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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
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Zani, Lorenzo. "Studies on the zinc mediated phenyl and alkynyl addition to carbon heteroatom double bonds." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980571707.
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Kunchithapatham, Kamala. "Development of Calcium and Palladium Catalysts for the Formation of Carbon-Carbon and Carbon-Heteroatom Bonds." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337955731.
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ZAGHI, ANNA. "Batch and continuous-flow synthetic processes for the formation of carbon-carbon and carbon-heteroatom bonds." Doctoral thesis, Università degli studi di Ferrara, 2017. http://hdl.handle.net/11392/2488074.
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L’organocatalisi è un ramo della catalisi che utilizza piccole molecole organiche per promuovere trasformazioni chimiche in cui si ha la formazione di nuovi legami carbonio-carbonio e/o carbonio-eteroatomo. L’impiego di questa metodologia può offrire numerosi vantaggi: gli organocatalizzatori, infatti, sono in grado di operare in condizioni blande, anche in mezzi acquosi, senza richiedere l’utilizzo di metalli di transizione. Quest’ultima caratteristica risulta particolarmente favorevole nel caso della sintesi di composti che non tollerano contaminazione da parte di metalli come i prodotti di interesse farmaceutico e, più in generale, i composti ad attività biologica. Inoltre, gli organocatalizzatori hanno generalmente basso costo e sono facilmente reperibili.
La chimica in flusso continuo rappresenta una valida alternativa a quella in condizioni batch grazie ai numerosi vantaggi che derivano sia dalla natura del processo in continuo che dalla piccola dimensione dei canali nei quali avviene la reazione chimica. Tra i possibili benefici si possono ricordare la riduzione dei rischi, la sostenibilità, la facilità di scale-up e la semplicità di automazione/monitoraggio dei normali parametri di reazione (velocità di flusso, temperatura, pressione e stechiometria di reazione).
Alcuni svantaggi tipici dell’organocatalisi, come il riciclo dell’organocatalizzatore e l’alto loading spesso necessario per certe trasformazioni, possono essere superati grazie all’eterogeneizzazione degli stessi organocatalizzatori. Questa permette di applicare una procedura in flusso continuo in maniera efficace arrivando a raggiungere alti livelli di stereoselettività e di produttività.
La maggior parte degli studi riportati in letteratura riguardanti la sintesi asimmetrica in flusso continuo utilizza catalizzatori supportati su materiale polimerico o su particelle inorganiche, che costituiscono il letto fisso all’interno di macro- o microreattori.
In questa tesi sono riportate metodologie batch ed in flusso continuo per la formazione di legami carbonio-carbonio e carbonio-eteroatomo, promosse da organocatalizzatori che agiscono attraverso una catalisi via enammina o ione imminio, oppure sfruttando la reattività di umpolung.Organocatalyzed reactions in which organic molecules catalyze single or multiple chemical transformations were found to be an efficient synthetic tool for creating various carbon-carbon and carbon-heteroatom bonds throughout the synthesis of a wide range of achiral and chiral acyclic as well as cyclic derivatives. The benefits of organocatalytic reactions include the use of inexpensive and readily available organic compounds as catalysts, as well as increased synthetic efficiency as no metal traces have to be removed at the end of the processes. This last feature is particularly suited to the preparation of biologically relevant compounds that do not tolerate contamination. The continuous-flow approach has recently emerged in the organic chemistry community as an interesting and alternative method to batch processing for performing chemical transformations. This technology has a number of attractive advantages that are related both to the nature of the continuous process and to the small size of the channels in which the reactions occur. These include (i) large surface to volume ratios and enhanced mixing quality; (ii) superior mass and heat transfer and, hence, improved operational safety; (iii) good real-time reaction monitoring by incorporating in-line analytical devices, allowing fast reaction screening and optimization; (iv) improved scalability. Typical drawbacks of organocatalysis such as organocatalyst recycling and the high catalyst loading often required for several transformations may be overcome by the heterogeneization of organocatalysts that allows the set-up of effective continuous-flow procedures endowed with high levels of stereoselectivity and productivity. The majority of the reported studies on asymmetric flow organocatalysis utilize the active catalyst immobilized on either polymeric or inorganic particles as packing material of macro- and micro-reactors. In this thesis are reported batch and continuous-flow synthetic approaches for the formation of carbon-carbon and carbon-heteroatom bonds, mediated by organocatalysts acting via enamine and iminium catalysis, and umpolung reactivity.
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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.
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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
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Kyne, Robert E. "Strategic Applications of Pinacolato Allylboron Reagents: New Reactions in Enantioselective Allyl-Allyl Cross-Coupling and Allylboration to Form New Carbon-Heteroatom Bonds." Thesis, Boston College, 2012. http://hdl.handle.net/2345/3163.
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Thesis advisor: James P. MorkenDetailed within this dissertation are three new reactions involving allylboron reagents. Chapter 1 describes the development of Pd-catalyzed allyl-allyl cross-coupling for the preparation of enantioenriched all-carbon quaternary stereogenic centers. This methodology represents a novel approach to a significant challenge for synthetic chemists. Subsequently, an allyl-allyl cross-coupling is described which generates functionally differentiated 1,5-dienes. Such structures allow for several chemoselective manipulations, which add a significant practical note to this cross-coupling methodology. Chapter 2 details the development of the allylboration of nitrosobenzene with (Z)-crotylboronate derivatives, which results in the formation of branched allylic alcohols. This methodology provides a regioselective complement to standard boron oxidation conditions
Thesis (PhD) — Boston College, 2012
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Hossain, Asik [Verfasser], Oliver [Akademischer Betreuer] Reiser, Burkhard [Akademischer Betreuer] Koenig, and Arno [Akademischer Betreuer] Pfitzner. "Catalytic Construction of Carbon-Heteroatom Bonds by Shining Visible-Light on Transition-Metal Photocatalysts / Asik Hossain ; Oliver Reiser, Burkhard Koenig, Arno Pfitzner." Regensburg : Universitätsbibliothek Regensburg, 2021. http://d-nb.info/1225121388/34.
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Majek, Michal [Verfasser], von Wangelin Axel [Akademischer Betreuer] Jacobi, Burkhard [Akademischer Betreuer] König, Frank-Michael [Akademischer Betreuer] Matysik, and Mancheño Olga [Akademischer Betreuer] García. "Activation of arene-heteroatom bonds by photoredox catalysis with visible light / Michal Majek ; Axel Jacobi von Wangelin, Burkhard König, Frank-Michael Matysik, Olga García Mancheño." Regensburg : Universitätsbibliothek Regensburg, 2016. http://d-nb.info/1120117488/34.
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Tseng, Nai-Wen. "Transition Metal-catalyzed Carbon-carbon/Carbon-heteroatom Bond Formation Reactions Utilizing Strained Ring Systems." Thesis, 2009. http://hdl.handle.net/1807/19101.
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This thesis focuses on the development of carbon-carbon/carbon-heteroatom bond forming reactions using strained ring systems under transition metal catalysis. The first chapter describes the use of bifunctional organoboron reagents with a rhodium catalyst to synthesize carbocycles through a cascade sequence. The reaction of norbornene derivatives gives vinylcyclopropane and cyclopentene products in moderate to good yield. The mechanistic proposal and insights into the reaction mechanism are presented. Preliminary results from studies toward an enantioselective sequential addition/cyclization process are described. The methodology is subsequently applied in the synthesis of a variety of polycyclic heteroaromatics using bifunctional heteroaryl boronate esters.
The second chapter describes studies toward the formation of carbon-heteroatom bonds using cyclopropane derivatives. Under a recently developed Pd(OAc)2/PhI(OAc)2 catalytic system, methylenecyclopropanes are isomerized to substituted pyridines via a sequential fragmentation/cyclization process. Under same reaction conditions, allylic acetate products are obtained from the isomerization of cyclopropanes through a similar process.
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Tsui, Chit. "New Synthetic Applications of Rhodium-Catalyzed Carbon-Carbon and Carbon-Heteroatom Bond Forming Reactions." Thesis, 2013. http://hdl.handle.net/1807/36019.
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This thesis is divided into four chapters that describe the new development in rhodium-catalyzed addition reactions and asymmetric ring opening (ARO) reactions of strained alkenes.
Chapter 1 describes a regioselective Rh(I)-catalyzed addition reaction of arylboronic acids to unactivated alkenes - protected allylic amines and allyl sulfones. These formal hydroarylation processes have significantly advanced the substrate scope. Comprehensive studies were carried out to optimize the reaction conditions and a wide range of arylboronic acids were employed. The reaction was found to be linear-selective and a mechanism based on functional group- directing effects has been proposed.
Chapter 2 discloses the discovery of Rh(I)-catalyzed addition of arylboronic acids to (benzyl- /arylsulfonyl)acetonitriles. Novel β-sulfonylvinylamine products were formed in a stereoselective fashion (Z-alkene). Upon hydrolysis, β-keto sulfones were obtained with a broad scope of aryl and sulfonyl substituents. These (Z)-β-sulfonylvinylamines were useful synthons in the synthesis of unsymmetrical polysubstituted pyridines via 1-aza-allyl anion intermediates as well as 1,4- benzothiazine derivatives via intramolecular cyclization. Chapter 3 reports the use of two new nucleophiles in Rh(I)-catalyzed ARO of oxabicyclic alkenes - water and triethylamine trihydrofluoride. In the water-induced ARO, an unprecedented domino ARO/isomerization process was discovered which led to the formation of 2-hydroxy-1- tetralones. By modifying the reaction conditions, trans-1,2-diols can be obtained in excellent enantioselectivity. Using triethylamine trihydrofluoride as a nucleophile, an aliphatic C-F bond was constructed enantioselectively in the ring-opening process which provided fluorinated building blocks containing both allylic fluoride and fluorohydrin units.
Finally, Chapter 4 details the development of a one-pot synthesis of a chiral dihydrobenzofuran framework using Rh-catalyzed asymmetric ring opening and Pd-catalyzed C-O coupling. The product can be obtained in excellent enantioselectivity without isolation of intermediates. Systematic metal-ligand studies were carried out to investigate the compatibility of each catalytic system using product enantiopurity as an indicator.
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BERRINO, ROBERTA. "Studies on the transition metal-catalyzed C-C and C-heteroatom bond forming reactions." Doctoral thesis, 2012. http://hdl.handle.net/11573/918824.
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Newman, Stephen. "Reversible Oxidative Addition in Palladium Catalysis: New Methods for Carbon–Carbon and Carbon–Heteroatom Bond Formation." Thesis, 2012. http://hdl.handle.net/1807/34824.
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The development of new, improved methods for forming carbon–carbon and carbon–heteroatom bonds is the basic goal in synthetic organic chemistry. In the Lautens group, many recent advances have been made using late transition metals such as rhodium and palladium. One such research project involves the synthesis of indoles through tandem C–N and C–C coupling reactions using gem-dibromoolefin starting materials, and this area serves as a starting point for the research described.
Chapter 1 describes a method by which the tandem use of gem-dibromoolefins can be halted to give intramolecular monocoupling reactions, maintaining one of the carbon–bromine bonds which can serve as a useful handle for further functionalization. The use of copper as a catalyst is key to this reaction, as it features a unique mechanism for carbon–heteroatom bond formation. Benzofurans and benzothiophenes can be prepared by this method.
Chapter 2 describes the synthesis of 2-bromoindoles using an intramolecular Buchwald–Hartwig amination of gem-dibromoolefins. It is found that the products are more reactive towards palladium(0) than the starting material, and the use of a bulky phosphine ligand which facilitates reversible oxidative addition is required. This represents one of the first catalytic applications of this step in synthesis.
Chapter 3 further explores the concept of reversible oxidative addition in a novel carbohalogenation reaction of alkenes. Aryl iodides tethered to alkenes are treated with a palladium(0) catalysts, which can undergo the basic steps of oxidative addition, carbopalladation, and novel sp2 carbon–iodine reductive elimination. This process is remarkably simple in concept, and is a waste-free, atom economically method for preparing new carbon–carbon bonds.
Chapter 4 discusses various limitations to the carbohalogenation methodology, and seeks to overcome these problems. The use of aryl bromide starting materials can be accomplished by adding an iodide source to the reaction, allowing halide exchange of palladium(II) intermediates to occur. Intermolecular and asymmetric variants are also explored. Computational studies are discussed which reveal useful mechanistic details of the catalytic cycle, and this information is used in the development of novel phosphine ligands.
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Dhineshkumar, J. "Iodine and Copper Catalyzed Oxidative Cross Coupling Reactions : Design and Development of Carbon-Carbon and Carbon-Heteroatom Bond Forming Reactions." Thesis, 2016. http://hdl.handle.net/2005/3020.
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Design and Development of Carbon-Carbon and Carbon-Heteroatom Bond Forming Reactions” is divided into two sections. Section-A, contains two chapters, describes the catalytic ability of iodine for cross coupling reactions. Section-B, divided into three chapters, presents the azidation of organic scaffolds under oxidative conditions.
Section A
Chapter 1 presents a C-H functionalization of tetrahydroisoquinolines using iodine as a catalyst under aerobic conditions.1 This methodology employs Cross Dehydrogenative Coupling (CDC) strategy as a key step, which is highly atom economical as it doesn’t require pre-functionalized starting materials.2 Owing to the importance of tetrahydroisoquinoline moiety which is present in the umpteen natural products, considerable attention has been put up to functionalize tetrahydroisoquinoline scaffold.3 Iodine a non-metal which is non-toxic was found to catalyze the C-H functionalization of tetrahydroisoquinolines with a variety of nucleophiles such as coumarin, alkyl phosphite, phenols, indoles, acetone and dialkyl malonoates were coupled to it. Significant mechanistic study has been carried out to find the possible intermediate and support the mechanistic proposal. A few representative examples are highlighted in Scheme 1.1
Synopsis
Scheme 1: A CDC coupling of tetrahydroisoquinoline with variety of nucleophiles
Chapter 2 describes the Cross Hetero Dehydrogenative Coupling (CHDC) reactions of amines, alcohols and sulfoximines with various phosphites.4 Phosphoramidates and phosphate esters are structural scaffolds that are present in a variety of biologically active molecules.5 The conventional methods for synthesizing phosphoramidates/phosphate esters largely involve treating alcohol/amine with appropriate phosphorus halides which generates stoichiometric amount of halogen waste.6 Due to the usage of stoichiometric reagents and difficulties associated with the reported methods, there is a need for developing a protocol which is catalytic and mild. Therefore, we developed a method which employs catalytic amount of iodine and aq. H2O2 as a sole oxidant under milder conditions. Using this methodology, variety of phosphoramidates, phosphorous triesters and sulfoximine derived
Synopsis
Scheme 2: Phosphorylation of amines, alcohols and sulfoximines phosphoramidates have been synthesized with great efficiency and environmentally benign conditions. A few representative examples are highlighted in Scheme 2.4
Section B
Chapter 1 of Section B demonstrates a mild way of synthesizing quaternary azides from α-substituted active methylene compounds which will serve as surrogates for several unnatural amino acid derivatives.7 Azidation has emerged as one of the efficient methods to introduce nitrogen atom in to the organic molecules.8 Azides are versatile functional groups which can be converted to amine, amide, and nitro compounds by simple modification. Moreover, azides are potential handle for “click” chemistry and provide late stage modifications in drug candidates, biomolecules and polymers, etc.9 Azidation of 1,3-dicarbonyl compounds is challenging, as both azides and 1,3-dicarbonyl compounds are nucleophilic in nature. In this section of the thesis, azidation of 1,3-dicarbonyl compounds has been carried out using tetrabutyl ammonium iodide (TBAI) as a catalyst, aq. TBHP as an oxidant and TMSN3 as a azide source. This method uses water as a solvent under mild reaction conditions to generate
Synopsis
quaternary azides in good to excellent yields. This operationally simple, practical, mild and green method provides an opportunity for synthesizing a variety of azidated β-keto esters, amides and ketones in good yields, Scheme 3.7 The application of this methodology has been demonstrated by synthesising a few triazole and pyrazolone derivatives.
Scheme 3: Azidation of 1,3-dicarbonyl compounds
Chapter 2 of Section B comprises the azidation and peroxidation of β-napthol derivatives using dearomatization strategy. Azidation and peroxidation are efficient ways to introduce nitrogen and oxygen into organic molecules, which serve as surrogates for amines and alcohol functional groups. In the present study, the azidative or peroxidative dearomatization of naphthol derivatives have been described. The azidation of β-napthol derivatives has been achieved by using CuBr (5 mol %) as a catalyst, TMSN3 as an azide source and aq. TBHP as an oxidant. Whereas, the peroxidation β-napthol derivatives has been accomplished using CuBr (5 mol %) in the presence of aq. TBHP at ambient reaction conditions.10 The products obtained are naphthalenone derivatives, which serve as valuable
Synopsis
synthetic intermediates and has potential handle for further functionalization.11 Several α-amino or α-peroxy naphthalenones are synthesized using this method in good yields. The usefulness of the methodology has been illustrated by synthesizing a few chiral azides and peroxides in good yields and with moderate enantioselectivity Scheme 4.10
Scheme 4: Dearomatizative azidation and peroxidation of 2-naphthols
Chapter 3 reveals the azidation of indole at C-2 position by employing CuBr (10 mol %) as a catalyst and aq. TBHP as an oxidant in acetonitrile under reflux conditions (Scheme 5).12 The C-H functionalization of indole at C-2 position is one of pivotal methods, since it paves a way for synthesizing a variety of indolo-alkaloids.13 Azide is a versatile functionality which can be converted to several other nitrogen containing functional groups such as
Synopsis
Scheme 5: Azidation of indoles
amine, amide, triazole, etc.9 A variety of functional groups were tolerated under the reaction conditions, and furnished the azidated product in good to excellent yields. Through radical inhibition study, we presume that the reaction may be proceeding through radical mechanism. In Scheme 5, a few representative examples are depicted.
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Rokade, Balaji Vasantrao. "Copper-Catalyzed Novel Oxidative Transformations : Construction of Carbon-Hetero Bonds." Thesis, 2014. http://etd.iisc.ernet.in/2005/3479.
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The thesis entitled “Copper-Catalyzed Novel Oxidative Transformations: Construction of Carbon-Hetero Bonds” is divided into two main sections. Section A deals with the utility of azide as a nitrogen source for C-N bond formation, which is further divided into 4 chapters, and section B presents decarboxylative radical coupling reaction for C-heteroatom bond formation which is further divided in to two chapters.
Section A
Chapter 1 describes an approach for the direct synthesis of nitrile from the corresponding alcohols using azide as a nitrogen source. Nitrile functionality is a versatile and ubiquitous which occurs in a variety of natural products. Nitrile functionality can be easily transformed into a variety of functional groups and products such as aldehydes, ketones, acids, amines, amides and nitrogen-containing heterocycles, such as tetrazoles and oxazoles. In this chapter a successful attempt for developing a novel methodology to oxidize benzylic and cinnamyl alcohols to their corresponding nitriles in excellent yields has been described. This strategy uses DDQ as an oxidant and TMSN3 as a source of nitrogen in the presence of a catalytic amount of Cu(ClO4)2·6H2O. A few representative examples are highlighted in Scheme 1.1
Scheme 1. Oxidative conversion of alcohols to nitriles
Second chapter represents a protocol for the synthesis of 1,5-disubstituted tetrazoles from the corresponding secondary alcohols. Among heterocyles, tetrazole and its derivatives are important class of nitrogen containing molecules. Due to their well-known biological activities as well as vast applications in pharmaceuticals and material science, they are potential targets for synthetic organic chemists. Therefore, a simple and user-friendly method for the synthesis of tetrazole is desirable. In this chapter, a mild and convenient method to synthesize 1,5-disubstituted tetrazoles using easily accessible secondary alcohols by employing TMSN3 as a nitrogen source is developed. This reaction is performed in the presence of a catalytic amount of Cu(ClO4)2·6H2O using DDQ as an oxidant under ambient conditions (Scheme 2).2
Scheme 2. Oxidative conversion of secondary alcohols to tetrazoles
Third chapter presents a method for synthesizing amides from their corresponding secondary alcohols. Amide functionality is a crucial backbone in peptide chemistry, it also serve as an important precursor or intermediate for variety of organic transformations. In this contention, a mild and convenient method to synthesize amides using easily accessible secondary alcohols by employing TMSN3 as a nitrogen source is developed. This reaction is performed in the presence of a catalytic amount of Cu(ClO4)2·6H2O using DDQ as an oxidant under ambient conditions (Scheme 3).3
Scheme 3. Oxidative conversion of secondary alcohols to amides
Additionally, the application of this methodology has also been revealed for the synthesis azides directly from their alcohols. Some of the representative examples are shown in the Scheme 4.3
Scheme 4. Direct conversion of alcohols to their azides.
Fourth chapter describes highly chemoselective Schmidt reaction. The classical Schmidt reaction involves the formation of new carbon-nitrogen bonds in a reaction of a carbon-centred electrophile with hydrazoic acid followed by loss of nitrogen, which usually occurs via a rearrangement. It is well known that under the Schmidt reaction conditions, ketones and carboxylic acids are converted into their corresponding amides and amines respectively, whereas aldehydes furnish a mixture of formanilides and nitriles. In this chapter, Schmidt reaction of aldehydes to obtain their nitriles without formation of the corresponding formanilide is presented (Scheme 5).4 It was also observed that aromatic ketones and acids functionalities were intact under the reaction condition, unlike the conventional Schmidt reaction.
Scheme 5. Highly chemoselective Schmidt reaction
Section B
It is divided into two chapters, describes a copper catalyzed decarboxylative radical coupling for the synthesis of vinyl sulfones and nitroolefins (Scheme 6).
Scheme 6. General strategy for the second part
First chapter narrates a strategy for synthesizing nitroolefins from the α,β-unsaturated carboxylic acids. Nitroolefins represent a unique class of nitro compounds, which have multifaceted utility in organic synthesis. They possess antibacterial, rodent-repelling, and antitumor activities. They serve as important intermediates in organic synthesis. Nitroolefins also react with a variety of nucleophiles, and their electron-deficient character renders them as a powerful dienophiles in Diels-Alder reactions. In our attempt to use the decarboxylative strategy, this chapter describes a method for the nitrodecarboxylation of substituted cinnamic acid derivatives to their corresponding nitroolefins. This nitrodecarboxylation reaction is performed using catalytic amount of CuCl in the presence of air using TBN as a nitrating source (Scheme 7).5 Besides, the reaction provides a useful method for the synthesis of β,β-disubstituted nitroolefin derivatives which are generally difficult to access from other conventional methods. Scheme 7. Decarboxylative nitration
Second chapter presents a new protocol for the synthesis of vinyl sulfones from the α,β-unsaturated carboxylic acid. Vinyl sulfones are versatile building blocks, which find their utility as Michael acceptors and used in cycloaddition reactions. This functional group has also been shown to potently inhibit a variety of enzymatic processes, and thus provides unique properties for drug design and medicinal chemistry. Vinyl sulfones are prominent in medicinal chemistry owing to their wide presence in pharmaceutically active molecules, such as enzyme inhibitors and biological activity. In this chapter, we report a method for the construction of C-S bonds via ligand promoted decarboxylative radical sulfonylation of ,-unsaturated carboxylic acids to synthesize vinyl sulfones using Cu catalysis (Scheme 8).6 This is the first report for this particular conversion.
Scheme 8. Decarboxylative sulfonation
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Dubland, Joshua. "Studies towards Developing Diastereoselective SN1 Reactions of α-Keto Carbocations." Thesis, 2010. http://hdl.handle.net/1807/24246.
Full textAbstract:
Although α-keto carbocations have been demonstrated to be viable intermediates in solvolysis reactions, their applications in synthesis are scarce. These species can be considered to be equivalent to “reversed polarity” enolates and, as such, could be useful for the asymmetric formation of carbon-carbon and carbon-heteroatom bonds. In principle, facial selectivity in additions to α-keto carbocations may be induced using easily removed ester, amide, or imide chiral auxiliaries. Efforts to achieve such diastereoselective SN1 reactions of α-keto carbocations are described herein.
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IAZZETTI, ANTONIA. "Transition Metals Catalysis in C-C and C-Heteroatom Bonds Forming Reactions." Doctoral thesis, 2013. http://hdl.handle.net/11573/917801.
Full textAbstract:
Transition metals catalysis represents an important and
versatile tool for the organic synthesis. Indeed its use is associated
with several advantages in terms of reaction selectivity, and
“atom economy”. In the last decade the growing utilization of
transition metals catalysis has deeply influenced and modified the
design of heterocyclic synthesis as testified by the wide amount
of studies on the palladium-catalyzed cross-coupling reaction that
in 2010 led Prof. Richard F. Heck (University of Delaware,
USA), Prof. Ei-ichi Negishi (Purdue University, USA) and Prof.
Akira Suzuki (Hokkaido University, Japan) to achieve the Nobel
Prize for Chemistry.
In this context, during my doctorate activity, we investigated the
construction of heterocyclic rings and the production of
derivatives of heterocyclic compounds of biological interest
through palladium, copper and gold catalyzed reactions.
As part of our studies on the palladium catalysis we developed
several synthetic strategy for the construction of different classes
of compounds such us functionalized 2,3-dihydrofurans,
substituted 2,3-substituted quinolin-4-(1H)-ones,
dibenzo[a,c]carbazoles, 2-amino ketones and aryl sulfones. Then,
the economic attractiveness of copper-based methods and the
growing interest in copper-catalyzed syntheses stimulated us to
investigate some copper-catalyzed protocol. In this area we
studied the oxidation reaction of the 1,2-diarylethanones and the
cyclization reaction of the N-(2-bromoaryl)enaminones to obtain
2,4-diarylbenzo[b][1,4]oxazepines. Finally, using gold complexes
we developed a new sinthetical approach to 2,4-diaryl-2,3-
dihydro-1H-benzo[b][1,4]diazepines.
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Gujadhur, Rattan K. "The formation of aryl -carbon and aryl -heteroatom bonds using copper(I) catalysts." 2003. https://scholarworks.umass.edu/dissertations/AAI3110494.
Full textAbstract:
Copper(I) complexes of type [Cu(PPh3)3X] (where X: Br, Cl), [Cu(PPh3)2NO3], Cu(L)(PPh 3)2X (where X: PF6, NO3, ClO4 and L: phenanthroline, diimine, neocuproine), Cu(L)(PPh3)X (where X: Br and L: phenanthroline, di-imine, neocuproine) are synthesized and characterized to study their catalytic activities in carbon-heteroatom bond formation reactions. The geometrical parameters illustrate that there is a correlation between bite angles and copper-phosphorous bond lengths in mononuclear chelated copper(I) complexes. These complexes had wider bite angles than mononuclear non-chelated copper(I) complexes. Screening of the mononuclear copper(I) complexes in aryl-oxygen bond formation reactions show that the complexes [Cu(PPh3)3Br] and [Cu(neocup)(PPh3)Br] catalyzed the formation of a range of substituted diphenyl ethers at 20 mol% and 10 mol% catalyst loadings respectively. The polynuclear copper(I) complexes fail to catalyze the same reaction. In aryl-nitrogen bond formation reactions, the same complexes [Cu(PPh3)3Br] and [Cu(neocup)(PPh 3)Br] enable the formation of a range of diaryl and triaryl amines. The protocol with [Cu(PPh3)3Br] is used for the successful synthesis of o.o′.o ″-amino-trisbenzoic acid-trimethylester at 170°C in o-dichlorobenzene. This molecule is eluded by the Hartwig-Buchwald protocol. The well-defined complex [Cu(neocup)(PPh3)Br] is further investigated for the formation of aryl-sulfur and aryl-selenium bonds. Optimization and control experiments in this area show that using neocuproine as an additive with CuI, in the presence of NaOt-Bu, in toluene allows the development of protocols for a range of aryl-sulfides and aryl-selenides. In the second protocol, the change of base to K2CO3 allows the coupling of a range of electron-poor iodides to the respective diaryl selenides. The observed results point to the potential of copper(I) catalysts as alternatives to palladium-based protocols, for the formation of aryl-O, N, S and Se bonds under mild conditions.
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Zani, Lorenzo [Verfasser]. "Studies on the zinc mediated phenyl and alkynyl addition to carbon heteroatom double bonds / vorgelegt von Lorenzo Zani." 2006. http://d-nb.info/980571707/34.
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Feng, Yuee. "Synthesis and reactivity of ruthenium and platinum complexes with non-dative heteroatomic ligands studies of carbon-hydrogen bond activation /." 2007. http://www.lib.ncsu.edu/theses/available/etd-12132007-121728/unrestricted/etd.pdf.
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