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Dissertationen zum Thema „Organic reaction methodology“
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1
Bhuiyan, Mosharef Hossain. „Synthetic organic reaction new methodology and applications“. Thesis, University of North Bengal, 2003. http://hdl.handle.net/123456789/772.
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2
Biswas, Kinkar. „Development of organic reaction methodology using polymar-supported reagents, focused microwaves and on-water chemistry“. Thesis, University of North Bengal, 2016. http://ir.nbu.ac.in/handle/123456789/2745.
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Larson, Shawn E. „Enantioselective Brønsted and Lewis Acid-Catalyzed Reaction Methodology: Aziridines as Building Blocks for Catalytic Asymmetric Induction“. Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4357.
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Chiral molecules as with biological activity are plentiful in nature and the chemical literature; however they represent a smaller portion of the pharmaceutical drug market. As asymmetric methodologies grow more powerful, the tools are becoming available to synthesize chiral molecules in an enantioselective and efficient manner.
Recent breakthroughs in our understanding of phosphoric acid now allow for Lewis acid catalysis via pairing with alkaline earth metals. Using alkaline earth metals with chiral phosphates is an emerging approach to asymmetric methodology, but already has an influential record.
The development of new conditions for the phosphoric acid-catalyzed highly enantioselective ring-opening of meso-aziridines with a series of functionalized aromatic thiol nucleophiles is described in this thesis. This methodology utilizes commercially available aromatic thiols, a series of meso-aziridines, and a catalytic amount of VAPOL calcium phosphate to explore the substrate scope of this highly enantioselective reaction.
Additionally, the development of new conditions for a catalytic asymmetric aza-Darzens aziridine synthesis mediated by a vaulted biphenanthrol (VAPOL) magnesium phosphate salt is described in this thesis. Using simple substrates, this methodology explores the scope and reactivity of a new magnesium catalyst for an aziridination reaction capable of building chirality and complexity simultaneously.
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Cavitt, Marchello Alfonzo. „Stress relief: Exercising Lewis acid catalysis for donor-acceptor cyclopropane ring-opening annulations, a basis for new reaction methodologies“. Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54448.
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Nature’s biodiversity is complex and filled with beauty and wonder which are all observable on the macroscopic scale. This exquisiteness of nature’s intricacies are mirrored on the molecular level such that substances, large or small, are assembled to serve as signaling molecules, protective agents, and fundamental composites of higher-order frameworks for the operation and survival of life. Over the years, chemists have isolated and synthesized these molecules, known as natural products, to understand and evaluate their functions in biology and potential for medicinal applications.
Although bioactive natural products demonstrate medicinal promise, poor pharmacological effects require further derivatization because semisynthesis is not sufficient to refine adverse pharmacokinetics. For some active molecules, isolation results in poor yields. In addition to small quantity isolation, many natural products, reflecting the immense complexity of biology itself, pose difficult synthetic challenges to organic chemists because of skeletal heterogeneity, stereochemical complexity, and substitution divergence. As a result of these synthetic obstacles to natural product utilization, improvements are needed in current chemical approaches, and new innovative methodologies for synthesis and chemical space exploration are necessary.
Pharmaceutically relevant frameworks, natural products, and synthetic biologically active molecules are comprised of polycarbocyclic and heterocyclic scaffolds. Traditionally, cycloadditions, transannular transformations, and annulation reactions serve as powerful methods for polycyclic formation. In order to assemble diverse polycycles, donor-acceptor cyclopropanes are useful, versatile synthetic equivalents for C-C bond formations. By taking advantage of the strain within these unique, polarized systems, differing molecular architectures can be accessed directly to perform contemporary organic synthesis. Moreover, the donor-acceptor cyclopropanes initially utilized in these studies provided a fundamental basis for new methods to synthesize other relevant scaffolds. Unique, efficient, Lewis acid-catalyzed intramolecular cyclization strategies for the construction of functionalized polycycles using Friedel-Crafts-type alkylation sequences are presented to expand the reaction repertoire of the molecular architect. Generally, products were formed from commercially-available starting materials in high yields with broad scope. The methodologies were demonstrated to be modular, operationally simple, and amenable to different substitution patterns and functional groups to afford tetrahydroindolizines, heteroaromatic cyclohexenones, hydropyrido[1,2-a]indoles, pyrrolo[1,2-a]indoles, pyrrolo[3,2,1-ij]quinolines, pyrrolizines, and tetrahydrobenzo[ij]quinolizines. To demonstrate the utility of the methodologies devised, progress toward, (±)-rhazinicine, a natural product, is discussed.
This dissertation is organized into six chapters: (1) an introduction, paradoxical stress and molecular strain’s utility in synthesis; (2) annulation reactions for the formation of heteroaromatic cyclohexenones; (3) hydropyrido[1,2-a]indole formation via an In(III)-catalyzed cyclopropane ring-opening/Friedel-Crafts alkylation sequence; (4) tetrahydroindolizine formation and progress toward the total synthesis of (±)-rhazinicine (5) pyrrolo[1,2-a]indole synthesis using a Michael-type Friedel-Crafts cyclization approach; and (6) a versatile protocol for the intramolecular formation of functionalized pyrrolo[3,2,1-ij]quinolines.
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Pelletier, Sophie Marie-Clémentine. „One-pot nitro-Mannich cascade reactions : new methodologies and synthetic applications“. Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:283641bf-bb4e-48a8-8a28-2e048b8c4ea6.
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Pyrrolidine and pyrrolidinone rings are common motifs found in many biologically active natural products and drugs. Accordingly, our work focuses on the development of new methodologies for their one-pot synthesis. An efficient diastereoselective nitro-Mannich / lactamisation reaction cascade of methyl 3-nitropropanoate with cyclic and acyclic imines for the direct preparation of trans-monocyclic and fused tricyclic pyrrolidinone derivatives was developed. The reaction is easy to perform, broad in scope and tolerates a wide variety of functional groups. For the monocyclic methodology, 28 examples with a very good average yield of 72% and excellent diastereocontrol (typical dr >98:2) were obtained using optimized conditions and varying the amine and the aldehyde reagents. The methodology has been extended to the synthesis of 1,3,5-trisubstituted 4-nitropyrrolidinone derivatives using α-substituted 3-nitropropanoate. Using a one-pot protocol, 22 derivatives were synthesised in good yields (65% average) and diastereomeric ratios ranging from 3:1 to 30:1 in favor of the trans/trans diastereoisomer. In addition, the nitro-Mannich / lactamisation cascade of methyl 3-nitropropanoate was developed further to allow the rapid synthesis of 5-isopropyl-4-nitropyrrolidin-2-one from reaction with ammonium acetate and 1-butyl-4-nitropyrrolidin-2-one from reaction with formaldehyde. Also, the synthetic utility of the nitro-pyrrolidinones formed was exemplified through various functional group modifications: the selective reduction of the lactam carbonyl, the reduction of the nitro group in the presence or absence of a carbonyl group and the reductive removal of the nitro group. The development of an enantioselective version of the cascade under chiral Brönsted acid catalysis provided promising results (up to 90% ee). Moreover, various studies were undertaken to understand the mechanism of the reaction and the nitro-Mannich / latamisation cascade is now well understood. Furthermore, a formal synthesis of rac-Slaframine in 8 steps and 15% overall yield was achieved and it inspired additional work towards a nitro-Mannich / epoxide ring opening cascade.
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Martinez, Ariza Guillermo, und Ariza Guillermo Martinez. „Exploiting Molecular Diversity to Access Biologically Relevant Chemotypes“. Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621718.
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Small-molecule libraries with enhanced structural diversity are of value in drug discovery campaigns where novel biologically active hits are desired. As such, multicomponent reactions (MCRs) have proven fruitful to enhance the molecular diversity of chemical collections and expedite forward progression of the drug discovery chain. Bicalutamide (Casodex), an anticancer drug, and Telaprevir (Incivek), an antiviral, are two examples of marketed drugs that can be synthesized using an MCR. The research topic of this dissertation involves the design, discovery, and development of novel MCRs and new combinations of MCRs with post-condensation modifications to generate over twenty-five new drug-like scaffolds in an operationally friendly, atom-economical, time- and cost-effective fashion. The developed chemical methodologies possess inherent 'iterative efficiency','high exploratory power', and 'bond forming efficiency' that allow them to quickly explore chemical space and navigate the 'hypothesis-synthesis-screening' loop that is key for a medicinal chemistry project. The prepared molecules were submitted to the Community for Open Antimicrobial Drug Discovery (CO-ADD) for antimicrobial screening against pathogens that are known to cause drug-resistance infections.
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Jha, Satadru. „Organic reactions methodology : studies on carbon-nitrogen hetero bond forming reactions“. Thesis, University of North Bengal, 2004. http://hdl.handle.net/123456789/745.
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Baldwin, I. Craig. „New methodology involving allylic substitution and conjugate addition reactions“. Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/27583.
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Chapter one reviews routes to the generation of α-aminophosphonates and α-aminophosphonic acids. These biologically important compounds are synthesised in both racemic and enantiomerically enriched forms. The second chapter describes the results of conjugate addition reactions of lower order cuprates to diethylvinylphosphonate followed by an electrophilic quench to give a range of alkylphosphonates. The third and fourth chapters are concerned with the generation of enantiomencally enriched α-aminophosphonates and α-aminoesters via palladium catalysed allylic substitution reactions With allyl acetate the resulting products were isolated with an enantiomeric excess of up to 19%. With 1,3-diphenyl-2-propenyl acetate products with both high diastereomeric and enantiomeric excesses were isolated with the best being 75 % de and 97 % ee.
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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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Bentley, Scott Alexander. „Asymmetric conjugate addition reactions“. Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:9e619a66-6277-48c2-8a2e-24f8206e52b3.
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This thesis is concerned with the asymmetric conjugate addition reactions of a range of chiral nucloeophiles. Chapter 1 introduces the conjugate addition reaction as a valuable carbon-carbon and carbon-heteroatom bond forming reaction in organic chemistry, and explores the asymmet- ric conjugate addition of a range of chiral and achiral carbon and nitrogen nucleophiles to a range of acceptors. Chapter 2 explores the use of the N-benzyl-N-(α-methylbenzyl)amino group as a chi- ral auxiliary, by employing the attempted conjugate additions of both N-benzyl-N-(α- methylbenzyl)hydrazine and N -benzyl-N -(α-methylbenzyl)hydroxylamine as chiral ammo- nia and water equivalents respectively. Chapter 3 describes the asymmetric and stereoselective preparation of a range of 4,4- disubstituted isoxazolidin-5-ones from the conjugate addition of lithium (S)-N-tert-butyl- dimethylsilyloxy-N -(α-methylbenzyl)amide. The isoxazolidin-5-ones are then globally de- protected via hydrogenolysis, giving rise to the corresponding β2,2,3-amino acids. Chapter 4 focuses on the development of a protocol to effect the conjugate addition of a chiral aniline equivalent. The scope of the reaction is delineated by varying both the nu- cleophile and the α,β-unsaturated ester. Finally, cyclisation of the β-N-arylamino esters to the corresponding tetrahydroquinolines is explored, and an application to the synthesis of the natural product (−)-angustureine is presented. Chapter 5 contains full experimental procedures and characterisation data for all com- pounds synthesised in Chapters 2, 3 and 4.
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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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Mondière, Aurélie. „Réactions multicomposants et applications : synthèse de cyclopent[b]indoles et pyrrolo[1,2-a]indoles : synthèse diastéréosélective de lignanes tétrahydrofuraniques trisubstitués“. Phd thesis, Université Claude Bernard - Lyon I, 2010. http://tel.archives-ouvertes.fr/tel-00837814.
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Ce mémoire de thèse est composé de deux parties distinctes ayant comme thématique commune, les réactions multicomposants (MCR). Nous nous sommes intéressés dans un premier temps au développement d'une nouvelle MCR conduisant à des dérivés de l'indole, hétérocycle rencontré dans de nombreuses substances naturelles et composés biologiquement actifs. Nous avons ainsi mis au point un nouvelle méthodologie MCR séquentielle, rapide et efficace permettant d'accéder sélectivement, à partir des trois mêmes substrats (un précurseur indolique, un alcyne vrai et un accepteur de Michael) à deux familles de composés : les cyclopent[b]indoles ou les pyrrolo[1,2-a]indoles par une simple inversion de l'ordre des réactions. Puis dans un deuxième temps, nous avons élaboré une nouvelle synthèse totale diastéréosélective de lignanes tétrahydrofuraniques trisubstitués, connus pour leur abondance dans la nature et leurs propriétés biologiques très variées. Cette synthèse courte est composée de trois étapes clés : une réaction de cyclofonctionnalisation multicomposants palladocatalysée, une déméthoxycarboxylation -élimination utilisant des conditions de Krapcho modifiées et une réaction de type Hayashi-Miyaura permettant d'introduire le deuxième groupement aryle. Cette dernière réaction d'addition conjuguée a représenté le défi de cette synthèse et a donc fait l'objet d'une étude particulière sur un substrat modèle.
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Mciteka, Lulama Patrick. „Novel applications of Morita-Baylis-Hillman methodology in organic synthesis“. Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1007598.
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The overall approach in the present investigation has been to explore applications of the Morita-Baylis-Hillman (MBH) reaction in asymmetric synthesis and in the continuation of systems with medicinal potential. To this end, a series of varied camphor-derived acrylate esters was prepared to serve as chiral substrates in asymmetric Morita-Baylis- Hillman reactions. Reduction of N-substituted camphor-10-sulfonamides afforded the 3- exo-hydroxy derivatives as the major products. Acylation of the corresponding sodium alkoxides gave the desired 3-exo-acrylate esters, isolation of which was complicated by concomitant formation of hydrochlorinated and diastereomeric competition products. Bulky camphorsulfonamides containing alkyl, dialkyl, aromatic and adamantyl groups were selected as N-substituents with the view of achieving stereoselective outcome in subsequent MBH reactions. The synthesis of novel camphor-derived Morita-Baylis-Hillman adducts using various pyridine-carboxaldehydes proceeded with exceptionally high yields with diastereoselectivities ranging from 7-33 % d.e. Both 1D and 2D NMR and HRMS techniques were employed to confirm the structures and an extensive study of the electropositive fragmentation patterns of a number of camphor-derived chiral acrylate esters was conducted. Attention has also been given to the application of MBH methodology in the construction of heterocyclic ‘cinnamate-like’ AZT conjugates which were designed to serve as dualaction HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. A number of pyridine carboxaldehyde-derived MBH adducts were synthesized using methyl, ethyl and t-butyl acrylates in the presence of 3-hydroxyquinuclidine (3-HQ) as catalyst. The yields for these reactions were excellent. The resulting MBH adducts were acetylated and subjected to aza-Michael addition using propargylamine. The resulting alkylamino compounds were then used in ‘Click reactions’ to form the targeted AZT-conjugates in moderate to excellent yield. In silico docking of computer modelled AZT-conjugates into the HIV-1 integrase and reverse transcriptase enzyme-active sites and potential hydrogen-bonding interaction with active-site amino acid residues were identified. The electrospray MS fragmentations of the AZT and the novel AZT-conjugates were also investigated and common fragmentation pathways were identified.
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Parker, Mariah L. „The Investigation of Oxidative Addition Reactions of Metal Complexes in Cross-Coupling Catalytic Cycles Based on a Unique Methodology of Coupled Ion/Ion-Ion/Molecule Reactions“. VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5651.
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Popular catalytic cycles, such as the Heck, Suzuki, and Negishi, utilize metal centers that oscillate between two oxidation states (II/0) during the three main steps of catalysis: reductive elimination, oxidative addition, and transmetallation. There has been a push to use less toxic, cheaper metal centers in catalytic cycles, leading to interest in first-row transition metals, such as nickel and cobalt. With these metals, the cycles can potentially pass through the +1 oxidation state, which acts as reactive intermediates, undergoing oxidative additions to form products, potentially with radical characteristics. The oxidative addition steps of catalytic cycles are critical to determining overall rates and products, however in many cases, these steps have not been amenable to study, in either condensed phase or gas phase, in the past. Through the use of electron transfer dissociation (ETD) technology on a modified Thermo Electron LTQ XLTM mass spectrometer, it is possible to generate intermediates in these catalytic cycles, including those in unusual oxidation states. Using sequentially coupled ion/ion-ion/molecule reactions, the reduced, reactive intermediate can be readily generated, isolated, and studied.As a model set of reactions, the mono- and bis-phenanthroline complexes of Fe(I), Co(I), Ni(I), Cu(I), and Zn(I) were formed by reduction of the corresponding M(II) species in an ion/ion reaction with the fluoranthenyl radical anion. The chemistry of the M(I) species was probed in ion/molecule reactions with allyl iodide. In order to explore ligand effects and the scope of oxidative addition reagents further, bipyridine and terpyridine were studied with these five first-row transition metal complexes while using an acetate series and other substrates for oxidative additions. Through these studies, the roles of the metal and ligand in dictating the product distributions and reaction rates were assessed. Metal electron count, ligand flexibility, and coordination number are critical factors. The overall reactivity is in accord with density functional theory calculations and mirrors that of proposed intermediates in condensed-phase catalytic cycles. In addition, second- and third-row transition metals (Ru(I), Pd(I), and Pt(I)) were explored with bipyridine, mono- and bis-triphenylphosphine, and 1,2-bis(diphenylphosphino)benzene ligation schemes. A variety of oxidative addition reagents were surveyed to determine the scope of reactivity and preference toward metal-carbon bond formation or carbon radical formation.
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Cui, Wenge Cui Wenge. „Part 1, Glyoxal-guanine DNA adducts, derivatization, structure, stability and new detection methodology ; Part 2, Nitrosation studies of oxazolines and imidazolines and the synthesis of N-cyclopropyl aromatic amines /“. free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9998477.
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Van, Allen Derek. „Methodology and mechanism: Reinvestigating the Ullmann reaction“. 2004. https://scholarworks.umass.edu/dissertations/AAI3136788.
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We have combined the tools of organometallic chemistry with those of organic chemistry, and explored methodology and mechanism of palladium and copper-based catalysis. Organometallic chemistry plays a prominent role in industrial and academic laboratories, and developments in this field continue to expand our fundamental understating of chemical reactions. Herein, we report on a specific failure of a palladium-catalyzed coupling reaction, and the subsequent development of alternative copper-based methodologies. We have developed a new cross coupling protocol for the synthesis of unsymmetrical triarylphosphines, using copper-based catalysis. Furthermore, we conducted a thorough investigation into the mechanism of the centuryold Ullmann coupling. Our mechanistic research is based on rational experimental design intended to address fundamental questions regarding copper-based catalysis. One such question is: what is the nature of the reaction intermediate( s); our data is inconsistent with copper(III) intermediates.
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Srimannarayana, Malempati. „Topics In Synthetic Methodology : From Heterocycles To Hydride Transfers“. Thesis, 2009. https://etd.iisc.ac.in/handle/2005/1992.
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This thesis, largely describing diverse studies in organic synthesis, is divided into three parts. Part I, titled ‘Heterocycles’, describes in two chapters studies directed towards elaborating certain thiazole and oxazole derivatives as useful synthons. Part II, titled ‘Hydride transfers’, describes in two chapters synthetic and some mechanistic studies involving the Cannizzaro and Tishchenko reactions, apart from work with chirally-modified alumino and borohydride reagents. Finally, Part III, titled ‘Miscellaneous studies’, describes structural studies on cyclic carbonates. (For structural formula see the abstract.pdf file.)
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Srimannarayana, Malempati. „Topics In Synthetic Methodology : From Heterocycles To Hydride Transfers“. Thesis, 2009. http://etd.iisc.ernet.in/handle/2005/1992.
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This thesis, largely describing diverse studies in organic synthesis, is divided into three parts. Part I, titled ‘Heterocycles’, describes in two chapters studies directed towards elaborating certain thiazole and oxazole derivatives as useful synthons. Part II, titled ‘Hydride transfers’, describes in two chapters synthetic and some mechanistic studies involving the Cannizzaro and Tishchenko reactions, apart from work with chirally-modified alumino and borohydride reagents. Finally, Part III, titled ‘Miscellaneous studies’, describes structural studies on cyclic carbonates. (For structural formula see the abstract.pdf file.)
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Moulins, Jonathan. „Synthesis of Heterocycles via Chemoselective Geminal Acylation of 2-Methoxyoxazolidines, E/Z Isomerization in the Metathesis of Allyl Alcohol Derivatives with a First-Generation Ruthenium Catalyst, and Interception of Nazarov Reaction Intermediates of Allenyl Vinyl Ketones with Arenes“. 2013. http://hdl.handle.net/10222/37454.
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Heterocycles were prepared through the geminal acylation of 2-methoxyoxazolidines with 1,2-bis(trimethylsilyloxy)cyclobutene. It was found that when water was excluded from the standard reaction conditions, regioselectivity of the ring expansion step was reversed, resulting in preferential rupturing of the endocyclic C-O bond instead of the C-N bond. Further cyclization resulted in the generation of 6,5-fused ring systems. The aqueous procedure was found to be applicable to 1,2-bis(trimethylsilyloxy)cyclopentene, resulting in the analogous 6,6-fused ring systems, while the anhydrous procedure failed to promote ring expansion. Tricyclic 6,5,6-fused ring systems were obtained with meso-7,8-bis(trimethylsilyloxy)bicyclo[4.2.0]oct-7-ene using the anhydrous procedure, while the intermediate generated under aqueous conditions failed to undergo ring closing. Allylic alcohol derivatives were subjected to homodimerization in the presence of a first-generation ruthenium catalyst. Previous work suggested that thermodynamic equilibration to the E-isomer was not a significant process for first-generation catalysts. However, product E/Z ratios were, in general, observed to increase significantly over time. In addition, an atmosphere of ethylene promoted reversion to the terminal olefins, leading to rapid E/Z equilibration, albeit at the expense of yield. Brief exposure to ethylene over the course of reaction resulted in a high E/Z ratio in a moderate yield. A 6,6,5-fused ring system was synthesized via the tandem Nazarov cyclization-intramolecular Friedel-Crafts alkylation of the corresponding allenyl vinyl ketone. The presence of electron donating substituents on the arene, as well as a two-carbon tether linking the arene to the allenyl vinyl ketone, were crucial to the success of the reaction. The intermolecular trapping of an allenyl vinyl ketone with substituted arenes was also investigated. Trapping occurred primarily at the electronically preferred position a, while sterically encumbered substrates tended to trap preferentially at the less hindered position c. Surprisingly, 1,3,5-trisubstituted arenes trapped almost exclusively at position a, having overcome significant steric crowding, demonstrated by hindered rotation about the newly formed carbon-carbon bond.
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(10730742), Henry J. Hamann. „Amine-Boranes: Synthesis and Applications“. Thesis, 2021.
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Reported herein is a brief summary of the history,
properties, and applications of amine-boranes. The past methods devised for
their preparation are described and the routes used to produce the compounds
used in the work presented here are detailed. Building on prior synthetic
approaches to amine-boranes, a new carbon dioxide mediated synthesis is
presented. Proceeding through a monoacyloxyborane intermediate, the borane
complexes of ammonia, primary, secondary, tertiary, and heteroaromatic amine
are provided in 53-99% yields. Utilizing the amine-boranes obtained from the
methods described, two divergent methods for direct amidation are introduced.
The first uses amine-boranes as dual-purpose reagents, where the carboxylic
acid is first activated by the borane moiety to form a triacyloxyborane-amine
complex. This allows the delivery of the coordinated amine to form the amide
products. A series of primary, secondary, and tertiary amides were prepared in 55-99% yields using this protocol, which
displays a broad functional group tolerance. Extended from this dual-purpose
methodology, a catalytic amidation is described. Utilizing ammonia-borane as a
substoichiometric (10%) catalyst, a series of secondary and tertiary amide are
prepared directly from carboxylic acids and amines in 59-99% yields, including
amines containing typically borane reactive functionalities including alcohols,
thiols, and alkenes. Amine-boranes are additionally used in two borylation
methodologies. By reaction with n-butyl lithium, the amine-boranes are
converted to the corresponding lithium aminoborohydrides, which upon reaction
with a terminal alkyne provides the alkynyl borane-amine complexes in 65-98%
yields. This process is compatible with both alkenes and internal alkynes, as
well as a range of aprotic functionalities. A new strategy for aminoborane
synthesis is also described and applied to the borylation of haloarenes.
Activation of a series of amine-boranes with iodine produces the iodinated
amine-borane, which undergoes dehydrohalogenation with an appropriate base to
produce either monomeric or dimeric aminoboranes. Several aminoboranes were
synthesized exclusively as the monomeric species, which due to their greater
reactivity, were used directly in the synthesis of a series of aryl boronates
in 65-99% yields.
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Li, Jian-yuan. „The modification of brucine derivatives as chiral ligands and its application in the asymmetric synthesis“. Thesis, 2014. http://hdl.handle.net/1805/6464.
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Indiana University-Purdue University Indianapolis (IUPUI)The modification of brucine derivatives as chiral ligands and the use of a multifaceted chiral ligand, brucine diol, under different reaction conditions to produce various optical isomers is described. In Chapter 1, the generation of a number of brucine derivatives is described. Taking the advantage of brucine-diol’s excellent molecular recognition capability for multiple organic functional groups, we focused on the synthetic modifications of brucine-diol and the synthesis of brucine N-oxide. We also produced various brucine derivatives with different functional moieties in good yields and selectivities. In Chapter 2, we described the investigation of brucine N-oxide catalyzed Morita-Baylis-Hillman (MBH) reaction of alkyl/aryl ketones. Brucine N-oxide was used as a nucleophilic organic catalyst in the MBH reaction of alkyl vinyl ketone. In addition, asymmetric MBH reactions of alkyl vinyl ketones with aldehydes were investigated using a dual catalysis of brucine N-oxide and proline. In this dual catalyst system, proline was found to form iminium intermediates with electron-deficient aryl aldehydes, while the N-oxide activated vinyl ketones provided enolates through the conjugate addition. Our dual catalysis approach also allowed the development of MBH reaction of aryl vinyl ketones. In Chapter 3, brucine diol-copper complex catalyzed asymmetric conjugate addition of glycine (ket)imines to nitroalkenes is discussed. Stereodivergent catalytic asymmetric conjugate reactions for glycine (ket)imines with nitroalkenes were achieved using various chiral catalysts derived from a single chiral source, brucine diol. Both syn- and anti-conjugate addition products were obtained with high diastereoselectivity and enantioselectivity. In Chapter 4, enantiodivergent production of endo-pyrrolidines from glycine (ket)imines using brucine diol-copper complex is described. The [3+2] cycloaddition reaction of glycine imines and activated alkenes was performed to produce endo-pyrrolidines. The reversal of enantioselectivity was observed for endo-pyrrolidines between concerted and stepwise reaction pathways. The three new brucine derivatives produced in this study would potentially work as organocatalysts and chiral ligands with metal ion in asymmetric synthesis. The brucine diol-metal complex catalyzed reactions laid a good foundation for catalytic asymmetric reactions, where a single chiral source was used to control the absolute and the relative stereochemical outcomes of reactions. Understanding the molecular-level interactions between catalyst and substrates will provide insightful mechanistic details for the stereodivergent approaches in asymmetric catalysis.