Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 14 of 14 for “"phase-transfer catalysts"”.
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Synthesis of nitrogen-containing heterocycles using nitro compounds as building blocks: Part I: Synthesis of 3-substituted azepanes. Part II: Synthesis of 1-azoniapropellanes as phase transfer catalysts
… of chiral, enantiopure 1-azoniapropellanes as phase transfer catalysts has been developed. In the first method, the tandem [4+2]/[3+2] cycloaddition of nitroalkene was applied as the key step, wherein a chiral, enantiopure vinyl ether, a nitroalkene and a vinyl ketone were rapidly assembled. …
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The Syntheses of Bis-Guanidium Salts and Their Applications in Asymmetric Mukaiyama Type SN2 Alkylation Reactions
… and successfully synthesized a new type of phase-transfer catalysts with full alkylated guanidiums as functional centers and applied these catalysts in asymmetric catalysis of 1,4-dicarbonyl compounds via Mukaiyama type SN2 alkylation reactions. Firstly, a series of bis-guanidium salts were …
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Dioxirane-mediated epoxidation of alkenes: The development of catalytic and asymmetric protocols
… biphasic conditions has been accomplished using phase transfer catalysts bearing a carbonyl group. Optimal epoxidation conditions employ 10 mol % of 1-dodecyl-1-methyl-4-oxopiperidinium trifluoromethanesulfonate (9d$\sp+$OTf$\sp-)$ in a $\rm CH\sb2Cl\sb2$/pH $7.5{-}8.0$ biphase using potassium …
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Synthesis of Resveratrol and Its Analogs, Phase-Transfer Catalyzed Asymmetric Glycolate Aldol Reaction, and Total Synthesis of 8,9-Methylamido-Geldanamycin
… relative to resveratrol (24 μM). Cinchona phase-transfer catalysts (PTC) were developed for glycolate aldol reactions to give differentially protected 1,2-diol products. Silyl enol ether of diphenylmethoxy-2,5-dimethoxyacetophenone reacted to generate benzhydryl-protected products. O-Allyl …
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Development of novel methodologies utilizing quaternary ammonium salts as catalysts
… this thesis (Chapter 3) details development of a phase transfer catalyzed [2,3]-sigmatropic rearrangement of allyloxy carbonyl compounds. Initial investigation focused on identifying viable substrate classes that would undergo selective [2,3]-rearrangement under phase transfer conditions. Under …
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Desymmetrilizing Organic Molecules via Structural Functionalization
… the design and synthesis of new chiral phase-transfer-catalysts were performed. In these days, asymmetric catalyses have been among the most interesting and active research areas in organic and pharmaceutical sciences because chiral centers exist in numerous drugs and related materials. …
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Diversity oriented, computer guided catalyst design: Application of chemoinformatics to catalysis
… and efficiently design active and selective catalysts for unsolved problems and novel transformations in synthetic organic chemistry. Chapter 2 focuses on the iterations of development that have resulted in the current chemoinformatic workflow, and Chapter 3 focuses on applications of the …
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Producing Enantiopure Secondary Alcohols via a Silylation based Kinetic Resolution and a One-Pot Polishing Sequence
… silyl ethers through the use of chiral fluoride phase transfer catalysts. Initially, desilylation was attempted with a variety of commercially available catalysts and fluoride sources including: ammonium salt catalysts with potassium fluoride, nucleophilic catalysts with benzoyl fluoride, and an …
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The chemistry of British bituminous coals : an assessment of phase transfer catalysed reactions in the determination of coal structure
… for study. Procedures were developed, using phase transfer catalysts (PTC's), to degrade the solvent insoluble fractions of the coals. PTC's are of interest because they have the potential to bring about selective high conversion reactions, under mild conditions, (often in the past, severe …
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Integrated continuous-flow chemistry enabled by multistage separations
… solvent recovery to in-line removal of phase transfer catalysts. The thesis provides opportunities for future directions. For example, improvement in unit operations, such as pumping, solid handling, evaporation, and process control, will be needed to reach the potential of flow …
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CONSTRUCTING CHIRAL CENTRES VIA O→C ARYL AND ACYL MIGRATIONS: EXPLORING REACTION POTENTIAL
… The discussion begins with the application of phase transfer catalysts, based on cinchona alkaloids, for the induction of chirality in ketone-based precursors. Further discussion continues with the synthesis of amide-based substrates from lactones and amines, and the use of C2-symmetric chiral …
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Optimalisation de la radiosynthèse et production au niveau de la curie d'acides aminés aromatiques marqués au fluor-18
… nca enantioselective synthesis using a chiral phase-transfer catalyst requires some chemicals (i.e. corrosive HBr gas) arduous to handle and store and reactions at low and high temperature (0°C, 200°C) difficult to implement into a commercially available synthesizer. Important chemical …
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Asymmetrische Weitz-Scheffer-Epoxidierung mit optisch aktiven Hydroperoxiden oder Phasentransferkatalysatoren
… den Mechanismus des enantioselektiven Sauerstofftransfers aufzuklären. In einer weiteren Studie werden Chinconin- und Chinconidin-abgeleitete optisch aktive Phasentransferkatalysatoren (PTK) IV zur asymmetrischen Epoxidierung von Enonen II mit racemischen Hydroperoxiden I genutzt, wobei …