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.
Results
Showing 1 to 20 of 21 for “"phase transfer catalysis"”.
-
Phase transfer catalysis: catalyst screening, reaction development, and mechanism analysis
… of a [2,3]-Wittig rearrangement under phase transfer catalysis (PTC) reaction conditions was investigated. Supplementing these studies, a deeper understanding of the PTC mechanism was sought for the alkylation of phenol. In regards to the asymmetric PTC (APTC) alkylation, a small …
-
An investigation of phase transfer catalysis employing quantitative structure-activity relationships
… quantitative structure activity relationships to phase transfer catalysis (PTC) has been explored. The primary focus was on hydroxide-initiated PTC reactions, such as enolate alkylations. The tandem [4+2]/[3+2] cycloaddition of nitroalkenes was applied as the key transformation in the preparation …
-
I. Catalyst development in asymmetric phase transfer catalysis employing QSAR methods II. Computational investigations on the stereochemical course of the addition of allylsilanes to aldehydes
Part I of this dissertation describes the investigation in APTC employing a chemoinformatic analysis of the alkylation of a protected glycine imine with libraries of enantiomerically enriched quaternary ammonium ions. The synthesis of the quaternary ammonium ions follows a diversity oriented …
-
Interactions of Nitrated Aromatics With Electron Rich Species: Chiral and Achiral
… of Meisenheimer complexes under conditions of phase transfer catalysis helped to rationalize the enantioselectivity observed in these systems. Quaternary ammonium cations are identified as stabilizing factors for the negatively charged Meisenheimer complexes in non-polar organic solvents. The …
-
Palladium-Imidazolium Carbene Catalyzed Heck Coupling Reactions and Synthesis of a Novel Class of Fluoroanthracenylmethyl PTC Catalysts
… catalyst or for alkene product formation. Phase-Transfer Catalysis (PTC) is a very useful approach and has been widely used in synthetic organic chemistry. A novel class of fluoroanthracenylmethyl PTC catalysts were synthesized and explored for asymmetric glycolate and glycine alkylation. …
-
An approach to catalytic asymmetric electrocyclization
… for [1,5]-electrocyclization using chiral phase-transfer catalysis. These reactions afford the electrocyclized products in excellent yield and diastereoselectivity with enantiomeric excess up to 68 %. These transformations offer a glimpse of the potential of electrocyclic reactions. In …
-
Development of Micro to Milli-Scale Multiphase Reactors with and Without Solids for Integration Into Mini-Monoplants
… larger scale vessels inherit both reduced heat transfer through a loss in surface-to-volume ratio, and decreased mass transfer through solvent dilution. As a result, pharmaceutical production processes are often run at suboptimal efficiency with large amounts of waste relative to the amount of …
-
Desymmetrilizing Organic Molecules via Structural Functionalization
… Particularly, those associated with asymmetric catalysis are actively pursued and published in nearly all organic related journals widely. Obviously, desymmetrization chemistry can serve as powerful tools for many important synthesis processes. Those reactions that benefited from …
-
Synthesis of multicyclic ring systems including an alternate route to Meyers’ lactam derivatives
… through a central C5 to axial chirality transfer. The aim of this project will be directed towards the design of alternative strategies in the synthesis of keto-ester Meyers’ lactam derivatives. Leading on to provide new atropos derivatives bearing different substituents to envisage them …
-
Geochemical Aspects of Waste Disposal
… characterisation are reported in this work. Phase-transfer catalysis is used to convert phenols to ethers in the presence of montmorillonite. Extension of this method to other systems of chemical interest are described. The interaction of different copper(II) compounds with montmorillonite …
-
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 …
-
Total Syntheses of (+)-Geldanamycin, (-)-Ragaglitazar, and (+)-Kurasoin A and Phase-Transfer-Catalyzed Asymmetric Alkylation
… glycolate alkylation has been developed using phase-transfer-catalysis (PTC). Diphenylmethoxy-2,5-dimethoxyacetophenone with trifluorobenzyl cinchonidinium catalyst and cesium hydroxide provided alkylation products at —35 °C in high yield (80-99%) and with excellent enantioselectivity (up to …
-
Studies in organobismuth chemistry
… including the use of mathematical reactions, phase-transfer catalysis and microwave energy. The preparation of a range of trivalent and pentavalent organobismuth carboxylates is reported and their infra-red , 13C, lH nmr spectra. The compounds were evaluated as paint driers and in cases found …
-
I. Facile preparation of ortho-fluorophenols from non-aromatic precursors and investigation of applications to fluorine-18 labeling II. Resin-supported silyl ester precursors for kit-like radiolabeling with fluorine-18
… radiolabeling was achieved using organic soluble phase transfer catalysis under carrier-added conditions. Although labeling under non-carrier-added conditions is still a work in progress, our current progress points to a new approach to label electron-rich aromatic rings rapidly and at high …
-
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 …
-
Harnessing cheminformatics for catalyst design I. Investigation into a general, asymmetric synthesis of cinchona alkaloid analogs towards asymmetric phase transfer II. Development of an enantioselective brønsted acid catalyzed four-component Ugi reaction
… alkaloids were studied against an asymmetric phase transfer catalyzed cyclopropanation reaction. Second, (R)-BINOL derived phosphoric acids were studied in regards to the brønsted acid catalyzed Ugi reaction. In regards to Cinchona alkaloids, the concentration was first on methodology develop …
-
Organocatalytic asymmetric mannich-type reactions: an easy approach to optically active amine derivatives
… to obtain the aza-Henry adducts, by using chiral phase transfer catalysis, with a broad range of substituents as R-group and excellent results, unprecedented for Mannich-type transformations (Scheme II). With the optimised protocol in hand we have extended the methodology to the other Mannich-type …
-
Exploration of Carbon-oxygen and Carbon-nitrogen Bond Formation Utilizing Trichloroacetimidates and Investigations of New Reactions Mediated By Oxoammonium Salts
… in an enantioselective manner utilizing anionic phase transfer catalysis. Expansion of the N-oxoammonium salt mediated additions of alkenes with primary alcohols, water, and isatin was also initiated.</p>
Page 1 of 2