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 20 of 42 for “"organocatalysis"”.
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Hemiaminals : a new chemotype for organocatalysis
Jorgensen and List introduced enantioselective α-amination of an aldehyde with an azodicarboxylate as the electrophile using L -proline enamine catalysis in 2002. Following borohydride reduction, the α-hydrazino alcohol was obtained in high yield (93-99%) and enantioselectivity (86-97%). …
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Mechanism-Guided Studies of Brønsted Acid and Base Organocatalysis
We have studied the mechanism of the reaction of N-Boc imines and acetylacetone in the presence and absence of chiral phosphoric acid catalysts. In order to gain mechanistic insight into the asymmetric Mannich reaction, a structurally homologous series of N-Boc imines and BINOL-derived phosphoric …
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Studies in Synthesis and Organocatalysis: (i) The Design and Synthesis of Novel Electron Deficient Dienes and their Application in the First Enamine Activated Organocatalytic 1,6-Conjugate Addition. (ii) The Development of a New Organocatalytic Methodology through the Combination of DNA-Based Catalysis and Organocatalysis
A novel approach to substrate design led to the development of charge de-localized extended Michael acceptors. Using this methodology a family of both alkyl and aryl bis-phenylsulfonyl butadienes were synthesised and characterised. The first enamine activated organocatalytic 1,6- conjugate addition …
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Designing and optimizing tandem bio- and chemo-catalyzed cascade reactions to access industrially relevant chemicals in mild, aqueous conditions
… biosynthetic means alone. The recognition of organocatalysis as a distinct field in the early 2000s sparked a flood of new research featuring small organic molecules as catalysts. These small molecule catalysts work in ambient conditions and are typically non-toxic and environmentally …
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Design and Synthesis of Chiral Triazolium and Thiazolium Salts Incorporating Hydrogen-Bonding Motifs as Organocatalysts
… condensation is the rst reported example of organocatalysis, and has been studied and used in organic synthesis for over 200 years. Originally catalysed by the cyanide anion, the reaction can also proceed with thiamine as a catalyst. Since then, many N- heterocyclic carbene (NHC) catalysts …
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ASYMMETRIC ORGANOCATALYTIC HENRY REACTION OF β–SUBSTITUTED α-KETO ESTERS VIA DYNAMIC KINETIC RESOLUTION
… catalysis. Particularly, the asymmetric organocatalysis is introduced in detail. Then the historical background and development of dynamic kinetic resolution are summarized, especially, those organocatalytic methods are introduced in detail. In Chapter 2, the diastereo- and …
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Development of New Organic Photoredox Catalysis Driven by Visible Light
… in modern organic synthesis. In recent decades, organocatalysis has become one of the viable tools in organic synthesis with notable features including easy manipulation, low cost, and/or less susceptible to air and moisture. Organophotoredox catalysis has merged as a front runner in …
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New axially chiral amine organocatalysts
Organocatalysis has become one of the most popular areas of research within organic chemistry over the past 15 years. This is due to the fact that, usually under mild conditions, it is possible to access either highly functionalized or previously inaccessible structural motifs using this relatively …
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Carbonyl Catalysis: Hydrolysis of Organophosphorus Compounds and Application in Prebiotic Chemistry
Since late 1990s, organocatalysis has been widely explored in many aspects and achieved various difficult transformations. In this field, carbonyl catalysis, which could be traced back to 1860 has been developed with impressive progress including asymmetric variants. Over the years, major …
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Sintesi di molecole organiche enantiomericamente arricchite con l'uso della catalisi organica
The main topic of this thesis is the use of organocatalysis to synthesize organic compounds enantiomerically enriched. The first matter is about the synthesis of α-amino thioester derivatives through a tandem condensation-intramolecular rearrangement-protonation, this is a conceptually novel chiral …
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NEW GREEN TECHNOLOGIES FOR ORGANOCATALYTIC ASYMMETRIC EPOXIDATION APPLICATIONS IN SYNTHESIS
… brief introduction and historical background of organocatalysis, chromene substrates and asymmetric epoxidation reactions. Towards the end of the chapter, several examples are described of past and current development of asymmetric epoxidation by organocatalysts. In the last part of Chapter 1, …
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Use of organocatalysts in stereoselective organic synthesis
The main topic of thesis is the use of organocatalysis to synthesize cyclobutanones derivatives. Cyclobutanone derivatives are useful molecular building blocks for the construction of complex molecular structures. Surprisingly, however, the use of organocatalysts to functionalize cyclobutanones is …
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Synthesis of novel cycloperoxides
… be the focus of this thesis, specifically using organocatalysis. Chapter 1 contains a review of organocatalysed peroxidations from the literature and within the research group to date. The key aims and objectives of this project are also outlined. Chapter 2 describes the generation of a diverse …
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EXPLORING UNPRECEDENT SYNTHETIC ROUTES FOR CHIRAL AMINO DERIVATIVES
… through the integration of photoredox catalysis, organocatalysis, transition-metal catalysis, and continuous-flow chemistry. The work explores the synthetic potential of light-driven processes to access reactive open-shell intermediates under mild and sustainable conditions, enabling …
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Methodology studies on the synthesis of chiral, non-racemic aza-quaternary centres
… of the Chapter the emphasis shifts to using an organocatalysis approach involving an ephedrine -hydrazide organocatalyst in conjunction with enantioselective amination methodology using an azodicarboxylate. Chapter Three shifts to a substrate -controlled approach based on using chiral malonate …
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NH-Isoxazolidines as Organocatalysts
… chapter gives an overview of state-of-the-art organocatalysis. Reactions are discussed in terms of the catalytic mechanism and a selection of reactions catalysed by each route is included. The second chapter discusses the design of two generations of N-unsubstituted isoxazolidine frameworks as …
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Synthesis and antibacterial evaluation of diverse small molecules
… and Staphylococcus aureus. First we extend organocatalysis to the field of diversity-oriented synthesis as a powerful means to generate molecular diversity and complexity in small molecule screening collections. We then study a family of potential biofilm inhibitors identified from a diverse …
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An Exploration of Ion Pairing Interactions as a Tool to Control Regioselectivity in Iridium-Catalysed C–H Borylation
… success seen by ion pairing in enantioselective organocatalysis, this interaction has rarely been used for other types of selectivity, such as positional selectivity. This thesis explores the possibility of implementing ion pairing in transition metal catalysis for control of regioselectivity. …
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Catalytic and Biological Applications of Benzoxaborolones
… and makes them of particular interest for organocatalysis and in chemical manipulation of biological systems. In Chapter 2, I describe the development of an organocatalytic process for the conversion of biomass-derived sugars to 5-hydroxymethylfurfural. Building on previously reported …
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Addressing the ongoing threat of antimicrobial resistance: synthetic investigations of novel amicetin and B-lactam antibiotics
… and green chemistry techniques such as organocatalysis and visible-light photocatalysis, which were utilized to synthesize the relevant compounds described in this study. Chapter 2 provides background on the natural antibiotic, amicetin, and a current literature review on the synthesis …
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