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 20 for “"Stereochemical Control"”.
-
Stereochemical control in lanthipeptide biosynthesis
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2025-05-01
-
Chemistry and synthesis of 3(2H)-furanones and 4,5-dihydro analogues: mechanistic investigations and stereochemical control
The subject matter of this thesis relates to the chemistry of the five-membered oxygen heterocycles – 3(2H)-furanones and their 4, 5-dihydro analogues. Chapter one of the thesis is a review of the relevant chemistry of the compounds: their synthesis and key transformations. In chapter two, new …
-
I. Stereochemical Control of Chiral Assembly and Liquid Crystal Phase Formation of Nonamphiphilic Molecules in Water II. Control Bacterial Quorum Sensing and Quorum Sensing-mediated Activities Using Small Unnatural Molecules
… mesogens.</p> <p>Chapter 2 presents a study of stereochemical control on assembly and liquid crystal formation by nonamphiphilic molecules. Three stereoisomers of a disodium chromonyl carboxylate derivative, 5´DSCG-diviol, were designed and synthesized. The chiral stereoisomers formed chiral …
-
Stereochemical aspects of virginiamycin biosynthesis: biosynthesis of antibiotic A33853
… found to be precursors, thus giving evidence of stereochemical control in the formation of the oxazole moiety. This information allowed for postulation of a ring closure pathway. Stereochemical investigations were also carried out on the dehydroproline unit and it was shown that both (R) and (S) …
-
Total Synthesis of Oligomeric Cyclotryptamine Alkaloids
I. Total Synthesis and Stereochemical Assignment of (–)-Psychotridine We report the first enantioselective total synthesis and stereochemical assignment of (–)-psychotridine. The application of our diazene-directed assembly of enantiomerically enriched cyclotryptamines afforded a highly convergent …
-
SYNTHETIC STUDIES ON THE SAFRAMYCINS A, B AND S: A TOTAL SYNTHESIS OF SAFRAMYCIN B
… are the convergent approach and the method of stereochemical control. Studies directed towards adapting the saframycin B synthesis to the synthesis of saframycins A and S are also described. These studies have resulted in the synthesis of a compound structurally related to the saframycins but …
-
Self-Assembly of Enantiopure Subcomponents into Functional Metal–Organic Cages
… in this thesis aims to explore methods of controlling the stereochemistry of cages by incorporating enantiopure building blocks into the structures to synthesise enantiopure cages. In chapter 2 and 3, an enantiopure subcomponent was synthesised and differing degrees of stereochemical …
-
The synthesis of pyrrolizidine alkaloids
… was also prepared. The synthetic route gave good stereochemical control of the key asymmetric centers. Completion of the synthesis requires only reduction of a methyl ester and removal of a mesityl protecting group.</p>
-
Synthesis of Dimeric Pyrrole-Imidazole Alkaloids
… ageliferin skeleton to massadine skeleton with stereochemical control, followed by an oxidative cyclization to construct the oxo-bridge. An asymmetric total synthesis of ageliferin is described, featuring an early installation of 2-azidoimidazole for the oxidative radical cyclization and a …
-
Silicon-Directed Nazarov Cyclization
… in good yields with predictable and complete control over the position of the double bond. An extensive study of the scope, mechanism, and stereochemical outcome of the reaction is also reported. This variant of the Nazarov cyclization is quite general for the preparation or annelation of …
-
Synthesis of pyrrolizidine diols via azide-diene cycloadditions
… carried out. Conclusive results regarding the stereochemical control of the C-7 substituent were attained and used for the formal stereospecific syntheses of pyrrolizidinediols 8, 9, 10, and 11. The possibility of asymmetric induction was also investigated, and was realized in the microbial …
-
Use of organocatalysts in stereoselective organic synthesis
… direct aldol reactions with reasonable stereocontrol. - After, we synthesized 2,3-disubstituted cyclobutanones through direct aldol reactions involving 3-substituted cyclobutanones and aryl aldehydes catalyzed by N-phenylsulfonyl (S)-proline and via asymmetric nitro-Michael reaction of …
-
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
… to Michael acceptors as the key strategy. Stereochemical control was achieved by the application of Corey-Itsuno reduction of the nitro diketone intermediate. Starting from nitromethane and -chloropropiophenone, rapid access to 2,8-diphenyl-1-azoniapropellane and …
-
Development of novel polymeric architectures for applications in drug delivery and studies towards the synthesis of perfect polymers by iterative exponential growth "Plus" (IEG+)
… glycol) (PEG) macromonomer, provided highly controlled BASP formation reactions. Combination of this new crosslinker with a novel acid-labile doxorubicin (DOX)-branch-PEG macromonomer provided BASPs that simultaneously degrade and release DOX in cell culture. In vitro cell viability studies …
-
A total synthesis of aphidicolin
… as acceptors demonstrated that considerable stereochemical control may be exercised over the Michael reaction. In addition to work on the Michael reaction, the utility of a novel annulation procedure was demonstrated in the one-pot construction of the AB rings of aphidicolin. The required …
-
Optimisation of chemoenzymatic processes in asymmetric synthesis
… chapter a summary of literature discussing the stereochemical control of baker’s yeast (Saccharomyces Cerevisae) mediated reduction of ketones by the introduction of sulfur moieties is presented, and sets the work of Chapter 2 in context. The focus of the second chapter was the synthesis and …
-
Design and Application of Nanostructured Flavin Photocatalysts
… of industrially relevant products with precise stereochemical control. This thesis details the design and application of novel flavin photocatalysts through the combination of polydopamine (PDA). It is shown that PDA not only acts as a carrier of the flavin, but actively engages in the catalytic …
-
The Synthesis and Photophysical Properties of New Polymetallic Complexes Designed for Use in Photoinitiated Electron Collection
The goal of this research was to develop stereochemically defined multimetallic systems for use as light absorbers and electron donor / light absorber dyads in photoinitiated electron transfer and electron collection. The basis for the stereochemical control was provided by the symmetric bridging …
-
Radical based molecular design of discrete and stereoregulated oligomers via photomediated RAFT single unit monomer insertion (photo-RAFT SUMI)
… have dedicated themselves to achieve such dual control during the synthesis of synthetic polymers in order to emulate such structurally perfect biopolymers. Despite the success of directly utilizing natural monomers (nucleotides and amino acids) to create such macromolecules, researchers are now …
-
Exploring the Structural, Magnetic, Optical, and Catalytic Properties of High-Spin Materials
… studies using cyclohexene oxide demonstrate stereochemical control and unique reactivity pathways. The catalytic performance varies with the 4f metal and counterion, demonstrating the modularity and adaptability of these systems for green chemistry applications.