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 25 for “"Polyenes"”.
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Feynman-Dyson perturbation theory applied to model linear polyenes
… insertions. The results of calculations on polyenes show that consideration of this approach is warranted, as the contribution of the second- order terms is significant. The computer program, written during the course of the research reported here, is discussed as well.
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Polyenes by regioselective, living polymerization using molybdenum alkylidene bis(carboxylate) initiators and Ziegler-natta catalysis employing new zirconium diamido complexes
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1997.
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Total synthesis and study of the antilipoperoxidant peridinin, synthesis of versatile MIDA boronate building blocks, and a general strategy for the synthesis of polyenes
Taking advantage of the inherent modularity present in the majority of small molecule natural products, we envision that a building block based approach involving the iterative cross-coupling of MIDA boronate containing molecules can be a universal platform for the preparation of small molecules. …
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The Synthesis, Characterisation and Electrical Conductivity of Poly(Styrene-Co-Acetylene)
… been made to synthesise polyacetylene oligomers (polyenes) by modifying the Ziegler/Natta type catalysts commonly used to synthesise polyacetylene. The polyenes were characterised using U.V./Visible and infra-red spectroscopy together with GPC and GCMS.
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Structural Characterisation and the Diagenetic Pathways of C25 Highly Branched Isoprenoid Hydrocarbons
… isolation and characterisation of five HBI polyenes. The stereochemistry of the chiral centres was not reported however. The concentrations of HBIs often decrease with depth in sediment cores but the reasons for this are unknown.
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Discovery and development of novel antifungal agents for the treatment of Candida auris infections
… three main classes of antifungal drugs: azoles, polyenes, and echinocandins. The emergence of new fungal species, such as Candida auris, which displays high resistance and mortality rates (30-60%), has further complicated treatment efforts. Thus, there is a critical need for new therapeutic …
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Oxidative Heck Reactions with Terminal Olefins
… to generate linear E-arylated olefins. Polyenes are prevalent motiefs in natural products and pharmaceuticals. Polyene functionality often requires mild and selective synthetic methods. The Heck vinylation uses orthogonally reactive C-H bonds and these bonds are often easy to carry …
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Advances in Multiconfiguration Pair Density Functional Theory and Applications to Excited State, Singlet-Triplet Gaps and Magnetism
… such as singlet-triplet gaps in polyacenes and polyenes. Finally, the challenges in MC-PDFT have been explored and active-space dependence of MC-PDFT energy and other components is investigated.
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Enantioselective, Lewis base-catalyzed transformations: I. Polyene sulfenocyclization (preparative and mechanistic aspects) II. Sulfenofunctionalization of alkenyl boronates enabled by 1,2-boronate migration
… enantioselective sulfenocyclization of polyenes (Chapter 2). Sulfenyl group transfer from a highly reactive, cationic, Lewis acid-base adduct to an unactivated alkene generates a cyclic thiiranium ion, which serves as the initiating event for a highly stereoselective polyene cyclization …
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Synthesis and properties of novel macrocycles and related chromophoric benzenoid compounds
… electronic systems such as heteroaromatics and polyenes. An extensive collaborative study of chromophore formation in resorcinarene solutions is also described here. The study reveals that upon oxidation, the reversible conversion to acyclic precursors occur first, and then these precursors …
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Unravelling the impacts of palaeoecology, palaeoenvironment and lithofacies on sedimentary organic NSO compounds
… C30 or C25 highly branched isoprenoid (HBI) polyenes. The strong enrichment of sulfurized C35 bacteriohopanepolyols can be developed as an indicator of the low levels of oxygen exposure prior to sulfurization, which occur only in the Dynow and Schöneck formations. The prominent enrichment of …
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Developing novel drug combinations for treatment of invasive fungal infections
… to three classes of antifungals: Azoles, polyenes, and echinocandins. The emergence of new fungal species, especially C. auris, marked by high resistance profiles and increased mortality rates (30-60%), has further exacerbated the limitations in its therapeutic options. This emphasizes the …
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Catalysis, Synthesis, and Materials in Support of Chemical Understanding and Global Health
Chapter 1: Skipped polyenes featuring high (E)-selectivity and varying methyl substitution patterns are synthesized using a nickel-catalyzed cross-coupling reaction between allyl trifluoroacetates and vinyl bromides. The utility of this cross-electrophile coupling is showcased in part by the …
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Applications of electronic structure theory to problems in strong-field chemistry, inorganic chemistry, and nanomaterial systems
… strong-field ionization of a series of linear polyenes of increasing length: ethylene, butadiene, hexatriene, and octatetraene. Also tested is the ionization dependence on parameters of the ionization model, basis set size, and number of states included in the simulation.</p> <p> Chapters 5-7 …
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Targeting the Rho1 GTPase signalling pathway in <i>Aspergillus fumigatus</i>
… is dominated by three antifungal classes. Polyenes and azoles target the fungal cell membrane, and echinocandins target β-glucan synthesis in the fungal cell wall. However, they all have significant drawbacks in terms of toxicity, drug-drug interactions and/or efficacy.<br/><br/>The current …
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"Sugar Coat" Genetic & chemical validation of <i>Aspergillus fumigatus</i> cell wall targets
… is limited to three antifungal classes (polyenes, triazoles and echinocandins) all of which have significant contraindications in terms of toxicity, drug-drug interactions and/or efficacy. With no new antifungal classes in late stage clinical trials what is required is the …
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Upcycling of Polystyrene, Polyolefin, and Polyvinyl Chloride Waste into Chemicals, Surfactants, and Lubricants
… reactions that would otherwise produce low-value polyenes. The results reveal that PVC undergoes dechlorination, chain scissions, and alkylation in the presence of AlCl3 at 70 °C, furnishing polyalphaolefin mimics of controlled viscosity and no polyene byproduct. The rheological and tribological …
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Total Synthesis of Marine Macrolide Mangrolide D
Total synthesis of mangrolide D is described in this dissertation. A highly convergent 16-step total synthesis has been accomplished, featuring three robust and interchangeable bond forming reactions: Suzuki cross coupling, ring closing metathesis and α-selective glycosylation reaction. The …
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