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Showing 1 to 18 of 18 for “"Pyrans"”.
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The synthesis of some naphthol (2,3-c) pyrans
Bibliography: p. 60-61.
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Synthesis of naphtho{2,3-c}pyrans including the aphin-derived quinone A'
Chapter One describes the synthesis of a trifluoroethylnaphtho-1, 4-quinone via a regiospecific trifluoroacetylation of an appropriately substituted naphthalene. Chapter Two describes the synthesis of the methyl ethers of the naturally occurring quinones A and deoxyquinone A for evaluation of their …
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i) Design and Synthesis of Butadiene Substrates for Organocatalytic Transformations ii) Synthesis of Functionalized Biaryls and Pyran Derivatives
… this thesis details the synthesis of 2-amino-4H-pyrans from the conjugate addition of malononitrile to aryl formyl acrylonitriles and the synthesis of 3,4 dihydro-2H-pyrans through Inverse Electron Demand Hetero-Diels-Alder (IEDHDA) cycloaddition reactions. An asymmetric variant of the synthesis …
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Syntheses related to some naturally occurring naphthopyranquinones
… - the latter affording several naphtho[2,3-c]pyrans in high yield. Previous routes to (±)-isoeleutherin and (±)-deoxyquinone A dimethyl ether have been recorded, but they give rise to a mixture of eleutherin and isoeleutherin in the first case, and a mixture of deoxyquinone A dimethyl ether …
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Applications of the achmatowicz rearrangement in natural product synthesis
… of a-hydroxyisobenzofurans. Spirocyclic pyrans such as Polymaxenolide are structurally complex molecules, containing large amounts of functionality. The biological activity of Polymaxenolide is unknown and there have been no total syntheses reported to date.
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Studies in Naphthopyran chemistry
… epoxidation of the double bond, the naphthopyrans are more reactive than the corresponding benzopyrans. Particular reactivity was exhibited by the [1,2-b] and [2,3-b] systems, which were also prone to electrophilic attack in the naphthalene moiety. Ring opening reactions of the …
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Some benzo- and naphtopyrans by novel cyclisations
… cyclise to afford naphtho[2,3-c]pyrans when treated with two molar equivalents of cerium(IV) ammonium nitrate. It has also been shown that these naphthalenes cyclise readily and in high yield to give naphthopyrans when treated with potassium-t-butoxide in dimethylformamide under …
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Palladium (II) / sulfoxide - promoted strategies for efficient and selective allylic C-H oxidations
… heterocycles (chromans, isochromans, and pyrans). The discovery that a wide range of alcohols were competent nucleophiles under uniform reaction conditions (catalyst, solvent, temperature) highlighted the generality of the method. From mechanistic studies, we have hypothesized that the …
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The synthesis of derivatives of naturally occurring naphthalenes
… in the formation of two angular naphtho[l,2-c]pyrans with the same relative stereochemistry of the pyran ring. An interesting bromine migration occurred after isomerisation had taken place. However, it is suggested that decreasing the size of the C-4 protecting group on the naphthalene nucleus …
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Novel Conjugate Additions and Cyclizations on Multiyne Systems
… with an O-nucleophile to generate 2-methylene-2H-pyrans. In the second approach, a zwitterionic intermediate generated from acetyl ketene and DABCO undergoes a Michael addition with terminal alkynyl ketones, followed by ring closure to form 3-acyl-substituted 4-pyrones. Chapter 4 provides a novel …
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Polymer pyrolysis and oxidation studies in a continuous feed and flow reactor : cellulose, polystyrene, and polyethylene
… C are carbonyl compounds, hydrocarbons, furans, pyrans, and anhydrosugars. Cellulose in the presence of NaCl (5% of Cl) shows higher decomposition of levoglucosan and more rapid conversion of major initial products to CO and CO_2. Formation of major initial products, C_6 oxygenated species, …
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Multi-Configurational Investigation of Thermolytic Pathways of Highly Strained Ring Systems
… was explored in more detail for several trans pyrans and pyridines and also for trans cyclohexene and several of its functional isomers. The ground state geometries for each structure were computed using the multi-configurational self consistent field method (MCSCF) with a cc-pVDZ basis set, …
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Investigations of benzothienopyrans and related compounds
… benzothieno[2,3-b]- and [3,2-b]- pyrans has been investigated. The [2,3-b] isomers exist preferentially as their dienone valence tautomers. In the latter series, the pyran form predominates and the compounds exhibit photochromism providing that an aryl substituent is present at …
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Total Synthesis of the Unique Pederin Family Member Psymberin & Chemical Studies Toward Saliniketal Family Members: Saliniketal a, Salinisporamycin and Rifsaliniketal
This manuscript consists of six chapters. The first four chapters involve the psymberin/irciniastatin A project. Psymberin was isolated from a psammoncinal sponge possessing an unprecedented differential cytotoxicity profile, whereas irciniasatin A was isolated from the marine sponge Ircinia ramose …
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Selective C—H oxidations for complex molecule synthesis and diversification
… protected 1,2-diols, polyoxidized motifs and syn-pyrans). This work represents a novel application of C—H oxidation to achieve synthetic versatility. A highly selective intermolecular oxidative Heck vinylation is also described that forms di- and polyenes from simple α-olefins. Notably the Heck …
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Nucleophilic Carbon-Carbon Bond-Forming Reactions of 2-Methylenetetrahydropyrans
<p>Reactions with 2-methylenetetrahydropyrans are underutilized in the literature, especially with respect to general methods demonstrating their nucleophilic nature. This work provides three general methods toward the synthesis of 2-β-oxygenated pyranyl substrates, which are key structural …
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Synthese von Cyclopenta[c]pyran-3(5H)-on und Cyclopenta[c]pyran-3(7H)-on als Vorstufen von Cyclopenta[c]pyranen
Die bisher unbekannten a-Pyrone Cyclopenta[c]pyran-3(5H)-on und Cyclopenta[c]pyran-3(7H)-on wurden auf zwei unabhängigen Synthesewegen hergestellt. Die Reaktivität der neuen a-Pyrone wurde untersucht. Das Hauptaugenmerk lag dabei auf der Synthese von Cyclopenta[c]pyranen.