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 68 for “"heterocycle"”.
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Multicomponent Heterocycle Syntheses Based upon Sonogashira Coupling-Isomerization
Die Studien zur Optimierung der Kupplungƒ{Isomerisierungsƒ{Reaktion (KIR); Eintopf, MultikomponentSynthese von Heterozyklen
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Donor-Acceptor Cyclobutanes and Their Application for Heterocycle Synthesis and Progress Towards Biselide A
The chemistry of cyclobutane-1,1-diester has been investigated with aldehydes and alkyne reaction partners independently of each other. Under Yb(OTf)3 catalysis donor-acceptor cyclobutanes undergo a formal [4+2] cycloaddition with aldehydes to generate tetrahydropyrans exclusively in a cis …
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Development and applications of copper(I) hydride catalysis in asymmetric reactions and heterocycle synthesis
… patterns, sensitive functional groups and heterocycles are tolerated in this reaction, which significantly expands the range of accessible products compared to existing hydroacylation methodology. Although mechanistic studies are ongoing, we propose that CuH-catalyzed silylation of …
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New explorations in visible-light mediated energy and single electron transfer for nitrogen heterocycle synthesis
… of biologically important nitrogen containing heterocycles, investigating both single electron transfer and energy transfer methods. The results section of this thesis is presented in three chapters, each focusing on a different ring size, namely 4, 5 and 6 membered nitrogen heterocycles. …
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Stereoselective Heterocycle Synthesis via Alkene Difunctionalization: Bulky Phosphine Ligands Enable Pd-Catalyzed Arylhalogenation, Arylcyanation and Diarylation
… in organic chemistry has been developing new heterocycle syntheses. Research in the Lautens group has led to many advances in this field, specifically using Rh and Pd as catalysts. Our group recently discovered the Pd-catalyzed aryliodination reaction which proceeds via a challenging C(sp3)–I …
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On the biosynthesis and discovery of ribosomally synthesized and post-translationally modified peptides
… (RiPPs) that all contain thiazole and oxazole heterocycles derived from cysteine, serine, and threonine residues, respectively. The thiazole/oxazole heterocycle is installed over two distinct steps. First, the cyclodehydratase cyclizes an unmodified cysteine, serine, or threonine residue to a …
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The Study of Au(III) Compounds and their Interaction with Zinc Finger Proteins
… expanded this system to Au(III)-(nucleobase/N-heterocycle) compounds. Novel Au(III)(dien)(N-heterocycle) compounds, including the first Au(III)N3(N-purine) examples, were synthesized. As previously reported for [AuCl(dien)]Cl2, these compounds exhibit pH dependency of the 1H NMR chemical shifts …
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The use of organotellurium heterocycles as precursors for novel organometallic compounds
The reactions of group 16 heterocycles with organometallic reagents are described. Thiophenes have been used as models for organic sulfur in coal and their reactivity towards triiron dodecacarbonyl has been investigated. Reaction of unsubstituted thiophene with Fe3(CO)12 results in desulfurisation …
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Modified Purines. Rearrangement Through 5-Substituted Purine Intermediates
… (b) since substitution at C(5) of the monocyclic heterocycle results in substitution on C(8) in the corresponding imidazo{1,5-a}-1,3,5-triazine. Incorporation of a ribosyl unit or analogous moiety at the C(5) position of the monocyclic heterocycle could give, after cyclization-rearrangement, …
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Synthesis of pyridines and azaindoles via Diels-Alder reactions of tosyl cyanide with vinyl- and heteroarylallenes
Pyridines are an important class of heterocycle with widespread applications in a variety of areas. The efficient synthesis of highly substituted pyridines is an ongoing goal of modem synthetic chemistry. Part I of this thesis describes a new synthetic strategy for the synthesis of highly …
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Synthesis of 2(3H)-furanones via electrophilic cyclization
… functionally-substituted heterocycles and carbocycles. A variety of highly substituted 2(3H)-furanones are readily prepared from 3-alkynoate esters and the corresponding acids via electrophilic cyclization. This highly efficient approach proceeds under mild conditions, …
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Biosynthetic engineering of plantazolicin natural products
… enzymes were exquisitely selective, installing heterocycles only at predefined positions within the precursor peptides while leaving neighboring residues unmodified. Nearly all substitutions at positions normally harboring heterocycles prevented maturation of a PZN variant. No variants …
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Synthesis of Partially Saturated Bicyclic Heteroaromatics: sp3-Enriched Scaffolds for Drug Discovery
… patterns, variation of the 5-membered heterocycle (Figure i, green) and increased size of the saturated ring (Figure i, blue). Furthermore, careful selection of the substituents, heterocycle and size of the saturated ring would enable the synthesis of screening libraries within the …
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SYNTHESIS OF N-HETEROCYCLES VIA PALLADIUM-CATALYZED REDUCTIVE CYCLIZATION REACTIONS OF NITROARENES AND NITROALKENES USING FORMIC ACID DERIVATIVES AS CO SURROGATES
… cyclization reaction of nitroarenes to produce N-heterocycles has been investigated for more than four decades using CO as a cheap reductant, but it is still a fascinating area for research and advancements. On the other hand, using toxic CO gas is accompanied by many disadvantages. Thus, the …
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The Multicomponent Synthesis of Pyrroles from Cylcopropane S Using a One Pot Pd(0) Catalyzed Dehydrocarbonylation Protocol
… cyclopropane diester. This affords the desired heterocycle efficiently with a wide variety of substitution. When one esters bears an allyl group a Tsuji dehydrocarbonylation reaction may take place resulting in the formation of a 4,5-dihydro-1,2-oxazine. This motif contains a vinylogously acidic …
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Synthesis of pyridines via [4 + 2] cycloadditions of vinylallenes with azadienophiles
Pyridines are an important class of heterocycle with widespread applications. However, the efficient preparation of substituted pyridines remains a challenge in organic synthesis. This thesis describes new annulation strategies for the synthesis of highly substituted pyridines that involve [4 + 2] …
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Quantitative structure activity relationships of monoamine oxidase catalyzed oxidation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine analogs
… studied were 4-aryloxy analogs, 4- aromatic heterocycle analogs, and 4-phenyl analogs. The conformer with phenyl ring to tetrahydropyridine dihedral angles similar to a low energy conformer of I-methyl-4-(2'-methyl-phenyl)-1,2,3,6- tetrahydropyridine is the most active conformer. Results …
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The synthesis of novel organometallic materials.
… properties, complexes based on the sulphur heterocycle DMIT have been studied extensively for several decades. The literature is abundant with materials exhibiting semiconducting and metallic properties and up to early 2000 there are eight examples of DMIT based superconductors. In the case …
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New optical materials containing isobenzofuran
Isobenzofuran, a member of the benzo[c]heterocycles, is an extremely reactive molecule with unusual electronic properties. In this thesis we investigate the integration of isobenzofuran subunits into conjugated optical materials. We discuss the properties of isobenzofuran, its role in organic …
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Conjugated polymer based materials via the incorporation of polymerizable units
… by anodic electropolymerization of phenylene-heterocycle moieties, affording conducting polymers. All of these three block copolymers were readily deposited on the electrode substrates, and their cyclic voltammograms revealed an excellent reversibility in the redox cycles. The deposited …
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