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 28 for “"intramolecular cyclization"”.
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Mechanistic studies of asymmetric induction at benzylic centers of organolithium species
… a part of the substrate, so the reaction is an intramolecular cyclization.
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THE STUDY OF PYRENEDIONE AS A PHOTOREDOX CATALYST AND A FLUOROMETRIC PROBE FOR VISUAL DETECTION AND QUANTIFICATION OF TRYPTOPHAN
… Moreover, amination of PYD followed by intramolecular cyclization via C-H activation is disclosed. Finally, the selective oxidation of tryptophan and cysteine, among other amino acids by 1,8-PYD is presented. An easy and sensitive method for the visual detection and quantification of …
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Modular Synthesis and Hydroalkylation of Vicinally Functionalized Ketopiperazines: A solution to the Piperazine Problem
… towards functionalized piperazines include intramolecular cyclization of appropriately tethered on acyclic precursors as well as α-C–H functionalization of intact piperazine rings. Although effective for the most part, these methods suffer from drawbacks such as the use of expensive …
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Mechanistic Studies of Vitamin B(12)-Catalyzed Dechlorination and Carbon-Carbon Bond-Forming Reactions
… and dienes containing one aryl alkene underwent intramolecular cyclization in good yields. 1,2-Disubstituted and trisubstituted alkenes were unreactive. Mechanistic investigations using radical traps suggest the involvement of benzylic radicals, and the lack of diastereoselectivity in the product …
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Molecular design for controlling morphology in organic electronics
… polycyclic heteroaromatic building block via intramolecular cyclization reactions. The second section explores the electrochemical properties of SNS units for the opportunity to enhance conjugation via electrochemical methods.
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Synthesis and utility of electronically diverse polycyclic aromatics
… aromatic precursors: electrophilic and oxidative cyclizations. Chapters One and Two describe research directed towards expansion of electrophilic cyclizations that utilize alkyne functionality to construct aromatized systems. Strongly-acidic conditions provide transient cationic intermediates that …
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Model Compounds for the Photoactivation of Glycosyl Donors
… of various photosensitizers, to induce an intramolecular cyclization. This cyclization leads to the generation of an oxonium intermediate that may alkylate other nucleophiles, which should be analogous to a glycosylation reaction. It was determined that a moiety with an internal sensitizer …
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Synthesis and Biosynthesis of Polyketide Natural Products
… the regiochemistry of dehydration and cyclization in the biosynthetic pathway of the marine polyketide spiculoic acid A. The molecule's key intramolecular cyclization was proposed to occur through a linear chain containing an abnormally dehydrated polyene system. We synthesized a …
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Asymmetric Synthesis of 1,3-Amino Alcohols and Tropinone Derivatives From Enantiopure Sulfinimines
… imines) as precursors for acid-catalyzed cascade cyclizations. Chiral N-sulfinyl b-amino ketones derived from N-sulfinyl b-amino Weinreb amides, serve as novel and direct precursors to syn and anti N-sulfinyl 1,3-amino alcohols through stereoselective reductions. General reduction conditions have …
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Nature's approach toward ring formation and structural diversity in ergot alkaloid biosynthesis
… genes encoding the enzymes that carry out these cyclizations are believed to be well conserved across divergent fungal species. Here we describe in vivo gene disruption experiments in Aspergillusfumigatus that allowed us to identify candidate enzymes that were directly involved with the …
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Developing Structure-Activity-Relationships for Metal-Ligand-Cooperative (MLC) Complexes using PR2NR′2 Ligands
… for challenging reactions. Inclusion of an intramolecular acid/base site on the ligand manifold of an organometallic complex has allowed for new mechanistic pathways and enhanced reactivity. This thesis delves into understanding organometallic complexes in catalysis by systematic tuning the …
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Development and applications of acid degradable polymeric materials
… new mechanism for degrading polyurethanes called CyclizAtion-Triggered Chain (CATCH) cleavage. CATCH cleavage features a simple glycerol-based acyclic acetal unit as a kinetic and thermodynamic trap for chain shattering. Thus, transient oxocarbenium ion formation with an organic acid induces …
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CYCLIZATION-BASED SITE-SELECTIVE N-TERMINAL CYSTEINE CONJUGATION, PEPTIDE STAPLING AND HISTONE DEACETYLASE (HDAC) PROBING
Cyclization reactions play an important role in synthesizing a significant number of small molecule scaffolds for various purposes, including drug discovery. However, the application of cyclization reactions in the modifications of biomolecules in a single step is still limited. This dissertation …
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Co-Delivery of Peptide QK and WKYMVm for Minimally Invasive Therapeutic Angiogenesis in Treating Critical Limb Ischemia
… also degradable into non-acidic products through intramolecular cyclization. In this work, we investigated the hydrolytic degradation of copolymers composed of 5-hydroxyl trimethylene carbonate (HT) and 5-butyrate-trimethylene carbonate (BtT), as well as terpolymers containing trimethylene …
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Development of Novel Nicotinic Receptor Mediated Therapeutic Agents: Synthesis and Biological Evaluation of Novel Epibatidine Analogs and the First Total Synthesis of Anabasamine and Related Analogs
… ring systems were furnished via an intramolecular cyclization from a trans 1, 4 disubstitituted amino-cyclohexane derivative. The functionalized cyclohexane ring was formed via a [4+2] Diels-Alder cyclization reaction between the acetamidoacrylate and Danishefsky's diene. These 1- …
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Building a Better Model for the Molybdenum Cofactor: A New Class of Molybdenum Dithiolene Complexes
… structures were observed, as dehydration and intramolecular cyclization of the alcohol group resulted in pyrrole ring formation, and treatment with triphenylphosphine resulted in pyran ring closure on the pyrazine ring of the quinoxaline or pterin ligands, as observed in S2BOQO, S2BMOPP, and …
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Development of Electrochemical Sensors Suitable for In Vivo Detection for Neurotransmitters
… different rate constants for the first order intramolecular cyclization reaction, the catecholamines can be distinguished by monitoring the current at collector electrodes activated at different distances from the generator. In vitro detection of dopamine in the presence of multiple …
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Design and synthesis of novel biologically active flavones and isoflavones
… terminal alkyne via Sonogashira coupling. The intramolecular cyclization was carried out through an electrophilic borylative reaction followed by immediate esterification to furnish the benzopyran core with a boronic ester at 3-position. Subsequent Suzuki-Miyaura coupling reaction allowed for …
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Strategies and Tactics for the Synthesis of Polycyclic Alkaloids
… retrosynthesis was devised that proposes a novel intramolecular cyclization approach of an ynal and ketone to deliver the bridging butenolide moiety of these natural products. The development of this reaction and its application toward the synthesis of various <italic>Securinega</italic> alkaloids …
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