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 26 for “"formal synthesis"”.
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I Peptide isosteric replacement preparation using zinc-mediated chain extension-aldol reactions II Formal synthesis of (+)-Brefeldin A III Zinc-mediated chain extension reactions with substituted carbenoids
… reaction as the key step. An asymmetric formal synthesis of (+)-Brefeldin A has been developed in which the zinc-mediated ring expansion/oxidation/elimination method constitutes a key step. Preparation of beta-alkyl-gamma-keto esters through a chain extension reaction using substituted …
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Synthetic studies of ecteinascidin 743 and fennebricin B
… research and commercial use is from laboratory synthesis. Many syntheses of Et-743 have been reported including three total syntheses, two formal syntheses and two semisyntheses. The biological activities of fennebricin B were unknown due to the scarcity of this natural product. However, …
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Stereoselective Heterocycle Synthesis via Alkene Difunctionalization: Bulky Phosphine Ligands Enable Pd-Catalyzed Arylhalogenation, Arylcyanation and Diarylation
… heterocycle syntheses. Chapter 1 describes the synthesis of three different classes of heterocycles using the alkene aryliodination methodology: isochromans, chromans, and dihydroisoquinolinones. The use of amine bases was found to be key in these transformations. The dihydroisoquinoline …
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A facile conversion of beta-keto carbonyl compounds to alpha, beta-unsaturated-gamma-oxo carbonyl systems and a study of ketal -derived oxonium ylides
… of this chemistry was demonstrated through a formal synthesis of R-(-)-pyrenophorin, an asymmetric total synthesis of (+)-patulolide A and a racemic synthesis of patulolide B. An extensive study of ketal-derived oxonium ylides and the subsequent rearrangement was also accomplished. The …
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Tandem benzannulation-ring closing metathesis strategy for the synthesis of benzo-fused nitrogen heterocycles ;
… closing metathesis strategy for the efficient synthesis of benzo-fused nitrogen heterocycles such as dihydroquinolines, benzazepines, and benzazocines has been developed. This strategy is based on the benzannulation reaction of ynamides with cyclobutenones or [alpha]-diazo ketones to generate …
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Two enantiodivergent syntheses of balanol and the chemoenzymatic synthesis of oseltamivir
… the Burgess reagent and its application to the synthesis of enantiomerically pure ~-amino alcohols. This methodology has been exploited in the formal enantiodivergent synthesis of the (+)- and (-)-isomers of balanol. Also described is a second generation approach to both balanol enantiomers; …
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Progress in nucleophilic catalysis and development of nickel-catalyzed cross-couplings of propargylic halides
… the application of this coupling reaction to the formal synthesis of a-cembra-2,7,1 1-triene-4,6-diol. The last section of this thesis (Section 2.5) discusses the development of the first asymmetric Negishi reaction of arylzinc reagents with secondary electrophiles.
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Chiral acyl radicals generated by visible light enable stereoselective access to 3,3-disubstituted oxindoles: application toward the synthesis of (–)- and (+)-physovenine
… and its application toward the stereoselective synthesis of 3,3- disubstituted oxindoles via an additional-cyclisation cascade sequence to acrylamide precursors. 6 oxindoles were produced in up to 85% yield, with moderate diastereoselectivity of up to 2.2:1, but which could be easily separated …
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Rhodium-catalyzed epoxide-opening cascades toward brevisin and hemibrevetoxin B
… I. Rhodium-Catalyzed Epoxide-Opening Cascades: Formal Synthesis of (-)-Brevisin [chemical formula inserted] [Rh(CO)₂Cl]₂ was found to be an effective catalyst for endo-selective cyclizations and cascades of epoxy-(E)-enoate alcohols, thus enabling the synthesis of oxepanes and oxepanecontaining …
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1. Chromium(0)- Promoted Higher Order Cycloaddition Reactions: Studies Toward The Total Synthesis Of The Cyclocitrinols And Echinopines A And B 2. Total Synthesis Of (±)-Debromoflustramine B Via [4+1] Cyclization Of An Indole Isocyanate And A Bis(alkylthio)carbene
<p>A facile and short stereoselective synthesis of the functionalized tetracyclic core structure of the cyclocitrinols, a family of unusual C25 steroid isomers, has been accomplished. The key structural unit, the bicyclo[4.4.1]A/B ring system, was constructed by a regioselective Cr(0)-promoted [6π …
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Synthesis of pyrrolizidine diols via azide-diene cycloadditions
… methodology in the context of natural product synthesis was demonstrated by extending its applicability to the heteroatom (nitrogen) case thus allowing access to the alkaloid field. This novel methodology involved the intramolecular union of a hypovalent nitrogen atom equivalent and a …
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Processing The Program: Considering The Architectural Brief
… of analysis. The design is then intended to be a formal synthesis. This reductionist approach to architectural program degenerates the capacity of the program to merely solidified functional relationships. Additionally, this approach limits the concept of the program to the initial pre-design …
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Asymmetric Synthesis of 1,3-Amino Alcohols and Tropinone Derivatives From Enantiopure Sulfinimines
… This methodology was applied to a concise formal synthesis of the piperidine-containing natural product, (-)-pinidinol, through an intramolecular cascade-cyclization of a masked-oxo N-sulfinyl 1,3-amino alcohol. Special conditions were found for the syn reduction of these substrates. …
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Synthesis of Amphibian Alkaloids and Development of Acetaminophen Analogues
… of new synthetic methods and procedures for the synthesis of novel compounds with unique biological properties. This research has led to the development of two new synthetic strategies for the construction of two novel amphibian alkaloids. In addition, the efforts have led to the large-scale …
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The Application of sSPhos as a Chiral Ligand in Palladium-Catalysed Reactions: Arylative Dearomatisations, and Heteroarylative Cyclisations with Alkenes
… with aryl bromide electrophiles, for the synthesis of chiral indolines and 2,3-dihydrobenzofurans. This project is ongoing and being continued by Paul Jirsch, a visiting Master’s student in the Phipps group. The final chapter presents an enantioselective formal synthesis of a natural …
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Rhodium-Catalyzed Enantioselective Desymmetrizations of Oxabicyclic Alkenes and Alkene Difunctionalization via Nickel-Catalyzed Arylcyanation
The synthesis of heterocycles using transition metal catalysis is a topic of broad interest in the field of organic chemistry. Transition metal catalysts allow many diverse bond disconnections to be realized, allowing for many ways to assemble heterocycles. Many of the transformations developed in …
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Syntheses of C-glycoside natural products via oxocarbenium cationic intermediates
… dissertation highlights studies into the total synthesis of C-glycoside natural products via oxocarbenium cationic intermediates with a brief introduction given in the first chapter. The second chapter examines our approach to the first total synthesis and absolute configuration of the …
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Development and application of carbon-carbon bond forming methodologies
… chiral building blocks as shown through the formal synthesis of the known pharmaceutical Xyzal©. Reaction discovery implementing a series of propargyl arnides lead to the development of unique Ag catalyzed 5-exo and 6-endo cyclizations to produce novel oxazolines and oxazines respectively. A …
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Peri-substituted dithianaphthalenes as sources of reactive intermediates in organic chemistry
… thiophenes. SO transfer was applied in a formal synthesis of Plavix® and the naturally occurring thioperillene. Mechanistic studies on the SO transfer reaction indicated that the rate-determining step was independent of the diene, and first-order with respect to trisulfide-2-oxide. C-H …
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New explorations in visible-light mediated energy and single electron transfer for nitrogen heterocycle synthesis
… of visible-light mediated photocatalysis for the 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, …
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