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Showing 1 to 20 of 26 for “"Diels-Alder cycloaddition."”.
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Synthesis and Determination of the Absolute Configuration of the Bicyclic Guanidine Core of Batzelladine A and the Development of a Novel [4+2] Inverse Electron Demand Hetero Diels -Alder Cycloaddition and Its Application Toward the Synthesis of the Tricyclic Guanidine Fragment Within Batzelladine A
… of a novel [4+2] inverse electron demand hetero Diels-Alder cycloaddition amendable for synthesis of the tricyclic guanidine portion. These studies culminated in the first synthesis of the bicyclic guanidine core within batzelladine A, which was demonstrated by accessing in enantiospecific …
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Complex botanical natural products: Synthesis of cephalotaxus esters and of the C19-diterpenoid skeleton of aconitum and delphinium alkaloids
… alkaloids is described. Key steps include a Diels–Alder cycloaddition of a cyclopropene with a 2,5-dioxycyclopenta-1,3-diene, a second Diels–Alder cycloaddition with a 2,5-dihydroazepine 2π component, an intramolecular N-acyliminium cyclization, and a radical conjugate addition.
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Asymmetric Total Synthesis of (+)-Nominine: Development of a Dual Cycloaddition Strategy for the Synthesis of the Hetisine Alkaloids
A dual cycloaddition strategy for the synthesis of the hetisine alkaloids has been developed and applied to the asymmetric total synthesis of nominine. The approach relies on an early stage intramolecular aza-1,3-dipolar cycloaddition of a 4-oxidoisoquinolinium betaine with an ene-nitrile …
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Total synthesis of (±)-cis-trikentrin B, (±)-herbindole A and (±)-herbindole B. investigation into the regioselectivity of 6,7-Indole aryne cycloadditions
… (±)-herbindole B via intermolecular indole aryne cycloaddition are described. The 5,6,7-tribromoindole was synthesized via Leimgruber-Batcho indole synthesis protocols. The main question would be whether the key intermediate 5,6,7-tribromo-N-TBSindole would undergo selective metal-halogen exchange …
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Total synthesis of lycoricidine via photochemical dearomative dihydroxylation
… transpositive Suzuki coupling. Hetero-Diels-Alder cycloaddition is used to form the syn-1,4-amidoalcohol functionality. This new route completes the total synthesis of lycoricidine in eight steps, shorter than any previously completed synthesis.
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Chemoenzymatic Formal Total Syntheses of Tetrodotoxin and an Approach to Daphenylline
… iodobenzene or benzyl acetate and a [4+2] hetero-Diels-Alder cycloaddition/Kornblum–DeLaMare rearrangement sequence to construct a common enone intermediate. The resulting key enone was transformed into Fukuyama's intermediate in four steps, into Alonso's intermediate in six steps, and into Sato's …
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Bromonium-Initiated Epoxide-Opening Cascades : total Synthesis of ent-Dioxepandehydrothyrsiferol and Synthetic Studies toward (+)-Scholarisine A
… highlights of the route include: 1) cisselective Diels-Alder cycloaddition reaction to construct strained 5,6-fused hydrindanones, 2) a novel indole formation via an in-situ aza-Wittig reaction, and 3) a selective enolization and hydrolysis sequence of a diketone substrate to provide rapid access …
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Probing the Impact of Solvent on Lewis Acid Catalysis via Fluorescent Lewis Adducts
… was confirmed by titration data and catalytic Diels-Alder cycloaddition and hydrosilylation reactions, illustrating that solvation effects can be appropriately gauged by a LAU value determined from the FLA method.
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Green chemistry : dense carbon dioxide and water as environmentally benign reaction media
(cont.) was investigated in scCO₂, and the cycloaddition between cyclopentadiene and methyl vinyl ketone (MVK) was studied in an scCO₂/liquid water environment. Nitrogen chemistry, specifically the synthesis of nitrogen heterocycles from amines, was also studied in scCO₂ and scCO₂/liquid water …
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APPLY LADDER OF CHEMICAL CIRCULARITY: RECYCLING OF RARE EARTH ELEMENTS RECOVERED FROM ELETRONIC WASTE AS A CATALYST IN ORGANIC REACTION.
… efficiency and selectivity. Additionally, a Diels-Alder cycloaddition was performed using chiral auxiliaries, promising results in terms of both reaction yield and enantioselectivity. The thesis also explores sustainable catalytic approaches by testing reactions using fluorescent lamps …
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Strategies towards the synthesis of prostaglandin analogues
… routes involves a Lewis-acid mediated retro Diels-Alder (rDA) reaction as the final step in liberating a 4, 5 disubstituted cyclopent-2-ene-1- one under extremely mild conditions. The first approach involves installation of the a-chain followed by base-mediated methodology to affect …
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Synthesis of derivatives of 4H-cyclopenta[ def]phenanthren-4-one and development of synthetic strategies for the polycyclic aromatic hydrocarbons with carbon frameworks represented on the surface of C60
… coupling then afforded the formal [4+2] Diels-Alder cycloaddition adduct 60, which in turn underwent tautomerization to give 61. Reduction with tri-n-butyltin hydride then gave the ketal 62 in 46% overall yield from 56a. Hydrolysis of the ketal 62 gave the ketone 51 in 97% yield.;Another …
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NH-Isoxazolidines as Organocatalysts
… of NH-isoxazolidines as catalysts in the Diels-Alder cycloaddition reaction, the Michael addition reaction and the Aldol condensation reaction is discussed. It has been demonstrated that the NH-isoxazolidines are effective in iminium ion catalysis and act as enantioselective …
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General method for the synthesis of pseudodisaccharides. Diels-Alder approach to the synthesis of pseudodisaccharides
… to a "true" sugar. The methodology is based on a Diels-Alder cycloaddition of vinyl sugars and appropriately substituted pyran-2-ones, followed by chemical manipulation of the resulting cycloadducts. The thesis also describes the synthesis of inhibitors of Golgi ¿-mannosidase II and glucokinase. …
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Probing regioselectivity in the Diels -Alder cycloadditions between *[60]fullerene and aryl substituted acenes
… 4,7-diphenylisobenzofuran, 5, is reported. The Diels-Alder reaction between 5 and p-benzoquinone in boiling glacial acetic acid yields an unprecedented exo,exo anti dual cycloaddition product, 16b, in excellent yield and with 100% diastereoselectivity. Differences between the reactivity of 5 and …
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Imidazolidinones in amine catalysis
… group is evaluated as an asymmetric catalyst for Diels-Alder cycloaddition reactions. A substrate and reaction scope is presented and the conformational preference of the imidazolidinone is probed to rationalise the origins of enantioselectivity. In Chapter 3, further understanding of the …
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Explorations with Polycarbocyclic Cage Compounds
… Pi-facial and regioselectivity in the thermal Diels-Alder cycloaddition between hexacyclo[11.2.1.02,12.05,10.05,15.010,14]hexadeca-6,8-diene- 4,11-dione and ethyl propiolate have been explored. This reaction proceeds via stereospecific approach of the dienophile toward the syn face of the diene …
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Computational and experimental studies of acenes, starphenes and [60]fullerene derivatives
… PAH is generated and captured in situ by Diels-Alder cycloaddition of the fullerene. Both syn,syn- and syn,anti- diastereomers of the fullerene trisadduct are generated with the syn,syn- formed as the dominant species. Fullerene pi -- pi interactions are believed to drive the formation of …
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Leveraging the Photochemistry of N-Nitrosamines for Their Aqueous Detection, and Development of a Novel Hemi-Iptycene for Porous Polymers
… monomer is constructed by the one-pot Diels–Alder cycloaddition–dehydrochlorination of 2-chlorotriptycene quinone with diphenylfulvene, which is performed as a neat melt. Other attempted synthetic routes to the quinone are described as well. Lastly, preliminary results from the …
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Synthesis and Characterization of Multi-Component Polymeric Materials Prepared via Free Radical Polymerization
… derivatives that were synthesized from facile Diels-Alder cycloaddition reactions of cyclopentadiene with a-olefins containing electron withdrawing groups. Subsequent hydrolysis of the anhydride offered further versatility and provided an avenue to introduce aqueous base solubility into Nb/MAH …
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