Physical Sciences and Mathematics Commons^™

Stereochemical Investigation Of A Novel Tandem Intramolecular Diels-Alder Reaction, Katie Pelham

Chemistry Senior Theses

The Diels-Alder reaction has become a prominent synthetic tool due to the effectiveness for which it facilitates the construction of new carbon-carbon bonds to form six-membered rings. Since first reported in 1952, Intramolecular Diels-Alder (IMDA) reactions have been widely employed for complex synthesis, especially for natural products. Our lab was the first to report a Tandem Intramolecular Diels-Alder (TIMDA) reaction, and TIMDA reactions have similarly proved powerful in the synthesis of natural products. Predicting the absolute stereochemistry of the major products of such intramolecular reactions is complicated by the competition between steric factors imposed by the necessary distortion of the …

Principles Of Surface Chemistry Central To The Reactivity Of Organic Semiconductor Materials, Gregory J. Deye

Dissertations

Organic thin-films are rapidly becoming implemented as semiconducting materials in electronic devices and as a result, surface reactivity plays an increasingly important role in the improvement of semiconducting properties. My dissertation addresses how organic thin-films react with gaseous molecules. Previous reports of chemical reactions on organic surfaces claim, “phase rebuilding reaction mechanisms,” whereby reactions only proceed if chemisorbed adsorbate molecules are able to traverse through voids in the molecular lattice. The over-assumptions of this model and lack of correlation to reaction temperature make understanding of organic substrate reactivity incomplete. In contrast, I argue applied heat causes deformation of the molecular …

Novel Reactions Of Donor-Acceptor Cyclopropanes, And Diels-Alder Approach Towards Fargesine And Fumimycin, Polydoros Kyriacou

Electronic Thesis and Dissertation Repository

The first chapter of this thesis consists of two related projects that explore novel reactivity of donor-acceptor cyclopropanes, specifically 2-substituted cyclopropane 1,1-diesters. The first project involves the nucleophilic ring opening of donor-acceptor cyclopropanes with potassium organotrifluoroborates. It was found that during the ring opening of the cyclopropane, the diesters of the cyclopropane formed a malonyl-BF₂ complex. The complex could then be hydrolyzed to afford substituted malonates. The reaction was limited to aryl cyclopropanes and potassium alkynyltrifluoroborates. The second project in this chapter explores modifying the Kerr group’s previous synthesis of tetrahydro-1,2-oxazines, such that geminal allyl, methyl esters are now …

Cycloaddition Chemistry For The Synthesis Of Heterocyclic Compounds And Progress Towards The Total Synthesis Of Grandilodine A, Andrew C. Stevens

Electronic Thesis and Dissertation Repository

This thesis describes three separate research projects within the broad topic of synthetic organic chemistry. The synthesis of alkyl-substituted siloles and their reactivity in Diels-Alder chemistry is reported. Furthermore, the cleavage of the bicyclic adducts by Tamao-Fleming oxidation has been achieved which reveals a highly substituted cyclohexene-1,4-diol structure.

The second chapter describes the cycloaddition chemistry of alkoxy-activated cyclobutane dicarboxylates with aldehydes, nitrones and nitrosoarenes. The cycloaddition occurs, in the case of aldehydes, with uniformly high diastereoselectivity to afford tetrahydropyrans in good to excellent yield. When nitrones were used as the dipolarophile the cycloaddition occurs in a rather unselective manner though …

Responsive Materials Via Diels-Alder Chemistry, Gregory Alan Strange

Master's Theses

The corrosion of infrastructure imposes a significant monetary cost, and at times human cost, upon society. Methods to improve corrosion resistance of materials are described herein which utilize the reversibility of the Diels-Alder reaction to impart thermal responsiveness upon materials. Such stimuli responsiveness can potentially play a role in self healing properties which lead to reduced cracking and thus increased corrosion protection.

Reversible Diels-Alder chemistry was utilized to manipulate the surface energy of glass substrates. Hydrophobic dieneophiles were prepared and attached to glass slides and capillaries to yield a nonwetting surface. Thermal treatment of the surfaces cleaved the Diels-Alder linkage, …

Cyclopentadienone Conversions To Terephthalates And Cycloadditions Of Alkynes And Azides, Sarah E. Bragg

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Cyclopentadienone derivatives can be converted via a Diels-Alder reaction to multifunctional terephthalate derivatives, which can then be converted to poly(phenylene vinylene) derivatives. It was demonstrated that terephthalate derivatives can be simply and reproducibly synthesized from 2,5-diethoxycarbonyl-3,4-diphenylcyclopentadienone with a variety of acetylenes, having yields ranging from 63% to quantitative yields. The terephthalate derivatives synthesized varied from oils to crystalline solids, but were readily isolated and generally had high rates of completion despite expected steric factors. Terephthalate derivatives with pendent acetylenes were formed in reactions with as low as a 3:1 ratio of diacetylene to cyclopentadienone. A terephthalate derivative with a pendent …

The Synthesis, Reduction, And Chlorination Of 5-Alkoxy-2,3-Diphenylterephthalates, Rachel Marie Sayers

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A series of alkoxy, phenylated terephthalates has been synthesized as monomer precursors to the corresponding poly(phenylene vinylene)s (PPV). The hydroxy, phenylated terephthalate was synthesized via: 1) a Diels-Alder cycloaddition between an ethynyl boronic ester and a cyclopentadienone (CPD) with subsequent hydrolysis/oxidation of the boronate ester or 2) a Diels-Alder cycloaddition between vinylene carbonate and CPD followed by thermolysis of the bridged adduct. The hydroxy, phenylated terephthalate was alkylated via a phase-transfer reaction with iodomethane, propargyl bromide, benzyl chloride, allyl bromide, and bromobutane to produce the alkoxy, phenylated terephthalates in yields from 38.6- 91.1%. The alkoxyterephthlates were reduced with lithium aluminum …

Towards The Total Synthesis Of Haplomyrtin, Nora Ellen Hunter

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Haplomyrtin, a 1-aryl-2,3-naphthalide lignan obtained from Turkish Haplophyllum myrtifolium and Haplophyllum telephioides offers a number of synthetic challenges with the incorporation of two aromatic hydroxyl groups at positions C4 and C7 on the naphthalene ring system and regiospecific condensation of the γ-lactone ring. Improvements towards the total synthesis of haplomyrtin were pursued with commercially available vanillin and piperonal in a total of 8 separate steps. All steps have excellent reproducibility. This strategy includes bromination of protected vanillin to yield 2-(4-(4-methoxybenzyloxy)-2-bromo-5-methoxyphenyl)-1,3-dioxolane and 2-(4-(benzyloxy)-2-bromo-5-methoxyphenyl)-1, 3-dioxolane in 48% and 88% yield respectively, and incorporation of the fully functionalized pendant aryl ring through a …

Synthetic Approach To Epibatidine From 1-(Phenylsulfonyl)Pyrrole, Brandon G. Vanness

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The goal of this research was to synthesize the natural product epibatidine, a non-opiate analgesic and nicotinic acetylcholine agonist isolated from Epipedobates tricolor. A synthetic pathway utilizing a Diels-Alder cycloaddition of a 3-pyridyl substituted pyrrole and tosylacetylene was conceived based upon the original mass spectral fragmentation pathway of epibatidine determined by Daly. Although this pathway had been previously attempted using 1-(triisopropyl)-3-[5-(2-chloropyridyl)]pyrrole in the key Diels-Alder step, the lack of cycloadduct suggested that a pyrrole with a more electron withdrawing protecting group was required for this step. Therefore, synthesis of 1-(phenylsulfonyl)-3-[5-(2-chloropyridyl)]pyrrole via a palladium catalyzed cross-coupling reaction of 1-(phenylsulfonyl)-3-pyrroline and …