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