171 |
Utilizing Terminal Alkenes in Asymmetric Synthesis: Development and Application of Efficient Diboration/Cross-Coupling CascadesMlynarski, Scott Nathan January 2014 (has links)
Thesis advisor: James P. Morken / The first highly enantioselective diboration of unfunctionalized terminal alkenes has been developed using a platinum-phosphonite complex. This transformation produces versatile 1,2-bis(boronate)esters that can manipulated chemoselectively to generate a pletheroa of enantioenriched structural motifs. When combined with an appropriate palladium catalyst, the diboration product undergoes an efficient alkyl boron cross-coupling with aryl and vinyl electrophiles producing a wide range of enantioenriched homobenzylic and homoallylic boronates. Alternatively, when the 1,2-bis(boronate)ester diboration product contains an adjacent Z-olefin (derived from diboration of cis-1,3-dienes), allylation to aldehydes can be achieved delivering the syndiastereomer of product exclusively with excellent chirality transfer. Notably, the products obtained from the two described reactions contain an additional boronate moiety, which can be further functionalized through known carbon-boron bond transformations. / Thesis (PhD) — Boston College, 2014. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.
|
172 |
Synthesis, characterization and catalytic applications of tantalum and niobium alkyl, alkylidene and olefin complexesFellmann, Jere Douglas January 1980 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Jere Douglas Fellmann. / Ph.D.
|
173 |
Late transition metal-carboryne complexes and their reactions with alkenes and alkynes. / CUHK electronic theses & dissertations collectionJanuary 2010 (has links)
Abstract not available. / Qiu, Zaozao. / Adviser: Zuowes Xie. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 150-161). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
|
174 |
Construction of Functionalized Heterocycles by Palladium-catalyzed Domino Reactions with Strained AlkenesThansandote, Praew Petcharat 23 February 2011 (has links)
The Lautens group has a long-standing interest in developing novel approaches to heterocycle synthesis. One such approach is a Pd-catalyzed, norbornene-mediated domino reaction which can form up to three carbon-carbon bonds in one synthetic sequence. The key additive is norbornene which acts similar to a catalyst by assembling the scaffold to enable the formation of a carbon-carbon bond, though is not incorporated into the final compound. The reaction involves C-H bond functionalization as a key step and a Pd(IV) complex as a key intermediate.
The goal of the current thesis was to introduce reactive heteroatoms to this domino reaction for the first time, with particular focus on the introduction of nitrogen. Methodologies were developed to present novel syntheses of heterocycles with high pharmaceutical interest. Our initial study focused on the selective functionalization of thiophenes to give multi-substituted sulfur compounds. To synthesize pharmaceutically important nitrogen heterocycles, we demonstrated for the first time that an amination reaction was compatible with the domino reaction. This development led to novel approaches to synthesize substituted indolines, indoles, tetrahydroquinolines, benzomorpholines, phenoxazines, dihydrodibenzoxazepines, tetrahydroisoquinolines, tetrahydroisoquinolinones and tetrahydrobenzazepines.
In contrast to the use of norbornene in a catalytic manner, we demonstrated that heterocycles could also be synthesized by the incorporation of strained alkenes. We developed a conceptually novel approach to generate nitrogen heterocycles by using norbornadiene as an acetylene synthon. A palladium-catalyzed annulation of substituted haloanilines with norbornadiene led to functionalized indolines. These indolines could be rapidly converted to benzenoid-substituted indoles and tricyclic indolines, which form the core of many biologically active compounds. Extension to the use of substituted halobenzamides led to functionalized isoquinolinones.
Finally, we embarked on a study to perform selective palladium-catalyzed C-H functionalization reactions with N-iodoarylpyrroles and strained alkenes. We will present the reaction conditions necessary to favour aryl C-H functionalization over pyrrole C-H functionalization.
|
175 |
Construction of Functionalized Heterocycles by Palladium-catalyzed Domino Reactions with Strained AlkenesThansandote, Praew Petcharat 23 February 2011 (has links)
The Lautens group has a long-standing interest in developing novel approaches to heterocycle synthesis. One such approach is a Pd-catalyzed, norbornene-mediated domino reaction which can form up to three carbon-carbon bonds in one synthetic sequence. The key additive is norbornene which acts similar to a catalyst by assembling the scaffold to enable the formation of a carbon-carbon bond, though is not incorporated into the final compound. The reaction involves C-H bond functionalization as a key step and a Pd(IV) complex as a key intermediate.
The goal of the current thesis was to introduce reactive heteroatoms to this domino reaction for the first time, with particular focus on the introduction of nitrogen. Methodologies were developed to present novel syntheses of heterocycles with high pharmaceutical interest. Our initial study focused on the selective functionalization of thiophenes to give multi-substituted sulfur compounds. To synthesize pharmaceutically important nitrogen heterocycles, we demonstrated for the first time that an amination reaction was compatible with the domino reaction. This development led to novel approaches to synthesize substituted indolines, indoles, tetrahydroquinolines, benzomorpholines, phenoxazines, dihydrodibenzoxazepines, tetrahydroisoquinolines, tetrahydroisoquinolinones and tetrahydrobenzazepines.
In contrast to the use of norbornene in a catalytic manner, we demonstrated that heterocycles could also be synthesized by the incorporation of strained alkenes. We developed a conceptually novel approach to generate nitrogen heterocycles by using norbornadiene as an acetylene synthon. A palladium-catalyzed annulation of substituted haloanilines with norbornadiene led to functionalized indolines. These indolines could be rapidly converted to benzenoid-substituted indoles and tricyclic indolines, which form the core of many biologically active compounds. Extension to the use of substituted halobenzamides led to functionalized isoquinolinones.
Finally, we embarked on a study to perform selective palladium-catalyzed C-H functionalization reactions with N-iodoarylpyrroles and strained alkenes. We will present the reaction conditions necessary to favour aryl C-H functionalization over pyrrole C-H functionalization.
|
176 |
Quantum chemical studies of olefin epoxidation and benzyne biradicals /Lundin, Angelica. January 2007 (has links)
Univ., Diss.--Göteborg, 2007. / Enth. außerdem 5 Zeitschriftenaufsätze.
|
177 |
Infra-red spectra of olefines and organic sulphur compounds with some applications to the structure and vulcanisation of rubber.Sheppard, Norman. January 1947 (has links)
Thesis--St. Catharine's College, Cambridge. / Typescript (carbon) with ms. corrections. Without thesis statement. Appendices 1-3 by N. Sheppard and G.B.B.M. Sutherland. Bibliography: leaves 209-216.
|
178 |
Investigation of poly(pyrrolone-imide) materials for the olefin/paraffin separationBurns, Ryan Lance 28 August 2008 (has links)
Not available / text
|
179 |
The role of epoxidation in 4-vinylcyclohexene-induced ovarian toxicity.Smith, Bill J. January 1990 (has links)
The basis for the species difference between B6C3F1 mice (susceptible) and Fischer 344 rats (resistant) to 4- vinylcyclohexene (VcH)-induced ovarian tumorigenicity was investigated. Greater than 95% of a single oral 400 mg/kg dose of [¹⁴C]VCH was eliminated in 48 hr by mice and rats. Approximately 50-60% of the administered dose was excreted in the urine, while the remaining 30-40% of the dose was expired as organically soluble radioactivity. VCH-treated mice had dramatically higher blood concentrations of the VCH metabolite VCH-1,2-epoxide compared to VCH-treated rats. Furthermore, mouse hepatic microsomes catalyzed the conversion of VCH to VCH-1,2-epoxide at greater rates than rat hepatic microsomes. The destruction of oocytes was used as an index of ovarian toxicity to compare the potency of VCH and VCH epoxides in the mouse and rat. VCH markedly reduced the number of small oocytes in mice while no detectable change in oocyte number occurred in rats. Epoxide metabolites of VCH destroyed oocytes in both species at lower doses than VCH. Inhibition of VCH epoxidation reduced VCH-1,2-epoxide blood levels and partially protected mice from VCH-induced ovarian toxicity. Thus, the conversion of VCH to epoxides and the subsequent destruction of oocytes are critical steps in the induction of ovarian tumors by VCH. Rats may be resistant because the amount of VCH converted to epoxides is insufficient to destroy oocytes. The biochemical basis for the species difference in the rate of VCH epoxidation by hepatic microsomes from mice and rats was investigated. studies using inducers and inhibitors of certain cytochrome(s) P450 showed that hepatic microsomes of female mice perform VCH epoxidation at greater rates than rats because of the constitutive expression of P450 IIA and lIB forms. Hepatic microsomes of human females perform VCH epoxidation at lower rates than rats. This suggests that if the rate of epoxidation of VCH by the liver is the most important factor determining susceptibility to VCH toxicity then the rat may better model the response of humans exposed to VCH than mice.
|
180 |
Investigations into the Ruthenium Catalyzed Ring Opening and Dimerization Reactions of Oxabicyclic AlkenesJack, Kelsey 04 December 2012 (has links)
Oxabicyclic alkenes have been the focus of many synthetic studies as they are versatile compounds which act as synthetic intermediates to produce a variety of useful heterocyclic, carbocyclic and acyclic products. The nucleophilic ring opening reaction of oxabenzonorbornadiene was studied. Methanol was the primary nucleophile used throughout the investigation, however various other alcohol nucleophiles were also tested for their efficacy. The effects of substitution were explored, providing ring opened products in yields of up to 81%. The [2+2] cyclodimerization reaction of oxanorbornadienes was also examined providing the first examples of dimers of this kind. The scope was expanded to include other 2,3-diester oxanorbornadienes as well as various C1 substitutions. Changing the ester moiety did not affect the reaction, however the addition of a C1 alkyl substituent did result in lower yields. Moderate yields of up to 66% were obtained. Additionally, a new ruthenium complex was discovered in the process.
|
Page generated in 0.0326 seconds