2,473 research outputs found
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Synthetic studies of the Thio-Nazarov Cyclization, Biomimetic Total Syntheses of Shimalactones and Exiguamines, and Synthesis of Photoswitchable Dopamine Analogs
No full textSynthetic studies of the Thio-Nazarov CyclizationBiomimetic Total Syntheses of Shimalactones and ExiguaminesSynthesis of Photoswitchable Dopamine AnalogsVladimir SofiyevDoctor of Philosophy in ChemistryUniversity of California, BerkeleyProfessor Dirk Trauner, Co-ChairPart 1 of this thesis describes progress towards thio-Nazarov electrocyclization utilizing substrates with a removable docking group, such as alkyl sulfides, for Lewis acid coordination. This work builds on the successful asymmetric catalysis of Nazarov electrocyclization using non-removable docking groups for coordination of Lewis acids.Parts 2 and 3 of this thesis describe the biomimetic syntheses of the natural products shimalactones and exiguamines respectively. While the synthesis of alkaloids exiguamines A and B is an improvement of our previous work, the synthesis of polyketides shimalactones A and B is their first synthesis and describes a novel intramolecular addition of a b-ketolactone across a diene. Both syntheses feature pericyclic reactions in their key step biomimetic cascade reactions.Part 4 of this thesis describes the synthesis of photoswitchable derivatives of dopamine, containing azobenzenes
Entertainer: Pieter-Dirk Uys
No full textThis booklet celebrates the life and work of Pieter-Dirk Uys, internationally acclaimed playwright, author, role-model and one of South Africa's living treasures
Entertainer: Pieter-Dirk Uys
No full textThis booklet celebrates the life and work of Pieter-Dirk Uys, internationally acclaimed playwright, author, role-model and one of South Africa's living treasures
Entertainer: Pieter-Dirk Uys
No full textThis booklet celebrates the life and work of Pieter-Dirk Uys, internationally acclaimed playwright, author, role-model and one of South Africa's living treasures
Formal Techniques and Self/Other Relations in the Novels of Dirk Bogarde
No full textThe thesis foregrounds the distinctive contribution Dirk Bogarde made to
contemporary writing in a second career that developed in parallel to his screen
commitments. It dispels the notion that Bogarde followed a familiar path as an actor
who wrote books. Instead it establishes his reputation as an innovative writer whose
formal technique was substantially influenced by the textual systems of cinema and
the cross-fertilisation from acting to writing.
In examining the formative factors that steered Bogarde towards authorship, the
thesis addresses the role of performance as a generative factor in the evolution of the
novels, establishing a discursive link with Bakhtinian dialogism, and specifically,
transgredience as a formal imperative. Secondly, it affords a critical insight into why
the major concerns with staging and performativity preoccupy his writing career.
The thesis claims that Bogarde was an empirically dialogical writer whose use
of camera-eye narration fostered the proliferation of competing discourses across the
fiction. This formal dynamic is centred on the relationship between stages and
dialogism, which incorporates the work of Erving Goffinan as a complementary
critique to Bakhtinian theory with its emphasis on self-presentation. The concern
with socially-constructed behaviour leads the thesis to address the associated issues of
stereotyping and 'otherness', which in terms of body politics is articulated by the
mono logic drive to confine the sexual 'other' to a fixed representation.
Bogarde's ability to draw on cinematic and performance techniques identifies
an area of expertise unavailable to most other writers. This is an unusual repository
of skills to bring to writing which is why the thesis makes the claim for his singular
achievement as a contemporary author. There are fruitful points of intersection to be
explored in this respect with the work of Christopher Isherwood, whom Bogarde read
and admired, as a basis for further research. It is hoped that the thesis will play its
part in opening up new possibilities for Bogarde's writing to be re-visited by future
critics
"The end of national models? Integration courses and citizenship trajectories in Europe"
No full textSeveral European countries have recently introduced or are planning to introduce citizenship trajectories (voluntary or obligatory inclusion programs for recent immigrants) or citizen integration tests (tests one should pass to be able and acquire permanent residence or state citizenship). Authors like Joppke claim this is an articulation of a more general shift towards the logic of assimilation (and away from a multicultural agenda) in integration policy paradigms of European States. Integration policies would even be converging in such a fashion that it would no longer make sense to think in terms of national models for immigrant integration. One cannot deny the empirical fact of diffusion of civic integration policies throughout Europe. This paper claims there is, however, still sufficient distinctiveness between immigrant integration policies in order to continue and use an analytical framework which distinguishes national models
Pro-apoptotic activity of lipidic α-amino acids isolated from Protopalythoa variabilis
No full textLipidic alpha-amino acids (LAAs) have been described as non-natural amino acids with long saturated or unsaturated aliphatic chains. In the continuing prospect to discover anticancer agents from marine sources, we have obtained a mixture of two cytotoxic LAAs (1a and 1b) from the zoanthid Protopalythoa variabilis. The anti-proliferative potential of 14 synthetic LAAs and 1a/1b were evaluated on four tumor cell lines (HCT-8, SF-295, MDA-MB-435, and HL-60). Five of the synthetic LAAs showed high percentage of tumor cell inhibition, while 1a/1b completely inhibited tumor cell growth. Additionally, apoptotic effects of 1a/1b were studied on HL-60 cell line. 1a/1b-treated cells showed apoptosis morphology, loss of mitochondrial potential, and DNA fragmentation. (C) 2010 Elsevier Ltd. All rights reserved
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I. Total Synthesis of Smenochromene B and Halenaquinone and II. Studies on the Chemical and Biological Properties of Azobenzene Photoswitches
No full textPart one of this dissertation describes synthetic efforts toward two separate but structurally related groups of marine sesquiterpene quinone natural products, the smenochromene/likonide family and halenaquinone, and culminates in the total synthesis of smenochromene B and halenaquinone. The total synthesis of smenochromene B and efforts towards likonide A centered around the use of smenochromene D as a synthetic intermediate. A macrocyclic ring contraction and double bond isomerization was the key transformation necessary to produce smenochromene B. During the optimization of the synthesis of smenochromene D, two different and remarkable oxidative dimers were isolated, and the mechanism by which they are formed is discussed. Additionally, density functional theory calculations were used to investigate the oxa-6π electrocyclization used to synthesize smenochromene D and are believed to be biologically relevant to the markedly different levels of enantiomeric excess observed within members of the structural family. Halenaquinone, a biologically active pentacyclic quinone isolated from the marine sponge Xestospongia exigua, is biosynthetically related to the smenochromene/likonide family. The total synthesis of halenaquinone reported here features two key steps: a diastereoselective intramolecular Heck reaction, which sets the all-carbon quaternary stereocenter, and an intramolecular inverse-electron-demand Diels-Alder cycloaddition using a vinyl-orthoquinone methide as a diene. This is the first application of such a Diels-Alder cycloaddition to total synthesis. In order to better understand the Diels-Alder reaction, density functional theory calculations were performed to analyze two relevant transition states. Part two describes several projects focused around the synthesis of photoswitchable azobenzene ligands. In order to build on previous work that demonstrated photoregulation of wild-type voltage-gated potassium channels by membrane permeable blockers, a new series of compounds was synthesized with red-shifted absorption maxima. Two new azobenzene containing blockers were identified as being able to regulate voltage-gated potassium channels by toggling between darkness and irradiation with 472 nm light; one compound blocked voltage-gated potassium channels in the trans form, the other in the cis form. Additionally, azobenzene compounds based on the drugs lidocaine and retigabine were synthesized, and preliminary biological data are reported. Finally, the syntheses of azobenzene analogs of the anti-cancer and life-extending (in lower organisms) compound resveratrol and a related protein-tyrosine kinase inhibitor piceatannol are reported
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Total Synthesis of (+)-Spectinabilin, Taiwaniaquinoids, Synthetic Progress toward Aspergillin PZ, and Synthesis of a Photoswitchable Agonist of Glutamate Receptor-dMAG
No full textA new and highly enantioselective synthetic route to γ-methoxypyranone addressed the long unsolved racemization problem in literature. A concise total synthesis of (+)-Spectinabilin was achieved with this method in 10 linear steps. Concept of kinetic resolution with temporary stereocenter was used to improve the enantiomeric excess.A new variant of Nazarov reaction, aromatic Nazarov triflation was discovered which allowed rapid access of polycyclic ring skeleton. The triflation product, indene triflate, was further elaborated with modern palladium cross coupling methods in the total syntheses of many taiwaniaquinoid natural products. Also, the triflation method worked well with electron rich and neutral substrates and was not compatible with electron deficient substrates.Effort toward total synthesis of Aspergillin PZ was described. The biomimetic synthetic hypothesis was pursued. Synthesis of all components was achieved. Future work would be focused on mild reaction condition to bring all components together to for the key intermediate for Aspergillin PZ.Finally, based on the similar principle of previous work in our group, a photoswitchable agonist for metabotropic glutamate receptors was designed and synthesized. Preliminary results confirmed the agonist activity and reversible isomerization with radiation of light of different wavelengths. Further studies are under investigation under collaboration
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