Dissertations / Theses on the topic 'Asymmetric induction'
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1
Smith, Alan Arthur. "Remote asymmetric induction." Thesis, University of Kent, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.280317.
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Selim, Mohammed Refat Moustafa. "Studies on asymmetric induction." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/33892.
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As a part of our studies on asymmetric induction, four topics were investigated in this thesis. Firstly, optically active menthyl and neo-menthyl phos-phonoacetates were prepared and the reaction of their anions with aldehydes and ketones studied, modest asymmetric induction was observed. A chiral phosphonamide anion was also synthesised which shows good selectivity on reaction with ethyl bromide. Secondly, the reactions of aldehydes and ketones with chiral organolithium compounds were investigated. The best results were obtained with a chiral lithiated dithiane, when a ratio of (1:1.9) was obtained in a 1,5-asymmetric induction. Thirdly, the chiral and achiral-2-substituted-l,3- butadienes were synthesised using silicon as a control element. During this work, it was observed that addition of TMSCH2 MgCl with chiral aldehydes produced one diastereo-isomer. For a practical reason it was not possible to determine which one, although a prediction was made based on Cram's rule. The asymmetric Diels-Alder reactions of chiral- 2-substituted dienes were also investigated. Finally, racemic and optically active nitrones were synthesised with preliminary investigations of their reactions with Grignard reagents showing hopeful signs of 1,2-asymmetric induction.
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Large, Janet. "Asymmetric induction using heterocyclic precursors." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272951.
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Harmat, Nicholas J. S. "Chiral phosphine oxides in asymmetric induction." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317929.
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Staines, Cyril Spiteri. "Sensorless position estimation in asymmetric induction machines." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267588.
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Older, Jamie Edward John. "Asymmetric induction of n4-iron diene complexes." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368217.
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The use of tricarbonyliron chemistry in asymmetric synthesis is of increasing importance. With this comes the need for efficient and reliable techniques for the production of enantiopure starting materials. The methods currently available, although effective, are often long winded and wasteful. The development of a chiral hydride abstraction reagent analogous to the triphenylcarbenium species would be of great value in terms of improved yields and simplification of strategy. This thesis details the development of a system based around the dibenzosuberane frame-work. Two different chiral biases have been introduced to the structure leading to a potential double stereodifferentiation effect. Substitution of the 'backbone' of the structure has yielded enantiomeric excesses of up to 54%. The smaller, chiral aryl bias has given e.e.s in the region of 10%. Moreover the synthetic route to the backbone substituted examples has been greatly improved and is now suitable for use on a multigram scale.
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Moir, Jennifer Helen. "Heteromolecular asymmetric induction using novel homochiral magnesium reagents." Thesis, University of Strathclyde, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249127.
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Knight, Roland Laurence. "Synthesis of and asymmetric induction by chiral azolium salts." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624792.
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Mcginley, Jared Joseph. "Lateralized Induction of Cardiovascular Responses: Exploring Asymmetric Autonomic Regulation." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/32888.
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There is clear evidence that the autonomic nervous system (ANS) is lateralized at both the peripheral as well as the central levels of the nervous system. Both the vagus and the sympathetic ganglia asymmetrically innervate the sino-atrial node and the myocardium of the heart. This lateralization has also been observed in afferent as well as efferent projections to nuclei in the brainstem, hypothalamus, and amygdala. Where laterality has not been as clear is in regions of the frontal lobe dedicated to the regulation of autonomic nervous system responses. This study addressed that issue via the implementation of lateralized autonomic response-evoking tasks. With the use of cardiovascular and electrodermal measures, the present study indexed autonomic responses to lateralized stimuli. This study also explored the role of lateralization within sex as well as in relation to reported gender identity. The findings lend support to the right hemisphere as serving a dominant role in regulating sympathetic nervous system activity, while lending less conclusive support for lateralization of parasympathetic nervous system regulation. Men demonstrated greater lateralization for sympathetic nervous system responses across several different metrics of autonomic indices. The exploration of gender variables in relation to lateralization of autonomic responses was generally not supported.Master of Science
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Hiratake, Jun. "STUDIES ON ASYMMETRIC INDUCTION BASED ON ENANTIOTOPIC GROUP DIFFERENTIATION." Kyoto University, 1989. http://hdl.handle.net/2433/78215.
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Netherton, Matthew Russell. "Asymmetric induction and reaction selectivity in solid state organic photochemistry." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0012/NQ61151.pdf.
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Harding, Mervyn. "Asymmetric induction in the 1,7 ring closure of diene-conjugated diazo-compounds." Thesis, University of Edinburgh, 1990. http://hdl.handle.net/1842/10933.
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This thesis describes an investigation into the asymmetric induction found in the electrocyclisation of diazo-componds having α, β, γ, δ-unsaturation. It is thought that the reaction involves two steps, first, an 8 π electron 1,7-electrocyclisation in which orbital overlap at the termini of the π system is achieved via a helical transition state; and second, an intramolecular suprafacial sigmatropic [1,5] hydrogen shift. The results reported here are concerned with the effect of the presence of a chiral substituent at the terminal trans position of the conjugated system in the first step. The second step transfers the chirality stereospecifically, creating a new chiral centre. By measurement of the diastereomeric ratio and a determination of the relative configuration of the two chiral centres, the face selectivity of the chosen chiral groups were assessed. When the medium sized group in the chiral substituent was an alkoxy or hydroxy group, cyclisation at the more hindered face of the alkene in its lowest energy conformation predominated. Polar repulsion effects are thought to be the factors controlling the conformation of the chiral group. When the medium sized group was an alkyl group or an alkoxide ion, the less hindered face was preferred. In the former, steric repulsion effects are believed to dominate the conformation. While, in the latter, polar attraction between the cation and the nitrogen of the diazo-group may stabilize the preferred conformation.
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Evans, Melanie Daryl. "Asymmetric induction in reactions of chiral carboxylic esters and silyl enol ethers." Thesis, Rhodes University, 1998. http://hdl.handle.net/10962/d1006762.
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Several camphor and pinane derivatives have been synthesised and evaluated for use as chiral auxiliaries in asymmetric synthesis. Various blocking groups have been attached to the camphor skeleton in attempts to improve stereofacial selectivity; these include α-methoxybenzyl and xylyl groups, and novel stereoisomeric ketal moieties derived from meso- and (R,R)-(-)-2,3-butanediol. Benzylation reactions carried out on the lithium enolates of ester derivatives of the camphor-derived chiral auxiliaries afforded α-benzylated products in 5-60% diastereomeric excess. Stereochemical aspects have been explored using high resolution NMR, X-ray crystallographic and computer modelling techniques, and hydrolysis of selected α-benzylated products has permitted the diasteroselective bias to be confirmed. Opposite configurations at the new stereogenic centre are clearly favoured by the xylyl and ketal blocking groups - an observation rationalised in terms of the presence or absence of chelating potential in the blocking group. Baylis-Hillman reactions carried out on a series of specially prepared camphor-derived acrylic esters containing the ketal blocking group exhibited both low diastereoselectivities (0-30% d.e.) and very long reaction times. Chiral silyl enol ethers, synthesised using both pinane and camphor derivatives as chiral auxiliaries, showed up to 20% diastereomeric excess in MCPBA oxidation, alkylation and Mukaiyama reactions. Attempts to bring the prochiral centre in the silyl enol ether substrates closer to the chiral auxiliary, and thus improve the stereofacial selectivity, proved unsuccessful. The silyl enol ether derivatives, however, display interesting fragmentation patterns in their electron impact mass spectra, which were investigated using a combination of high resolution MS, comparative low resolution MS and metastable peak analysis.
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Kamath, Anushree. "Contribution à la synthèse totale de l'alcaloïde (-)-205B." Thesis, Grenoble, 2011. http://www.theses.fr/2011GRENV021/document.
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Une approche hors ‘pool chiral' du système tricyclique 8b-azaacenaphthylène de l'alcaloïde (-)-205B a été développé. Cet alcaloïde, caractérisé par son squelette tricyclique rarement rencontré dans les produits naturels, a suscité un intérêt scientifique important ces dernières années du à son activité biologique potentiel vis à vis de maladies neurodégénératives. Cependant, due à sa très faible bio-disponsibilitié son mode d'action détaillée est actuellement inconnue. Notre stratégie se caractérise par plusieurs transformations remarquables. Une cycloaddition thermique [2 + 2] hautement stéréosélective et une expansion de cycle via un réarrangement de Beckmann donnent accès à un lactame fonctionnalisé. Une réaction de Mannich vinylogue fournit efficacement un buténolide qui est ensuite rapidement transformé en un motif indolizidinone. Après méthylation de cet intermediaire bicyclique, une réaction de cyclisation de type aza-Prins, rarement utilisée en synthèse, conduit à un intermédiaire avancé possédant le système tricyclique qui caractérise le produit naturel. Ainsi, cette approche défini une base solide pour une nouvelle voie d'accès à cet important et particulièrement rare alcaloïde isolé à partir de peau de grenouille néotropicales Dendrobates pumilio considerée comme espèce protégéeA non-chiral pool approach to the 8b-azaacenaphthylene ring system of the frog poison alkaloid (-)-205B has been developed. This rare tricyclic alkaloid has been of considerable synthetic interest in recent years owing to its potential biological activity against neuronal disorders. However, due to lack of material, a detailed study of the mode of action of this natural product has not yet been reported. Our strategy features several noteworthy transformations. A highly diastereoselective thermal [2+2] cycloaddition and a ring expansion through Beckmann rearrangement generates the functionalised lactam intermediate. An efficient vinylogous Mannich reaction then provides access to a butenolide, which subsequently leads to an indolizidinone ring system. After installation of a methyl group on this bicyclic intermediate, a relatively unexplored aza-Prins cyclization has been successfully employed to obtain an advanced intermediate, possessing the desired tricyclic system found in the natural product. This approach has laid a solid foundation for a novel access to this potentially important but scarce alkaloid extracted from a neotropical frog Dendrobatus pumilio that is threatened to be endangered
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Gibson, K. "Studies towards the synthesis of the spongistatins and remote asymmetric induction in aldol reactions." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599398.
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Spongistatin 1/ altohyrtin A (1) is a member of a family of naturally occurring marine derived macrolide natural products. These natural products possess potent cytotoxicity. All the spongistatins possess a highly complex 42-membered macrolide ring comprised of two spiroacetal systems, a hemi-acetal ring and a tetrahydropyran ring. The thesis describes the asymmetric synthesis of 108, a C16-C28 fragment incorporating the CD spiroacetal rings (scheme A). The first part of the synthesis of aldehyde 154 and ketone 158. The key steps are chelationcontrolled additions of nucleophiles to aldehyde 134, the kinetic resolution of alcohol 118 using the Sharpless asymmetric epoxidation, and a palladium catalysed Wacker oxidation (scheme B). (Fig. 9034) The second part of the dissertation describes the synthesis of spiroacetals 108 and 110 by the cyclisation of dihydropyranone 192. Aldehyde 154 was coupled to ketone 158 via a boron mediated aldol reaction. Oxidation and mild acid catalysed cyclisation afforded dihydropyranone 192, which could be cyclised to spiroacetals 108 and 110 (scheme C). The final part of the thesis describes the remarkable facial selectivity of ketone 158 in boron mediated aldol reactions. Additions of boron enolate 296 to simple achiral aldehydes proceeds with >90% diastereoselectivity in favour of the 1,5-anti diastereomer 294, the reaction is operating with an unprecedented degree of remote 1,5-asymmetric induction. These aldol products can be elaborated by stereoselective reduction to form 1,3,5 polyoxygenated arrays 320-322 and 333. This methodology has great potential application for the synthesis of 1,3-polyol natural products (scheme D). The origins of the 1,5-remote asymmetric induction were investigated by the application of molecular modelling.
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Salles, Junior Airton Gonçalves 1977. "Sintese do fragmento C29-C39 da sangliferina A." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248450.
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Orientador: Luiz Carlos DiasDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Este trabalho relata a síntese assimétrica do fragmento C29-C39 do potente imunossupressor sangliferina A. O plano sintético utiliza como etapa-chave a reação aldólica com indução 1,5-anti entre a metil cetona 7.3 e o aldeído 31.3(S). A metil cetona 7.3 foi obtida a partir da amida de Weinreb 10.3 utilizando como etapas principais, reação de Horner-Wadsworth-Emmons, epoxidação régio- e diastereosseletiva e abertura de epóxido com cuprato de alta ordem. A amida 10.3 foi obtida a partir da reação aldólica entre N-propioniloxazolidinona 12.3 e a metacroleína mediada por titânio e hidroboração diastereosseletiva. O rendimento total para obtenção do fragmento C29-C39 foi de 18% para 16 etapas.
Abstract: This work describes the stereoselective synthesis of the C29-C39 fragment of the immunosuppressant sanglifehrin A. Our strategy involved a diastereoselective boron-mediated 1,5-anti aldol reaction of methyl ketone 7.3 with chiral aldehyde 31.3(S) as the key step.j Methyl ketone 7.3 is viewed as arising from Weinreb amide 10.3. Key steps in this approach are Horner-Waddsworth-Emmons homologation, selective epoxidation and epoxide ring opening with a higher order cuprate. The Weireb amide 10.3 is available from a titanium mediated aldol reaction of N-propionyloxazolidinone 12.3 with metacrolein followed by a diastereoselective hydroboration. This approach to the C29-C39 fragment of sanglifehrin A requires 16 steps and produced the desired molecule in 18% overall yield.
Mestrado
Quimica Organica
Mestre em Química
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Degenbeck, Helmut. "Transfer of chirality in new supramolecular complexes as design principle for future asymmetric catalysts." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/37353.
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En el curso de esta Tesis Doctoral, se sintetizaron librerías de (1,2)-diaminas enantiopuras y 2,2’-bifenoles pro-quirales. La transferencia de quiralidad desde la diamina al bifenol, mediante puentes de hidrógeno o coordinación a un metal (ZnII, CuII), fue demostrada por dicroísmo circular (DC). El comportamiento en disolución de los complejos supramoleculares (usando puentes de hidrógeno), así como sus constantes de asociación, fue estudiado mediante valoraciones de RMN, UV-vis y ITC. La determinación de las configuraciones absolutas de los complejos de ZnII se consiguió mediante la resolución de las estructuras de
rayos-X y los estudios de DC, tanto a un nivel teórico como experimental. Un nuevo ligando fosforado, potencialmente catalítico, fue preparado a partir de
2,2’-bifenol, mostrando el camino para el desarrollo de nuevos catalizadores supramoleculares.During the course of the thesis libraries of chiral (1,2)-diamines and prochiral 2,2’-biphenol derivatives were synthesised. The transfer of chirality from the diamine to the biphenol moiety mediated either by hydrogen bonding or coordination to a metal centre (ZnII, CuII) was demonstrated by CD (circular dicroism). The behaviour in solution of the hydrogen bonded complexes was investigated by NMR spectroscopy, UV-vis and ITC titrations (determination of association constants. The determination of absolute configurations of the ZnII complexes was achieved by X-ray structure determination and CD analyses both on the experimental and theoretical level. Last but not least, a new potentially catalytic phosphane ligand was derived from a dynamically racemic 2,2’-biphenol derivative.
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Pham, Vinh C. "Asymmetric induction using methyl (S)-lactate and application to the synthesis of Bao Gong Teng A." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23652.pdf.
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Larson, Shawn E. "Enantioselective Brønsted and Lewis Acid-Catalyzed Reaction Methodology: Aziridines as Building Blocks for Catalytic Asymmetric Induction." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4357.
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Chiral molecules as with biological activity are plentiful in nature and the chemical literature; however they represent a smaller portion of the pharmaceutical drug market. As asymmetric methodologies grow more powerful, the tools are becoming available to synthesize chiral molecules in an enantioselective and efficient manner.
Recent breakthroughs in our understanding of phosphoric acid now allow for Lewis acid catalysis via pairing with alkaline earth metals. Using alkaline earth metals with chiral phosphates is an emerging approach to asymmetric methodology, but already has an influential record.
The development of new conditions for the phosphoric acid-catalyzed highly enantioselective ring-opening of meso-aziridines with a series of functionalized aromatic thiol nucleophiles is described in this thesis. This methodology utilizes commercially available aromatic thiols, a series of meso-aziridines, and a catalytic amount of VAPOL calcium phosphate to explore the substrate scope of this highly enantioselective reaction.
Additionally, the development of new conditions for a catalytic asymmetric aza-Darzens aziridine synthesis mediated by a vaulted biphenanthrol (VAPOL) magnesium phosphate salt is described in this thesis. Using simple substrates, this methodology explores the scope and reactivity of a new magnesium catalyst for an aziridination reaction capable of building chirality and complexity simultaneously.
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Sivik, Mark R. "The synthesis and study of optically active organometallic complexes and their application to asymmetric induction chemistry /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487780865409064.
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McLeod, Douglas Dale. "Some studies on asymmetric induction and double asymmetric induction of the rhodium(II)-catalyzed carbon-hydrogen insertion reaction of alpha-diazoacetamides and alpha-diazo-alpha-(methoxycarbonyl)acetates and the synthesis of (2S, 3R)-3-amino-2-hydroxydecanoic acid." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq39147.pdf.
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Bennett, George Douglas. "Factors influencing asymmetric induction during indium-promoted allylation reactions of aldehydes and imino compounds in aqueous solution /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487945744573671.
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Rigotti, Thomas. "Synthesis and metal complexes of C2 symmetric ligands obtained from (R)-(+)-Betti and dialdehydes for asymmetric induction reactions." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/9335/.
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The aim of this master’s research thesis was the employment of an enantiopure 1,3-aminoalcohol, the 1-(α-aminobenzyl)-2-naphthol, known as Betti base, for the synthesis of some novel compounds which show a C2 symmetry. Some of these compounds, after derivatization, were used as ligands in association with transition metals to prepare some catalysts for enantioselective catalytic reactions. Some aminoalcohol (Salan-type) derivatives of these compounds were obtained upon reduction and in some cases it was possible to obtain complexes with transition metals such as Mn, Ni, Co and Cu. Furthermore a novel 6-membered analogue bisoxazoline ligand, 2,6-bis((R)-1-Phenyl-1H-naphtho[1,2-e][1,3]oxazin-3-yl)pyridine, was obtained and from it two Cu-complexes were prepared. The metal complexes were employed in some reactions to test the asymmetric induction, which was in some cases up to discrete values.
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Llewellyn, David B. "Design, synthesis and catalytic properties of chiral counteranions on transition metal catalysts : a new route to asymmetric induction." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82918.
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The design of enantioselective transition metal catalyzed reactions is an important area of chemical research. The purpose of this study was to develop a new method to incorporate chirality into transition metal catalysis via ion pairing interactions. This has led to the development of the first enantioselective transition metal catalyzed reaction using a chiral counteranion as the sole source of asymmetry.In chapter two, the synthesis of a chiral bis(1,1'-bi-2-naphtholato)borate anion is described. This anion can be incorporated into cationic copper(I) complexes via anion exchange, which has allowed its effect on the copper(I) catalyzed aziridination and cyclopropanation reactions to be examined. In the cyclopropanation reaction, it was found that changing the chirality of the counteranion in the presence of (R,R)-2,2'-isopropylidenebis(4-phenyl-2-oxazoline), a chiral ligand, results in a change in the enantioselectivity of the cyclopropanes formed by over 30%. The influence of the chiral counteranion in the absence of a chiral ligand was also explored.
Chapter three describes the use of the copper(I) bis((R)-1,1' -bi-2-naphtholato) borate salt as a chiral NMR shift reagent. The coordination of the (R) and (S) enantiomers of 2,2'-bis(di-p-tolyl-phosphino)-1,1 '-binaphthyl (tol-BINAP) to copper(I) bis((R)-1,1' -bi-2-naphtholato) borate in CD2Cl2 results in well resolved 1H NMR (400 MHz) resonances for the two enantiomers. Examination of standard solutions of 2,2'-bis(di-p-tolyl-phosphino)-1,1 '-binaphthyl demonstrate that the copper complex can be used as an effective NMR shift reagent over a wide range of enantiomeric compositions.
In chapters four and five, the synthesis of a new class of peptide-based chiral counteranions, and their incorporation into copper(I) catalysts via ion exchange, is described. Studies on the copper(I) catalyzed cyclopropanation of styrene with ethyl diazoacetate demonstrate that ion-pairing with these anions can provide a novel method to incorporate a copper cation into a chiral alpha-amino acid environment for asymmetric catalysis. (Abstract shortened by UMI.)
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Huhn, Richard A. (Richard Andrew). "Computational study on the origins of asymmetric induction in Pd-catalyzed cross-coupling reactions and suggestions for improvements thereupon." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/42916.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references.
The origins of asymmetric induction in the Suzuki-Miyaura cross coupling reaction are investigated computationally with density functional theory. Monophosphine-bound palladium complexes are analyzed in the context of oxidative addition to aryl halides, and ligands are explored in terms of steric and electronic effects relevant to oxidative addition. As one of the most successful ligands to date for the asymmetric Suzuki reaction, KenPhos is given substantial attention and subjected to detailed structural analysis. The analysis leads to proposals for new ligands that may enhance the asymmetry of oxidative addition, and some initial synthetic work in that capacity is presented Thesis Supervisor: Professor Stephen L. Buchwald
by Richard A. Huhn.
S.M.
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Ashford, Polly-Anna. "Remote asymmetric induction in the organocatalytic azaDarzens synthesis of peptide aziridines : towards the assembly of new glycopeptide antibiotic analogues." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/54410/.
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The widespread development of bacterial resistance to antibiotics is an ongoing process which represents a growing problem for modern medicine. Vancomycin is used as a drug of last resort against methicillin-resistant Staphylococcus aureus (MRSA), but the increasing prevalence of vancomycin-resistant bacteria has intensified the search for new antibiotics. The introductory chapter of this thesis presents an overview of publications reporting the synthesis of glycopeptide analogues and derivatives in the last decade, highlighting the successful approaches which have brought new pharmaceutical drugs to the market. The results and discussion section of this work focusses first on the synthesis of a triaryl biether structure, which is a common feature of the glycopeptide antibiotic family and represents the beginning of a versatile synthetic approach towards natural products like orienticin C and vancomycin. The second discussion chapter describes the development of an asymmetric organocatalytic aza-Darzens aziridination protocol using diazopeptides and amino acid imines as substrates. A structurally diverse range of peptide aziridines are reported in yields and diastereoselectivity of up to 99%. It is anticipated that the remote asymmetric induction methodology described in this thesis will be applicable not only to the synthesis of novel glycopeptide antibiotics and other peptide-based pharmaceutical compounds, but also to the more general asymmetric synthesis of natural and unnatural amino acids.
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Takeda, Ryohei. "Effect of Chiral Solvent and Pressure on the Dynamic Screw-Sense Induction to Poly(quinoxaline-2,3-diyl)s." Kyoto University, 2017. http://hdl.handle.net/2433/227637.
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Barbieri-Arhancet, Graciela I. "New oxy-dihydrofuran annulation methodology." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-09162005-115038/.
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Fan, Chaxing. "Contribution to nano or micro crystallization induction in silica-based glass by femtosecond laser irradiation." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112170/document.
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Le traitement par laser femtoseconde dans des matériaux transparents est prometteur du fait de la possibilité de contrôler le dépôt d'énergie dans le temps et dans l'espace. Il ouvre ainsi des possibilités fantastiques pour la fabrication de nouveaux matériaux composites multifonctionnels en manipulant la taille, la forme et l'orientation des cristaux non linéaires dans les verres. Cette thèse contribue principalement à la maîtrise de la nano ou micro cristallisation dans des verres à base de silice pour le développement de nouveaux matériaux électro-optiques multi-fonctionnels par l’irradiation au laser femtoseconde. On démontre la faisabilité du traitement des matériaux par le laser femtoseconde pour remodeler les propriétés optiques linéaires et non linéaires ou de la fabrication de micro / nano agrégats, ainsi que les formes et les orientations (en particulier agrégats asymétriques), les tailles et les distributions (à l'échelle sub-micrométrique). Le mémoire débute par un chapitre introductif sur l’investigation de l’écriture par laser impulsionnel ultra-bref dans la silice pure, ainsi que dans le verre à base de silice, afin de bien maîtriser l’inscription avec ce nouveau type de laser. Nous discutons les effets des paramètres du laser sur l’écriture, telle que la vitesse de déplacement du faisceau et la polarisation du laser, sur les propriétés optiques et les structures atomiques, par exemple, la biréfringence, les champs de contraintes et le changement d’arrangement atomique. Il est mis en évidence des effets orientationnels et directionnels spécifiques de l’interaction de ce type de laser avec les verres. Le mécanisme associé fait probablement intervenir l'inclinaison du front de la phase du champ de l’impulsion par rapport au déplacement du faisceau dans le solide. La précipitation des cristaux LiNbO3 orientés dans le verre avec l’irradiation laser femtoseconde est réalisée dans le cas d’une fréquence de répétition élevée (typ. 300 kHz) permettant l’accumulation de chaleur. Des cristaux orientés avec leur axe polaire aligné dans la direction d’inscription du laser ont été fabriqués en manipulant le gradient de température par le réglage des paramètres du laser. L’imagerie microscopique de génération de seconde harmonique (GSH) montre le caractère cristallin asymétrique et fournit des informations sur les orientations dominantes favorisées lors des processus de cristallisation. Les résultats de diffraction d’électrons rétrodiffusés (EBSD) fournissent des informations détaillées sur l’orientation des cristaux et révèlent la structure des lignes écrites notamment tailles et dispersion des orientations. En outre, des débuts de modélisation ont été réalisés pour se diriger vers une maîtrise de l’écriture de structures linéaires cristallines. Une autre section du mémoire rapporte l’étude de reformation par l’irradiation avec le laser femtoseconde de nanoparticules d'or quasi-sphériques ou quasi-tige dans le verre à base de silice. Les nanoparticules d'or de la taille de 3-4 nm ont été précipitées par traitement thermique. Après l’irradiation par le laser, des mesures optiques d'absorption, de biréfringence et de dichroïsme ont été effectuées pour étudier la modification de la forme de nanoparticules d'or dans le verre. Les simulations théoriques ont été menées pour interpréter les résultats expérimentaux basés sur la théorie de Gans et le modèle de Drude avec les constantes diélectriques connus de l'or. Enfin, des stratégies de conception efficaces sont aussi suggérées pour le futur pour des applications possibles utilisant la précipitation, la forme et l'orientation des micro/nanoparticules en 3DFemtosecond laser processing in transparent materials is promising owing to the accessible control of energy deposition in time and in space. In this regime, it opens fantastic opportunities to manufacture novel multifunctional composite materials by manipulating the size, shape and orientation of nonlinear crystals with intrinsic symmetry embedded in glasses. This dissertation mainly contributes to the control of nano or micro crystallization inside silica-based glasses for the development of novel multifunctional electro-optical materials by femtosecond laser irradiation. We demonstrate the feasibilities of femtosecond laser materials processing for re-shaping linear and non-linear optical properties in silica-based glass by inducing or fabricating different micro/nanoclusters as well as their shapes and orientation (especially asymmetric clusters), sizes, and distributions (at the sub-micrometer scale). In this thesis, it firstly covers a chapter for the investigation on ultrafast asymmetric orientational writing in pure silica as well as in silica-based glass in order to well master the laser writing. We discuss the effects of the laser parameters on asymmetric writing such as writing speed and the laser polarization by the femtosecond-laser generated optical properties and structures, e.g., birefringence, phase change and surface topography of the cross section of laser tracks. The mechanism of orientational dependent writing is likely due to the oblique pulse front tilt affected by the polarization orientation plane leading to different anisotropic photosensitivity. 3D photo-precipitation of oriented LiNbO3-like crystals in glass with femtosecond laser irradiation is also achieved at high repetition rate (typ. 300 kHz). Oriented crystals with their polar axis mostly aligned with the laser scanning direction have been fabricated by manipulation of the temperature gradient in adjusting the laser parameters. Second harmonic generation (SHG) microscopy demonstrates optical activity of crystalline features and provides some orientation information suggestive of certain dominant or favored orientations. Electron back-scattering diffraction (EBSD) results provide more detailed local crystal orientation information and illustrate interesting features of the structure of the lines, with regions of distinctly different grain sizes and orientations. Furthermore, modeling the temperature gradient was proposed for better understanding the formation mechanism of the orientation of femtosecond laser-induced crystallization when the laser is moved (not only in the static mode). Quasi-spherical or quasi-rod gold nanoparticles in silica-based glass can be re-shaped by femtosecond laser irradiation studying through their properties, and their orientation appears to be parallel to the written lines. Gold nanoparticles in the size range of 3-4 nm were precipitated by post heat-treatment. After ultrafast laser irradiation, optical absorption, birefringence and dichroism measurements are performed to investigate the modification of gold nanoparticle shape in glass. Theoretical simulations have been carried out to interpret the experimental results based on the Gans' theory and Drude model together with the known dielectric constants of gold. Furthermore, feasible applications and efficient design strategies are also referred for future devices based on micro/nanoclusters 3D precipitation, shaping and orientation mastering
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Pinheiro, Savio Moita. "Indução assimétrica remota na adição de enolatos de boro de metilcetonas quirais a adeídos quirais e aquirais." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248471.
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Orientador: Luiz Carlos DiasTese (doutorado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: As reações aldólicas com enolatos de boro de metilcetonas quirais contendo o protetor p-metóxi- benzilideno cetal (105 e 106) levaram a obtenção do diastereoisômero com indução 1,5-anti em boas seletividades. A avaliação do processo de dupla-diastereosseletividade da metilcetona 105 mostrou que existe uma influência parcial por parte do aldeído no nível de seletividade. Reações aldólicas com metilcetonas acíclicas 1,2-syn-dissubstituídas contendo os grupos protetores PMB (108) e TBS (107) levaram ao isômero 1,5-anti em baixa seletividade. O emprego das metilcetonas contendo a relação 1,2-anti entre os seus estereocentros mostrou baixos níveis de indução 1,5-anti para a metilcetona 109 e 1,5-syn, para a metilcetona 110, eliminando a possibilidade de competição entre as induções 1,4-syn e 1,5-anti. Com o objetivo de compreender os fatores que controlam a reação aldólica, outros estudos estão em andamento no nosso grupo de pesquisas.
Abstract: We report herein that good to excellent levels of 1,5-anti stereoinduction are obtained in boron enolate aldol reactions of 1,2-syn -alkoxy methyl ketones with achiral aldehydes, when the b-alkoxy protecting group is part of a benzylidene ketal. The strong internal stereoinduction of the b-alkoxy stereocenter of the boron enolates dominates the overall stereochemical outcome of the corresponding aldol addition reactions, leading to the 1,5-anti products with good levels of diastereoselectivities. Even with the use of acyclic a-methyl-b-alkoxy methyl ketones, the b-stereocenter plays a dominant role in determining the sense of 1,5-anti asymmetric induction, although lower levels of diastereoselectivities were obtained. Due to the lower energy difference observed between transition states, it looks like a mismatched relationship case as a competition between 1,4-syn induction from the a-methyl stereocenter and 1,5-anti induction from the b-alkoxy stereocenter. The results showed a predominance of 1,5-induction in competition with 1,4-induction.
Doutorado
Quimica Organica
Doutor em Ciências
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Mazzier, Daniela. "Functionalized short peptides and polypeptides: from organic reactions, through secondary structure control, to supramolecular applications." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424844.
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Short helical peptides
Peptides with a well-defined helical conformation were examined with the aims of reinforcing their secondary structure or using their rigid conformation to control asymmetric induction over long distances.
In the first example, two consecutive i, i+4 intramolecular side chain-to-side chain macrocyclization reactions of different type, carried out on a preformed, partially helical linear peptide resulted in a double stapled, overlapping, bicyclic oligopeptide system. A detailed CD and NMR conformational study revealed that the mixed 310/α-helical conformation exhibited by the original linear peptide is converted into a fully-developed α-helix in the bicyclic peptide. In parallel, both the helix overall content and stability are significantly increased. In the second part, an achiral Aib-based helical foldamer was appropriately functionalized with the photoswitchable fumaramide/maleamide linkage, thus obtaining a system in which a screw sense preference may be activated by the absorption of UV light. The trans configuration in the fumaramide linkage holds the chiral residue away from the achiral portion of the oligomer, preventing the induction of a conformational preference. However, after photoisomerization, the cis configuration of the maleamide brings the chiral and achiral portions into proximity, generating a pronounced preference for one of the two possible, helical screw senses. In conclusion, we showed that it is feasible to use light to switch on and off the ability of the molecules to react strereoselectively in a chain extension reaction, or to modulate helix-to-helix communication.
Functionalized helical polypeptides
The well-known, rod-like α-helical polypeptide poly(γ-benzyl-L-glutamate) (PBLG) was selected for this study. The possibility to create self-assembled microstructures with different characteristics, shapes and functions from different PBLG-conjugates was explored.
Mono- and bis-fullerene (C60)-PBLG conjugates were obtained by one-pot thiol-ene chemistry. These systems showed the propensity to self-assemble in water creating precise bulky microstructures of toroidal or vesicular shape. In a second part, we reported the synthesis of star-shaped carbon quantum dots (CQDs)-PBLG conjugates that self-assemble into microstructures and retain the characteristic emission properties of the native dots. CQDs, prepared by microwave-assisted carbonization of Arg and 1,2-ethylendiamine in water, were used either as initiators to afford a daisy-like peptide-polymer structure, or as capping agents towards more elaborated hybrid nanostructures that self-assemble into supramolecular aggregates of spherical shape. Finally, smart microstructures with photoresponsive behavior was obtained by the insertion of azobenzene-containing α-amino acids in PBLG systems. We created two systems, with either C2- or C3-symmetry, that self-assemble in spherical structures. The change in their 3D-structure after light irradiation is followed by a variation in the morphology of the aggregates.
Self-assembling short peptides
The synthesis and self-assembly properties of two different peptide systems were studied. The first series of compounds contain the photoswitchable α-amino acid bis[p-(phenylazo)benzyl]glycine, which undergoes a reversible cis-trans isomerization upon exposure to light at the appropriate wavelengths. Derivatives and short peptides containing this α-amino acid are able to promote the formation of well-ordered supramolecular structures. Interestingly, the morphological transition observed after UV-light irradiation proved to be reversible due to the presence of the two side-chain azobenzene groups.
In the second part, we investigated the hydrophobic, terminally-protected dipeptide Boc-L-Cys(Me)-L-Leu-OMe that it is able to hierarchically self-assemble producing nano-, micro- and macroscale complex architectures, including hollow rods, under appropriate conditions. Our results suggested that its self-assembly properties might be related to the occurrence in its single crystal structure of a supramolecular sixfold helix motif. Subsequently, we decided to chemically modify the molecule to obtain a diacetylene derivative. This final compound is able to form an organogel or spherical aggregates, which undergo a topochemical polymerization under UV-light irradiation.Peptidi elicoidali corti In questo lavoro di tesi sono stati studiati diversi peptidi caratterizzati da una ben definita conformazione elicoidale con lo scopo di stabilizzarne la struttura secondaria oppure di sfruttare la loro conformazione rigida come mezzo per controllare l’induzione asimmetrica su lunghe distanze. Il primo esempio, un sistema oligopeptidico biciclico doppiamente stabilizzato, è stato ottenuto tramite due reazioni di macrociclizzazione che hanno coinvolto le catene laterali dei residui in posizione i e i+4 di un peptide lineare. Un’indagine conformazionale dettagliata, condotta utilizzando le spettroscopie CD ed NMR, ha rivelato che la conformazione mista 310/α-elica, osservata per il peptide lineare, risulta completamente convertita in una struttura ad elevato contributo α-elicoidale nel peptide biciclico. In parallelo, sia il contenuto totale di elica sia la stabilità risultano significativamente aumentati. Nel secondo caso, un foldamero achirale elicoidale a base di Aib è stato opportunamente funzionalizzato con il gruppo fotoisomerizzabile fumarammide/maleammide contenente un residuo chirale. In questo modo è stato ottenuto un sistema in cui è stato possibile influenzare il senso di spiralizzazione dell’elica grazie all’uso di luce ultravioletta. La configurazione trans nella fumarammide, infatti mantiene il residuo chirale lontano dal segmento achirale dell’oligomero, rendendo impossibile l’induzione di una conformazione preferenziale. Tuttavia dopo l’isomerizzazione, la configurazione cis della maleammide consente alla parte chirale e a quella achirale di essere spazialmente vicine, con conseguente induzione di chiralità e adozione di un senso preferenziale di spiralizzazione. Sfruttando questo principio è stato quindi possibile utilizzare la luce per accendere o spegnere la capacità del sistema di reagire stereoselettivamente, oppure di modulare la comunicazione di chiralità tra due segmenti elicoidali. Polipeptidi elicoidali funzionalizzati Con lo scopo di ottenere tramite self-assembly microstrutture con differenti caratteristiche, forme e funzioni sono stati sintetizzati diversi sistemi coniugati a base di poli(γ-benzil-L-glutammato) (PBLG). Sistemi polipeptidici contenenti una o due unità di fullerene sono stati ottenuti tramite reazione tiol-ene one-pot. Questi due polimeri hanno mostrato una diversa propensione ad auto-assemblarsi in ambiente acquoso, formando microstrutture di forma toroidale oppure di tipo vescicolare. Come ulteriore esempio è stata riportata la sintesi di sistemi coniugati a base di PBLG e carbon quantum dots. I CQDs, preparati per trattamento in microonde a partire da una soluzione acquosa di arginina e 1,2-etilendiammina, sono stati usati come iniziatore, ottenendo una struttura polimerica a forma di stella, oppure come agente cappante, portando alla formazione di microstrutture più complesse. I sistemi ottenuti sono in grado di autoassemblarsi formando aggregati supramolecolari di forma sferica che mantengono le caratteristiche proprietà di emissione dei dots originali. Infine, microstrutture “smart” con comportamento fotoresponsivo sono state ottenute inserendo amminoacidi a base di azobenzene all’interno del sistema polipeptidico. Sono state quindi sintetizzate due strutture polipeptidiche con simmetria C2 e C3 che hanno evidenziato la formazione di strutture sferiche tramite self-assembly. Il cambiamento della loro struttura tridimensionale in seguito ad irraggiamento è accompagnato da una variazione nella morfologia degli aggregati. Peptidi corti auto-assemblanti In questo ultimo capitolo sono discusse la sintesi e le peculiari proprietà di self-assembly mostrate da due diversi sistemi peptidici. La prima serie di composti contiene l’amminoacido fotoisomerizzabile bis[p-(fenilazo)benzil]glicina, che è in grado di isomerizzare reversibilmente tra le due forme cis/trans in seguito ad irraggiamento con luce di adeguata lunghezza d’onda. Derivati e peptidi corti contenenti questo amminoacido sono in grado di promuovere la formazione di strutture supramolecolari ordinate. Inoltre, grazie alla presenza delle due unità di azobenzene sulle catene lineari, la transizione morfologica osservata in seguito ad irraggiamento si è dimostrata essere reversibile. Nella seconda parte di questo studio è stato esaminato il comportamento del dipeptide idrofobico protetto Boc-L-Cys(Me)-L-Leu-OMe. La formazione di nano-, micro- e macro- architetture complesse, tra cui bacchette caratterizzate da una cavità interna, è stata osservata in diverse condizioni sperimentali. I risultati ottenuti suggeriscono che le proprietà di self-assembly sono correlate all’organizzazione delle molecole nel cristallo singolo in cui è stata osservata la presenza di una particolare struttura supramolecolare elicoidale formata da sei molecole. Successivamente è stato deciso di modificare il dipeptide in modo da ottenere un derivato diacetilenico. Questo derivato è in grado di formare un organogel o delle strutture sferiche che possono subire polimerizzazione topochimica per irraggiamento UV.
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Berkous, Rabiaa. "Greffage de modèles du NADH sur deux nouveaux supports insolubles. Synthèse et réactivité d'un modèle du NADH en série indolo (2,3-b)-pyridine : réduction de substrats non activés." Rouen, 1994. http://www.theses.fr/1994ROUES042.
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Le greffage de réactifs modèles du NADH a été réalisé sur deux nouveaux supports: un matériau mixte silice-polymère et un polymère acrylique à chiralité intrinsèque. Dans les deux cas, la réduction de substrats classiques a été possible. Avec le second support, une induction asymétrique a été observée. Afin d'effectuer la réduction de substrats non activés en présence d'acides de Lewis capables d'activer de tels substrats, un modèle en série indolo (2,3-)pyridinique a été synthétisé. Il est stable et possède une réactivité élevée. Il est le premier modèle du NADH à avoir permis la réduction quasi quantitative de l'acétophénone. Il a également permis de réduire une large gamme de cétones non activées. Le modèle chiral de la même série a réduit l'acétophénone et le phénylglyoxylate de méthyle avec des excès énantiomériques intéressants. Un modèle non chiral en présence d'acides de Lewis chiraux a aussi permis d'observer une induction asymétrique
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Naim, Ahmad. "Conception rationnelle, synthèse et caractérisation de composés à transition de spin chiraux." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0007.
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D'importants progrès ont été accomplis dans le domaine des matériaux à transition despin depuis leur première observation par Cambi en 1931. La combinaison de lachiralité avec le magnétisme résulte en de nouvelles propriétés très intéressantes quiouvrent la voie pour de potentielles applications technologiques. Ce manuscrit décritles résultats obtenus par diverses stratégies poursuivies vers des matériauxmoléculaires non-centrosymétriques à transition de spin par combinaison decomplexes à transition de spin avec des anions chiraux à symétries D3 et D2Many advancements in the field of spin crossover materials have been carried outsince the first observation by Cambi in 1931. The combination of chirality andmagnetism yields fascinating properties that open the way for potential technologicalapplications. Obtaining new non-centrosymmetric magnetic compounds yieldsinteresting subjects for non-linear optical studies or crystallography. This manuscriptdescribes the results obtained by various strategies pursued toward spin crossovernon-centrosymmetric molecular materials by combining spin crossover complexes withchiral anions based on D3 and D2 symmetric anions
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Bernardes-Genisson, Vania. "Induction asymétrique dans la réaction intermoléculaire de Pauson-Khand et synthèse formelle de la (+)-brefeldine-A." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10144.
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La réaction de Pauson-Khand, une cycloaddition entre un alcène, un alcyne et du monoxide de carbone représente l'une des méthodologies, mettant en jeu des métaux de transition, les plus efficaces pour préparer des cyclopentenones. L'emploi d'un auxiliaire de chiralite lie directement au partenaire acetylenique de cette réaction nous a permis, dans un premier temps, de développer une version asymétrique de la réaction intermoléculaire de pauson-khand. La réussite de cette stratégie a été possible grâce à la mise au point d'une méthode efficace et générale de préparation de complexes de cobalt d'ethers acétyléniques terminaux qui est basée sur l'utilisation d'un groupe silane comme élément protecteur de l'hydrogène acétylénique. Un travail initial d'évaluation des auxiliaires de chiralite, nous a permis d'élire le trans-deux-phenylcyclohexanol comme étant l'inducteur de choix dans notre cas. L'addition conjuguée hautement diastereoselective de réactifs organométalliques sur le cycloadduit enantiopur de Pauson-Khand, issu de la cyclisation avec le norbornadiene, nous a permis de développer une méthode de préparation enantioselective de cyclopentenones quatre-substituées, obtenues après réaction de retro diels-alder. Enfin, pour démontrer l'efficacité et l'importance de cette approche, nous avons réalisé une synthèse formelle enantioselective de la brefeldine-a naturelle, un macrolide intéressant pour ses activités immunodépressives
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Danielsson, Jakob. "Stereoselective Nucleophilic Additions to Aldehydes and Synthesis of α-Amino-β- Hydroxy-Esters." Licentiate thesis, KTH, Organisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-95467.
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This thesis deals with the development of new reaction methodology as well as stereochemical investigations. The first part concerns the investigation of 1,2- and merged 1,2- and 1,3- asymmetric induction in Mukaiyama aldol additions to α-heteroatom and α,β- heteroatom substituted aldehydes respectively. In particular, the unexpected 1,2-syn selectivity obtained in the addition of sterically hindered nucleophiles to α-chloroaldehydes is examined, and an explanation for the observed stereochemical trends is proposed. The second part describes the development of a novel entry to α-amino-β- hydroxy esters by a 1,3-dipolar cycloaddition reaction of aldehydes and azomethine ylides, generated by thermolysis of aziridines. The third part deals with our efforts to develop a novel entry to vicinal all- carbon quaternary centers, based on an intramolecular domino Heck- carbonylation reaction using tetrasubstituted olefins.QC 20120611
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Beck, Daniel Antony Speedie, and beckautomatic@gmail com. "Stereoselective intramolecular Michael addition reactions of pyrrole and their application to natural product syntheses." The Australian National University. Research School of Chemistry, 2006. http://thesis.anu.edu.au./public/adt-ANU20070130.130009.
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Chapter one; (-)-Rhazinilam and (-)-Rhazinal: Alkaloids with Anti-mitotic Properties Derived from Kopsia teoi, provides the background information behind the motives that initiated this research project. The plant alkaloid (-)-rhazinilam [(-)-1] and its naturally-occurring derivative (-)-rhazinal [(-)-13] both exhibit potent anti-mitotic activities and, as such, are interesting targets for total synthesis. Chapter one is a review of the literature regarding these two compounds and discusses the occurrence, proposed biosynthetic origins, structural elucidation and biological activites of compound (-)-1 and that of its analogues including alkaloid (-)-13. Previous total syntheses of these two compounds are then examined, concluding with the only reported total synthesis of compound (-)-13. Developed within the Banwell research group, this total synthesis produced the racemic modification of alkaloid (-)-13 due to a lack of any stereocontrol in the key intramolecular Michael addition step. This unprecedented key step, involving cyclisation of the C2 of pyrrole onto an N-tethered and ?,?-disubstituted acrylate to produce a quaternary-carbon stereogenic centre, would be of greatly enhanced utility if it could be achieved in a catalytic-enantioselective fashion. The realisation of this goal is the central aim of the research conducted within this thesis.
¶
Chapter two; Investigating Asymmetric Induction in the Intramolecular Michael Addition of pyrrole to N-Tethered Acrylates and Related Species, introduces the model study used to direct research towards achieving the goal of asymmetric induction in the title process. The model is a somewhat simplified version of the original process used in the total synthesis of compound (-)-13 involving cyclisation of the C2 of pyrrole onto an N-tethered and ?-monosubstituted Michael acceptor, to produce a tertiary-carbon stereogenic centre. This simplification allows the rapid synthesis of a broad range of potential substrates for use in the title process, thus enabling the investigation of various different approaches to inducing asymmetry therein. High levels of asymmetric induction are observed with the use of chiral substrates or catalysts, facilitating the synthesis of both 6- and 7-membered rings annulated to pyrrole with construction of the relevant tertiary-carbon stereogenic centre in enantio-enriched form. For the reactions producing a 6-membered ring annulated to pyrrole, unambiguous proof of the absolute sense of asymmetric induction observed in the intramolecular Michael addition event is established using a chemical correlation study involving elaboration of a key indolizine-type cyclisation product, to the plant alkaloid of known absolute stereochemistry, (-)-tashiromine [(-)-75]. For the reaction producing a 7-membered ring annulated to pyrrole, the same information is obtained via X-ray crystallographic analyses of a dibrominated derivative of a key pyrroloazepine-type cyclisation product.
¶
Chapter three An Enantioselective Total Synthesis of the Alkaloid (-)-Rhazinal: An Anti-mitotic Agent Isolated from Kopsia teoi., focuses on the application of methodology developed in the previous chapter, to the original goal of inducing asymmetry in the intramolecular Michael addition reaction, involving cyclisation of the C2 of pyrrole onto an N-tethered and ?,?-disubstituted acrylate to produce a quaternary-carbon stereogenic centre. This is ultimately achieved in a catalytic-enantioselective fashion, resulting in the first such total synthesis of the anti-mitotic alkaloid (-)-rhazinal [(-)-13].
¶
Chapter four Extending the Reaction Manifold to the Syntheses of Related Natural Products: A Formal Total Synthesis of (+)-Aspidospermidine and Syntheses of (-)-Rhazinilam and (-)-Leuconolam from (-)-Rhazinal, describes three extensions to the reaction manifold used in the enantioselective total synthesis of alkaloid (-)-13:
The acquisition in an enantioselective manner, of an intermediate previously obtained in racemic form, en route to the racemic modification of the natural product (±)-aspidospermidine [(±)-134], constitutes a formal and enantioselective total synthesis of (+)-aspidospermidine
[(+)-134].
The direct deformylation of (-)-rhazinal [(-)-13], is carried out, to produce the parent alkaloid
(-)-rhazinilam [(-)-1].
The pyrrole ring present in (-)-rhazinilam [(-)-1] is oxidised, to produce the related natural product (-)-Leuconolam [(-)-12] which has not, hitherto, been prepared by total synthesis.
¶Chapter five contains the experimental procedures and characterisation data associated with compounds described in chapters two to four.
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TALAGA, PATRICE. "Synthese et activite biologique de tolerogenes potentiels." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13101.
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Essais d'induction de tolerance aux haptenes de type alpha-methylene gamma butyrolactones (amgbl) responsables de nombreuses allergies de contact. Synthese de differents tolerogenes potentiels hydrosolubles de la forme lactone-derives lysinyl et lactone-derives cysteinyl. Etude de l'induction asymetrique observee lors de l'addition de michael d'un dipeptide (voc-cys-ala-ome) a differentes amgbl. Observation d'un parallelisme entre cette induction asymetrique et l'enantioselectivite de la reponse immunitaire dans le phenomene de l'allergie croisee
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Molvinger, Karine. "Hydrogénations énantiosélectives sur catalyseurs mixtes : nickel-oxazaborolidines." Université Joseph Fourier (Grenoble ; 1971-2015), 1998. http://www.theses.fr/1998GRE10229.
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Les oxazaborolidines sont devenues un puissant outil pour la reduction enantioselective des cetones avec des exces enantiomeres eleves. Cependant la separation catalyseur / produit est difficile a realiser, le milieu etant homogene. Le defit etait de fixer une oxazaborolidine a la surface d'un metal catalyseur d'hydrogenation. Ainsi bh#3 serait remplace par h#2 et l'inducteur chiral ne serait pas detruit lors de la separation de l'alcool, realisee par simple decantation. Dans un premier temps nous avons prepare des nano-particules de borure de nickel de composition massique nib#2. Ce catalyseur a ete caracterise par plusieurs methodes physico-chimiques (analyse centesimale, surface bet, surface metallique, infra-rouge, microscopie electronique, auger). Nous avons ensuite greffe une oxazaborolidine sur la surface de nib#2 par addition d'un amino alcool. Plusieurs amino alcools ont ete etudies, differents substrats ont ete hydrogenes (isophorone, 4-methyl-2-pentanone), les exces enantiomeres obtenus sont faibles (respectivement 4% et 3,6%). Cependant il est important de signaler qu'un catalyseur utilise plusieurs fois conserve la meme enantioselectivite et que si l'amino alcool s (+) conduit a l'alcool r (-), l'emploi de l'isomere r (-) de l'amino alcool fournit l'alcool s (+) avec le meme exces enantiomere. Les faibles exces enantiomeres obtenus lors de ces hydrogenations contrastent avec les excellents resultats (ee = 95%) observes lors de la reduction par bh#3. Le complet accord observe entre les proprietes enantioselectives des deux methodes de reductions par bh#3 (homogene et heterogene) met en evidence la formation d'oxazaborolidine. Cette molecule chirale est tres solidement fixee a la surface des particules de catalyseur.
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Obaid, Ramzy R. "Detection of rotating mechanical asymmetries in small induction machines." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/13527.
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Prado, Wellington do. "Análise comparativa do desempenho de um motor de indução trifásico tradicional e um motor de indução trifásico assimétrico com alimentação monofásica." Universidade Federal de Uberlândia, 2013. https://repositorio.ufu.br/handle/123456789/14550.
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The main objective of this work is to perform a comparative study between a three phase induction motor squirrel cage traditional and asymmetrical three-phase induction motor. Were used two motors of the same power, the motor being powered by an asymmetrical voltage source phase. In the studies we investigated the behavior of various quantities such as yield, starting current, voltage sags, power factor, and the power supplied by each machine. With the results obtained from practical experiments, it was found that the asymmetric motor features a number of advantages over traditional engines, which makes it an excellent choice when the application requires the drive loads of high power and not has a three-phase supply.O objetivo principal deste trabalho é realizar um estudo comparativo entre um motor de indução trifásico do tipo gaiola de esquilo tradicional e um motor de indução trifásico assimétrico. Foram empregados dois motores com a mesma potência, sendo o motor assimétrico alimentado por uma fonte de tensão monofásica. Nos estudos foi investigado o comportamento de várias grandezas como rendimento, corrente de partida, afundamentos de tensão, fator de potência, bem como as potências fornecidas por cada máquina. De posse dos resultados obtidos através de experimentos práticos, pôde-se constatar que o motor assimétrico apresenta uma série de vantagens em relação aos motores tradicionais, o que o torna uma excelente opção quando a aplicação exige o acionamento de cargas de potências elevadas e não se dispõe de um sistema trifásico de alimentação.
Mestre em Ciências
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Shaukat, Usman. "Performance Analysis of Unskewed Asymmetrical Rotor for LV Induction Motors." Thesis, KTH, Elektrisk energiomvandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109726.
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This master thesis presents a comparative analysis of the starting performance and losses at rated operation for a 15 kW, 4-pole industrial induction motor, mounted with standard skewed, unskewed and unskewed asymmetrical die-cast aluminium rotors through measurements and simulations. It is a well-known fact that rotor skewing suppresses the synchronous torques at low speeds and also reduces the audible noise of the machine. However, the casting process results in a low resistive path between the rotor bars and the iron laminations, for skewed rotors, this promotes the flow of inter-bar currents. These currents, flowing between the rotorbars, increase the harmonic torques during a start and create additional losses at rated operation. For standard unskewed rotors, these losses are ideally zero, but these rotors may produce high audible noise. Studies have shown that rotors with asymmetrical rotor slot pitch can reduce the audible noise level in unskewed machines. By removing the skew, the inter-bar current losses are suppressed to a negligible level; ultimately increased machine efficiency is obtained. In this work the electrical performance is verified through measurements on the built prototypes. Direct-on-line starts and rated performance for motors with different rotor slot arrangements is simulated using 2D FEM tool FCSmek. The three prototypes are tested in the laboratory according to IEC 60034-2-1 standard and the simulation results are in good agreement with the measured results. An additional test for the measurement of high frequency delta connected stator winding currents for each prototype machine is also performed, in order to study the losses induced in the stator winding. Results have shown that by introducing the proposed asymmetry in the rotor slots, the synchronous torques at low speeds are suppressed effectively, thus, improving the starting performance of the asymmetrical rotor compared to the standard unskewed rotor. Additionally, a higher pull-out torque is obtained for the unskewed rotor motor compared to the standard skewed rotor motor. However, the losses were more or less re-distributed in the unskewed rotor motor, resulting in similar efficiency as the standard skewed rotor motor. One important observation is that; to capture the inter-bar current losses which are estimated to be 5.5% of the total losses, requires more accurate methods of measurements than the existing. And sufficient repeatability must be achieved; alternatively one should rely on statistical data obtained from measurements on several number of motors.
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Serna, Calvo Eva Teresa. "Diagnostics of rotor asymmetries in inverter fed, variable speed induction machines." Berlin Logos-Verl, 2009. http://d-nb.info/99519422X/04.
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Spiridon, E. "Anger induction and ambient interventions : effects on cardiovascular activity and frontal EEG asymmetry." Thesis, Liverpool John Moores University, 2017. http://researchonline.ljmu.ac.uk/6829/.
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Background and aims: The experience of anger could affect cardiovascular (CV) and electro-encephalographic (EEG) parameters but such parameters could vary within the motivational context. Although models of motivational contexts were proposed by CV literature as challenge/threat (Blascovich & Tomaka, 1996) and by frontal EEG asymmetry literature as approach/avoidance (Harmon-Jones, 2004a) little is known whether a negative emotion such as anger could be indexed by CV and EEG responses within motivational contexts. Anger in a threat context may be particularly detrimental for health due to low control compared to anger in a challenge context, where control is high. Hence, the aim of the research was twofold: 1. to investigate how a motivational context (challenge vs. threat) influences the cardiovascular system and frontal EEG asymmetry during anger induction protocols and 2. to analyse the efficacy of ambient interventions (music, light) to reduce the impact of anger on cardiovascular responses. Affective computing through the use of ambient intelligence technology could be used to promote positive emotion or to ameliorate negative moods. Method: There were two anger induction protocols within the thesis. Firstly, anger was manipulated using an experimenter effect (i.e., rude vs. polite experimenter). Participants were exposed to a computer-based problem-solving task under conditions of control and no control which represented the motivational contexts of challenge/threat. Secondly, anger was induced by exposing participants to a time constrained driving schedule on a simulated route with financial penalties for any delays to arrive to the destination. Motivation was manipulated by exposing participants to traffic delays at an early (challenge) and later point (threat) on a simulated driving route. STAXI-2 (Spielberg, 1999) was used to measure anger states and motivation was measured by Confidence and Perceived Control Scale from Dundee Stress State Questionnaire (Matthews & Desmond, 1998). Psychophysiological variables included: blood pressure (BP), cardiovascular impedance (ICG), frontal EEG asymmetry, and facial electromyography (fEMG). Results: The cardiovascular and EEG results of the present thesis pointed to a circumplex model of anger with quadruplet facets along cardiovascular responses to challenge/threat contexts in conjunction with approach/avoidance tendencies where a threat motivation with avoidance was indexed by increased blood pressure and cardiac output and by greater right frontal activation. The difference in the approach-threat responses was the activation of the left hemisphere. The challenge-avoidance state was defined by increased total peripheral resistance (TPR), systolic blood pressure (SBP), heart rate (HR), mean arterial pressure (MAP) and greater right frontal hemisphere activation. No frontal asymmetric activity was identified in the challenge-approach, but increased TPR, SBP, HR and MAP were observed. The ambient intervention results suggested that cardiovascular responses (e.g., SBP) could be reduced by low activation music or blue ambient light. Discussion and conclusions: Anger in the context of challenge can be distinguished from anger in the context of threat via a specific pattern of CV (systolic BP) and EEG measures (frontal peripheral brain site). Ambient interventions (low activation music or blue light) could be factors in modulating physiological reactions while driving; discrepancies between self-report measures and physiological responses, low sensitivity of impendence data to manipulations and low impact of various colour ambient lights on cardiovascular responses were addressed within a theoretical and methodological.
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Piva, Olivier. "Photodeconjugaison enantioselective de systemes conjugues." Reims, 1988. http://www.theses.fr/1988REIMS001.
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Pérollier, Céline. "Synthèse de nouvelles métalloporhyrines chirales à substituants cyclopropaniques : applications en catalyse d'époxydation asymétrique et en reconnaissance moléculaire d'enantiomères." Université Joseph Fourier (Grenoble ; 1971-2015), 1998. http://www.theses.fr/1998GRE10191.
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Le biocartol ou acide (1r)-cis-hemicaronaldehydique, un compose cyclopropanique enantiopur provenant de la synthese industrielle d'insecticides pyrethroides, est utilise comme synthon pour la preparation de nouvelles porphyrines chirales. Nous decrivons la synthese d'amides du biocartol, puis la synthese des porphyrines correspondantes par condensation avec le pyrrole. Celles-ci sont obtenues exclusivement sous la forme de l'atropoisomere , avec un rendement variant de 7 a 60%. Une serie de complexes de manganese (iii) de ces chiroporphyrines, derivees d'amides et d'esters du biocartol, ont ete prepares. Ces complexes sont de bons catalyseurs pour l'epoxydation asymetrique d'olefines prochirales. Les substrats a structure rigide cyclique sont epoxydes avec la plus grande selectivite. Ainsi, des exces enantiometriques allant jusqu'a 86% ont ete obtenus pour l'epoxydation du 1,2-dihydronaphtalene en (1s, 2r)-epoxy-1,2,3,4-tetrahydronaphtalene. L'influence de differents facteurs (nature des substituants, solvant, ligand axial, metal) sur la reactivite et l'enantioselectivite ont ete etudies. Des etudes structurales par resonance magnetique nucleaire et par diffraction des rayons x ont permis d'etablir une correlation entre structure et induction asymetrique dans cette serie. Nous avons mis en evidence que l'encombrement sterique au niveau du centre metallique lors de l'epoxydation est le determinant principal de l'enantioselectivite. Ces resultats sont interpretes par un modele geometrique de l'approche de l'olefine vers le centre metallique. La complexation d'amines derivees d'olefines prochirales par les chiroporphyrines de cobalt (iii) a egalement ete etudiee.
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Simonato, Jean-Pierre. "Chimie de coordination de la tétraméthylchiroporphyrine avec le fer(III), le cobalt(III) et le rhodium(III) : applications à l'analyse d'énantiomères d'amines, à la complexation énantiosélective d'aminoalcools, et à la catalyse d'aziridination asymétrique." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10051.
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Des complexes metalliques de la tetramethylchiroporphyrine, de symetrie et possedant des groupements meso derives du biocartol, ont ete synthetises, caracterises, et utilises dans quatre axes de recherches. _la caracterisation du complexe bis-ethanol de la tetramethylchiroporphyrine de fer(iii), en solution et en phase solide, revele que ce compose presente un etat de spin inhabituel : le spin intermediaire pur (s = 3/2). _l'insertion d'un metal diamagnetique, le cobalt(iii), coordonnant les amines au cur de la porphyrine, a permis l'analyse qualitative et quantitative de la composition de derives d'amines par resonance magnetique nucleaire du proton. Cette methode s'est averee precise, fiable, rapide et tres facile d'utilisation. _l'addition de -aminoalcools sur cette meme molecule resulte en la complexation preferentielle d'un enantiomere. Les aspects cinetiques et thermodynamiques ont ete abordes, et une explication quant a l'enantioselectivite observee est avancee sur la base de liaisons hydrogene intramoleculaires de type c-h___o. _parmi differentes complexes de la tetramethylchiroporphyrine, ceux de fer(iii) et de manganese(iii) ont donne les meilleurs resultats pour la catalyse d'aziridination asymetrique, avec des exces enantiomeriques allant jusqu'a 57% pour le styrene. Un point remarquable est l'induction asymetrique opposee de ces deux catalyseurs, chacun favorisant la formation majoritaire d'un enantiomere.
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Azevedo, Mariangela Burgos Martins de. "Synthèse énantiosélective de (gamma)-butyrolactones : ()-méthylénolactocine, (-)-acide protolichestérinique, (-)-blastmycinolactol, (+)-blastmycinone, (-)-NFX-2 et (+)-antimycinone." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10116.
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La cycloaddition du dichlorocetene avec des éthers d'enols chiraux conduit à des cyclobutanones fonctionnalisées avec une diastéréosélectivité élevée. Cette réaction est basée sur la différenciation des faces de la double liaison de l'oléfine chirale. Des intermédiaires de pureté enantiomerique élevée, comme les gamma-butyrolactones, sont obtenus à partir des cycloadduits. Au cours de ce travail, nous avons effectué les premières synthèses enantioselectives des produits naturels suivants: la (moins)-methylenolactocine et l'(moins)-acide protolichesterinique. Ces alpha-méthylène-gamma-butyrolactones possèdent des propriétés antibiotiques et antitumorales importantes. Dans cette partie du travail une réaction d'alpha-méthylation de gamma-butyrolactones a été mise au point. Dans un deuxième temps, nous avons effectué la synthèse asymétrique d'un certain nombre de gamma-butyrolactones beta-oxygénées: (moins)-blastmycinolactol, (plus)-blastmycinone, (moins)-nfx-deux et (plus)-antimycinone, composés issus des antibiotiques antimicynones a(trois) et a(un) respectivement
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Chitroju, Rathna. "Improved performance characteristics of induction machines with non-skewed symmetrical rotor slots." Licentiate thesis, KTH, School of Electrical Engineering (EES), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-11510.
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Induction machines convert more than 55% of electrical energy into various other forms in industrial and domestic environments. Improved performance, especially by reduction of losses in induction machines hence can significantly reduce consumption of electricity. Many design and control methods are adopted to make induction machines work more efficiently, however certain design compromises are inevitable, such as skewing the rotor to improve the magnetic noise and torque characteristics increase the cross current losses considerably in a cage rotor, degrading the efficiency of the motor. Crosscurrent losses are the dominating stray losses which are dependent on several factors among them are percentage skew and the contact resistance between the rotor bars and laminations. It is shown in this thesis that implementing a design change which has non-skewed asymmetrical distribution of rotor slots can serve the same purpose as skewing i.e., reduction of the magnetic noise, thereby avoiding the negative effects of skewing the rotor slots especially by reducing the cross-current losses.
Two design ethodologies to introduce asymmetry in rotor slots are proposed and the key performance characteristics like torque ripple, radial air gap forces are computed both numerically and analytically. Radial forces obtained from the finite element method are coupled to the analytical tool forcalculating the magnetic noise. A spectral method to calculate and separate the radial forces into vibration modes and their respective frequencies is proposed and validated for a standard 4-pole induction motor. The influence of rotor slot number, eccentricity and skew on radial forces and magnetic noise are studied using finite element method in order to understand the vibrational and acoustic behavior of the machine, especially for identifying their sources. The validated methods on standard motors are applied for investigating the asymmetrical rotor slot machines.
Radial air gap forces and magnetic noise spectra are computed for the novel dual and sinusoidal symmetrical rotors and compared with the standard symmetrical rotor. The results obtained showed reduced radial forces and magnetic noise in asymmetrical rotors, both for the eccentric and noneccentric cases. Based on the results obtained some guide lines for designing asymmetrical rotor slots are established. Magnitudes of the harmful modes of vibration observed in the eccentric rotors, which usually occur in reality, are considerably reduced in asymmetrical rotors showing lower sound intensity levels produced by asymmetrical rotors. The noise level from mode-2 vibration in a 4-pole standard 15 kW motor running with 25% static eccentricity is decreased by about 6 dB, compared to the standard rotors. Hence improved performance can be achieved by removing skew which reduces cross current losses and by employing asymmetrical rotor slots same noise level can be maintained or can be even lowered.
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Vedreño, Santos Francisco Jose. "Diagnosis of electric induction machines in non-stationary regimes working in randomly changing conditions." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/34177.
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Tradicionalmente, la detección de faltas en máquinas eléctricas se basa en el uso de la Transformada Rápida de Fourier ya que la mayoría de las faltas pueden ser diagnosticadas con ella con seguridad si las máquinas operan en condiciones de régimen estacionario durante un intervalo de tiempo razonable.
Sin embargo, para aplicaciones en las que las máquinas operan en condiciones de carga y velocidad fluctuantes (condiciones no estacionarias) como por ejemplo los aerogeneradores, el uso de la Transformada Rápida de Fourier debe ser reemplazado por otras técnicas.
La presente tesis desarrolla una nueva metodología para el diagnóstico de máquinas de inducción de rotor de jaula y rotor bobinado operando en condiciones no estacionarias, basada en el análisis de las componentes de falta de las corrientes en el plano deslizamiento frecuencia. La técnica es aplicada al diagnóstico de asimetrías estatóricas, rotóricas y también para la falta de excentricidad mixta.
El diagnóstico de las máquinas eléctricas en el dominio deslizamiento-frecuencia confiere un carácter universal a la metodología ya que puede diagnosticar máquinas eléctricas independientemente de sus características, del modo en el que la velocidad de la máquina varía y de su modo de funcionamiento (motor o generador).
El desarrollo de la metodología conlleva las siguientes etapas:
(i) Caracterización de las evoluciones de las componentes de falta de asimetría estatórica, rotórica y excentricidad mixta para las máquinas de inducción de rotores de jaula y bobinados en función de la velocidad (deslizamiento) y la frecuencia de alimentación de la red a la que está conectada la máquina.
(ii) Debido a la importancia del procesado de la señal, se realiza una introducción a los conceptos básicos del procesado de señal antes de centrarse en las técnicas actuales de procesado de señal para el diagnóstico de máquinas eléctricas.
(iii) La extracción de las componentes de falta se lleva a cabo a través de tres técnicas de filtrado diferentes: filtros basados en la Transformada Discreta Wavelet, en la Transformada Wavelet Packet y con una nueva técnica de filtrado propuesta en esta tesis, el Filtrado Espectral. Las dos primeras técnicas de filtrado extraen las componentes de falta en el dominio del tiempo mientras que la nueva técnica de filtrado realiza la extracción en el dominio de la frecuencia.
(iv) La extracción de las componentes de falta, en algunos casos, conlleva el desplazamiento de la frecuencia de las componentes de falta. El desplazamiento de la frecuencia se realiza a través de dos técnicas: el Teorema del Desplazamiento de la Frecuencia y la Transformada Hilbert.
(v) A diferencia de otras técnicas ya desarrolladas, la metodología propuesta no se basa exclusivamente en el cálculo de la energía de la componente de falta sino que también estudia la evolución de la frecuencia instantánea de ellas, calculándola a través de dos técnicas diferentes (la Transformada Hilbert y el operador Teager-Kaiser), frente al deslizamiento. La representación de la frecuencia instantánea frente al deslizamiento elimina la posibilidad de diagnósticos falsos positivos mejorando la precisión y la calidad del diagnóstico. Además, la representación de la frecuencia instantánea frente al deslizamiento permite realizar diagnósticos cualitativos que son rápidos y requieren bajos requisitos computacionales.
(vi) Finalmente, debido a la importancia de la automatización de los procesos industriales y para evitar la posible divergencia presente en el diagnóstico cualitativo, tres parámetros objetivos de diagnóstico son desarrollados: el parámetro de la energía, el coeficiente de similitud y los parámetros de regresión. El parámetro de la energía cuantifica la severidad de la falta según su valor y es calculado en el dominio del tiempo y en el dominio de la frecuencia (consecuencia de la extracción de las componentes de falta en el dominio de la frecuencia). El coeficiente de similitud y los parámetros de regresión son parámetros objetivos que permiten descartar diagnósticos falsos positivos aumentando la robustez de la metodología propuesta.
La metodología de diagnóstico propuesta se valida experimentalmente para las faltas de asimetría estatórica y rotórica y para el fallo de excentricidad mixta en máquinas de inducción de rotor de jaula y rotor bobinado alimentadas desde la red eléctrica y desde convertidores de frecuencia en condiciones no estacionarias estocásticas.Vedreño Santos, FJ. (2013). Diagnosis of electric induction machines in non-stationary regimes working in randomly changing conditions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34177
TESIS
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Calet, Serge. "Chimie organometallique d'heterocycles a trois chainons (carbonylation, desulfuration, couplage)." Paris 6, 1987. http://www.theses.fr/1987PA066292.
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