Relevant bibliographies by topics / Enantioselectivity / Dissertations / Theses
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Dissertations / Theses on the topic 'Enantioselectivity'

Author: Grafiati
Published: 4 June 2021
Last updated: 25 July 2025

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1

McDermott, Michael Cory. "Asymmetric Heck reaction : conformational effects and enantioselectivity." Thesis, University of East Anglia, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426670.

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2

Onakunle, Ojo Adegboyega. "Studies on the enantioselectivity of bacterial lactonases." Thesis, University of Kent, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362189.

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3

Luo, Junfei. "Controlling regioselectivity and enantioselectivity in C-H activation." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/9550.

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The direct functionalisation of C-H bonds has emerged in recent years as an efficient and atom-economic alternative to the traditional cross coupling reaction. One of the challenges towards this goal is the selective transformation of a particular C-H bond amongst many other C-H bonds. This thesis describes studies on the use of CO2 as a traceless promoter for controlling meta-regioselective arylation of phenols and a separate investigation into an enantioselective arylation of pre-chiral η6-arene tricarbonyl chromium complexes. The introduction provides a general review of recent advances in
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4

Moa, Sara. "Quantum chemical modelling of enantioselectivity in alcohol dehydrogenase." Licentiate thesis, Stockholms universitet, Institutionen för organisk kemi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-142437.

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Biocatalytic methods of synthesis are becoming increasingly important in industry. Using enzymes as catalysts allows highly selective reactions to be performed under milder physical conditions and in a more environmentally benign fashion than most corresponding chemical catalysts. Enzymes have in general evolved to perform one type of reaction on a limited set of molecules, and hence there is often a need to alter the specificity of an enzyme to suit a desired process. Understanding the details of enzymatic catalysis at a quantum mechanical level enables the intelligent redesign of these macro
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5

Wood, Stephen A. "The analytical and biological enantioselectivity of substituted 2-aminotetralins." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/843160/.

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The enantiomeric discrimination properties of a number of commercial chiral HPLC stationary phases have been examined using a series of 2-aminotetralin analogues. The mobile phase conditions for each column were varied in order to optimise the separation for the largest number of analytes. Factorial experimental design techniques were used to test the empirically derived mobile phase combinations. A primary limitation of factorial design optimisation strategies, the number of experiments required, was overcome by the development of a simultaneous factorial design method utilising the selectivi
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6

Thurnhofer, Saskia. "Concentrations and enantioselectivity of anteiso-fatty acids in food." Aachen Shaker, 2007. http://d-nb.info/98772004X/04.

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7

Thurnhofer, Saskia. "Concentrations and enantioselectivity of anteiso-fatty acids in food /." Aachen : Shaker, 2008. http://d-nb.info/98772004X/04.

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8

Hyde, G. "Ab initio studies of weak force mediated molecular enantioselectivity." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604912.

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This thesis project investigates two of the mechanisms that have been postulated to explain the origin of the molecular homochirality found in living systems. These mechanisms are i. the Yamagata-Rein Hypothesis, which predicts that the weak neutral currents between electrons and nucleons result in a Parity-Violating Energy Difference (PVED) between a pair of molecular enantiomers; and ii. the Vester-Ulbricht Hypothesis, which predicts that the β-particles produced during weak force mediated nuclear β-decay interact differently with each of a pair of molecular enantiomers. Both hypotheses pred
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9

Gillon, Karen A. "Scalemic β amino alcohols : their synthesis and use in asymmetric synthesis." Thesis, University of Strathclyde, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248481.

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10

Mezzetti, Alessandra. "Origins of pseudomonas cepacia lipase enantioselectivity towards chiral primary alcohols." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84295.

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Pseudomonas cepacia lipase (PCL) is a highly enantioselective catalyst in the hydrolysis or formation of esters. It shows high enantioselectivity towards esters of chiral primary alcohols. Several scientists have tried to explain this enantioselectivity via modelling studies, however their results are in disagreement.<br>To explain PCL enantioselectivity towards chiral primary alcohols, we coupled structural studies and modelling of PCL-transition state analogue complexes containing pure enantiomers of chiral primary alcohols as alcohol moieties.<br>We first elucidate the different enan
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11

Stevenson, Lorna Caroline. "Novel screening method for enzyme activity and enantioselectivity using SERRS." Thesis, University of Strathclyde, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401503.

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12

Eichler, Anja. "Investigations of self-sufficient P450cam monooxygenases for activity and enantioselectivity." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/investigations-of-selfsufficient-p450cam-monooxygenases-for-activity-and-enantioselectivity(27df0fa8-b671-4593-8ec0-f993a31e120c).html.

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Catalytic, selective C-H bond activation for the oxidative hydroxylation RH → ROH of simple or complex compounds is of significant interest in synthetic organic chemistry. One of the major classes of enzymes used for C-H bond activation are cytochrome P450 monooxygenases (EC 1.14.X.X), which can promote chemo-, regio- and stereoselective oxidations under mild reaction conditions. For the current study, catalytically self-sufficient forms of biocatalyst P450cam-RhFRed were investigated. These self-sufficient P450 systems were previously created by fusing the reductase domain of P450 RhF (CYP116
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13

Tin, Sergey. "Rh catalysed hydrogenation of enamines : factors affecting the rate and enantioselectivity." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/10599.

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14

Weissfloch, Alexandra N. E. "Predictive rules for the enantioselectivity of hydrolases towards alcohols and amines." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0030/NQ64691.pdf.

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15

Ottosson, Jenny. "Enthalpy and Entropy in Enzyme Catalysis : A Study of Lipase Enantioselectivity." Doctoral thesis, Stockholm : Tekniska högsk, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3216.

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16

Weissfloch, Alexandra N. E. "Predictive rules for the enantioselectivity of hydrolases towards alcohols and amines." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37601.

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To help organic chemists use enzymes as synthetic reagents, guidelines are needed to help them choose an appropriate enzyme.<br>We proposed reliable empirical substrate rules that predict the stereochemical outcome of reactions catalyzed by hydrolases. These rules, developed through a combination of substrate screening and literature surveys, are based on the difference in size of the substituents at the stereocenter of substrates. One proposed rule predicts the enantiopreference of cholesterol esterase, lipase from Pseudomonas cepacia, and lipase from Candida rugosa towards secondary alcohols
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17

Thurnhofer, Saskia [Verfasser]. "Concentrations and enantioselectivity of anteiso-fatty acids in food / Saskia Thurnhofer." Aachen : Shaker, 2008. http://d-nb.info/1161312935/34.

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18

Fernández, Álvaro Elena [Verfasser]. "Engineering and analysis of the enantioselectivity of esterases / Elena Fernández Álvaro." Greifswald : Universitätsbibliothek Greifswald, 2011. http://d-nb.info/1012034658/34.

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19

Aydemir, Adnan [Verfasser]. "Modeling of enzyme catalyzed racemic reactions and modification of enantioselectivity / Adnan Aydemir." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover, 2010. http://d-nb.info/1009543792/34.

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20

Liu, Andrew Man Fai. "Developing novel lipases from Bacillus thermocatenulatus to improve enantioselectivity by directed evolution." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0035/MQ64395.pdf.

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21

Liu, Andrew Man Fai 1975. "Developing novel lipases from Bacillus thermocatenulatus to improve enantioselectivity by directed evolution." Thesis, McGill University, 1999. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=30691.

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In order to make use of enzymes in unnatural applications more efficiently, novel enzymes have to be developed and they may arise from an existing enzyme with similar performance. The fast way to improve the performance of the enzyme is by directed evolution. It alters a naturally existing protein, without in depth knowledge of the starting enzyme and produces mutants containing the required activities.<br>The lipase from Bacillus thermocatenulatus is an alko-thermophilic enzyme. Optimization of the lipase production is carried out for use with the new screening method using a pH indicator to
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22

Kamikawa, Takashi. "Enantioselectivity and Chemoselectivity in Palladium-Catalyzed Grignard Cross-Coupling of Aryl Triflates." 京都大学 (Kyoto University), 1998. http://hdl.handle.net/2433/157165.

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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである<br>Kyoto University (京都大学)<br>0048<br>新制・論文博士<br>博士(理学)<br>乙第9788号<br>論理博第1334号<br>新制||理||1061(附属図書館)<br>UT51-98-G387<br>(主査)教授 林 民生, 教授 鈴木 仁美, 教授 大須賀 篤弘<br>学位規則第4条第2項該当
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23

Linney, Lynda. "Theoretical modelling of transition states for asymmetric processes." Thesis, University of Bath, 1995. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296296.

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24

Gérard, Doriane. "Séparation par voie enzymatique d'énantiomères de profènes : optimisation du biocatalyseur et mise en oeuvre en dioxyde de carbone supercritique." Phd thesis, Toulouse, INPT, 2016. http://oatao.univ-toulouse.fr/17770/1/Thesis_Gerard_2.pdf.

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La séparation de deux énantiomères est un procédé d’intérêt pour l’industrie pharmaceutique. En effet, souvent un seul des énantiomères exerce l'activité biologique requise. Cette problématique est abordée ici par l'utilisation d'enzymes énantiosélectives qui est une alternative intéressante aux méthodes conventionnelles (chromatographie chirale, synthèse asymétrique ou cristallisation). Cette approche a été mise en oeuvre pour les molécules de la famille des profènes (l’Ibuprofène, le Kétoprofène ou le Naproxène par exemple) qui sont des acides 2- arylpropioniques et constituent une classe im
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25

Rotticci, Didier. "Understanding and engineering the enantioselectivity of candida antarctica lipase b towards sec-alcohols." Doctoral thesis, KTH, Chemistry, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2988.

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26

ASNAGHI, DONATA. "Supramolecular porous crystals: anesthetic vapors uptake and enantioselective recognition properties." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2018. http://hdl.handle.net/10281/199107.

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La mia tesi tratta di materiali cristallini microporosi e delle loro proprietà di adsorbimento di gas e liquidi. Mi sono occupata di cristalli dipeptidici e di metal-organic frameworks. Innanzittutto, ho analizzato i Valil-Alanina, Alanil-Isoleucina, Valil-Valina, Alanil-Isoleucina e Isoleucil-Valina e ho testato le loro capacità di assorbimento di anestetici volatili. Sono state condotte isoterme di adsorbimento di enflurano, isoflurano, alotano, desflurano e dietiletere a 298 e a 273 K. VA, VV e AI presentano un’affinità elevata per i guests, rappresentata da calori isosterici superiori a 3
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27

Carroll, John Robert. "Selectivity and enantioselectivity in the palladium catalysed hydrogenation of pyrazine and some substituted pyrazines." Thesis, University of Hull, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342963.

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28

Kong, Fanji. "Synthesis and Application of New Chiral Ligands for Enantioselectivity Tuning in Transition Metal Catalysis." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1011774/.

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A set of five new C3-symmetric phosphites were synthesized and tested in palladium-catalyzed asymmetric Suzuki coupling. The observed reactivity and selectivity were dependent upon several factors. One of the phosphites was able to achieve some of the highest levels of enantioselectivity in asymmetric Suzuki couplings with specific substrates. Different hypotheses have been made for understanding the ligand effects and reaction selectivities, and those hypotheses were tested via various methods including DOSY NMR experiments, X-ray crystallography, and correlation of catalyst selectivity with
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29

Ren, Yajun. "Dual organocatalysis for the development of Michael-initiated enantioselective organocascades." Thesis, Ecole centrale de Marseille, 2015. http://www.theses.fr/2015ECDM0005.

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Les travaux de recherche fondamentale présentés ici sont ancrés au cœur de la chimie organique de synthèse moderne, et plus particulièrement dans le domaine de la multi-organocatalyse énantiosélective. Dans ce manuscrit, nous avons identifié deux organocascades originales et démontré la pertinence synthétique de l'une d'elle par des applications en synthèse totale de produits naturels. L’originalité de ce travail repose sur l’utilisation d’un NHC de la classe des 1,3-imidazol-2-ylidenes comme base de Brønsted ou base de Lewis organocatalytique<br>The basic research work presented herein is anc
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30

Gall, Markus Georg [Verfasser]. "Investigations on enantioselectivity and thermostability of carboxylesterases by means of protein engineering / Markus Georg Gall." Greifswald : Universitätsbibliothek Greifswald, 2014. http://d-nb.info/1052731449/34.

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31

Ruch, Aaron A. "Design of New Monodentate Ligands for Regioselectivity and Enantioselectivity Tuning in Late Transition Metal Catalysis." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849723/.

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The ability of gold(I) to activate many types of unsaturated bonds toward nucleophilic attack was not widely recognized until the early 2000s. One major challenge in gold catalysis is the control over regioselectivity when there are two or more possible products as a result of complicated mechanistic pathways. It is well know that the choice of ligand can have dramatic effects on which pathway is being followed but very rarely are the reasons for this selectivity understood. The synthesis of new acyclic diaminocarbenes was developed and a study of the ligand effects on the regioselectivity of
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32

Zoroufchian, Moghadam Peyman. "Molecular simulation studies of gas adsorption and separation in metal-organic frameworks." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7595.

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Adsorption in porous materials plays a significant role in industrial separation processes. Here, the host-guest interaction and the pore shape influence the distribution of products. Metal-organic frameworks (MOFs) are promising materials for separation purposes as their diversity due to their building block synthesis from metal corners and organic linker gives rise to a wide range of porous structures. The selectivity differs from MOF to MOF as the size and shapes of their pores are tuneable by altering the organic linkers and thus changing the host-guest interactions in the pores. Using mai
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33

Leal, Luiz Henrique Queiroz 1983. "Ligantes quirais via arilação de Heck-Matsuda = aplicação na alquinilação enantiosseletiva de aldeídos pró-quirais e na redução de cetonas pró-quirais." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249885.

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Orientadores: Carlos Roque Duarte Correia, Diogo Seibert Lüdtke<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química<br>Made available in DSpace on 2018-08-20T02:45:10Z (GMT). No. of bitstreams: 1 Leal_LuizHenriqueQueiroz_M.pdf: 1546385 bytes, checksum: 4ce60e2af123f00d362d203dcc39ae49 (MD5) Previous issue date: 2011<br>Resumo: Álcoois secundários e propargílicos quirais são importantes blocos sintéticos por sua versatilidade e potencial aplicação na construção de estruturas mais complexas. O presente trabalho teve como objetivo a síntese de ligantes aminoálcoo
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34

Cai, Aijie. "Pd-catalyzed Allylic Substitution for Construction of Quaternary Stereocenters." Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668819.

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Des del primer treball inicial de Tsuji i Trost, hi ha hagut un ràpid progrés durant les últimes dècades en el desenvolupament de lligands quirals i l'abast de reacció dels electròfils i nucleòfils aplicables en reaccions de substitució al·lílica catalitzades per Pd. A més, s'han utilitzat reaccions de substitució al·lílica asimètriques asimètriques catalitzades per Pd en la síntesi total d'una varietat de molècules quirals complexes, proporcionant una evidència sòlida de la utilitat de la metodologia AAA en el control tant de la regio com de l'enantio-selectivitats. Malgrat els nombrosos aven
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35

Milan, Michela. "Oxidation of unactivated C-H bonds catalyzed by manganese complexes: control over site-selectivity and enantioselectivity." Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/664865.

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The oxidation of aliphatic C-H bonds is a very powerful reaction because it allows the functionalization of inert C-H bonds, converting them into a suitable sites for further chemical elaboration. It also represents one of the most challenging reactions in modern synthetic organic chemistry because the multitude of aliphatic C-H bonds in a molecule makes site selective oxidation particularly difficult. Moreover, the introduction of chirality represents an unmet but very appealing challenge, because the asymmetric oxidation of hydrocarbons produces chiral compounds of high value in organic synt
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36

Horsman, Geoffrey Paul. "Directed evolution and structure-assisted random mutagenesis to enhance enantioselectivity of an esterase from Pseudomonas fluorescens." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33759.

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By screening a low number of Pseudomonas fluorescens (PFE) mutants, directed evolution identified a mutant with modestly improved enantioselectivity (from Ewild-type = 12 to EThr230Ile = 19) toward the useful chiral synthon methyl 3-bromo-2-methylpropionate (MBMP). A homology model of HE revealed that the mutation was far away from the enzyme active site and may contribute to increased enzyme flexibility.<br>In a second approach to improving enantioselectivity of PFE toward MBMP, the homology model was used to select amino acid residues near the stereocenter of the docked tetrahedral intermedi
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37

Bächle, Florian [Verfasser]. "Determining the Enantioselectivity of Chiral Catalysts – Mass Spectrometry as a Mechanistic and Screening Tool / Florian Bächle." München : Verlag Dr. Hut, 2015. http://d-nb.info/1077403992/34.

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38

Wang, Zheng. "Characterization of Recombinant Chloroperoxidase, and F103A and C29H/C79H/C87H Mutants." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/414.

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Mechanistically and structurally chloroperoxidase (CPO) occupies a unique niche among heme containing enzymes. Chloroperoxidase catalyzes a broad range of reactions, such as oxidation of organic substrates, dismutation of hydrogen peroxide, and mono-oxygenation of organic molecules. To expand the synthetic utility of CPO and to appreciate the important interactions that lead to CPO’s exceptional properties, a site-directed mutagenesis study was undertaken. Recombinant CPO and CPO mutants were heterologously expressed in Aspergillus niger. The overall protein structure was almost the same as th
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39

Haglöf, Jakob. "Enantiomeric Separations using Chiral Counter-Ions." Doctoral thesis, Uppsala universitet, Avdelningen för analytisk farmaceutisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-130049.

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This thesis describes the use of chiral counter-ions for the enantiomeric separation of amines in non-aqueous capillary electrophoresis. The investigations have been concentrated on studies of the influence, of the chiral counter-ion, the solvent, the electrolyte and the analyte, on the enantioselective separation. Modified divalent dipeptides have been introduced in capillary electrophoresis for the separation of amino alcohols and chiral resolution of amines. Association constants for the ion-pair between dipeptide and amino alcohol could be utilized for development of separation systems wit
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40

Sandström, Anders G., Ylva Wikmark, Karin Engström, Jonas Nyhlén, and Jan-E. Bäckvall. "Combinatorial reshaping of the Candida antarctica lipase A substrate pocket for enantioselectivity using an extremely condensed library." Stockholms universitet, Institutionen för organisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-74997.

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A highly combinatorial structure-based protein engineering method for obtaining enantioselectivity is reported that results in a thorough modification of the substrate binding pocket of Candida antarctica lipase A (CALA). Nine amino acid residues surrounding the entire pocket were simultaneously mutated, contributing to a reshaping of the substrate pocket to give increased enantioselectivity and activity for a sterically demanding substrate. This approach seems to be powerful for developing enantioselectivity when a complete reshaping of the active site is required. Screening toward ibuprofen
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41

Sigrist, Michel. "Phosphine and halide ligand-driven control of regio-and enantioselectivity in Pd-catalyzed hydrocarbonylation of unactivated alkenes." Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAF031.

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Depuis leur découverte, les réactions de carbonylation ont fait l'objet d'une attention considérable dans le développement de méthodologies efficaces en chimie organique. Les processus de carbonylation permettent la synthèse directe de précieux composés carbonylés à partir d'hydrocarbures insaturés, de monoxyde de carbone et de nucléophiles. L'hydroformylation est une réaction de carbonylation particulière à forte valeur marchande, qui utilise un hydrure à la place d'un réactif nucléophile pour produire des aldéhydes. La thèse de doctorat visait à développer des transformations de carbonylatio
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42

Ren, Yajun. "Dual organocatalysis for the development of Michael-initiated enantioselective organocascades." Electronic Thesis or Diss., Ecole centrale de Marseille, 2015. https://nuxeo.centrale-marseille.fr/nuxeo/nxdoc/default/d7b852bf-beff-4fa1-bb67-3502ff77cac9/view_documents?tabIds=%3A&.

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Les travaux de recherche fondamentale présentés ici sont ancrés au cœur de la chimie organique de synthèse moderne, et plus particulièrement dans le domaine de la multi-organocatalyse énantiosélective. Dans ce manuscrit, nous avons identifié deux organocascades originales et démontré la pertinence synthétique de l'une d'elle par des applications en synthèse totale de produits naturels. L’originalité de ce travail repose sur l’utilisation d’un NHC de la classe des 1,3-imidazol-2-ylidenes comme base de Brønsted ou base de Lewis organocatalytique<br>The basic research work presented herein is anc
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43

You, Zhen. "New Catalytic Enantioselective Functionalizations of Alcohols through Silylation and Tosylation." Thesis, Boston College, 2009. http://hdl.handle.net/2345/919.

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Thesis advisor: Marc L. Snapper<br>A survey of silicon-based reactions and potential for Lewis base catalysis was presented. An efficient site- and enantioselective catalytic silylation of triols is disclosed. The protocol is applied to total syntheses of cleroindicins D, F and C. Catalytic kinetic resolution of &#946;-hydroxyketones is disclosed. A readily available amino acid-based catalyst promotes the kinetic resolution with high efficiency. A presentation of catalytic enantioselective tosylation of syn-1,2-diols is disclosed<br>Thesis (PhD) — Boston College, 2009<br>Submitted to: Boston C
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44

Prado, Viviana da Silva. "Estudos visando a síntese do alcaloide indolizidínico (+)-ipalbidina." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/75/75133/tde-17042012-164758/.

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A ipalbidina é um alcaloide indolizidínico com propriedades analgésica e antirradicais livres. Este alcaloide possui como fonte natural a Ipomoea alba L., uma espécie de dama-da-noite, sendo isolado das suas sementes na forma de aglicona da ipalbina (ligada à D-glicose). A ipalbidina possui estrutura química relativamente simples, porém sua síntese na forma enantiomericamente pura se apresenta como um desafio sintético. Dentre as inúmeras rotas de síntese da ipalbidina, apenas quatro são enantiosseletivas. Neste trabalho de dissertação é apresentada uma nova estratégia sintética visando a prep
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45

Capitta, Francesca. "Use of organocatalysts in stereoselective organic synthesis." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00807093.

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The main topic of thesis is the use of organocatalysis to synthesize cyclobutanones derivatives. Cyclobutanone derivatives are useful molecular building blocks for the construction of complex molecular structures. Surprisingly, however, the use of organocatalysts to functionalize cyclobutanones is rare, especially when the substrate bears substituents. In this thesis, we present the enantioselective transformations and functionalizations of substituted cyclobutanones which employ readily-available amino acids (or derivatives) and thiourea derivatives as organocatalysts. - The first transformat
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46

Myllymäki, V. (Vesa). "Design, synthesis and testing of new chiral sulfide catalysts for Corey-Chaykovsky reaction." Doctoral thesis, University of Oulu, 2001. http://urn.fi/urn:isbn:9514265718.

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Abstract The first part of this monograph discusses the asymmetric, ylide based, reagent controlled epoxidations. Both different chiral ylides and epoxidation processes, stoichiometric and catalytic, are reviewed. In the following part, new chiral sulfide catalysts were discovered as enantioselective catalysts for the Corey-Chaykovsky reaction (epoxidation of aldehydes via sulfonium ylides). Using a crystal structure of an oxazolidine derivative as a starting point, a thiazolidine ligand family was designed, synthesized and finally employed as catalysts in the asymmetric epoxidation
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47

Lind, Maria E. S. "Quantum Chemical Modeling of Asymmetric Enzymatic Reactions." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-116694.

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Computational methods are very useful tools in the study of enzymatic reactions, as they can provide a detailed understanding of reaction mechanisms and the sources of various selectivities. In this thesis, density functional theory has been employed to examine four different enzymes of potential importance for biocatalytic applications. The enzymes considered are limonene epoxide hydrolase, soluble epoxide hydrolase, arylmalonate decarboxylase and phenolic acid decarboxylase. Besides the reaction mechanisms, the enantioselectivities in three of these enzymes have also been investigated in det
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48

Jacobsen, Elisabeth Egholm. "Synthesis of enantiopure building blocks for biologically active compounds by enzyme catalysis. Optimizing reaction conditions for increased enantioselectivity and activity." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-2098.

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<p>Efficient methods for synthesis of enantiomerically pure enantiomers of a series of secondary alcohols and butanoates have been performed by kinetic resolution of the racemic alcohols and esters catalyzed by lipase B from <i>Candida antarctica</i> (Novozym 435). The effect of the substrate structure on E was different for transesterifications of alcohols in organic media as compared to hydrolysis of esters in buffer. The influence of different acyl donors on the enantioselectivity has also been investigated.</p><p>Derivatives of 1-phenoxy-2-alkanols have been kinetically resolved by esterif
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49

Ellison, Matthew Christopher. "Ligand Effects in Gold[I] Acyclic Diaminocarbene Complexes and Their Influence on Regio- and Enantioselectivity of Homogeneous Gold[I] Catalysis." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc1538722/.

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This dissertation focuses on the computational investigation of gold(I) acyclic diaminocarbene (ADC) complexes and their application in homogeneous gold(I) catalysis. Chapter 2 is an in-depth computational investigation of the σ- and π-bonding interactions that make up the gold-carbene bond. Due to the inherent conformation flexibility of ADC ligands, distortions of the carbene plane can arise that disrupt orbital overlap between the lone pairs on the adjacent nitrogen atoms and the empty p-orbital of the carbene. This study investigated the affect these distortions have on the strength of the
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50

Ellison, Matthew Christopher. "Ligand Effects in Gold(I) Acyclic Diaminocarbene Complexes and Their Influence on Regio- and Enantioselectivity of Homogeneous Gold(I) Catalysis." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1538722/.

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This dissertation focuses on the computational investigation of gold(I) acyclic diaminocarbene (ADC) complexes and their application in homogeneous gold(I) catalysis. Chapter 2 is an in-depth computational investigation of the σ- and π-bonding interactions that make up the gold-carbene bond. Due to the inherent conformation flexibility of ADC ligands, distortions of the carbene plane can arise that disrupt orbital overlap between the lone pairs on the adjacent nitrogen atoms and the empty p-orbital of the carbene. This study investigated the affect these distortions have on the strength of the
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