Dissertations / Theses on the topic 'Chemoenzymatic catalysis'
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Horrobin, Tina M. "The chemoenzymatic synthesis of oligosaccharides." Thesis, University of Warwick, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307318.
Full textLuo, Yunfei. "Chemoenzymatic synthesis of C2 symmetric chiral dienes for asymmetric catalysis." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539483.
Full textBeluocine, T. "Chemoenzymatic synthesis of enantiopure arene cis-diols : applications in asymmetric homogenous catalysis." Thesis, Queen's University Belfast, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431407.
Full textGairola, Priyanka. "Association of Metal-Organic Framework and Transaminase for chemoenzymatic production of amines." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS107.
Full textDue to the scarcity of fossil resources, the chemical industry must today evolve to turn to new sources of raw material. Added to this are the ever-increasing environmental pressures that impose a reduction in the ecological and energy impact of the processes. Responding to these major technological challenges involves the design of new chemical processes making it possible, in particular, for the massive transformation of natural chemical resources (cellulose, lignin, algae, etc.) into high value-added chemicals that meet the so-called "Green chemistry" i, ii. In this context, heterogeneous catalysis is an essential tool since it makes it possible to accelerate the chemical reactions under sustainable conditions by making it possible to recycle the active phases ii. The development of processes that are increasingly adapted to today's industrial and environmental challenges, however, requires the development of new catalysts, in particular capable of reducing energy consumption even more, of saving atoms and of reducing as much as possible the quantities of reagents and solvents used as well as the waste produced. To do this, heterogeneous catalysts capable of catalyzing several chemical reactions in one step "in cascade" are particularly promising. [...] The overall goal of this thesis was to build a chemoenzymatic system capable of carrying out a cascade of two reactions allowing the transformation of alcohols into amines. For that it was proposed to immobilize on a crystalline organic-inorganic hybrid material called MOF (Metal-Organic Framework), a chemical catalyst, responsible for a first step of oxidation of alcohol to carbonyl compound, and a transaminase enzyme catalyzing the subsequent amine transfer step. The implementation of such a sophisticated system was a real challenge, especially because it was a question of finding reaction conditions (solvent, temperature, pH, and choice of chemical reagents) that are compatible with the working conditions of transaminases (mild reaction temperatures ≤ 60 ° C, at least partially aqueous solvents). This was a prerequisite for carrying out "one-pot" syntheses, where the two targeted reactions were to be catalyzed consecutively by the chemical catalyst and the enzyme in the same reaction medium without isolation of the intermediate carbonyl. It was also necessary to ensure the stability of the MOF in the reaction medium, and in particular the integrity of its structure in solvents containing the aqueous buffer solutions necessary for the stability of the enzymes. [...]
Warner, Madeleine. "Ruthenium-Catalyzed Hydrogen Transfer Reactions : Mechanistic Studies and Chemoenzymatic Dynamic Kinetic Resolutions." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-89263.
Full textAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 5: Mansucript.
Zan, Yifan. "Development of heterogeneous chemoenzymatic catalysts based on Metal-Organic Framework for the selective and eco-friendly amination of alcohols." Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS518.pdf.
Full textThe aim of this work was to develop a heterogeneous chemoenzymatic catalyst based on the use of Metal-Organic Frameworks (MOFs) as support for the eco-friendly amination of alcohols in a one-pot cascade synthesis. The cascade process is divided into two steps: an alcohol oxidation chemically catalyzed and the subsequent enantioselective amination of the resulting carbonyl intermediate catalyzed by a ω-transaminase enzyme (ω-TA). ZIF-8 was selected as MOF for its hydro- and thermo- stability, making it an ideal support for both chemical and biological catalysts. One of the key challenges was to select a chemical catalytic system for alcohol oxidation under mild aqueous conditions that is compatible with the working conditions of ω-TAs. In this context, two supported nanoparticles catalytic systems were developed for the aerobic alcohol oxidation. In the first system, Cu2+ active sites were heterogenized on ZIF-8 for benzyl alcohol oxidation in the presence of 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO). The leaching issue of Cu2+ during the catalytic process was overcome by reducing Cu2+ into Cu0 within ZIF-8 pores to form supported well-dispersed Cu0 nanoparticles. This catalyst exhibits high stability and selectivity, but is not active when using water as a solvent. In the second system, well-dispersed PdAu bimetallic alloy nanoparticles were formed on ZIF-8 (PdAu@ZIF-8) to catalyze base-free aerobic alcohol oxidation in water. The catalyst shows excellent activity under mild conditions, with the best performance obtained fora Pd/Au atomic ratio 9:1. Both catalysts were characterized using PXRD, N2-adsorption, TEM, HRTEM, and XPS. The second step of the cascade process involves the biocatalytic amination of the ketone. Two S-selective ω-TAs from Silicibacter pomeroyi (3HMU) and Chromobacterium violaceum were tested. The maximum yield of S-α-methylbenzylamine obtained by amination of acetophenone in the presence of 3HMU using L-alanine as the amine donor was 77%. Efforts to combine alcohol oxidation catalyzed by the ZIF-8-supported PdAu nanoparticles and enzymatic catalysis with 3HMU in a one-pot/one-step process revealed interferences between components of the two steps. Instead, a one-pot/two-step cascade process was developed, achieving an overall S-MBA yield of 49%. Attempts were finally made to immobilize 3HMU on PdAu@ZIF-8 in order to obtain the targeted fully heterogenized catalyst by first using physical adsorption, but the activity of the hence-immobilized ω-TAs was limited. Ni2+ modification of PdAu@ZIF-8 slightly improved the enzyme immobilization. Carbonyl-functionalized ZIF-8, obtained by a partial post-synthesis exchange of the 2-methylimidazolate ligands with carbonyl-imidazolate derivatives produced encouraging results, with a 4-fold improvement in activity of 3HMU immobilized on ZIF-8-90. As outlooks, this promising approach will be further investigated in forthcoming attempts to synthesize the entirely heterogeneous 3HMU@PdAu@ZIF-8 targeted in this PhD project
Zhang, Yan. "Chemoenzymatic Resolution in Dynamic Systems : Screening, Classification and Asymmetric Synthesis." Doctoral thesis, KTH, Organisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123089.
Full textQC 20130614
Farzam, Ali. "Preliminary Efforts Towards Achieving Transient Directing Group Chemistry Enabled via a Tandem and Cooperative Concurrent Chemoenzymatic Cascade." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42405.
Full textConcia, Alda Lisa. "Chemoenzymatic synthesis of sugar-related polyhydroxylated compounds, iminocyclitols and their derivatives as glycosidase inhibitors." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/113239.
Full textLa reacción aldólica es uno de los métodos más útiles y potentes para la formación de enlaces carbono carbono que permite, simultáneamente, la funcionalización y generación de nuevos centros estereogénicos adyacentes. Las aldolasas dependientes del fosfato de dihidroxiacetona (DHAP) catalizan estereoselectivamente la adición aldólica de DHAP a una gran variedad de aldehídos aceptores y han sido objeto de numerosos estudios que demuestran su utilidad como catalizadores en síntesis orgánica asimétrica. La principal limitación de esta clase de aldolasa es su estricta especificidad por el sustrato dador, la DHAP, que es un reactivo costoso y químicamente inestable. Por ello, los estudios dirigidos a la eliminación de la necesidad de la utilización de DHAP mediante estrategias de ingeniería de reacción, evolución dirigida, o a través del descubrimiento de nuevas enzimas naturales, son de gran interés. En este contexto el descubrimiento de la D-fructosa 6-fosfato aldolasa (FSA), una enzima natural que acepta dihidroxiacetona (DHA) como dador, ha sido de enorme importancia. El objeto de esta tesis es la aplicación de aldolasas dependientes de DHA y DHAP a la síntesis de compuestos quirales bioactivos. Los iminociclitoles son una clase de glicomiméticos muy atractivos en química médica ya que poseen actividad inhibidora de glicosidasas y glicosiltransferasas y, por tanto, con un vasto potencial terapéutico para el tratamiento de enfermedades como diabetes, infecciones virales y cáncer, entre otras. En este trabajo se describe una metodología quimioenzimática para la preparación de desoxiazúcares e iminociclitoles cuyas etapas clave son nuevas adiciones aldólicas estereoselectivas de dihidroxiacetona (DHA) e hidroxiacetona (HA) a diferentes aldehídos catalizadas por FSA. Mediante esta estrategia se han obtenido los iminociclitoles 1-deoxinojirimicina, 1-deoximannojirimicina y sus derivados N-alquilados, 1,4-dideoxi-1,4-imino-D-arabinitol y 1,4,5 trideoxi-1,4-imino-D-arabinitol y los desoxiazúcares 1-deoxi-D-xilulosa y 1 deoxi-D-ido-hept-2-ulosa. El 1,4-dideoxi-1,4-imino-D-arabinitol (DAB) y su enantiómero (LAB) son pirrolidinas polihidroxiladas con una amplia actividad inhibidora de varias glicosidasas. Las pirrolizidinas polihidroxilados son una clase de iminociclitoles bicíclicos que también poseen una importante actividad biológica. En este trabajo se presenta una estrategia quimioenzimática que emplea aldolasas dependientes de DHA y DHAP, para la síntesis de DAB y LAB, de una colección de sus derivados 2-aminometílicos y conjugados 2 oxo-piperazinicos y de nuevas pirrolizidinas polihidroxiladas de la familia de las casuarinas, todos con potencial actividad inhibidora de glicosidasas.
Fanfoni, Lidia. "Development of chiral nitrogen ligands for application in homogeneous catalysis." Doctoral thesis, Università degli studi di Trieste, 2010. http://hdl.handle.net/10077/3521.
Full textAim of this thesis is the synthesis of enantiomerically pure ligands for their application in asymmetric catalysis. In particular, the work is focused on the synthesis of three different classes of ligands. Chapters 2 and 3 deal with the synthesis of CNN-pincer and N-Nˈ(bipyridine) ligands respectively, obtained in both enantiomeric forms by stereocomplementary chemoenzymatic methods, while Chapter 4 presents the synthesis of P-N type ligands obtained from L-proline. The activity of the complexes that containing the optically pure synthesized ligands was also investigated.
XXII Ciclo
1980
Sardan, Melis. "Chemoenzymatic Synthesis Of Enantiomerically Enriched Gamma And Delta Lactones." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612404/index.pdf.
Full textcatalysts were used. These lactones were used to test their biological activities.
Mertens, Marie Anna Stephanie [Verfasser], Ulrich [Akademischer Betreuer] Schwaneberg, and Takashi [Akademischer Betreuer] Hayashi. "Combination of bio- and metal catalysts in chemoenzymatic cascade reactions / Marie Anna Stephanie Mertens ; Ulrich Schwaneberg, Takashi Hayashi." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1216040796/34.
Full textMertens, Marie Anna Stephanie Verfasser], Ulrich [Akademischer Betreuer] [Schwaneberg, and Takashi [Akademischer Betreuer] Hayashi. "Combination of bio- and metal catalysts in chemoenzymatic cascade reactions / Marie Anna Stephanie Mertens ; Ulrich Schwaneberg, Takashi Hayashi." Aachen : Universitätsbibliothek der RWTH Aachen, 2019. http://d-nb.info/1216040796/34.
Full textLin, Andrew Jeng Shyan. "The chemoenzymatic and enantioselective synthesis of biologically active resorcylic acid lactones (RALs)." Phd thesis, 2012. http://hdl.handle.net/1885/148247.
Full textJones, Matthew Thomas. "The chemoenzymatic synthesis of the lycorine framework and the synthesis of C-3-mono-alkylated oxindoles via the palladium-catalysed Ullmann cross-coupling reaction." Phd thesis, 2013. http://hdl.handle.net/1885/150048.
Full textI-HsiuChen and 陳怡琇. "Chemoenzymaticly Prepared Oligopeptides for Synthesis of Silica Colloidal Particles and Metal Nanoparticles/Mesoporous Silicas and Their Application as Catalyst." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/6943w3.
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