Tesis sobre el tema "Chemoselectivity"
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Hedfors, Cecilia. "Lipase chemoselectivity - kinetics and applications". Licentiate thesis, KTH, School of Biotechnology (BIO), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10232.
Texto completo
A chemoselective catalyst is preferred in a chemical reaction where protecting groups otherwise are needed. The two lipases Candida antarctica lipase B and Rhizomucor miehei lipase showed large chemoselectivity ratios, defined as (kcat/KM)OH / (kcat/KM)SH, in a transacylation reaction with ethyl octanoate as acyl donor and hexanol or hexanethiol as acyl acceptor (paper I). The chemoselectivity ratio of the uncatalyzed reaction was 120 in favour of the alcohol. Compared to the uncatalyzed reaction, the chemoselectivity was 730 times higher for Candida antarctica lipase B and ten times higher for Rhizomucor miehei lipase. The KM towards the thiol was more than two orders of magnitude higher than the KM towards the corresponding alcohol. This was the dominating contribution to the high chemoselectivity displayed by the two lipases. In a novel approach, Candida antarctica lipase B was used as catalyst for enzymatic synthesis of thiol-functionalized polyesters in a one-pot reaction without using protecting groups (paper II). Poly(e-caprolactone) with a free thiol at one of the ends was synthesized in an enzymatic ring-opening polymerization initiated with mercaptoethanol or terminated with either 3-mercaptopropionic acid or g-thiobutyrolactone.
Morey, James Vaughan. "Controlling the chemoselectivity of directed metallation". Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612284.
Texto completoMalmgren, Joel. "Iodonium Salts : Preparation, Chemoselectivity and Metal-Catalyzed Applications". Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-107694.
Texto completoAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.
Volkov, Alexey. "Catalytic Amide Reductions under Hydrosilylation Conditions". Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-129028.
Texto completoKamikawa, 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.
Texto completoKyoto University (京都大学)
0048
新制・論文博士
博士(理学)
乙第9788号
論理博第1334号
新制||理||1061(附属図書館)
UT51-98-G387
(主査)教授 林 民生, 教授 鈴木 仁美, 教授 大須賀 篤弘
学位規則第4条第2項該当
Marth, Gabriella. "The synthesis of polyfunctional pyrroles and the investigation of the chemoselectivity of their reactions". Thesis, University of Sunderland, 2009. http://sure.sunderland.ac.uk/3694/.
Texto completoSandford, Christopher. "The reactivity and chemoselectivity of nucleophilic boronate complexes : applications in cross-coupling, fluorination and trifluoromethylation". Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.730846.
Texto completoBlanco, Jiménez Carolina. "Norbornene functionalization through asymmetric pd- and rh-catalyzed carbonylation processes". Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/9109.
Texto completoThis thesis focuses on the study of the metal-catalyzed carbonylation of norbornene. The transformation of this substrate in esters and aldehydes offers potential applications for the production of valuable compounds in fine chemistry and perfumery industry. In this work we have performed studies on the palladium-catalyzed methoxycarbonylation of norbornene bearing monodentate and bidentate phosphine ligands achieving an important control of the selectivity towards the formation of the desired product. Mechanistic aspects of this reaction have been developed using nuclear magnetic resonance methods, including High-Pressure techniques. Finally, we have studied the asymmetric rhodium-catalyzed hydroformylation of norbornene using chiral 1,3-diphosphites ligands derived from carbohydrates. These catalytic systems have shown high activities with excellent stereoselectivities and moderate enantioselectivities.
Rueda, Becerril Montserrat. "Fluorination of alkyl radicals using electrophilic N-F reagents and investigation on the intramolecular chemoselectivity of alkoxy radicals". Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51510.
Texto completoScience, Faculty of
Chemistry, Department of
Graduate
Jalalian, Nazli. "Development and Applications of Hypervalent Iodine Compounds : Powerful Arylation and Oxidation Reagents". Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-75810.
Texto completoAt the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Accepted. Paper 5: Submitted. Paper 6: Manuscript.
Islam, Saidul. "Studies towards the chemical origins of life". Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/studies-towards-the-chemical-origins-of-life(afeac977-39db-4caa-bcbc-63643f5e9f3e).html.
Texto completoBrondani, Patrícia Bulegon. "Investigação da seletividade de mono-oxigenases frente a substratos orgânicos de boro ou de selênio". Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-03092012-142803/.
Texto completoIn this work we evaluated the selectivity (chemo or enantioselectivity) of four Baeyer-Villiger mono-oxigenases (BVMOS: PAMO, M446G PAMO, HAPMO and CHMO) in the presence of boron-containing or selenium-containing compounds. Initially, a series of boron-acetophenones were submitted to oxidation reactions mediated by BVMOs. The enzyme CHMO was chemoselective leading only to C-B bond transformation instead Baeyer-Villiger reaction. However, PAMO and PAMO M446G mediated both oxidations in 4-substituted substrates, and only the C-B transformation in 3-substituted substrates. The enzyme HAPMO leading to Baeyer- Villiger reaction and C-B transformation in all cases. When boron-containing alkenes were the substrates, only compounds with phenyl moiety in the structure were oxidized by BVMOs. It was observed only the C-B transformation and none of the epoxidation reaction. Chiral boron compounds were submitted to BVMOS mediated reactions in an attempt of enantioselective transformation. PAMO and M446G PAMO showed the best results leading, in most cases, to a satisfactory oxidation. However, only one compound was oxidized with great enantioselectivity (82-91% ee). Selenium-containing chiral compounds were also tested in reactions mediated by BVMOs. Again, PAMO showed the best results among BVMOs tested, but only when R2 e R1 = Ph the reaction occurred with great enantiosselectivity (97 % ee).
Fiss, Gabriela Fehn. "Síntese de heterociclos via reações de ciclocondensação de a-etiloxalil e -pirazolil(alquil) b-dimetilaminoenonas com1,2- OU 1,3-Dinucleófilos". Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/4175.
Texto completoChemoselective synthesis of ethyl 4-pirimidinecarboxylates and/or ethyl 5-pirimidineoxalates via cyclocondensation reaction of b-dimethylaminoenones [R1C(=O)C(=CNMe2)C(=O)CO2Et, where R1 = Ph, 4-MeC6H4, 4-MeOC6H4, 4-BrC6H4, 4-ClC6H4, 4-FC6H4, 4-O2NC6H4, 2-thienyl, benzo[b]furan-2-yl and CF3] with NCN 1,3- dinucleophiles such as benzamidine hydrochloride or 1H-1-pyrazolyl-carboxamidine hydrochloride (50-86%); utilization of ethyl 4-pirimidinecarboxylates (when R1 = Ph, 4-MeOC6H4, 4-FC6H4 and 2-thienyl) in the cyclization reaction with hydrazine monohydrate, leading to 7,8-dihydropyrimido[4,5-d]pyridazin-8-ones (81-92%). In this work it was also studied the condensation reaction of (3,5-dimethyl-1H-1- pyrazolyl)alkylketones with N,N-dimethylformamide dimethylacetal, with the aim to obtain b-dimethylaminoenones [PhC(=O)C(=CNMe2)(3,5-dimethyl-1H-1-pyrazolyl), PhC(=O)C(=CNMe2)(3,5-dimethyl-1H-1-pyrazolylmethyl) and MeC(=O)C(=CNMe2)(3,5-dimethyl-1H-1-pyrazolyl)] (92-98%); and synthesis of 1,4 -biazoles via cyclocondensation reaction of b-dimethylaminoenones with different 1,2-dinucleophiles such as hydrazine monohydrate, terc-butylhydrazine hydrochloride,phenylhydrazine hydrochloride, carboxymethylhydrazine or hydroxylamine hydrochloride (50-80%). The X-ray diffraction technique was used in the elucidation of the stereochemistry of PhC(=O)C(=CNMe2)(3,5-dimethyl-1H-1-pyrazolylmethyl) and regiochemistry of the cyclocondensation reactions.
Síntese quimiosseletiva de 4-pirimidinocarboxilatos de etila e/ou 5-pirimidinoxalatos de etila via reação de ciclocondensação de b-dimetilaminoenonas [R1C(=O)C(=CNMe2)C(=O)CO2Et, onde R1 = Ph, 4-MeC6H4, 4-MeOC6H4, 4-BrC6H4, 4-ClC6H4, 4-FC6H4, 4-O2NC6H4, 2-tienil, benzo[b]furan-2-il e CF3] com 1,3-dinucleófilos do tipo NCN, tais como cloridrato de benzamidina ou cloridrato de 1H-1-pirazolil-carboxamidina (50-86%); utilização de 4-pirimidinocarboxilatos de etila (quando R1 = Ph, 4-MeOC6H4, 4-FC6H4 e 2-tienil) na reação de ciclização com monoidrato de hidrazina, levando a 7,8-diidropirimido[4,5-d]piridazin-8-onas (81- 92%). Neste trabalho, também foi estudada a reação de condensação de (3,5-dimetil-1H-1-pirazolil)alquilcetonas com N,N-dimetilformamida dimetilacetal, visando a obtenção de b-dimetilaminoenonas [PhC(=O)C(=CNMe2)(3,5-dimetil-1H-1-pirazolil), PhC(=O)C(=CNMe2)(3,5-dimetil-1H-1-pirazolilmetil) e MeC(=O)C(=CNMe2)(3,5-dimetil-1H-1-pirazolil)] (92-98%); e síntese de 1,4 -biazóis via reação de ciclocondensação de b-dimetilaminoenonas com diferentes 1,2-dinucleófilos, tais como monoidrato de hidrazina, cloridrato de terc-butilidrazina, cloridrato de fenilidrazina, carboximetilidrazina ou cloridrato de hidroxilamina (50- 80%). A técnica de difração de raios-X foi utilizada na elucidação da estereoquímica de PhC(=O)C(=CNMe2)(3,5-dimetil-1H-1-pirazolilmetil) e regioquímica das reações de ciclocondensação.
Komiotis, Dimitri. "Synthese chimique et etude de substances cytotoxiques dirigees specifiquement contre les cellules cancereuses : conjugaison avec des proteines specifiques". Paris 7, 1988. http://www.theses.fr/1988PA077190.
Texto completoHammoud, Jana. "Evaluation des complexes dirhodium (II) tétraacétate-Carbène-N-Hétérocyclique pour la décomposition de diazoesters et applications en glycochimie Functionalization of GlucoPyranosides at position 5 by 1,5 C–H insertion of Rh(II)-Carbenes: Dramatic influence of the anomeric configuration". Thesis, Normandie, 2020. http://www.theses.fr/2020NORMIR03.
Texto completoThis work deals with the study of the catalytic properties of Rh₂L₄.NHC complexes towards diazoesters, and their application in the field of glycochemistry. We first developed a reproducible synthetic procedure for the preparation of these organometallic complexes. Furthermore, we have shown that the Rh₂(OAC)₄.IMes complexe was inducing the chemoselective decomposition of diazo esters, depending on their electronic properties. This unprecedented property opened the way to a switchable catalytic system. In the field of glycochemistry, the Rh₂L₄.NHC complexes made possible to improve the experimental conditions for the quaternization reaction of the anomeric position by C-H bond functionalization. Finally, the quaternization of position 5 of pyranosides by 1,5 C-H insertion of a Rh (II) metallo-carbene anchored on the primary position was developed
Nishimura, Rodolfo Hideki Vicente. "Preparação de novos carbenoides de magnésio visando à síntese de inibidores de protease do VIH-1". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-13052015-154647/.
Texto completoCarbenoids are a class of highly reactive intermediate compounds that play a key role in modern synthetic strategies. These species show a state very similar to that of singlet state carbenes since they have an ambiphilic character and react by a concerted mechanism, something that allows them to afford stereospecific products. Previous studies demonstrated the versatility of a mixed magnesium and lithium carbenoid (ClCH 2 MgCl·LiCl) in the reaction with a number of aromatic, aliphatic and heterocyclic aldehydes. In this way, the objective of this work was to study the chemoselectivity of such reagent and investigate its application in the diastereoselective synthesis of (2S,3S)-N-Boc-3-amino-1,2-epoxy-4-phenylbutane and its diastereoisomer of configuration (2R,3S). For the first part of the work we selected some aldehyde containing functional groups such as esters, nitriles, ketones and amide, among others. In summary, the magnesium carbenoid proved to be very efficient and chemoselective, leading to 14 functionalized chlorohydrins in good isolated yields. Nevertheless, when electron donating groups were present at the position 4 of the substrates ring, the resulting aldehyde showed a decrease in reactivity, which precluded us to obtain the desired product. Finally, preliminary studies aiming the preparation of the epoxides of configuration (2S,3S) and (2R,3S) were also investigated and the results are discussed in detail in the text.
HOUTTEVILLE, MARIE-CLAIRE. "Etude de la simple et de la double diastereoselectivite de la reaction d'aldolisation de l'acide propanedithioique : synthese de beta-oxodithioesters par oxydation chimioselective de beta-hydroxydithioesters". Caen, 1988. http://www.theses.fr/1988CAEN2006.
Texto completoMillan, Cabrera Reisel. "Computational study of heterogeneous catalytic systems. Kinetic and structural insights from Density Functional Theory". Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/161934.
Texto completo[CA] En aquest treball estudiem dues reaccions catalítiques rellevants per a la indústria i la localització de l'anió fluorur en la zeolita RTH, sintetitzada al mig fluorur. El capítol 3 és el primer capítol de resultats, on s'estudia la reducció quimioselectiva del nitroestireno en les superfícies Ni(111), Co(111), Cu(111) i Pd(111). El mecanisme generalment acceptat d'aquesta reacció està basat en l'esquema proposat per Haver-hi en 1898, en el qual la reacció pot transcórrer per dues rutes, la directa i la de condensació. En aquest capítol explorem totes dues rutes, i observem que la ruptura dels enllaços N-O i la conseqüent formació d'enllaços metall-O està més afavorida que la formació d'enllaços N-H en les superfícies Ni(111) i Co(111), a causa del caràcter oxofílico de tots dos metalls. Les etapes més lentes involucren la formació d'enllaços N-H. En les superfícies de metalls nobles com Pt(111) i Pd(111) s'observa el comportament contrari. La superfície Cu(111) és un cas intermedi comparat amb els metalls nobles i no nobles. A més, el nitroestireno interactua amb els àtoms de Cu de la superfície sol a través de grup nitre, amb la qual cosa és un candidat ideal per a aconseguir selectivitats prop del 100%. No obstant això, la superfície Cu(111) no és capaç d'activar la molècula d'H2. En aquest sentit, proposem un catalitzador bimetàl·lic basat en Cu, dopat amb un altre metall capaç d'activar a l'H2, com ara el Pd o el Ni. En els capítols 4 i 5 hem estudiat la reducció catalítica selectiva dels òxids de nitrogen (SCR, en anglés) amb amoníac. Usant mètodes de DFT, hem trobat rutes per a l'oxidació de NO a NO2, nitrits i nitrats amb energies d'activació relativament baixes. També, hem trobat que la reducció de Cu2+ a Cu+ requereix la participació simultània de NO i NH3. Posteriorment, hem estudiat la influència del NH3 en aquest sistema amb mètodes de dinàmica molecular. El NH3 interacciona fortament amb el Cu+ de manera que dues molècules d'aquest gas són suficients per a trencar la coordinació del catió Cu+ amb els oxígens de l'anell 6r, i formar el complex lineal [Cu(NH3)2]+. A més, els cations Cu2+ poden ser estabilitzats fora de la xarxa mitjançant la formació del complex tetraamincobre(II). A causa de la presència dels cations Cu+ i Cu2+ coordinats a la xarxa de la zeolita, apareixen bandes a la regió entre 800-1000 cm-1 de l'espectre infraroig. L'anàlisi de les freqüències IR de diversos models amb Cu+ i Cu2+ coordinats a l'anell 6r, o formant complexos amb amoníac indica que quan els cations Cu+ i Cu2+ estan coordinats als oxígens de l'anell 6r apareixen vibracions entre 830 i 960 cm-1. Freqüències en aquesta zona també s'obtenen en els casos en què NO, NO2, O2 i combinacions de dues d'ells estan adsorbidos en Cu+ i Cu2+. No obstant això, quan els cations Cu+ i Cu2+ estan fora de l'anell (no hi ha enllaços entre els cations de coure i els oxígens de l'anell 6r) no s'obtenen vibracions d'IR en aquesta regió de l'espectre. Aquests resultats indiquen que amb el seguiment de l'espectre IR durant la reacció SCR és possible determinar si els cations Cu+ i Cu2+ estan coordinats o no a l'anell de 6r en les etapes d'oxidació i reducció. Finalment, hem simulat el desplaçament químic de 19F, δiso, en la zeolita sintetitzada RTH. L'anàlisi del δiso dels diferents models utilitzats ens ha permés reconéixer la simetria del material sintetitzat, el qual pertany al grup espacial P1 i la nova cel·la unitat ha sigut confirmada experimentalment per difracció de raigs X. Finalment, hem assignat el senyal experimental que apareix en l'espectre de 19F a -67.2 ppm, al F- localitzat en un lloc T2, el qual és al seu torn la posició més estable. A més, el senyal a -71.8 ppm s'ha assignat a l'anió F- localitzat en un lloc T4.
[EN] In this work, we have studied two heterogeneous catalytic reactions and the localization of the fluoride anion in the as-made RTH framework, synthesized in fluoride medium. The first results, included in chapter 3, correspond to the chemoselective reduction of nitrostyrene on different metal surfaces, i.e, Ni(111), Co(111), Cu(111) and Pd(111). Until very recently, the reduction of the nitro group was explained on the basis of the general mechanism proposed by Haber in 1898 where the reaction can follow two routes, the direct and condensation route. We have explored the relevant elementary steps of both routes and found that because of the oxophilic nature of Ni and Co, the steps involving the dissociation of N-O bonds and formation of metal-O bonds are significantly favored compared with the other steps on both metal surfaces. In addition, the most demanding steps in terms of energy involve the formation of N-H bonds. These findings are in contrast to those of noble metals such as Pt and Pd, where the opposite behavior is observed. The behavior of Cu(111) lies in between the aforementioned cases, and also no chemical bonds between the carbon atoms of the aromatic ring of nitrostyrene and the Cu(111) surface is formed. For this reason, it might be an ideal candidate to achieve nearly 100 % selectivity. However, the Cu(111) surface does not seem to activate the H2 molecule. In this regard, we propose a bimetallic Cu-based catalyst whose surface is doped with atoms of a H2-activating metal, such as Ni or Pd. On another matter, we have also investigated the selective catalytic reduction of nitrogen oxides (SCR-NOx) and the main results are presented in the following two chapters, 4 and 5. By using static DFT methods, we found pathways for the oxidation of NO to NO2, nitrites and nitrates with relatively low activation energies. We also found, in agreement with experimental reports, that the reduction of Cu2+ to Cu+ requires the simultaneous participation of NO and NH3. Later, molecular dynamics simulations allowed us to assess the influence of NH3. The strong interaction of NH3 with the Cu+ cation is evidenced by its ability to detach Cu+ from the zeolite framework and form the mobile linear complex [Cu(NH3)2]+. Cu+ is no longer coordinated to the zeolite framework in the presence of two NH3 molecules. This observation and the fact that the T-O-T vibrations of the framework produce bands in the 800-1000 cm-1 region of the IR spectrum when perturbed by the coordination of Cu+ and Cu2+ cations, indicate that bands in the 800-1000 cm-1 regions should be observed when both copper cations are bonded to the framework oxygens. Finally, we have also studied NMR properties of the as-made pure silica RTH framework, aiming at locating the compensating fluoride anion. The calculation of the 19F chemical shift in different T sites and comparison with the experimental NMR spectra shows that the as-made RTH belongs to the P-1 space group with 16 Si, 32 O atoms, one fluoride anion and one OSDA cation. These results have been confirmed experimentally by XRD. In addition, we have assigned the experimental signal of 19F at -67.2 ppm to the fluoride anion in a T2 site, which in turn is the most stable location found, and the signal of -71.8 ppm to a fluoride anion sitting in a T4 site.
My acknowledgements to “La Caixa foundation” for the financial support through “La Caixa−Severo Ochoa” International PhD Fellowships (call 2015), to the Spanish Supercomputing Network (RES), to the Centre de Càlcul de la Universitat de València, to the Flemish Supercomputer Center (VSC) of Ghent University for the computational resources and technical support, and to the Spanish Government through the MAT2017-82288-C2-1-P programme
Millan Cabrera, R. (2021). Computational study of heterogeneous catalytic systems. Kinetic and structural insights from Density Functional Theory [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/161934
TESIS
Leroy, Corinne. "Modèles du NADH en série pyrrolo(2,3-b)pyridine. Réduction d'une nouvelle gamme de substrats : les énamides. Rôle respectif des deux auxiliaires chiraux lors de réductions asymétriques". Rouen, 1994. http://www.theses.fr/1994ROUES031.
Texto completoRatajczak, Fabien. "Synthèse et réactivité de nitroxydes chiraux". Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10134.
Texto completoSEGUINEAU, PASCALE. "Les reactions de wittig et wittig-horner en milieu protique peu basique". Nantes, 1989. http://www.theses.fr/1989NANT2014.
Texto completoRovira, Coll Mireia. "Reaction mechanisms involved in cross coupling processes catalysed by copper and nickel". Doctoral thesis, Universitat de Girona, 2017. http://hdl.handle.net/10803/403434.
Texto completoLes espècies aril-CuIII han estat proposades com les espècies a través de les quals operen els acoblaments tipus Ullmann. No obstant, aquestes espècies són molt reactives i difícilment detectables en els processos fonamentals que governen aquests acoblaments. La primera part d’aquesta tesi es centra en l’estudi de la reactivitat de complexes ben definits aril-CuIII davant de metilens actius (Reacció de Hurtley) i acetilens terminals (Reacció de Stepens-Castro). La següent part es centra en la síntesi i caracterització de complexes ben definits aril-NiII, anàlegs als de coure. La curta distància de l’enllaç Ni-C dissenteix la seva reactivitat davant diversos nucleòfils via eliminació reductiva. Per contra, aquestes espècies són reactives en presència de fonts electrofíliques de CF3+. En l’última part, ens centrem en l’estudi de les propietats estèriques dels lligands auxiliars coordinats al centre de coure i la selectivitat que presenten envers diferents nucleòfils en els sistemes estàndards de tipus Ullmann
Prat, Denis. "Epoxydations stereoselectives d'alcools olefiniques par l'eau oxygene a 30% catalysees par l'acide tungstique en milieu tamponne". Paris 6, 1988. http://www.theses.fr/1988PA066493.
Texto completoPham, Thi-Nhan Nguyen. "Thio-rearrangement de claisen : facilite, reversibilite, synthese de composes thiocarbonyles". Caen, 1987. http://www.theses.fr/1987CAEN2045.
Texto completoFigadère, Bruno. "Les composes organomanganeux mixtes : addition 1-2 selective sur des aldehydes ou des cetones portant un groupe fonctionnel, enolisation regioselective de cetones : application en synthese". Paris 6, 1987. http://www.theses.fr/1987PA066371.
Texto completoHlimi, Fouzia. "Cycloaddition de diarylnitrilimines sur des dérivés de la benzodioxine 1,4 et de la benzoxazine-1,4 : regiochimie de la réaction sur un alcene portant un groupe donneur et un groupe accepteur sur la même extrêmité". Besançon, 1987. http://www.theses.fr/1987BESA2018.
Texto completoGil, Filipe Carlos Teixeira. "Chemoselectivity of Immobilized Transition Metal Catalysts: a Computational Study". Tese, 2014. https://repositorio-aberto.up.pt/handle/10216/76131.
Texto completoGil, Filipe Carlos Teixeira. "Chemoselectivity of Immobilized Transition Metal Catalysts: a Computational Study". Doctoral thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/76131.
Texto completoTardiff, Bennett Joseph. "PALLADIUM-CATALYZED AMINE SYNTHESIS: CHEMOSELECTIVITY AND REACTIVITY UNDER AQUEOUS CONDITIONS". 2012. http://hdl.handle.net/10222/14784.
Texto completoHuang, Ching-Chun y 黃靖鈞. "Chemoselectivity in Heterobimetallic Palladium-Cobalt Tetraacetate Catalyzed Intramolecular C-H Bond Nitrene Insertion of Sulfamate Esters". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/99042310562377945650.
Texto completo中原大學
化學研究所
101
The purpose of this research is to study the chemoselectivity of intramolecular nitrene insertion of sulfamate ester catalyzed by PdCo (OAc) 4 which was synthesized from Pd(OAc) 2 and Co(OAc) 2. In this study, sulfamate ester compounds 9-13 were used as reactants, for the PdCo(OAc)4 catalyzed amination reaction of C-H bond. The chemoselectivity was analyzed from the product distribution of resulting oxathiazinane compounds.
Nath, Dinesh. "Metalated Nitriles: Ligand Exchange and Copper-Catalyzed Reactions". 2013. http://digital.library.duq.edu/u?/etd,162308.
Texto completoBayer School of Natural and Environmental Sciences;
Chemistry and Biochemistry
PhD;
Dissertation;
Chen, Airu y 陳愛如. "Applying Free Radical SH2' Reaction To The Free Radical Addition Cyclization Reaction To Investigate The Chemoselectivity And Steroselectivity". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/92206920319981756440.
Texto completo義守大學
生物技術與化學工程研究所
100
In recent years, the application of Free Radicals in Organic Synthesis was attractive, especially in chemoselectivity and stereoselectivity. The concerted mechanism of the free radical SH2' reaction when the leaving group of the substrate was halogen (Br, Cl), was discovered by this laboratory. The free radical addition to the double bond, the leaving group rupture and one bond forming were occurred simultaneously in the free radical SH2' reaction. The two p orbitals of two carbons must be parallel in order to form the bond, therefore, the orientation of the reaction somehow would be limited, and this might be helpful to promote the stereoselectivity of the reaction. The stereo-selectivity of free radical addition cyclization reaction might be raised if the free radical SH2' reaction is introduced to this reaction. Using tert-butyl radical with asymmetric diene [(2-chloropropenyl)-(1-Bromo-2-butenyl) ether、(3-acryl)-(2-chloromethylpropenyl) ether] to conduct free radical addition cyclization reaction, study the regio-selectivity、stereo-selective and addition cyclization path when the free radicals addition cyclization reaction, its free radical addition to different position on the double bond, and confirm the stereo structure by 1H NMR、13C NMR、DEPT、gCOSY、NOESY、gHSQC和gHMBC of nuclear magnetic resonance instrument.
Liptak, Vincent Paul. "Investigation of the chemoselectivity and efficiency of the benzannulation reaction of electron poor aryl Fischer carbene complexes : synthetic studies toward (+)-olivn /". 2000. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:9978043.
Texto completoDavi, Michaël. "Développement d'une nouvelle méthodologie d'oléfination catalysée par les complexes de cuivre : applications dans des réactions en tandem". Thèse, 2008. http://hdl.handle.net/1866/6553.
Texto completoPelletier, Guillaume. "Synthèse stéréosélective de pipéridines et activation électrophile chimiosélective d’amides en présence de dérivés de la pyridine". Thèse, 2013. http://hdl.handle.net/1866/10512.
Texto completoThe importance of natural products in the development of new drugs is undeniable. Unfortunately, the isolation and purification of those products from their natural sources provides normally very small amounts of the desired bioactive molecules. Consequently there is largely limited access to in-depth biological studies and/or to the large scale distribution of the bioactive compound. For example, the piperidine family contains a large diversity of bioactive compounds isolated from natural sources in very limited quantities (on the order of milligram scale). To address the issue, we have developed three new divergent synthetic approaches towards polysubstituted piperidines containing an activation/dearomatization sequence from a chiral and enantioenchired pyridinium salt. The first approach aims towards the synthesis of 2,5-disubstituted piperidines by the use of an intermolecular arylation reaction on 2-substituted 1,2,3,4-tetrahydropyridines. Then, we have developed a synthetic method for indolizidines and quinolizidines starting from secondary amides. The second approach leads to the formal synthesis of non-natural alkaloids via a highly diastereoselective and regioselective addition/cyclization from a common pyridinium intermediate. Finally, we have found a new approach for the synthesis of 2,6-disubstituted piperidines by the use of a directed lithiation sequence followed by either a Negishi cross-coupling reaction or a quench with an electrophilic reagent. The development of highly chemoselective and versatile transformations are crucial to organic chemists. We have issued the hypothesis that it could be possible to apply the chemoselectivity concept towards the functionalization of amides, one of the most encountered subunits in the structures of natural products. In the specific context of the thesis, the highly chemoselective transformations are realized on functionalized secondary amides. The method relies on the activation of the carbonyl function of the amide by triflic anhydride in presence of a weak base. Firstly, the activated amide can be selectively reduced to imine, aldehyde, or amine oxidation state in the presence of a poorly nucleophilic hydride source. Alternatively, a carbon nucleophile could also be employed in order to allow the synthesis of ketones or ketimines. By combining an amide with a pyridine derivative a cyclization/dehydration reaction was used for the synthesis of polysubstituted imidazo[1,5-a]pyridines. Moreover, we have briefly applied the activation conditions to the interrupted Beckmann rearrangement of ketoximes. We have finally developed a new synthetic pathway for iodoalkynes by using a one-pot homologation/elimination reaction from commercially available benzylic and allylic bromides. The present method is distinctively different from literature precedents by the simplicity of the reaction procedures and purifications which were optimized in order to be applied to large scale synthesis