Дисертації з теми "C–X bond"
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Taylor, Dawn. "Palladium-catalysed C-X bond formations." Thesis, University of Bath, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437449.
Повний текст джерелаVuong, Khuong Quoc Chemistry Faculty of Science UNSW. "Metal complex catalysed C-X (X = S, O and N) bond formation." Awarded by:University of New South Wales. Chemistry, 2006. http://handle.unsw.edu.au/1959.4/23015.
Повний текст джерелаMata, Campaña Yvette Angela. "Screening of Modular Carbohydrate Ligand Libraries in Asymmetric Metal-catalyzed C-C and C-X Bond Formation Reactions." Doctoral thesis, Universitat Rovira i Virgili, 2007. http://hdl.handle.net/10803/9090.
Повний текст джерелаAquesta tesi s'ha centrat en la síntesi de compostos derivats de la D-(+)-glucosa, de la D-(+)-fructosa i la D-(+)-galactosa i l'aplicació com a lligands de catalitzadors homogenis quirals en quatre reaccions asimètriques: substitució al·lílica, Heck, addició 1,2 i addició conjugada 1,4. Per assolir aquest objectiu, s'ha plantejat la síntesi de tres famílies de compostos: fosfit-oxazolina (L1-L5), fosfit-fosforoamidit (L6) i monofosfit (L7-L11) (Figura 1).
Després de la introducció (Capítol 1) i els objectius (Capítol 2), al capítol 3 es discuteix la síntesi i caracterització de les tres llibreries de compostos (L1-L11) i s'estudia l'aplicació de les tres llibreries a la reacció de substitució al·lílica asimètrica catalitzades per pal·ladi.
La primera llibreria de compostos fosfit-oxazolina (L1-L5) ha mostrat altes enantioselectivitats (fins a un 99%) i bones activitats en un ampli ventall de substrats amb diferents propietats electròniques i estèriques. S'han observat importants efectes al variar els substituents de l'anell oxazolina, de la quiralitat axial i dels diferents substituents del biaril. L'estudi de diferents intermedis de reacció pal·ladi al·lil mitjançant espectroscòpia de ressonància magnètica nuclear ha permès entendre el comportament catalític d'aquests compostos. L'estudi també ha indicat que l'atac nuclèofil té lloc preferentment al carboni al·lílic terminal localitzat trans al fosfit.
Figura 1. Fosfit-oxazolina (L1-L5), fosfit-fosforamidit (L6) i monofosfit (L7-L11).
Les reaccions de substitució asimètrica utilitzant els compostos fosfit-fosforoamidit (L6) han mostrat que l'excés enantiomèric depèn preferentment dels substituents de les posicions en para dels bifenils. Aquests efectes han estat diferents segons el tipus de substrat. S'han obtingut excessos enantiomèrics fins a un 89% i altes activitats utilitzant el substrat rac-1,3-difenil-acetoxipropè, rac-(E)-etil-2,5-dimetil-3-hex-4-enilcarbonat i el rac-3-acetoxicicloheptè. Pel substrat lineal 1-(1-naftil)al·lil acetat, aquests lligands han mostrat no ser útils en termes de regioselectivitat però s'han obtingut bons excessos enantiomèrics de fins a un 72%.
Si comparem aquests resultats amb els obtinguts amb els compostos fosfit-oxazolina (L1-L5) s'observa que el canvi de la funció oxazolina per la funció fosforoamidit té un efecte negatiu en la reacció de substitució al·lílica i en general decreixen les enantioselectivitats i la versalitat d'aquests compostos.
L'aplicació de la llibreria de compostos monofosfit (L7-L11) en la reacció de substitució al·lílica asimètrica ha mostrat moderades enantioselectivitats (fins a un 46%). Els resultats en la catàlisi es veuen afectats en gran mesura per la diferència en la mida de l'anell carbohidrat, de les configuracions del carboni-3 i del carboni-4 de l'esquelet del lligand i pel tipus de substituents de l'anell biaril.
El capítol 4 descriu l'aplicació dels compostos fosfit-oxazolina (L1-L5) com a lligands en la reacció de Heck asimètrica intermolecular. Una selecció correcta dels substituents en la funció oxazolina i del fosfit han permès obtenir excel·lents activitats (fins un 100% de conversió en 10 minuts), regioselectivitats i enantioselectivitats (fins un 99%) en un ampli rang de substrats utilitzant diferents fonts de triflat.
El capítol 5 descriu l'aplicació de les tres llibreries de compostos (L1-L11) a les reaccions d'addició 1,2 a aldehids catalitzades per níquel. En primer lloc, s'ha estudiat l'aplicació dels compostos L1-L6. S'ha observat que la selectivitat del procés depèn principalment del grup funcional unit a l'esquelet del lligand, de les propietats estèriques del substituent en la funció oxazolina i de l'estructura del substrat. S'ha obtingut fins a un 59% d'excés enantiomèric utilitzant el precursor de catalitzador que conté el lligand L3a. En canvi, la utilització de la llibreria de compostos monofosfit (L7-L11) ha mostrat elevades enantioselectivitats (fins a 94%) i activitats en diferents tipus de substrat utilitzant baixes concentracions de catalitzador i sense excés de lligand.
El capítol 6 descriu l'aplicació de les tres famílies de compostos (L1-L11) com a lligands en la reacció d'addició 1,4 catalitzada per coure de compostos organometàl·lics a diferents enones amb diferents propietats estèriques.
L'ús de les llibreries de compostos fosfit-oxazolina (L1-L5) i fosfit-fosforamidit (L6) han proporcionat bones enantioselectivitats (fins a 78%) en l'addició de reactius de trialquilalumini a diferents enones. En canvi, la llibreria de compostos monofosfit (L7-L11) ha mostrat bones activitats però enantioselectivitats fins a 57%.
The growing demand for enantiomerically pure compounds for the development of pharmaceuticals, agrochemicals and flavors has captured the interest of the chemist in the last few decades. Of the various methods for producing enantiopure compounds, enantioselective homogeneous metal catalysis is an attractive one. In this context, carbohydrates have many advantages: they are readily available, are highly functionalized and have several stereogenic centers. This enables series of chiral ligands to be synthesized and screened in the search for high activities and selectivities for each particular reaction.
In this context, this thesis focuses on the development of new chiral ligand libraries derived from carbohydrates, the synthesis of new catalyst precursors and their application in the Pd-catalyzed asymmetric allylic substitution, Pd-catalyzed asymmetric Heck reactions, Ni-catalyzed asymmetric addition of trialkylaluminium to aldehydes, and Cu-catalyzed asymmetric 1,4-conjugated addition of trialkylaluminium reagents to enones.
For this porpose, we have designed and syntezied 3 new sugar based ligand libraries: phosphite-oxazoline (L1-L5), phosphite-phosphoroamidite (L6) i monophosphite (L7-L11) (Figure 1).
After introduction (Chapter 1) and objectives (Chapter 2), in chapter 3 is discussed the synthesis and characterization of the ligand libraries (L1-L11) and and their application in the asymetric Pd-catalyzed allylic substituion reactions.
Using phosphite-oxazoline ligands (L1-L5) we observed important effects of the oxazoline substituents and the axial chirality and the substituents of the biaryl moieties. However, the effects of these parameters depended on each substrate. High enantioselectivities (up to 99%) and good activities have been achieved in a wide range of substrates with different steric and electronic properties.
The study of the Pd-1,3-diphenyl, 1,3-dimethyl and 1,3-cyclohexenyl allyl intermediates by NMR spectroscopy made it possible to understand the catalytic behaviour observed. This study also indicated that the nucleophilic attack takes place predominantly at the allylic terminal carbon atom located trans to the phosphite moiety.
Figura 1. Fosfit-oxazolina (L1-L5), fosfit-fosforamidit (L6) i monofosfit (L7-L11).
Asymmetric substitution reactions with catalyst precursors containing the phosphite-phosphoroamidite ligands showed that enantiomeric excesses depend strongly on the substituents at the para positions of the biphenyl moieties. However, these effects were different depending on the substrate in study. Enantiomeric excesses of up to 89% with high activities were obtained for rac-1,3-diphenyl-3-acetoxyprop-1-ene, rac-(E)-ethyl-2,5-dimethyl-3-hex-4-enylcarbonate and rac-3-acetoxycycloheptene. For the monosubstituted linear substrate 1-(1-naphthyl)allyl acetate, these ligands proved to be inadequate in terms of regioselectivities. However, we obtained good enantioselectivity by carefully selecting the substituents on the para position of the biphenyl moieties (ee's up to 72%).
If we compare these results with those from the catalyst precursors containing the previous phosphite-oxazoline ligands (L1-L5), we found that the replacement of the oxazoline moiety by a phosphoroamidite group decreased enantioselectivities and versatibility.
Asymmetric allylic alkylation with catalyst precursors containing the sugar-based monophosphite ligand library showed that the catalytic performance is highly affected by the size of the sugar backbone, the configurations at C-3 and C-4 of the ligand backbone and the type of substituents/configurations in the biaryl phosphite moiety. Low-to-moderate enantioselectivities (up to 46%) were obtained.
In the asymmetric Pd-catalyzed Heck reactions (Chapter 4) with catalysts precursors based on phosphite-oxazoline ligands, we obtained excellent activities (up to 100% conversion in 10 minutes), regio- (up to >99%) and enantioselectivities (up to 99%) were obtained in a wide range of substrates and triflate sources.
In the asymmetric Ni-catalyzed 1,2-addition of trialkylaluminium to aldehydes (Chpater 5) with catalysts precursors based on phosphite-oxazoline and phosphite-phosphoroamidite ligands, we found that the selectivity depends strongly on the type of functional group attached to the carbohydrate backbone, on the steric properties of the oxazoline substituents and on the substrate structure. Enantioselectivities up to 59% were obtained using the catalyst precursor containing the phosphite-oxazoline ligand L3a. In contrast to what we observed with the previous two ligand libraries, using sugar-based monophosphite ligands (L7-L11) provides high enantioselectivities (up to 94% ee) and activities in different substrate types, with low catalysts loadings and without excess of ligand.
In Chapter 6, we described the phosphite-oxazoline and phosphite-phosphoroamidite ligands as chiral auxiliaries in the asymmetric Cu-catalyzed 1,4-conjugated addition of trialkylaluminium reagents to several enones provides good enantioselectivities (up to 80% ee).
In the asymmetric Cu-catalyzed asymmetric 1,4-conjugated addition of trialkylaluminium reagents to several enones with catalysts precursors based on sugar monophosphite ligands, we found good activites and enantioselectivities up to 57% ee.
Borràs, Noguera Carlota. "Sustainable and cost-effective development of chiral metal-catalysts for C-H and C-X bond forming reactions." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/664741.
Повний текст джерелаLa obtención de compuestos enantioméricamente puros se ha convertido una necesidad que ha conducido a un importante progreso en la catálisis asimétrica, principalmente usando compuestos organometalicos quirales. Entre las diferentes estrategias en la optimización de los catalizadores para conseguir elevadas selectividades y actividades, el diseño y la correcta selección de ligandos quirales, modificando sus propiedades es fundamental y la más utilizada. Que un ligando sea fácil de sintetizar a partir de compuestos de partida accesibles y que estos ligandos sean estables y fáciles de manipular, tienen un elevado interés en la industria. En este contexto, el principal objetivo de esta tesis es la síntesis de distintas familias de ligandos quirales, cumpliendo con los requisitos previamente mencionados, y su posterior aplicación en distintas reacciones asimétricas de alto interés industrial: hidrogenación de alquenos funcionalizados y no funcionalizados catalizados por Rh y Ir, hidrogenación de cetonas catalizada por Ir, reacciones de substitución alílica catalizada por Pd y reacciones de substitución propargílica catalizada por Cu. Se han sintetizado diferentes familias de ligandos Fosfito/fosfinito-tioéter/selenoéter, carbeno-tioéter, amino-fosfito/fosfinito/fosfina, y varias familias de ligandos tridentados.
The obtaining of enantiomerically pure compounds has become a need that led to an important progress in asymmetric catalysis, mainly using organometallic chiral compounds. Among different strategies to optimize catalysts in order to obtain high selectivities and activities, the design and the correct selection of chiral ligands, modifying their properties, is fundamental and the most used strategy. Ligands easy to synthesize from readily accessible starting material and stable and easy to manipulate ligands, have a high interest in the industry. In this context, the main objective of this thesis is the synthesis of different chiral ligand families, according to the previously mentioned requirements, and their application in different asymmetric reactions with high industrial interest: Rh- and Ir-catalyzed hydrogenation of functionalized and minimally functionalized olefins; Ir-catalyzed hydrogenation of simple ketones; Pd-catalyzed asymmetric substitution of allylic acetates and Cu-catalyzed propargylic substitution. There have been synthesized different phosphite/phosphinite-thioether/selenoether, carbene-thioether, amino-phosphite/phosphinite/phosphine and various tridentated ligand families.
Mazuela, Aragón Javier. "Design and screening of biaryl phosphite-based ligand libraries for asymmetric reduction and c-c and c-x bond forming reactions." Doctoral thesis, Universitat Rovira i Virgili, 2012. http://hdl.handle.net/10803/96665.
Повний текст джерелаDuring the last years, phosphite-containing compounds have proved to be efficient ligands for several metal-catalyzed transformations. In this context, we have developed several phosphite-containing ligand libraries for their application in reactions leading to enantiomerically pure products. More concretely we have studied: (a) the synthesis and screening of 9 phosphite-nitrogen ligand libraries in the Ir-catalyzed hydrogenation of minimally functionalized olefins, Pd-catalyzed allylic substitution and Heck reactions. These ligand libraries have been designed by systematic modification of several ligand parameters. In all cases excellent activities, regio- and enantioselectivities (ee’s up to >99%) have been obtained for a broad range of substrates. These results compete favorably with those reported previously in the literature. (b) the screening of several types of phosphite containing ligand libraries in the Rh-catalyzed hydroformylation of vinylarenes, heterocyclic olefins and 1,1’-terminal enol esters obtaining promising results (ee’s up to 76%).
Esswein, Arthur J. "Late transition metal bimetallics for photocatalytic hydrogen production, M-X and C-H bond activation." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40970.
Повний текст джерелаVita.
Includes bibliographical references.
Broadly defined this thesis has focused on the design and study of molecular catalysts that engender multi-electron reactions and photoreactions on small molecule substrates relevant to solar energy conversion. Specifically the molecular design elements employed have focused on bimetallic complexes of late transition metals that exhibit an unusual two-electron mixed valence ground state. Initial studies focused on the mechanistic elucidation of the reported photocatalytic production of hydrogen from homogeneous hydrohalic acid solution using a two-electron mixed valence dirhodium complex. Studies aimed at understanding and improving the photochemical quantum efficiency for challenging M-X (X = CI, Br-) bond photoactivations were undertaken by incorporating gold into a heterobimetallic rhodium-gold construct. Additionally the organometallic reactivity of two-electron mixed valence diiridium cores was explored with a specific emphasis on C-H bond activations in order to extend the cooperative bimetallic reactivity observed in the dirhodium systems beyond HX and H2 substrates to alkanes and arenes.
by Arthur J. Esswein.
Ph.D.
Margalef, Pallarès Jèssica. "Screening of modular and readily available ligand libraries for C-X (X=H, C, N and O) bond forming reactions. The use of DFT studies for catalysts optimization." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/386578.
Повний текст джерелаEl creciente interés para la obtención de compuestos enantioméricamente puros para la obtención de compuestos enantioméricamente puros, ha conducido a un importante desarrollo de la catálisis asimétrica. En este contexto, esta tesis se centra en la síntesis de varias familias de ligandos quirales altamente modulares a partir de compuestos de fácil disponibilidad. Concretamente, se ha trabajado en la síntesis de ligandos fosfito-tioéter, fosfito-piridina, fosfito-triazoles y ligandos hidroaximida y tioamida. Todos ellos tienen en común que son sólidos, estables y por lo tanto de fácil manipulación. Estos ligandos se han aplicado en la hidrogenación de olefinas funcionalizadas y no funcionalizadas catalizada por Rh e Ir, en la reducción de cetonas mediante transferencia de hidrógeno catalizada por Rh y Ru, en reacciones de sustitución alílica catalizada por Pd y en el adición de organoaluminiatos a aldehídos catalizada por Ni. Además, en algunos casos se han realizado estudios DFT para agilizar el proceso de optimización de los ligandos. Así pues, se ha logrado la obtención de diferentes compuestos químicos quirales de alto interés sintético (ej. alcoholes, alcanos funcionalizados y no funcionalizados, alilos sustituidos) en grandes enantioselectividades y en el mejor de los casos se han conseguido los productos en su forma enantioméricamente pura (> 99% ee).
The growing interest in obtaining enantiomerically pure compounds in obtaining enantiomerically pure compounds has led to a significant development in the field of asymmetric catalysis. In this context, this thesis is focused on the synthesis of several families of highly modular chiral ligands from readily available compounds. Specifically, we worked on the synthesis of thioether-phosphite ligands, phosphite-pyridine, phosphite-triazole and hidroaximide and thioamide ligands. They all have in common that are solid, stable and therefore easy to handle. These ligands have been applied in the Rh- and Ir-catalyzed hydrogenation of functionalized and unfunctionalized olefins, in the Ru- and Rh-catalyzed asymmetric transfer hydrogenation of ketones, in Pd-catalyzed allylic substitution reactions and in the Ni-catalyzed addition of organoalumininum to aldehydes. Moreover, in some cases DFT studies have been performed to speed up the optimization of ligands. Hence, a variety of chiral chemical compounds of high synthetic interest (i. e. alcohols, functionalized and non-functionalized alkanes, substituted allyl) lhigh enantioselectivities were achieved and in some cases the products were obtained in their enantiomerically pure form(> 99% ee).
Mazloomi, Zahra. "New approaches to perfluoroalkylation of aromatic compounds, and tailor-made catalysts for C-X bond forming and water oxidation reactions. Mechanistic insights." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/450517.
Повний текст джерелаEsta tesis está dividida en dos partes: la primera parte se realizó en el Instituto Catalán de Investigación Química (ICIQ) desde 2012 hasta 2015, esta parte trata sobre la perfluoroalquilación de sustratos aromáticos e incluye dos proyectos principales. El objetivo del primer proyecto era la producción en flujo continuo de CuCF3 como reactivo trifluorometilado y la confirmación de su eficacia en la trifluorometilación de algunos haluros aromáticos, los cuales fueron tratados con CuCF3 y se convirtieron selectivamente en compuestos trifluorometilados. En el segundo proyecto, el objetivo era transformar varios haluros vinílicos a análogos trifluorometilados y pentafluoroetilados usando los reactivos nucleófilos CuCF3 y CuC2F5, los cuales habían sido utilizados previamente en el mismo grupo. La segunda parte se ha llevado a cabo en la Universidad de Rovira i Virgili (URV) a partir de 2015 hasta 2017. Esta parte trata sobre diferentes reacciones catalíticas de formación de enlaces C-X y estudios mecanísticos sobre de estas. Esta parte contiene 4 proyectos de investigación. Tres de ellos tratan sobre la síntesis y aplicación en varias reacciones catalíticas de gran relevancia de varios complejos de carbeno anormales con Ir (I), Ir (III) y Ru (II). Estos catalizadores altamente eficaces se aplicaron con éxito en la hidrogenación por transferencia de enlaces C = O, C = N y C = C, también en la deshidrogenación de alcoholes y la oxidación con agua. El último proyecto trata sobre la formación catalítica asimétrica de enlaces C-C con una nueva y versátil biblioteca de ligandos P-N quirales. Todos los objetivos de la segunda parte de la tesis se realizaron con éxito. En resumen, en esta tesis se han realizado diversas transformaciones químicas importantes, todas ellas de gran interés en la formación de productos farmacéuticos, agroquímicos, naturales, de química fina y en la producción de energía limpia. El trabajo hecho en esta tesis contiene aspectos fundamentales de la química y desde el punto de vista químico e industrial existe una gran demanda en el desarrollo y mejora de los procesos mencionados.
This dissertation divided into two main parts: the first part which had been done from 2012 until 2015 in Institute of chemical research of Catalonia (ICIQ) is about perfluoroalkylation of aromatic substrate including two main works. In the first project the goal was continuous flow production of CuCF3 as a trifluoromethylated reagent and confirming its efficiency in trifluoromethylation of some aromatic halides which were treated with batch made CuCF3 reagent and selectively converted to trifluoromethylated conterparts. In the second project the target was transforming several vinylic halides to trifluoromethylated and pentafluoroethylated analoges with nucleophilic CuCF3 and CuC2F5 reagents which were demonstrated previously in the same group. The later part has been carried out in the University of Rovira I Virgili (URV) from 2015 until 2017. Generally this part is about different catalytic C-X bond forming reactions with mechanistic insights which contains 4 research projects. Three of them are about synthesis and catalytic application of several Ir(I), Ir(III) and Ru(II) abnormal carbene complexes in several important and challenging catalytic reactions. These highly efficient catalysts successfully applied in transfer hydrogenation of C=O, C=N and C=C functionalities, alcohol dehydrogenation and water oxidation. The last project is asymmetric catalytic formation of C-C bond with a new and versatile chiral P-N ligand library. All of the objectives for the second part of thesis were performed successfully. In conclusion, various important chemical transformation were made in this thesis which all of them are vital in pharmaceuticals, agrochemicals, fine and natural products and the production of clean energy. The total works in this thesis are so important in chemistry and there is a huge demand about developing and improving the mentioned processes from the chemical and industrial point of view.
Smith, Daniel L. "Selective incorporation of the C-F bond as a conformational tool in quadruplex DNA ligand design." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3169.
Повний текст джерелаBiosca, Brull Maria. "Fitting the catalysts for effective enantioselective C-X bond forming reactions. Theoretically guided ligand design and mechanistic investigations." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/665121.
Повний текст джерелаLa creciente demanda de compuestos enantioméricamente puros, ha incrementado el interés por el desarrollo de metodologías para la obtención de dichos compuestos. Entre ellas, la catálisis asimétrica es la técnica mas utilizada. En dicha metodología, la elección del ligando quiral es clave para la obtención de elevada actividades i enantioselectividades. En este contexto, esta tesis se centra en la síntesis de diferentes familias de ligandos quirales altamente modulares a partir de productos de partida de elevada disponibilidad. Más concretamente, se ha trabajado en la síntesis de ligandos heterodadores P-oxazoline (P= fosfina, fosfinito, fosfito, fosforamidito), P-otros grupos N-dadores (P= fosfito, fosforamidito, fosfonito y N= tiazol, sulfoximina, hidrazona, amina, piridina), P-tioéter (P= fosfina, fosfinito, fosfito) i una familia de ligandos fosfina quiral-fosfito. Estos ligandos se han aplicado en la reacción de hidrogenación de olefinas funcionalitzadas i mínimamente funcionalitzadas catalizada por Rh i Ir, la reacción de substitución alílica y la reacción de protonación descarboxilativa de oxindolas ambas catalizadas por Pd. Además, en algunos casos, se han realizado cálculos computacionales en combinación con ensayos experimentales para estudiar el origen de las enantioselectividades obtenidas o bien para guiar la optimización de los ligandos.
The growing demand on enantiomerically pure compounds has stimulated the interest for the development of methodologies to obtain these compounds. Among them, asymmetric catalysis is one of the most employed tools. In this technic, the choice of the chiral ligand is fundamental to obtain high levels of activity and enantioselectivity. In this context, this thesis is focused on the synthesis of several families of highly modular chiral ligands from readily available starting materials. Particularly, we worked on the synthesis of P-oxazoline (P= phosphine, phosphinite, phosphite, phosphoroamidite), P-other N-donor groups (P= phosphite, phosphoroamidite, phosphonite and N= thiazole, sulfoximine, hydrazone, amine, pyridine), P-thioether (P= phosphine, phosphinite, phosphite) and a family of P*-stereogenic phosphine-phosphite ligands. These ligands have been applied in the Rh- and Ir-catalyzed hydrogenation of functionalized and minimally functionalized olefins, Pd-catalyzed allylic substitution reaction and Pd-catalyzed decarboxylative protonation. Furthermore, in some cases, DFT studies in combination with experimental ones have been performed to better understand the origin of the obtained enantioselectivities or in order to guide the ligand optimization.
Magre, Rosich Marc. "Design of tailor-made chiral ligand libraries for C-X bond forming reactions. Study of the key intermediates by NMR and DFT." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/396081.
Повний текст джерелаEl desarrollo de metodologías para la obtención de compuestos enantioméricamente puros ha incrementado durante las últimas décadas, debido a la importancia de estos productos quirales en la sociedad actual, ya que son la base de fármacos, insecticidas y perfumes, entre otros. La catálisis asimétrica en la que el catalizador está basado en un centro metálico i un ligando coordinado al metal, ha sido la técnica más usada en los últimos años. Estos complejos organometálicos ofrecen unas propiedades concretas, como por ejemplo su gran selectividad y elevada actividad. La modificación del ligando será clave para la obtención de elevados niveles de selectividad y actividad. Estos ligandos han de ser altamente modulables, lo que permitiría realizar cambios estructurales y así poder estudiar su influencia en la reacción. En este contexto, esta tesis doctoral se basa en la síntesis de ligandos quirales fosfito-nitrogeno y su aplicación en diferentes reacciones enantioselectivas catalizadas por metal. Más concretamente, se ha trabajado en la sustitución alílica asimétrica catalizada por paladio; la descarboxilación protonativa de alfa aril onxindolas catalizada por paladio, la hidrogenación asimétrica de olefinas poco funcionalizadas catalizada por iridio, la hidroboración asimétrica catalizada por iridio y la adición enantioselectiva de compuestos trialquilaluminio a aldehídos, catalizada por níque
Fine chemicals and natural product chemistry rely on enantiomerically pure compounds. The growing demand on these compounds has stimulated the research for efficient asymmetric processes, which provided high activity and selectivity with minimum energy consumption and minimum generation of byproducts. In drugs and also in natural product chemistry, one enantiomer has the desired properties whereas the opposite enantiomer is either inactive or has undesirable side-effects. The discovery of synthetic routes for obtaining enantiomerically pure compounds is therefore one of the most pursued goals in chemistry. Particularly, asymmetric catalysis is one of the most attractive approach because it can provide very high reactivity and selectivity. Usually, with this strategy, a transition-metal complex containing a chiral ligand catalyzes the transformation of a prochiral substrate to one enantiomer as major product. To reach high levels of reactivity and selectivity, several reaction parameters need to be optimized. For example, the design of a chiral ligand is perhaps one of the most crucial step. In this context, this thesis focuses on the development of new chiral ligand libraries, the synthesis of new chiral catalyst and their application in the Pd-catalyzed asymmetric allylic substitution, Pd-catalyzed decarboxylative protonation of oxindoles, Ir-catalyzed asymmetric hydrogenation, Ir-catalyzed asymmetric hydroboration and Ni-1,2-addition of organoaluminum to aldehydes.
Liu, Jie. "Substitution chemistry of the cobalt complexes RCCo3(CO)9 (R = H, CHO) with the diphosphine ligand: 4,5-bis(diphenylphosphino)-4-cyclopenten-1,3-dione (bpcd). Syntheses, X-ray structures and reactivity." Thesis, University of North Texas, 2001. https://digital.library.unt.edu/ark:/67531/metadc3043/.
Повний текст джерелаRibas, Salamaña Xavi. "Synthesis, structure and reactivity of novel CuI, CuII and CuIII complexes containing triaza and hexaaza macrocyclic ligands." Doctoral thesis, Universitat de Girona, 2001. http://hdl.handle.net/10803/8020.
Повний текст джерелаDurant el treball de tesi presentat s'ha desenvolupat la síntesi de nous complexes de Coure(I), Coure(II) y Cu(III) utilitzant lligands macrocíclics de tipus triaza i hexaaza, i s'han estudiat la seves propietats estructurals així com la seva reactivitat.
La reacció dels lligands triazacíclics H32m, H2Me33m i H33m amb sals de coure(II) dóna lloc a una reacció de desproporció de Cu(II) per obtenir-se en quantitats equimolars un complex organometàl·lic de Cu(III) i un complex de Cu(I). La caracterizació estructural exhaustiva dels complexes del tipus aryl-Cu(III) evidencia la formació d'un enllaç organometàl·lic entre l'àtom de Cu(III) i el carboni més próxim de l'anell aromàtic del lligand. Aquesta reacció, a més de representar una nova forma de desproporció en la química del Cu, suposa l'activació d'un enllaç C-H aromàtic a temperatura ambient que, mitjançant l'estudi cinètic d'aquesta desproporció per espectroscòpia UV-Vis, dels càlcul de l'efecte cinètic isotòpic utilitzant el lligand deuterat en el C-H de l'anell, juntament amb el recolzament teòrics dels càlculs DFT per a la optimització de geometries d'intermedis de reacció, ens permeten proposar un mecanisme de reacció pel nostre sistema, on l'activació de l'enllaç C-H aromàtic transcorre per la formació d'un enllaç de tipus agòstic C-H ? Cu(II),5 seguit de la desprotonació del C-H aromàtic per acció d'una base i posterior transferència electrònica per obtenir el complex organometàlic de Cu(III) i el complex de de Cu(I).
En quant a la reactivitat d'aquests complexes organometàl·lics aryl-Cu(III) s'ha observat que una base en medi aquós causa la inestabilitat d'aquests compostos, evolucionant cap a la inserció d'un àtom d'oxigen sobre la posició activada de l'anell aromàtic, per a donar lloc a un complex dinuclear de Cu(II) amb dos grups fenoxo actuant de pont entre els àtoms metàl·lics. La reacció transcorre per un intermedi colorejat, caracteritzat com el complex ayl-Cu(III) monodesprotonat en una de les seves amines benzíliques, els quals s'observen igualment en la reacció dels correponents complexos de Cu(I) amb oxigen molecular (O2). És en els nostres sistemes en els quals es descriu per primera vegada la participació d'intermedis organometàl·lics Cu(III)-C en processos d'hidroxilació aromàtica, tals com el desenvolupat per l'enzim tirosinasa o per alguns dels seus models químics de síntesi.6,7,8
S'han estudiat les propietats magnètiques dels quatre bis(fenoxo)complexes de Cu(II) descrits, obtenint-se uns acoplaments de tipus antiferromagnètic o ferromagnètic de diversa magnitud, depenent del solapament orbitalari a l'enllaç Cu-O, a través del qual es produeix el superintercanvi.
Nous complexos de Cu(I) sintetitzats amb lligands hexaazamacrocíclics han estat estudiats, i posant especial èmfasi a la seva reactivitat respecta a l'activació d'oxigen molecular (O2). S'ha observat una reactivitat diferenciada segons la concentració de complex de Cu(I) utilitzada, de manera que a altes concentracions s'obté un carbonato complex tetranuclear de Cu(II) per fixació de CO2 atmosfèric, mentre que a baixes concentracions s'observa la hidroxilació aromàtica intramolecular d'un dels anells benzílics del lligand, reacció que presumiblement transcorre per atac electrofílic d'un peroxo complex intermedi sobre el sistema ? de l'anell.6
Els resultats obtinguts en aquest treball ens mostren la facilitat per activar enllaços C-H aromàtics per metalls de transició de la primera sèrie (Cu, Ni) quan aquests estan suficientment pròxims a l'enllaç C-H, en unes condicions de reacció molt suaus (1atm., temperatura ambient). Els nous complexos organometàl·lics Aryl-Cu(III) són el producte d'una nova reacció de desproporció de Cu(II), així com un posició aromàtica activada que podria ser el punt de partida per l'estudi de funcionalització selectiva d'aquests grups aromàtics.
In the present thesis the synthesis of novel Cu(I), Cu(II) and Cu(III) complexes containing triaza and hexaaza macrocyclic ligands is described, as well as the study of their structural and reactivity properties.
Ligands H32m, H2Me33m and H33m react with Cu(II) salts at room temperature in CH3CN to afford an organometallic Cu(III) complex and a Cu(I) complex in equimolar amounts, constituting a new disproportionation reaction for Cu(II). An exhaustive structural characterization of Aryl-Cu(III) complexes shows the formation of an organometallic between theCu(III) center and the carbon form the aromatic ring. This reaction represents a novel disproportionation in copper chemistry and moreover, evidenciates the activation of an aromatic C-H bond at room temperature. Throughout kinetic studies by UV-Vis spectroscopy, determination of the KIE value by using the corresponding deuterated ligand and theoretical calculations at DFT level for the optimization of intermediate geometries, we have proposed a mechanism for this disproportionation reaction: the aromatic C-H bond activation occurs through the formation of an agostic C-H ? Cu(II) interaction, followed by the deprotonation of the aromatic proton by the action of a base and final electron transfer to obtain the Cu(III) and Cu(I) final complexes.
The organometallic Cu(III) synthesized are stable in protic media, but react with aqueous base to afford the insertion of an oxygen atom at the C-Cu(III) bond and finally obtain a dinuclear Cu(II) complex where two phenoxo groups are bridging between the metal centers. The reaction undergoes through the formation of a colored intermediate characterized as an Aryl-Cu(III) complex deprotonated in one of the benzylic amines. These intermediates are also observed in the reaction of the corresponding Cu(I) complexes with molecular oxygen (O2). The intermediacy of organometallic aryl-Cu(III) in aromatic hydroxylation processes such as the reactivity displayed by tyrosinase or some synthetic model systems, is first described in the present work.
Magnetic properties for the four bis(phenoxo)Cu(II) complexes have alse been investigated. Different magnetic couplings are observed yielding ferromagnetic and antiferromagnetic behavior of variable magnitudes, depending on orbital overlapping on the Cu-O bond, through which the superexchange occurs.
Novel Cu(I) complexes containing the hexaazamacrocyclic ligand H33+33m have been studied, with special attention on the reactivity towards the O2 activation. It has been observed a differential reactivity depending on the concentration of Cu(I) complex: if high Cu(I) concentration are used the product obtained consists on a tetranuclear carbonato complex by atmospheric CO2 fixation, while if low concentrations are used the intramolecular aromatic hydroxylation is observed, reaction that is proposed to undergo through an electrophilic attack of the peroxo group to the ? system of the aromatic ring.
Yang, Jian Brookhart Maurice S. "Iridium-catalyzed reduction of C-X bonds X = F, Cl, Br, I, O bonds with triethylsilane." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,2639.
Повний текст джерелаTitle from electronic title page (viewed Oct. 5, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry." Discipline: Chemistry; Department/School: Chemistry.
Beagley, Paul. "Ansa-titanocenes for enantioselective reduction of C=X bonds." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557602.
Повний текст джерелаJoan, Saltó de la Torre. "Development of tailor-made catalyst libraries for the construction of chiral C-X (X= C, N and O) bonds. Application to the synthesis of complex molecules." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/673144.
Повний текст джерелаLa demanda constante de compuestos enantioméricamente puros (fármacos, agroquímicos, aditivos...) ha impulsado el desarrollo de la catálisis asimétrica empleando compuestos organometálicos quiral como catalizadores. En este contexto, la síntesis de nuevos ligandos quirales es esencial para descubrir buenos sistemas catalíticos en catálisis asimétrica. Esta tesis se ha centrado en el desarrollo de tres nuevas ligandotecas quirales heterodadoras y su aplicación a la sustitución alílica catalizada por paladio. Se trata de ligandotecas estables al aire, de fácil manipulación y que se han sintetizado en pocas etapas a partir de productos de elevada disponibilidad y bajo precio. Combinando estudios teóricos y espectroscopia de RMN, hemos podido afinar racionalmente a los ligandos, mejorar la enantioselectividad e identificar las especies responsables de los resultados catalíticos. Además, los productos de sustitución alílica resultantes se utilizaron exitosamente para la síntesis de moléculas más complejas.
The constant demand for enantiomerically pure compounds (drugs, agrochemicals, additives ...) has driven the development of asymmetric catalysis using chiral organometallic compounds as catalysts. In this context, the synthesis of new chiral ligands is essential to discover good catalytic systems in asymmetric catalysis. This thesis has focused on the development of three new heterodonating chiral ligand libraries and their application to Pd-catalyzed allylic substitutions. These are ligand libraries stable in the air, easy to handle and have been synthesized in a few steps from readily available products and at low price. Combining theoretical studies and NMR spectroscopy, we were able to rationally fine-tune the ligands, improve enantioselectivity, and identify the species responsible for catalytic performance. In addition, the resulting allylic substitution products were successfully used for the synthesis of more complex molecules.
Addison, Desnoyer N. "Harnessing the reactivity of late transition metals for the making and breaking of C-X (X = O, S, N) bonds." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62437.
Повний текст джерелаScience, Faculty of
Chemistry, Department of
Graduate
Chang, Chao-Hui. "Haematopoietic stem/progenitor cell interactions with the bone marrow vascular niche." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:452da334-bd4e-45c7-a7bd-fc8767d1239c.
Повний текст джерелаCharbonneau, Valerie. "A study of the presence and impact of C-H()X- hydrogen bonds in phase-transfer catalysis." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27338.
Повний текст джерелаRogers, James L. "Major tea catechin inhibits dendritic cell maturation in response to microbial stimulation." [Tampa, Fla] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002176.
Повний текст джерелаRamaraj, A. "Activation of H-X (X = H, Si, B, C) Sigma Bonds in Small Molecules by Transition Metal Pincer Complexes." Thesis, 2017. http://etd.iisc.ernet.in/2005/3795.
Повний текст джерелаNaidu, Kola Sattaiah. "Chemistry of Ru(II) Complexes Bearing Sigma Bonded H-X (X = H, Si, C) Species/Fragments." Thesis, 2013. http://etd.iisc.ernet.in/2005/3383.
Повний текст джерелаDai, Shao-Bo. "Mechanistic and Structural Characterization of Thiamine Diphosphate Dependent Enzyme Transketolases from Human and E.coli." Doctoral thesis, 2017. http://hdl.handle.net/11858/00-1735-0000-002E-E412-C.
Повний текст джерелаLevasseur-Grenon, Olivier Y. "Assemblage moléculaire régi par la formation de bifluorènes : vers la formation de réseaux organiques covalents retenus par des liaisons carbone-carbone." Thèse, 2014. http://hdl.handle.net/1866/11465.
Повний текст джерелаCovalent organic frameworks (COFs) are ordered two-dimensional and three-dimensional frameworks assembled only from light atoms in the first and second rows of the periodic table. These frameworks have shown properties that make them potentially useful in the storage of molecular guests, in catalysis and in separation. COFs are typically obtained by a final condensation reaction, which makes their crystallization difficult and leads to materials that are inhomogeneous and impossible to characterize in detail. The p-xylylenes of Thiele and Tschitschibabin are molecules that have attracted interest because of their structures and magnetic properties. Subsequently, Wittig demonstrated that replacing diphenylmethylene fragments in these structures by fluorenylidene units allowed their oligomerisation to form tetrameric structures. In our study, we have investigated the assembly of fluorenylidene derivatives to obtain COFs. First, a linear derivative similar to that obtained by Wittig was prepared to verify the feasibility of assembly from a spirobifluorenyl core. These compounds were found to oligomerise to form a tetramer, as expected as well as a hexamer. Both results have been rationalized by a study of the crystal structures by X-ray diffraction. The three-dimensional packing has also been analyzed. Subsequently, tetrahedral derivatives were synthesized to study the possibility of analogous assembly leading to COFs. A first derivative was found to remain in its quinoidal form rather than oligomerise and a second derivative resulted in a partially assembled dimer. The structure of the latter suggests that a linear polymer could be formed by a further reaction.
Zhang, Zhiguo [Verfasser]. "Organocatalytic additions to C=X bonds (X=O, C, and NR) / vorgelegt von Zhiguo Zhang." 2008. http://d-nb.info/989062996/34.
Повний текст джерелаHsiao, Chia-Jung, and 蕭嘉榮. "Probing C–H…X hydrogen bonds in amide-functionalized imidazolium salts under high pressure." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/61437700750011292640.
Повний текст джерела國立東華大學
化學系
93
We have probed under high pressure the C–H hydrogen bonds formed by N,N’-disubstituted imidazolium ions having PF6-and Br- counterions. High-pressure infrared spectral profiles, x-ray crystallographic analysis, and ab initio calculations allow us to make a vibrational assignment of these compounds. The appearance of a signal for the free-NH unit (or weakly bonded N–H…F unit) in the infrared spectrum of the PF6- salt indicates that conventional N–H…O and N–H…N hydrogen bonds do not fully dominate the packing. It is likely that the charge-enhanced C2–H…F interactions, combined with other weak hydrogen bonds, disturb the formation of N–H hydrogen bonds in the PF6- salt. This finding is consistent with the pressure-dependent results, which reveal that the C2–H…F interaction is enhanced upon increasing the pressure. In contrast to the PF6- salt, the imidazolium C–H bonds of the Br- salt have low sensitivity to high pressure. This finding suggests that the hydrogen bonding patterns are determined by the relative hydrogen bond acceptor strengths of the Br- and PF6- ions.
Wilsily, Ashraf. "Enantioselective Conjugate Additions to Meldrum’s Acid Acceptors for the Synthesis of Quaternary Centres and Studies on Persistent Intramolecular C–H•••X (X = O, S, Br, Cl, and F) Hydrogen Bonds Involving Benzyl Meldrum’s Acids." Thesis, 2009. http://hdl.handle.net/10012/4650.
Повний текст джерелаPaddison, J. Robert. "X-ray crystallographic structures of diazomethyl [beta]-D-galactopyranosyl ketone and tetra-O-acetyl [alpha]-cyano glucose computer modeling of 2 and 3 calcium bound states of cardiac troponin C." 1988. http://catalog.hathitrust.org/api/volumes/oclc/18202382.html.
Повний текст джерела