Teses / dissertações sobre o tema "Allyic substitution"
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Yu, Xiaodan. "New functionalized alkylidenecyclobutanes : multicomponent synthesis and applications". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASF034.
Texto completo da fonteCyclobutane derivatives have become increasingly important as molecular building blocks because of their inherent ring strain that facilitates the selective modification of their structures for strategic used in organic synthesis. Cyclobutane rings also appear in the molecular structures of a wide panel of natural and synthetic molecules that display interesting biological activities. Within this large family, alkylidenecyclobutane subunits are encountered in natural products, such as providencin, and they exhibit enhanced reactivity providing access to complex molecular structures, including enlarged ring and highly functionalized cyclobutane derivatives. In our laboratory, we recently developed an efficient synthesis of functionalized cyclobutenes through a domino photochemical reaction starting from cyclopent-2-enones and ethylene. Based on this study, we first explored a straight-forward transformation of functionalized cyclobutenes into alkylidenecyclobutanes. We then combined both sequences in a domino-multicomponent process. This was accomplished in a single protocol, comprising a tandem photochemical [2+2]-cycloaddition / Norrish-I / γ-H transfer reaction followed by an acetal-protection and an allylic substitution reaction. Additionally, the intramolecular version of these reactions allowed the synthesis of complex fused-bicyclic alkylidenecyclobutanes. Finally, the post-funtionalization of selected alkylidenecyclobutanes was studied, aiming to prepare novel fused tricyclic compounds through a intramolecular [2+2] photochemical process
Xie, Jianing. "Advancing Pd-catalyzed Stereoselective Allylic Substitution Reactions". Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/670221.
Texto completo da fonteEsta tesis doctoral se centra principalmente en el desarrollo de nuevos métodos catalíticos (dominó) basados en la sustitución alílica catalizada por Pd para la síntesis estereoselectiva de pequeñas moléculas funcionales y heterociclos utilizando un diseño detallado de ligandos y sustratos. Esta tesis está organizada en cinco capítulos: el primer capítulo es una introducción general sobre los aspectos básicos de la química alílica. El segundo capítulo ilustra el primer método general para la preparación de éteres arílicos alílicos terciarios enantioenriquecidos mediante una eterificación regio- y enantio-selectiva catalizada por Pd de los VCCs en presencia de nucleófilos fenólicos. La regioselectividad de la reacción puede ajustarse selectivamente al producto lineal Z cambiando el ligando fosforamidito a un ligando monofosfina, demostrando así el papel crucial del diseño adecuado del ligando. El tercer capítulo describe el diseño de un nuevo alcohol alílico terciario equipado con un grupo carboxilo, que se utiliza en primer lugar para la síntesis de γ-lactamas α,β-insaturadas mediante una aminación alílica estereoselectiva catalizada por Pd, seguido por un proceso de ciclación intramolecular. Los estudios mecanisticos sugieren que el grupo carboxilo es crucial para esta transformación y actúa como un grupo funcional activador y estereodirector. El cuarto capítulo presenta un enfoque estereodivergente controlado por el ligando para la síntesis de γ-aminoácidos con configuración Z o E derivados de alcoholes alílicos terciarios y aminas secundarias. Los resultados experimentales destacan el papel crucial del ligando de soporte y el ángulo de mordedura de la difosfina. El quinto capítulo informa sobre un método general para la síntesis de caprolactamas insaturadas sustituidas a través de un proceso de aminación / ciclación en cascada utilizando vinil γ-lactonas como sustratos mediante el uso de un ligando fosforamidito recientemente desarrollado. Finalmente, se extrae una conclusión general para cada capítulo y también se discute la aplicación potencial de estas metodologías desarrolladas.
This doctoral thesis is mainly focused on the development of novel catalytic (domino) synthesis methods based on Pd-catalyzed allylic substitution for the stereoselective synthesis of functional small molecules and heterocycles utilizing a detailed ligand engineering and substrate design. The scope of this thesis is organized into five chapters: the first chapter is a general introduction on the regular aspects of allylic chemistry. The second chapter illustrates the first general method for the preparation of enantioenriched tertiary allylic aryl ethers through a Pd-catalyzed regio- and enantio-selective etherification of VCCs in the presence of phenolic nucleophiles. The regioselectivity of the reaction can be finely tuned to the Z-selective linear product by switching the phosphoramidite ligand to a monophosphine ligand, thus proving the crucial role of proper ligand engineering. The third chapter describes a newly designed tertiary allylic alcohol equipped with a carboxyl group, which is firstly used for α,β-unsaturated γ-lactams synthesis through Pd-catalyzed stereoselective allylic amination and intramolecular cyclization process. Mechanistic studies suggest that the carboxyl group is crucial for this transformation, and acts as an activating and stereodirecting functional group. The fourth chapter presents a ligand-controlled stereodivergent approach for the synthesis of either Z or E-configured γ-amino acids derived from tertiary allylic alcohols and secondary amines. The experimental results highlight the crucial role of the supporting ligand and the diphosphine bite angle. The fifth chapter reports a general method for substituted unsaturated caprolactam synthesis through a cascade amination/cyclization process using vinyl γ-lactones as substrate by using a newly developed phosphoramidite ligand. Finally, a general conclusion for each chapter is given and potential applications for these developed methodologies are also discussed.
Clizbe, Elizabeth Adair. "Assymmetric transition metal-catalyzed allylic substitution reactions". Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539737.
Texto completo da fonteCai, Aijie. "Pd-catalyzed Allylic Substitution for Construction of Quaternary Stereocenters". Doctoral thesis, Universitat Rovira i Virgili, 2019. http://hdl.handle.net/10803/668819.
Texto completo da fonteDes 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 avenços ja realitzats, forjar derivats al·lílics ramificats quirals de materials inicials senzills i fàcilment disponibles continua essent una tasca important en la química sintètica, a causa del potencial d’aquests compostos al·lílics quirals en campanyes postintèntiques. Les bastides al·líliques que porten estereocentrisme quaternari basades en reaccions de substitució al·lílica catalitzades per Pd encara no es troben en cap cas. en aquesta tesi, hem desenvolupat una metodologia eficient i concisa per a la síntesi d’amines al·líliques aral a-a-desubstituïdes amb alts nivells de regio i enantioselectivitat. A continuació, vam desbloquejar l’origen de la regio- i l’enantioselectivitat en la inusual aminació al·lílica mitjançant càlculs de la teoria funcional de densitat (DFT) en combinació amb experiments de control mecanicista. Finalment, es van dissenyar lligams quirials nous i eficients i el seu ús en la síntesi en regio- i enantioselectiva de catalitzats de Pd de sulfones al·líliques ramificades. La utilitat del mètode es demostrarà més mitjançant la síntesi del sesquiterpè (-) - Agelasidine A.
Since the early seminal work by J. Tsuji and B. M. Trost, there has been rapid progress in the development of chiral ligands and scope of the electrophiles and nucleophiles in Pd-catalyzed allylic substitution reactions over the past few decades. In addition, Pd-catalyzed asymmetric allylic substitution reactions have been applied in total synthesis of a variety of complex chiral molecules, providing solid evidence of the efficiency of this methodology in controlling both regio- and enatioselectivities. Despite the numerous advances realized, forging chiral branched allylic derivatives from simple and readily available starting materials continues to be an important task in synthetic chemistry, due to the potential of the allylic moiety for further elaboration and asymmetric synthesis. The building allylic scaffolds bearing quaternary stereocenters based on Pd-catalyzed allylic substitution still remain rather underexplored. In this thesis, we have develop a concise and efficient methodology for synthesis of chiral a,a-disubtituted allylic amines with high levels of regio- and enantioselectivity. And then, we unlocked the origin of the regio- and enantioselectivity in the unusual allylic amination by density functional theory (DFT) calculations in combination with mechanistic control experiments.Finally, we designed a novel and highly efficient ligand to mediate regio- and enantioselective synthesis of various chiral allylic sulfones featuring quaternary stereocenters. The utility of the method will be further demonstrated by the synthesis of the sesquiterpene (-)-Agelasidine A.
Takeda, Momotaro. "Copper-Catalyzed Asymmetric Allylic Substitution with Organo- and Silylboronates". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188504.
Texto completo da fonteBaldwin, I. Craig. "New methodology involving allylic substitution and conjugate addition reactions". Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/27583.
Texto completo da fonteDawson, Graham John. "Studies on the stereoselective palladium-catalysed allylic substitution reaction". Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/31866.
Texto completo da fonteTosatti, Paolo. "Metal-catalysed asymmetric allylic substitution reactions for array synthesis". Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.540583.
Texto completo da fonteKawatsura, Motoi. "Palladium-Catalyzed Allylic Substitution with a Monodentate Phosphine Ligand". 京都大学 (Kyoto University), 1998. http://hdl.handle.net/2433/157157.
Texto completo da fonteKyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第7163号
理博第1937号
新制||理||1043(附属図書館)
UT51-98-G92
京都大学大学院理学研究科化学専攻
(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1項該当
Ceban, Victor. "New methodologies in asymmetric allylic substitution and organocascade reactions". Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/397983/.
Texto completo da fontePopa, Dana Madeleine. "Modular phosphinooxazolines: synthesis and evaluation in allylic substitutions". Doctoral thesis, Universitat Rovira i Virgili, 2008. http://hdl.handle.net/10803/9025.
Texto completo da fonteLas fosfinooxazolinas (Figura 1) fueron descritas originalmente en 1993 por Pfaltz Williams y Helmchen1 de simultáneamente y han sido utilizadas en múltiples ejemplos de sustituciones alílicas enantioselectivas sobre una gran diversidad de sustratos.
En el primer capitulo de la Tesis, se recoge la síntesis y caracterización de una familia altamente modular de complejos de paladio-fosfinooxazolina. La metodología de síntesis empleada se describe en el Esquema 1.
La preparación de los epoxiéteres 1a-e a partir del epoxido de Sharpless ha sido descrita con anterioridad en nuestro grupo de trabajo.2 La apertura regioselectiva y estereoespecífica de los epoxiéteres con amoniaco (25% NH3 en solución acuosa, en tubo de presión o en condiciones de irradiación en microondas) ha conducido a los amino alcoholes enantiopuros 2a-e los cuales, sin previa purificación, han sido Nacilados seguido de activación del hidroxilo (como mesilato) y ciclación resultando las fluorooxazolinas 5a-e. En el siguiente paso, la substitución del átomo de flúor por derivados de fósforo aniónicos ha conducido a los ligandos fosfinooxazolina que finalmente han sido transformados en los complejos de paladio 7a-e. Los métodos preparativos empleados son fácilmente escalables y ha sido posible obtener con suma facilidad, en algunos casos, cantidades cercanas al gramo. En el segundo capítulo de la Tesis están recogidos los resultados obtenidos en la alquilación alílica mediada por la nueva familia de complejos [Pd(η3-alil)(PHOX)]PF6 7a-e. Los complejos descritos en este trabajo han mostrado una gran estereoselectividad en un amplio margen de temperaturas, sin prácticamente ninguna pérdida en la enantioselectividad en el rango de temperaturas comprendido entre temperatura ambiente y 130º C. En la Tabla 1 se resumen las mejores condiciones de reacción optimizadas para la alquilación alílica asimétrica de una serie de acetatos alílicos con nucleófilos derivados de ésteres malónicos. Se ha observado un caso sin precedentes de inversión de la enantioselectividad para el acetato de 1,3-dimetilalílo comparado con el substrato análogo difenil sustituído.
En el tercer capítulo de la Tesis están recogidos los resultados obtenidos con la nueva familia de complejos Pd-PHOX en la aminacion asimétrica de varios substratos alílicos con nucleófilos nitrogenados. El grado de estereoinducción alcanzado con nuestros ligandos, en algunos de los casos, ha sido superior a los resultados descritos en la literatura. En la tabla 2 se resumen las mejores condiciones de reacción desarrolladas para la aminación alílica asimétrica de una serie de acetatos alílicos con una gran variedad de nucleófilos nitrogenados.
En el cuarto capítulo presentamos un nuevo agente chiral de resolucion, para la determinación de la pureza óptica de aminas quirales. Las aminas primarias y secundarias fueron derivatizadas con el reactivo quiral por apertura del agente de resolución (fluoro epóxido 8) resultando en la formación de productos diastereoméricos los cuales son fáciles de identificar y cuantificar mediante 19F, 1H, 13C NMR y HPLC (Esquema 2).
Béton, Didier. "Synthesis of new phosphorus amidite ligands : iridium-catalyzed allylic substitution /". Heidelberg, 2008. http://opac.nebis.ch/cgi-bin/showAbstract.pl?sys=000253233.
Texto completo da fonteLitvinov, Alexander E. "Ortho-diphenylphosphanylbenzoyl-directed Palladium catalyzed allylic substitution with soft nucleophiles". [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:25-opus-61462.
Texto completo da fontePerrone, Sylvie. "Copper(I)-mediated anti-SN2' allylic substitution reactions with diorganozinc reagents". Diss., [S.l.] : [s.n.], 2006. http://edoc.ub.uni-muenchen.de/archive/00006218.
Texto completo da fonteCheng, Xiaohui. "Transition metal catalysed homogeneous hydroamination, allylic substitution and transfer hydrogenation reactions". Thesis, King's College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410013.
Texto completo da fonteBaxendale, Ian Richard. "An investigative study into group 6 metal catalysed allylic substitution reactions". Thesis, University of Leicester, 1999. http://hdl.handle.net/2381/33907.
Texto completo da fonteLe, Chi. "Efforts Toward Improved Allylic Substitution via Pd-Catalyzed C-H Activation". The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1396436482.
Texto completo da fonteSpangenberg, Thomas. "Synthesis of biomolecules using directed allylic substitution, multicomponent reaction and hydroformulation". Université Louis Pasteur (Strasbourg) (1971-2008), 2008. http://www.theses.fr/2008STR13250.
Texto completo da fonteAtomökonomische Reaktionen gewinnen in der organische Synthese eine zunehmend an Bedeutung, nicht nur bei der Herstellung einfacher Moleküle sondern auch für strukturell aufwendige und biologisch hochwirksame Moleküle wie z. B. Alkaloide und nicht natürliche Aminosäuren. [. . . ]
Hagelin, Helena. "Palladium-catalyzed aromatic coupling and allylic substitution : an experimental and theoretical study /". Stockholm, 1999. http://www.lib.kth.se/abs99/hage0528.pdf.
Texto completo da fonteJiang, Xingyu. "Iridium-Catalyzed Asymmetric Allylic Substitution Reactions with Unstabilized Enolates and Prochiral Enolates". Thesis, University of California, Berkeley, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13422366.
Texto completo da fonteThe following dissertation discuss the development of iridium-catalyzed asymmetric allylic substitution reactions with unstabilized enolates and prochiral enolates. These reactions include the enantioselective allylic substitutions with silyl ketene acetals, diastereo- and enantioselective allylic substitutions with ?-alkoxy ketones, and stereodivergent allylic substitutions with aryl acetic acid esters, azaaryl acetamides and azaaryl acetates. Chapter 1 provides a brief overview of transition-metal-catalyzed asymmetric allylic substitutions with enolates. This overview focused on the mechanism of allylations of enolates catalyzed by palladium complexes and iridium complexes. Additionally, methodologies for asymmetric allylations of unstabilized enolates are discussed in detail. Furthermore, this overview highlights the challenges and the strategies for the control of diastereoselectivity for the allylic substitutions with prochiral enolates. Chapter 2 describes the development of iridium-catalyzed enantioselective allylic substitution reactions with silyl ketene acetals, the silicon enolates of esters, under relatively neutral conditions. The ester products contain a quaternary carbon atom at the nucleophile moiety and a chiral tertiary carbon atom at the electrophile moiety. Chapter 3 describes the study on diastereoselective and enantioselective allylic substitution reactions with acyclic ?-alkoxy ketones. A metallacyclic iridium complex catalyzes the allylation of unstabilized copper(I) enolates generated in situ from acyclic ?-alkoxy ketones to form products with contiguous stereogenic centers. Chapter 4 describes the development of stereodivergent allylic substitutions with aryl acetic acid esters catalyzed synergistically by a metallacyclic iridium complex and a Lewis base co-catalyst. Through permutations of the enantiomers of the two chiral catalysts, all four stereoisomers of the products bearing two adjacent stereocenters are accessible with high diastereoselectivity and enantioselectivity. A stereochemical model is provided to understand the origin of high stereoselec-tivity. Chapter 5 describes a combination of catalysts that enable stereodivergent allylic substitution reactions with azaaryl acetamides and acetates. This combination of catalysts comprises a chiral metallacyclic iridium complex and a chiral bisphosphine-ligated copper(I) complex, which individually control the configuration of the electrophilic and nucleophilic carbon atoms, respectively. Chapter 6 extends from the work discussed in Chapter 5 and demonstrates iridium and copper complexes synergistically catalyze stereodivergent allylations to construct vicinal fully substituted and tertiary stereogenic centers in acyclic structures. In particular, fluorine-containing fully substituted stereocenters are readily constructed from fluorinated acetates.
Norinder, Jakob. "Asymmetric Synthesis and Mechanistic Studies on Copper(I)-Catalyzed Substitution of Allylic Substrates". Doctoral thesis, Stockholm : Department of Organic Chemistry, Stockholm University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1031.
Texto completo da fonteStranne, Robert. "Investigation of Symmetry and Electronic Effects in Asymmetric Palladium-Catalysed Allylic Substitutions". Doctoral thesis, KTH, Chemistry, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3283.
Texto completo da fonteO'Connor, Ryan. "Rhodium-catalysed allylic substitution with unstabilised carbon nucleophiles : asymmetric construction of carbon-carbon bonds". Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/17253/.
Texto completo da fonteZhou, Yuebiao. "New Strategies for the Development of Catalytic Regio- and Enantioselective Allylic Substitution and Conjugate Addition Reactions:". Thesis, Boston College, 2020. http://hdl.handle.net/2345/bc-ir:108959.
Texto completo da fonteChapter 1. Catalytic SN2”-Selective and Enantioselective Substitution Reactions. The first broadly applicable strategy for SN2”-selective and enantioselective catalytic allylic substitution will be presented. It will be shown that transformations can be promoted by 5.0 mol% of a sulfonate-containing NHC–Cu complex (NHC = N-heterocyclic carbene), and may be carried out by the use of a commercially available allenyl–B(pin) (pin = pinacolato) or a readily accessible silyl protected propargyl–B(pin). Products bearing a 1,3 diene, a silyl allenyl or a propargyl moiety were obtained in high efficiency and selectivities. Also provided is insight regarding several of the unique mechanistic attributes of the catalytic process, obtained on the basis of kinetic isotope effect measurements and DFT studies. These investigations indicated that cationic π-allyl–Cu complexes are the likely intermediates, clarifying the role of the s-cis and s-trans conformers of the intermediate organocopper species and their impact on E:Z selectivity and enantioselectivity. It will also be shown we were able to highlight the utility of the approach by chemoselective functionalization of various product types, through which the propargyl, allenyl, or 1,3-dienyl sites within the products can be converted catalytically and chemoselectively to several synthetically useful derivatives. Chapter 2. NHC–Copper–Hydride-Catalyzed Enantioselective Processes with Allenyl Boronates and its Application in Natural Product Synthesis. Here, the development of a catalytic process that delivers otherwise difficult-to-access organoboron compound will be detailed. These processes involve the combination of a hydride, an allenyl–B(pin) and an allylic phosphate. As will be discussed, two unique selectivity problems were solved: avoiding rapid Cu–H reduction of an allylic phosphate, while promoting its addition to an allenylboronate as opposed to the commonly observed Cu–B exchange. We were able to underscore the considerable utility of the approach by applications to preparation of the linear fragment of pumiliotoxin B (myotonic, cardiotonic) and the first enantioselective synthesis of netamine C (anti-tumor), which also served to confirm its stereochemical identity. Chapter 3. Catalytic Enantioselective Prenyl Conjugate Addition Reactions. In this final section, studies leading to the development of the first class of catalytic enantioselective strategies for prenyl conjugate additions will be detailed. At the core of these investigations was finding ways to overcome two problems. One challenge originated from the fact that highly activated allylmetal species often deliver product with low enantioselectivity. The other was that regioselectivity was difficult to control owing to a strong preference for γ-selective additions. As will be described, we were able to address these difficulties by the use of a hydroxy NHC-copper complex and 3,3-dimethyl allyl–B(pin) as a reagent. In the end, we were able to use acyclic as well as cyclic enoates as substrates. The results of DFT studies that provide insight regarding varying selectivity profiles with different chiral ligands will be discussed as well
Thesis (PhD) — Boston College, 2020
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
Müller, Constanze Annelie. "Mass spectrometric screening of chiral catalysts by monitoring the back reaction: Palladium-catalysed allylic substitution". Göttingen Cuvillier, 2008. http://d-nb.info/989139719/04.
Texto completo da fonteMüller, Constanze A. "Mass spectrometric screening of chiral catalysts by monitoring the back reaction : palladium-catalysed allylic substitution /". [S.l.] : [s.n.], 2008. http://edoc.unibas.ch/diss/DissB_8322.
Texto completo da fonteOlsson, Vilhelm. "Development of New Synthetic Routes to Organoboronates by Catalytic Allylic Substitution and C-H bond Functionalization". Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-27753.
Texto completo da fonteSelim, Khalid Bashir Shaaban. "Development of chiral ligand-copper(1)-catalyzed asymmetric conjugate addition and allylic substitution with organometallic reagents". 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/126604.
Texto completo da fonteMcGrath, Kevin Patrick. "Enantioselective Methods for Allylic Substitution and Conjugate Addition Reactions Catalyzed by N-Heterocyclic Carbene-Copper Complexes". Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:106792.
Texto completo da fonteChapter 1 Catalytic Enantioselective Addition of Organoaluminum Reagents Catalytic methods involving the enantioselective addition of both commercially available as well as in situ generated organoaluminum reagents are reviewed. An overview of additions to aldehydes, ketones, and imines is provided as well as the difficulties and limitations of such transformations. Furthermore, additions to unsaturation adjacent to a leaving group to form a new stereogenic center are examined. Finally, conjugate addition reactions wherein an organoaluminum reagent is added to an olefin adjacent to a carbonyl or nitro group are discussed. Chapter 2 Synthesis of Quaternary Carbon Stereogenic Centers through Enantioselective Cu-Catalyzed Allylic Substitution with Alkenylaluminum Reagents A method for the formation of 1,4-diene containing quaternary stereogenic centers through catalytic enantioselective allylic substitution is disclosed. The addition of alkyl- and aryl-substituted alkenylaluminum reagents to trisubstituted allylic phosphates is promoted by 0.5–2.5 mol % of a sulfonate-containing bidentate N-heterocyclic carbene–copper complex. Products containing a quaternary stereogenic center as well as a newly formed terminal olefin are obtained in up to 97% yield and 99:1 er with high site selectivity (>98:2 SN2’:SN2). The requisite nucleophiles are generated in situ through hydroalumination of terminal alkynes. The utility of the method is demonstrated through a concise synthesis of natural product bakuchiol. Chapter 3 A Multicomponent Ni-, Zr-, Cu-Catalyzed Strategy for Enantioselective Synthesis of Alkenyl-Substituted Quaternary Carbons Despite the widespread use of conjugate addition in organic synthesis, few reports pertain to the addition of nucleophiles to acyclic systems and none in which the nucleophile is an alkene. Herein, we report the first examples of enantioselective conjugate addition of alkenylmetal reagents to trisubstituted enones to form all-carbon quaternary stereogenic centers. Alkenylaluminum nucleophiles are prepared through a site-selective Ni-catalyzed hydroalumination of terminal alkynes and the requisite E-trisubsituted enones are the products of a regioselective Zr-catalyzed carboalumination/acylation of a terminal alkyne. Products are obtained in up to 97% yield and 99:1 er. A model for enantioselectivity, supported by DFT calculations, is proposed. Chapter 4 Formation of Tertiary Centers through Catalytic Enantioselective Conjugate Addition of Alkenylaluminum Reagents to Acyclic Enones We have developed an enantioselective NHC–Cu catalyzed synthesis of tertiary centers in acyclic systems using in situ generated alkenylaluminum reagents, as current methods typically rely on Rh-catalysis at high temperatures with alkenyl boronic acids in protic solvents. Moreover, most examples include chalcone-derived substrates, which, while more reactive, often preclude further functionalization. With the current method, we are able to couple a variety of alkenyl nucleophiles with α,β-unsaturated ketones. E- or Z-silylalkenylaluminum reagents, derived from hydroalumination of silyl-protected alkynes, lead to products in good yields and high enantioselectivities. Additionally, both the α- and β-alkenylaluminum reagents participate in the reaction. Chapter 5 Development of N-Heterocyclic Carbene–Cu Catalyzed Allylic Substitution of Diboryl Methane to Morita-Baylis-Hillman Derived Allylic Phosphates We have developed a method for the coupling of a geminyl diboron reagent with Morita-Baylis-Hillman derived trisubstituted ester-containing allylic phosphates. With 10 mol % of an in situ generated NHC–Cu complex and 1.5 equivalents of the boron reagent, we are able to form the desired product in high regio- and enantioselectivity with a 2,5-ditert-butyl containing carbene. Simple aryl substituents as well as those containing a halogen or an electron-withdrawing group furnish the desired products in up to 85% yield and 98:2 er. Alkyl-containing substrates are also competent reaction partners, although longer chain aliphatics results in slightly diminished enantioselectivity. We are pursuing the application of this method to the synthesis of α-methylene lactones which can be further functionalized to natural products like tubulin polymerization inhibitor (–)-steganone and glaucoma medication (+)-pilocarpine
Thesis (PhD) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
Gao, Fang. "Copper-Catalyzed Enantioselective Allylic Substitution Reactions with Organoaluminum and Boron Based Reagents Promoted by Chiral Sulfonate Bearing N-Heterocyclic Carbenes". Thesis, Boston College, 2013. http://hdl.handle.net/2345/bc-ir:101227.
Texto completo da fonteChapter 1. A Review of Catalytic Enantioselective Allylic Substitution (EAS) with Chiral Sulfonate Containing N-heterocyclic Carbenes (NHC). A comprehensive review of enantioselective allylic substitution reactions, which are promoted by a chiral N-heterocyclic carbene metal complex that features a unique sulfonate motif, is provided in this chapter. Reactions are classified into two categories. One class of transformations is catalyzed by a series of easily modifiable sulfonate bearing NHC-Cu complexes, with which a range of nucleophilic organometallic reagents (i.e., organozinc-, aluminum-, magnesium- and boron-based) that carry different carbon-based units are readily utilized in efficient and highly selective C-C bond forming processes. Another set of reactions exclude the use of a copper salt; catalytic amount of a sulfonate containing imidazolinium salt is capable of promoting additions of alkyl Grignard, zinc and aluminum species to easily available allylic electrophiles in a site- and enantioselective fashion. The mechanistic scenarios of both catalytic systems that account for the observed experimental data are discussed in detail. Chapter 2. Cu-Catalyzed Enantioselective Allylic Substitutions with Aryl- and Heteroarylaluminum Reagents. In this chapter, the first examples of EAS reactions of aryl- and heteroaryl-substituted dialkylaluminum reagents to a wide range of trisubstituted allylic phosphates are demonstrated through a facile and selective catalysis rendered possible by an in situ generated sulfonate containing NHC-Cu complex, delivering enantiomerically enriched olefin products that bear an all carbon quaternary stereogenic center. The requisite organometallic species are easily prepared from either the corresponding aryl- and heteroaryl halides, or through efficient and site selective deprotonation at the C-2 position of furan and thiophene; such aluminum entities are readily used in situ without the requirement of purification. Application to small molecule natural product synthesis is also carried out to illustrate the utility of the present protocol. Chapter 3. Cu-Catalyzed Enantioselective Allylic Substitutions with Alkenylaluminum Reagents. This chapter focuses on our research towards construction of enantioenriched tertiary and quaternary stereogenic centers that are substituted with two further functionalizable alkenes. The first combination of the study involves the addition of stereochemically well-defined trisubstituted alkenylaluminum reagents to disubstituted allylic phosphates; the transformation commences with a silyl-directed stereoselective hydroalumination and finishes with an enantioselective Cu-catalyzed EAS promoted by a sulfonate bearing NHC. Such reactions deliver molecules that feature silicon containing trisubstituted olefin adjacent to the tertiary stereogenic center; subsequent conversion of the versatile silicon group to a proton reveals the first set of examples that incorporate pure Z alkene in Cu-catalyzed EAS. The stereoselective and concise synthesis of naturally occurring small molecule nyasol demonstrates the utility of the above method. On a different front, Ni-catalyzed site-selective hydroalumination of terminal alkynes has opened new possibility of introducing 1,1-disubstituted olefins in Cu-catalyzed EAS in the formation of tertiary stereogenic center containing enantioenriched organic building blocks. Such catalytic hydrometallation procedure also allows efficient access to alkenylaluminums that are derived from the conventionally problematic aromatic alkynes. The importance of efficient and selective synthesis of terminal aryl-substituted alkenylaluminum species is showcased in NHC-Cu-catalyzed EAS reactions that construct all-carbon quaternary stereogenic centers; a three-step convergent synthesis of natural product bakuchiol in enantiomerically enriched form highlights the potential of the current protocol in chemical synthesis. Chapter 4 Cu-Catalyzed Enantioselective Allylic Substitutions with Alkenylboronic Acid Pinacol Ester Reagents and Applications in Natural Product Synthesis. Within this chapter, we disclose the efficient utilization of alkenylboron reagents in Cu-catalyzed EAS reactions, which lead to highly site and enantioselective formations of molecules that contain both tertiary and quaternary carbon stereogenic centers. Unlike their aluminum-based counterparts, the use of boron-based reagents allows effective delivery of sensitive organic function groups, such as a carbonyl, which would be incompatible in the hydrometallation process with dibal-H. Our efforts accumulate to the first report of incorporation of all carbon quaternary centers that are substituted with unsaturated ester and aldehyde units in the EAS products; such a method facilitates the concise diastereo- and enantioselective synthesis of Pummerer's ketone and it's trans isomer. Further development of the above protocol towards the construction of tertiary stereogenic centers requires the design of new chiral sulfonate-containing imidazolinium salts as the ligand precursors and has lead to the employment of a broader range of alkenylboron species, which feature readily functionalizable motifs. Subsequent demonstrations in enantioselective synthesis of a variety of small molecule natural products showcase the utility
Thesis (PhD) — Boston College, 2013
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
Soorukram, Darunee. "Copper(I)-mediated regio- and stereoselective allylic substitutions and their applications to natural product syntheses". Diss., [S.l.] : [s.n.], 2006. http://edoc.ub.uni-muenchen.de/archive/00006234.
Texto completo da fonteBricout, Hervé. "Isomérisation et substitution nucléophile en série allylique catalysées par des complexes phosphorés du nickel". Lille 1, 1997. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1997/50376-1997-21.pdf.
Texto completo da fonteOliver, Samuel. "Rhodium-catalysed allylic substitution with an acyl anion equivalent : asymmetric construction of acyclic quaternary carbon stereogenic centres". Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/8433/.
Texto completo da fonteLarsson, Johanna M. "Transition metal-catalyzed allylic and vinylic functionalization : Method development and mechanistic investigations". Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-89524.
Texto completo da fonteAt the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.
Arnold, Jeffrey Scott. "Rhodium-catalyzed asymmetric amination of trichloroacetimidates with application to nitrogen heterocycle synthesis". Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4565.
Texto completo da fonteGuillarme, Stéphane. "Synthèse de nouveaux nucléosides acycliques : étude de la réaction de substitution allylique sur des dérivés cyclobuténiques : approche vers la synthèse de nucléosides cyclobuténiques". Le Mans, 2002. http://cyberdoc.univ-lemans.fr/theses/2002/2002LEMA1009.pdf.
Texto completo da fonteThis work deals with the synthesis of acyclic and carbocyclic nucleosides as potential antiviral and antitumoral compounds. In the first part of our study, acyclic nucleosides, analogues of penciclovir, have been prepared by conjugate addition of nucleobases on different Michael acceptors. With this unusual way of synthesis of acyclic nucleosides, deaza nucleobases which are low nucleophile have been incorporated. Addition of nucleobases on Michael acceptors have generally proceeded with good regioselectivity. The regioselectivity has been elucidated by NMR studies, using the 2D experiment HMBC. Nucleosides have been tested for their antiviral and antitumoral properties. Two of them have an anti-herpes activity. In the second part, the synthesis of acyclic nucleosides containing a methylene group have been described. Nucleobases have been introduced by a substitution reaction on a compound containing a leaving group. Some problems of regioselectivity have been noticed with purines. In the last part of our work, we have studied the allylic substitution reaction catalysed by palladium on cyclobutene derivatives. We have showed the first example of nucleophile substitution on π-allylic cyclobutene-based complexes. The cyclobutene derivatives were synthesised and were then opposed to different nucleophiles. With few nucleophiles, cyclobutene compounds were not isolated but only its isomers obtained by thermal ring-opening of the cyclobutene. Configuration of dienes was proved by NOE experiments. The regioselectivity of the reaction has been also approached. Cyclobutene-based nucleosides could be prepared by this reaction using nucleobases as nucleophiles
Shi, Ying. "Copper-catalyzed Enantioselective Allylic Substitutions and Conjugate Additions Promoted by Chiral Sulfonate- or Alkoxy-containing N-heterocyclic Carbenes". Thesis, Boston College, 2017. http://hdl.handle.net/2345/bc-ir:107648.
Texto completo da fonteChapter 1. A Review of Sulfonate-Containing NHC Ligands in Copper-Catalyzed Enantioselective Transformations—Maneuvering Selectivities in Tight Space. A comprehensive review of enantioselective copper-catalyzed transformations, which are promoted by a chiral N-heterocyclic carbene metal complex that features a unique sulfonate motif, is provided in this chapter. Reactions have been categorized into four sets: allylic substitutions conjugate additions, Cu-B additions alkenes and multicomponent reactions. The mechanistic scenarios provided by DFT calculations accounts for their uniquely reaction profile in enantioselective allylic substitutions (EAS), enantioselective conjugate additions (EAS) and enantioselective Cu-B additions to alkenes. Mechanistic investigations (density functional theory calculations and deuterium labeling) point to a bridging function for an alkali metal cation connecting the sulfonate anion and a substrate’ s phosphate group to form the branched addition products as the dominant isomers via Cu(III) π -allyl intermediate complexes in EAS reactions. Sulfonate-bearing NHC ligand with different substitution patterns promote EAS reactions with different reactivity and enantioselectivity. We also developed a guideline to follow to choose the proper sulfonate-based NHC ligands according to the combination of the substrates and the nucleophiles. Chapter 2. NHC–Cu-Catalyzed Enantioselective Allylic Substitutions with Silyl-protected Propargyl Boron Reagent to Generate Tertiary and Quaternary Carbon Stereogenic Centers. Catalytic allylic substitution reactions involving a propargylic nucleophilic component are presented; reactions are facilitated by 5.0 mol % of a catalyst derived from a chiral N-heterocyclic carbene (NHC) and a copper chloride salt. A silyl-containing propargylic organoboron compound, easily prepared in multi-gram quantities, serves as the reagent. Aryl- and heteroaryl-substituted disubstituted alkenes within allylic phosphates and those with an alkyl or a silyl group can be used. Functional groups typically sensitive to hard nucleophilic reagents are tolerated, particularly in the additions to disubstituted alkenes. Reactions may be performed on the corresponding trisubstituted alkenes, affording quaternary carbon stereogenic centers. Incorporation of the propargylic group is generally favored (vs allenyl addition; 89:11 to >98:2 selectivity); 1,5-enynes can be isolated in 75−90% yield, 87:13 to >98:2 SN2′:SN2 (branched/linear) selectivity and 83:17−99:1 enantiomeric ratio. Utility is showcased by conversion of the alkynyl group to other useful functional units. Application to stereoselective synthesis of the acyclic portion of antifungal agent plakinic acid A, containing two remotely positioned stereogenic centers, by sequential use of two different NHC–Cu-catalyzed enantioselective allylic substitution (EAS) reactions further highlights utility. Chapter 3. NHC–Cu-Catalyzed Enantioselective Allylic Substitutions with Methylenediboron to Generate Tertiary and Quaternary Carbon Stereogenic Centers. A catalytic EAS method for the site- and enantioselective addition of commercially available di-B(pin)-methane to disubstituted allylic phosphates is introduced. Transformations are facilitated by a sulfonate-containing NHC–Cu complex and products are obtained in 63–95% yield, 88:12 to >98:2 SN2’/SN2 selectivity, and 85:15–99:1 enantiomeric ratio. The utility of the approach is highlighted by its application to the formal synthesis of the cytotoxic natural product rhopaloic acid A, in an all-catalytic-method synthesis route. Catalytic EAS methods of the di-B(pin) methane to Z-trisubstituted allylic phosphates are also disclosed and DFT calculations provide insights to the stereochemical models for those transformations and rationales for the choice of Z-trisubstituted allylic phosphates as the starting materials. Chapter 4. Enantioselective NHC–Cu-Catalyzed Prenyl Conjugate Additions to Enoates to Generate Tertiary Carbon Stereogenic Centers. An efficient catalytic protocol for generation of prenyl-bearing tertiary carbon stereogenic centers from aryl-substituted enoates was achieved in the presence of a chiral alkoxy-based NHC–Cu complex. A range of aryl and heteroaryl-substituted substrate were suitable substrates, the corresponding prenyl conjugate addition products were generated in up to 94% yield and 95:5 enantioselectivity. The utility of the current method has been shown in the application to the synthesis of a selective integrin antagonist. DFT calculations provided a stereochemical model for the ECA reaction employing alkoxy-containing NHC–Cu catalyst
Thesis (PhD) — Boston College, 2017
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
Defieber, Christian Volker. "Chiral olefins as novel ligands in asymmetric synthesis and the development of water and ammonia equivalents in iridium-catalyzed allylic substitution /". Zürich : ETH, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17170.
Texto completo da fonteMandai, Kyoko. "Cu-Catalyzed Enantioselective Allylic Substitutions with Organomagnesium and Organoaluminum Reagents Promoted by N-Heterocyclic Carbenes for the Formation of Quaternary Stereogenic Centers". Thesis, Boston College, 2010. http://hdl.handle.net/2345/1329.
Texto completo da fonteChapter One: An overview of Cu-catalyzed enantioselective allylic substitutions with organometallic reagents. Chapter Two: Development of Cu-catalyzed enantioselective allylic alkylations of allylic chlorides with Grignard reagents for the formation of all-carbon quaternary stereogenic centers is disclosed. Chapter Three: Development of Cu-catalyzed enantioselective allylic substitutions of allylic phosphates with alkyl, aryl, and heterocyclic aluminum reagents for the formation of quaternary stereogenic centers is discussed
Thesis (MS) — Boston College, 2010
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
Thomasset, Amélia. "Synthèse de carbènes N-hétérocycliques chiraux et applications en catalyse asymétrique". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-01070636.
Texto completo da fonteBalanta, Castillo Angelica. "Novel molecular and colloidal catalysts for c-c bond formation processes". Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/66243.
Texto completo da fonteThis doctoral thesis focuses on the synthesis and characterization of metal nanoparticles (Pd, Ni, Pt) stabilized by several types of ligands and the used of these nanoparticles in new C-C or C-heteroatom bond formation reactions: a) Pd-catalysed asymmetric allylic substitution reactions; b) Pd-catalysed asymmetric Suzuki-Miyaura coupling reactions; c) Ni-catalysed Suzuki-Miyaura coupling reactions; d) Pt-catalysed 1,4-addition of phenylboronic acid to 2-cyclohexen-1-one reaction. For each reaction, the synthesis and characterization of metal nanoparticles and molecular complexes using several types of ligands were performed and both types of catalytic systems were tested in the appropriate reactions. Remarkably, excellent enantioselectivities using Pd/phosphite ligand were obtained in allylic substitution reaction. An efficient recovery of the catalytic system was carried out using ionic liquids as reaction medium. New active and selective nanoparticles were synthesized and characterized. These nanoparticles were applied successfully in various C-C bond formation reactions.
Eichelsheim, Tanja. "Oligonucleotide based ligands in homogeneous transition metal catalysis". Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3168.
Texto completo da fontePosseme, Françoise. "Synthèse et évaluation biologique d'analogues borylés et fluorés de polyamines. Nouvelle voie d'accès stéréocontrôlée ayx (E)-(gamma-alocoxyallyl)boronates alpha-substutués". Rennes 1, 2001. http://www.theses.fr/2001REN10149.
Texto completo da fonteHallman, Kristina. "Asymmetric Catalysis : Ligand Design and Conformational Studies". Doctoral thesis, KTH, Chemistry, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3275.
Texto completo da fonteThis thesis deals with the design of ligands for efficientasymmetric catalysis and studies of the conformation of theligands in the catalytically active complexes. All ligandsdeveloped contain chiral oxazoline heterocycles.
The conformations of hydroxy- and methoxy-substitutedpyridinooxazolines and bis(oxazolines) during Pd-catalysedallylic alkylations were investigated using crystallography,2D-NMR techniques and DFT calculations. A stabilising OH-Pdinteraction was discovered which might explain the differencein reactivity between the hydroxy- and methoxy-containingligands. The conformational change in the ligands due to thisinteraction may explain the different selectivities observed inthe catalytic reaction.
Polymer-bound pyridinooxazolines and bis(oxazolines) weresynthesised and employed in Pd-catalysed allylic alkylationswith results similar to those of monomeric analogues;enantioselectivities up to 95% were obtained. One polymer-boundligand could be re-used several times after removal of Pd(0).The polymer-bound bis(oxazoline) was also used in Zn-catalysedDiels-Alder reactions, but the heterogenised catalyst gavelower selectivities than a monomeric analogue.
A series of chiral dendron-containing pyridinooxazolines andbis(oxazolines) were synthesised and evaluated in Pd-catalysedallylic alkylations. The dendrons did not seem to have anyinfluence on the selectivity and little influence on the yieldwhen introduced in the pyridinooxazoline ligands. In thebis(oxazoline) series lower generation dendrimers had a postiveon the selectivity, but the selectivity and the activitydecreased with increasing generation.
Crown ether-containing ligands were investigated inpalladium-catalysed alkylations. No evidence of a possibleinteraction between the metal in the crown ether and thenucleophile was discovered.
A new type of catalyst, an oxazoline-containing palladacyclewas found to be very active in oxidations of secondary alcoholsto the corresponding aldehydes or ketones. The reactions wereperformed with air as the re-oxidant. Therefore, this is anenviromentally friendly oxidation method.
Keywords:asymmetric catalysis, chiral ligand,oxazolines, conformational study, allylic substitution,polymer-bound ligands, dendritic ligands, crown ether,oxidations, palladacycle.
Newman, Louise M. "Asymmetric synthesis : approaches via enantiomerically pure acetal and oxazoline ligands". Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/13773.
Texto completo da fonteGillespie, Jason A. "Design and synthesis of wide bite angle phosphacyclic ligands". Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3100.
Texto completo da fonteChamseddine, Yssam. "Sondes mecanistiques chirales et/ou regioselectivement deuteriees : application a l'etude de quelques processus de substitution nucleophile". Paris 6, 1988. http://www.theses.fr/1988PA066133.
Texto completo da fonteBöhnisch, Torben. "C2-Symmetric Pyrazole-Bridged Ligands and Their Application in Asymmetric Transition-Metal Catalysis". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://hdl.handle.net/11858/00-1735-0000-0028-876A-6.
Texto completo da fonteLinstadt, Roscoe T. H. "A. Studies In The Allylic Substitution Chemistry Of Copper Hydride B. Stereoselective Silylcupration Of Conjugated Alkynes In Micellar Media C. Palladium-Catalyzed Synthesis Of 1,3-Butadienes and [3]-[6]Dendralenes D. Synthesis Of Small Molecule Underwater Adhesives Inspired By Mussels". Thesis, University of California, Santa Barbara, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10257794.
Texto completo da fonteCopper hydride (CuH) has been shown to enable a number of selective 1,2- and 1,4-reductions when complexed with the appropriate ligand, yet the allylic substitution chemistry of CuH has been much less studied. This dissertation describes the further study of CuH to perform sequential reductions on Morita-Baylis-Hillman (MBH) adducts. Specifically: I) Selectivity in the SN2’ reduction of MBH adducts was shown to be highly dependant on the nature of the ligand used. II) The reaction of MBH alcohols was shown to involve an initial dehydrogenative silylation with PMHS, where both the oligomeric nature and electronics of the initially formed trialkoxysilyl ether intermediate are important in determining both the observed stereoselectivity, and efficiency of the substitution. III) MBH ketones could be employed in tandem SN2’/1,2-reduction sequences to arrive at stereodefined allylic alcohols with central chirality.
Vinylsilanes are versatile intermediates in organic synthesis owing to numerous methods for their transformation into other functional groups that proceed with high stereoretention. While there are numerous methods to synthesize stereodefined vinylsilanes from alkynes, many existing methods require the use of highly reactive moisture intolerant reagents and harsh reaction conditions, features that limit the functionality that can be accommodated. Even fewer of these existing methods are conducted under environmentally responsible conditions. The use of Suginome’s reagent as a moisture tolerant source of nucleophilic silicon, small catalytic quantities of a simple copper(I) salt, and an aqueous solution of TPGS-750-M as an environmentally benign nonionic surfactant, is described herein as a highly effective combination of reagents that allows for the stereoselective silylcupration of conjugated alkynes giving access to a variety of (E)-β-silyl-substituted carbonyl derivatives under environmentally responsible conditions.
This dissertation also describes the application of substituted allenoates as electrophilic butadienyl coupling partners under palladium catalysis in aqueous micellar media. The substituted allenoates could then be transformed by the methods developed herein into a variety of 2-substituted butadienes, where the methods were then extended to provide entry into a variety of substituted [3]-[6]dendralenes. Specifically: I) Application of an additive based screen allowed for evaluation of functional group tolerance in the Pd-catalyzed coupling of substituted allenoates with boronic acids. II) Curiosity driven investigations to identify boron based sp3 coupling reagents compatible with the conditions of micellar catalysis led to the identification of OBBD alkylborinate reagents as stable and isolable coupling reagents, which was the applied to the synthesis of 2-alkyl 1,3-butadienes. III) An analogous vinylallenyl coupling partner that functions formally as an electrophilic [3]dendralene synthon was proposed, and a number of synthetic routes were examined to access this molecule. Optimization of the synthetic route allowed for access to multigram quantities of this material, where it was applied to the synthesis of variously substituted [3]-[6]dendralenes.
Efforts to understand the marine mussels mechanism of strong wet adhesion has been a subject of intense scientific investigation. Analysis of the peptide sequence of mfp-5, a mussel foot protein most correlated with interactions at the interface, revealed a high proportion of charged, hydrophobic, and catechol containing residues. Described in this dissertation is the synthesis of small molecule underwater adhesives by incorporation of these key features of mfp-5. These newly designed molecules formed adhesive bilayers underwater, and were shown to replicate and even exceed mfp-5’s strong wet adhesive energy, while also being orders of magnitude smaller than both the native mussel proteins or existing biomimetic adhesive platforms. By systematically varying key portions of these small molecular adhesives, the adhesive bilayers could be transformed into molecularly uniform monolayers which were applied to the nanofabrication of organic electronic devices.
Rovira, González Laura. "Design and Application of Bisphosphite Ligands with a Distal Regulation Site for Asymmetric Catalysis". Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/395211.
Texto completo da fonteSe ha estudiado el diseño y la síntesis de ligandos supramoleculares enantiopuros de tipo bisfosfito, juntamente con las propiedades de coordinación de estos ligandos con precursores de rodio y paladio. Los complejos de rodio y paladio derivados de estos ligandos supramoleculares se han aplicado como catalizadores en hidroformilaciones y substituciones alílicas asimétricas. Los ligandos diseñados contienen una cadena polioxietilénica, que es la responsable de la regulación a través de interacciones supramoleculares con los agentes de regulación, y que además contienen dos grupos fosfito derivados de dioles enantioméricamente puros que se coordinan al centro metálico y constituyen el centro catalítico. La estrategia supramolecular que se ha empleado en la presente Tesis Doctoral se basa en la interacción entre agentes de regulación diversos (sales de metales alcalinos, alcalinotérreos o lantánidos) con la cadena polioxietilénica del ligando, que sirve para modificar la geometría y flexibilidad del centro catalítico (efecto adaptativo del catalizador asimétrico). El uso de esta estrategia de regulación supramolecular ha permitido obtener enantioselectividades elevadas en reacciones de hidroformilación de olefinas heterocíclicas. Además, se ha podido regular para algunos alquenos heterocíclicos la regioselectividad de la reacción y se ha podido eliminar la formación de productos de isomerización asociados con la reacción de hidroformilación. Ligandos supramoleculares de tipo bisfosfito se han aplicado también en sustituciones alílicas asimétricas. Los efectos de regulación que se han obtenido en esta transformación han sido notables, aunque las enantioselectividades obtenidas han sido moderadas.
The design and synthesis of enantiopure supramolecular bisphosphite ligands, together with their coordination properties with rhodium and palladium precursors, have been studied. Rhodium and palladium complexes derived from these supramolecular ligands have been applied as catalysts in asymmetric hydroformylations and allylic substitutions. The designed ligands contain a polyoxyethylene motif, which is the responsible for regulation through supramolecular interactions with the regulation agents, and two phosphite groups derived from enantiomerically pure diol derivatives that bind the metal center and constitute the catalytic site. The supramolecular strategy that has been followed within the present Doctoral Thesis relies on the interaction between a number of regulation agents (alkali metal, alkaline earth metal or lanthanide salts) and the polyoxyethylene motif of the ligand, which serves for the fine modification of the geometry and flexibility of the catalytic center (adaptive effect of the asymmetric catalyst). This supramolecular regulation strategy has led to high enantioselectivities in hydroformylation reactions of heterocyclic olefins and has allowed the regulation of the regioselectivity in the hydroformylation of several cyclic olefins. Furthermore, the formation of byproducts associated with the hydroformylation process has also been suppressed with the use of the above mentioned regulation agents. Supramolecularly regulated bisphosphite ligands have also been applied to asymmetric allylic substitution reactions. Noteworthy regulation effects have been achieved in this transformation, though the enantioselectivies in the allylic substitutions remained moderate.