Bibliografie tematiche / Allyic substitution

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Letteratura scientifica selezionata sul tema "Allyic substitution"

Autore: Grafiati

Pubblicato: 2 novembre 2024

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Articoli di riviste sul tema "Allyic substitution"

Hastings, Alan. "Substitution Rates Under Stabilizing Selection". Genetics 116, n. 3 (1 luglio 1987): 479–86. http://dx.doi.org/10.1093/genetics/116.3.479.

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ABSTRACT Allelic substitutions under stabilizing phenotypic selection on quantitative traits are studied in Monte Carlo simulations of 8 and 16 loci. The results are compared and contrasted to analytical models based on work of M. Kimura for two and "infinite" loci. Selection strengths of S = 4Nes approximately four (which correspond to reasonable strengths of selection for quantitative characters) can retard substitution rates tenfold relative to rates under neutrality. An important finding is a strong dependence of per locus substitution rates on the number of loci.

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Vilotijevic, Ivan, Markus Lange e You Zi. "Latent (Pro)Nucleophiles in Enantioselective Lewis Base Catalyzed Allylic Substitutions". Synlett 31, n. 13 (4 giugno 2020): 1237–43. http://dx.doi.org/10.1055/s-0040-1707130.

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The use of latent nucleophiles, which are molecules that are not nucleophilic but can be activated to act as a nucleophile at an opportune time during the reaction, expands the scope of Lewis base catalyzed reactions. Here, we provide an overview of the concept and show examples of applications to N- and C-centered nucleophiles in allylic substitutions. N- and C-silyl compounds are superior latent (pro)nucleophiles in Lewis base catalyzed reactions with allylic fluorides in which the formation of the strong Si–F bond serves as the driving force for the reactions. The latent (pro)nucleophiles ensure high regioselectivity in these reactions and enable enantioselective transformations of Morita–Baylis–Hillman adducts by the use of common chiral Lewis base catalysts.1 Introduction2 Substitution of MBH Carbonates3 The Concept of Latent (Pro)Nucleophiles4 Enantioselective Allylation of N-Heterocycles5 Enantioselective Phosphonyldifluoromethylation of Allylic Fluorides6 Conclusion

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Lopes Jesus, A. J., Cláudio M. Nunes, Gil A. Ferreira, Kiarash Keyvan e R. Fausto. "Photochemical Generation and Characterization of C-Aminophenyl-Nitrilimines: Insights on Their Bond-Shift Isomers by Matrix-Isolation IR Spectroscopy and Density Functional Theory Calculations". Molecules 29, n. 15 (25 luglio 2024): 3497. http://dx.doi.org/10.3390/molecules29153497.

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The intriguing ability of C-phenyl-nitrilimine to co-exist as allenic and propargylic bond-shift isomers motivated us to investigate how substituents in the phenyl ring influence this behavior. Building on our previous work on the meta- and para-OH substitution, here we extended this investigation to explore the effect of the NH2 substitution. For this purpose, C-(4-aminophenyl)- and C-(3-aminophenyl)-nitrilimines were photogenerated in an argon matrix at 15 K by narrowband UV-light irradiation (λ = 230 nm) of 5-(4-aminophenyl)- and 5-(3-aminophenyl)-tetrazole, respectively. The produced nitrilimines were further photoisomerized to carbodiimides via 1H-diazirines by irradiations at longer wavelengths (λ = 380 or 330 nm). Combining IR spectroscopic measurements and DFT calculations, it was found that the para-NH2-substituted nitrilimine exists as a single isomeric structure with a predominant allenic character. In contrast, the meta-NH2-substituted nitrilimine co-exists as two bond-shift isomers characterized by propargylic and allenic structures. To gain further understanding of the effects of phenyl substitution on the bond-shift isomerism of the nitrilimine fragment, we compared geometric and charge distribution data derived from theoretical calculations performed for C-phenyl-nitrilimine with those performed for the derivatives resulting from NH2 (electron-donating group) and NO2 (electron-withdrawing group) phenyl substitutions.

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Bergbreiter, David E., Andrew Kippenberger e Zhenqi Zhong. "Catalysis with palladium colloids supported in poly(acrylic acid)-grafted polyethylene and polystyrene". Canadian Journal of Chemistry 84, n. 10 (1 ottobre 2006): 1343–50. http://dx.doi.org/10.1139/v06-076.

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Grafts of poly(acrylic acid) on polyethylene powder (PE-g-PAA) or polystyrene (PS-g-PAA) can be used to support Pd(0) crystallites that function like a homogeneous Pd(0) catalyst in some reactions. These Pd–PE-g-PAA catalysts were active in allylic substitution reactions in the presence of added phosphine ligand. A catalyst analogous to the Pd–PE-g-PAA powder catalyst on polystyrene (Pd–PS-g-PAA) was similarly active for allylic substitution and could also be used in Heck reactions at 80–100 °C in N,N-dimethylacetamide (DMA). Analysis of the product solutions for Pd leachate and a correlation of the Pd leaching with product formation in the allylic substitution chemistry for both types of catalysts suggests that the active catalysts in these reactions are leached from the support. In the case of the allylic substitution reaction, external triphenylphosphine and substrate together are required for the chemistry and Pd leaching.Key words: catalysis, palladium, allylic substitution, grafted polystyrene, supported catalysts.

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Kang, Suk-Ku, Dae-Yeun Kim, Ryung-Kee Hong e Pil-Su Ho. "Ruthenium-Catalyzed Allylic Substitution of Allylic Cyclic Carbonates". Synthetic Communications 26, n. 17 (settembre 1996): 3225–35. http://dx.doi.org/10.1080/00397919608004631.

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Shekhar, Shashank, Brian Trantow, Andreas Leitner e John F. Hartwig. "Sequential Catalytic Isomerization and Allylic Substitution. Conversion of Racemic Branched Allylic Carbonates to Enantioenriched Allylic Substitution Products". Journal of the American Chemical Society 128, n. 36 (settembre 2006): 11770–71. http://dx.doi.org/10.1021/ja0644273.

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Boussonnière, Anne, Anne-Sophie Castanet e Hélène Guyon. "Transition-Metal-Free Enantioselective Reactions of Organomagnesium Reagents Mediated by Chiral Ligands". Synthesis 50, n. 18 (20 giugno 2018): 3589–602. http://dx.doi.org/10.1055/s-0037-1610135.

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Organomagnesium reagents are among the most important reagents in organic chemistry because of their great utility in forming carbon–carbon bonds. Although most enantioselective reactions using these organometallics involve transmetalation, the past decade has witnessed impressive advances in direct chiral-ligand-mediated reactions of organomagnesiums. This short review presents an overview of these achievements in enantioselective nucleophilic additions and substitutions.1 Introduction2 Enantioselective Nucleophilic Additions2.1 Addition to C=O Bonds2.2 Addition to C=N Bonds2.3 Addition to C=C Bonds3 Enantioselective Substitution Reactions3.1 Sulfoxide–Magnesium Exchange3.2 Desymmetrization via Anhydride Opening3.3 Asymmetric Allylic Alkylation (AAA)4 Conclusion

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Thoke, Mahesh Bhagwan, e Qiang Kang. "Rhodium-Catalyzed Allylation Reactions". Synthesis 51, n. 13 (30 aprile 2019): 2585–631. http://dx.doi.org/10.1055/s-0037-1611784.

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Rhodium-catalyzed allylation reactions are well known for their unique selectivity and reactivity due to the high memory effect of Rh as compared to other metals. These reactions involve the substitution of allylic rhodium intermediates with a diverse range of different nucleophiles, leading to C–C and C–heteroatom bond formation. Modern organic chemists are, however, interested in atom-economical protocols under greener pathways and following recent increased understanding of mechanistic aspects of Rh-catalyzed allylation via the hydrofunctionalization of allenes or alkynes, great strides have made in the design and development of new atom-economical protocols. In this article, we review this field from its beginning to current state.1 Introduction2 Rhodium-Catalyzed Allylic Substitution3 Rhodium-Catalyzed Allylation with Allenes4 Rhodium-Catalyzed Allylation with Alkynes5 Rhodium-Catalyzed Allylation with Dienes6 Rhodium-Catalyzed Allylation by ARO of Oxabicyclic Alkenes7 Rhodium-Catalyzed Enantioselective Allylation in Natural Product and Drug Synthesis8 Conclusion

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Takeuchi, Ryo. "Iridium-Catalyzed Enantioselective Allylic Substitution". Journal of Synthetic Organic Chemistry, Japan 74, n. 9 (2016): 885–902. http://dx.doi.org/10.5059/yukigoseikyokaishi.74.885.

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Alexakis, A., e C. Falciola. "Copper-Catalyzed Asymmetric Allylic Substitution". Synfacts 2007, n. 7 (luglio 2007): 0714. http://dx.doi.org/10.1055/s-2007-968661.

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Più fonti

Tesi sul tema "Allyic substitution"

Yu, Xiaodan. "New functionalized alkylidenecyclobutanes : multicomponent synthesis and applications". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASF034.

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Les dérivés du cyclobutane sont devenus de plus en plus importants en tant que blocs de construction moléculaires en raison de leur contrainte cyclique inhérente et de la modification sélective de leurs structures qui peuvent être utilisées de manière stratégique dans la synthèse organique. Les cycles cyclobutane apparaissent également dans les structures moléculaires d'un large panel de molécules naturelles et synthétiques qui présentent des activités biologiques intéressantes. Au sein de cette grande famille, les sous-unités alkylidènecyclobutane sont rencontrées dans des produits naturels, tels que la providencine, et elles présentent une réactivité accrue permettant d'accéder à des structures moléculaires complexes, notamment des dérivés cyclobutane à cycle élargi et hautement fonctionnalisés. Dans notre laboratoire, nous avons récemment développé une synthèse efficace de cyclobutènes fonctionnalisés par une réaction domino photochimique à partir de cyclopent-2-énones et d'éthylène. Sur la base de cette étude, nous avons d'abord exploré une transformation simple de cyclobutènes fonctionnalisés en alkylidènecyclobutanes. Ensuite, nous avons combiné les deux séquences dans un processus domino à plusieurs composants. La réaction domino-MCR est réalisée selon un protocole unique, comprenant une réaction photochimique en tandem de cycloaddition [2+2] / Norrish-I / γ-H suivie d'une réaction de protection acétal et d'une réaction de substitution allylique. De plus, la version intramoléculaire de ces réactions a permis la synthèse d'alkylidènecyclobutanes bicycliques fusionnés complexes. Enfin, la post-fonctionnalisation des alkylidènecyclobutanes a été étudiée, dans le but de découvrir le nouveau composé tricyclique fusionné par un processus photochimique intramoléculaire [2+2]
Cyclobutane 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

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Xie, Jianing. "Advancing Pd-catalyzed Stereoselective Allylic Substitution Reactions". Doctoral thesis, Universitat Rovira i Virgili, 2020. http://hdl.handle.net/10803/670221.

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Aquesta tesi doctoral se centra principalment en el desenvolupament de nous mètodes catalítics (dòmino) basats en la substitució al·lílica catalitzada per Pd per a la síntesi estereoselectiva de petites molècules funcionals i heterocicles utilitzant un disseny detallat de lligants i substrats. Aquesta tesi està organitzada en cinc capítols: el primer capítol és una introducció general sobre els aspectes bàsics de la química al·lílica. El segon capítol il·lustra el primer mètode general per a la preparació d'èters arílics al·lílics terciaris enantioenriquits mitjançant una eterificación regio- i enantio-selectiva catalitzada per Pd dels VCCs en presència de nucleòfils fenòlics. La regioselectivitat de la reacció pot ajustar-se selectivament al producte lineal Z canviant el lligant fosforamidit a un lligant monofosfina, demostrant així el paper crucial del disseny adequat del lligant. El tercer capítol descriu el disseny d'un nou alcohol al·lílic terciari equipat amb un grup carboxil, que s'utilitza en primer lloc per a la síntesi de γ-lactames α,β-insaturades mitjançant una aminació al·lílica estereoselectiva catalitzada per Pd, seguit d’un procés de ciclació intramolecular. Els estudis mecanístics suggereixen que el grup carboxil és crucial per a aquesta transformació i actua com un grup funcional activador i estereodirector. El quart capítol presenta un enfocament estereodivergent controlat pel lligant per a la síntesi de γ-aminoàcids amb configuració Z o E derivats d'alcohols al·lílics terciaris i amines secundàries. Els resultats experimentals destaquen el paper crucial del lligant de suport i l'angle de mossegada de la difosfina. El cinquè capítol informa sobre un mètode general per a la síntesi de caprolactames insaturades substituïdes a través d'un procés d'aminació / ciclació en cascada utilitzant vinil γ-lactones com a substrats mitjançant l'ús d'un lligant fosforamidito recentment desenvolupat. Finalment, s'extreu una conclusió general per a cada capítol i també es discuteix l’aplicació potencial d'aquestes metodologies desenvolupades.
Esta 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.

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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.

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

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

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Takeda, Momotaro. "Copper-Catalyzed Asymmetric Allylic Substitution with Organo- and Silylboronates". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188504.

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Baldwin, I. Craig. "New methodology involving allylic substitution and conjugate addition reactions". Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/27583.

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Chapter one reviews routes to the generation of α-aminophosphonates and α-aminophosphonic acids. These biologically important compounds are synthesised in both racemic and enantiomerically enriched forms. The second chapter describes the results of conjugate addition reactions of lower order cuprates to diethylvinylphosphonate followed by an electrophilic quench to give a range of alkylphosphonates. The third and fourth chapters are concerned with the generation of enantiomencally enriched α-aminophosphonates and α-aminoesters via palladium catalysed allylic substitution reactions With allyl acetate the resulting products were isolated with an enantiomeric excess of up to 19%. With 1,3-diphenyl-2-propenyl acetate products with both high diastereomeric and enantiomeric excesses were isolated with the best being 75 % de and 97 % ee.

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Dawson, Graham John. "Studies on the stereoselective palladium-catalysed allylic substitution reaction". Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/31866.

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This thesis contains the preparation of a new design of ligand for the palladium catalysed allylic substitution reaction. The phosphine oxazoline ligands detailed in the thesis give high levels of enantiocontrol when used in conjunction with symmetrical allyl systems in the palladium catalysed allylic substitution reaction. For unsymmetrical allyl systems the palladium catalysed allylic substitution process proceeds with complete regiocontrol and high levels of stereocontrol are again observed. The products from the palladium catalysed allylic substitution reaction can be readily converted to succinic acids, γ-lactones and aryl propanoic acids.

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Tosatti, 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.

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Kawatsura, Motoi. "Palladium-Catalyzed Allylic Substitution with a Monodentate Phosphine Ligand". 京都大学 (Kyoto University), 1998. http://hdl.handle.net/2433/157157.

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本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである
Kyoto 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

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Ceban, Victor. "New methodologies in asymmetric allylic substitution and organocascade reactions". Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/397983/.

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Abstract (sommario):

Asymmetric organocatalysis and organometallic catalysis are rapidly developing. The first catalytic process can be traced back in the XIX century. Since then, research in the field of catalysis grew, especially in the last decades exponentially. Four projects involving organocatalysis are described in this thesis: “Highly enantioselective addition of anthrones to MBH-carbonates”, “Synergistic catalysis: Highly diastereoselective benzoxazole addition to Morita-Baylis-Hillman carbonates”, “Three-component diastereoselective cascade synthesis of thiohydantoins” and “Highly diastereoselective synthesis of spiropyrazolones”. A) Asymmetric allylic substitution Since Tsuji and Trost reported their first examples of allylic substitution catalysed by palladium salts in 1963, many examples of allylic substitution were published involving other types of transition metals. Later, in 2002, Kim et al. reported the first allylic substitution using a metal-free approach. Morita-Baylis-Hillman carbonates are important scaffolds in the synthesis of more complex molecules due to the presence of numerous functional groups. In this thesis two examples of asymmetric allylic substitution involving Morita-Baylis-Hillman (MBH) carbonates are described. Highly enantioselective addition of anthrones to Morita-Baylis-Hillman carbonates Anthrone derivatives are present in various natural sources and are known for their medicinal effects. We were interested in the enantioselective addition of anthrone to MBH-carbonates. The products were synthesised in very good yields and enantioselectivity by using a (DHQD)2AQN as catalyst. Moreover, a kinetic resolution was perfomed in order to better understand the mechanistic process. Synergistic catalysis: Highly diastereoselective benzoxazole addition to Morita-Baylis-Hillman carbonates Catalysis is one of the most efficient strategies for identifying new chemical reactions. Usually, a catalytic pathway relies on the interaction of a single catalyst with a single reagent in order to lower the energetic barrier. In some cases, the mono-catalytic concept is not enough and other strategies are used, in particular, synergistic catalysis. This consists in the activation of the electrophile and the nucleophile by two different catalysts for reaction to occur. Based on this idea, we studied the addition of benzoxazoles to Morita-Bayllis-Hillman carbonates by the use of two different catalysts (Metal Lewis acid and Organic Lewis base). Both catalysts work in a concerted way giving the final compound in high yield and diastereoselectivity. B) Organocascade reactions Synthesis of complex organic molecules is a challenge for every chemist. The aim is achieveing the final product in as few steps as possible using safer, cleaner and environmentally friendly techniques. One-pot reactions emerged as a powerful tool in creating several bonds in one step. Based on this idea, we studied two reactions: Three-component diastereoselective cascade synthesis of thiohydantoins Thiohydantoins have interesting medicinal applications such as antibacterial, antiviral, antimutagenic, etc. Synthesising these scaffolds in one step via three-component one-pot reaction was our main focus. We developed a three-component cascade reaction for the synthesis of thiohydantoins. The reaction between ?-amino esters, nitrostyrenes and aromatic isothiocyanates is efficiently promoted by organic bases to afford highly substituted thiohydantoins in moderate to good yields and diastereoselectivities. Highly diastereoselective synthesis of spiropyrazolones Spiro compounds are present in various natural products and are powerful active agents. We have developed a methodology for the synthesis of spiropyrazolone bearing fourchiral centres. The reaction was catalysed by a secondary amine in a Michael-aldol cascade fashion affording the product in very good yields and diastereoselectivity.

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Libri sul tema "Allyic substitution"

Kazmaier, Uli, a cura di. Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-22749-3.

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Kazmaier, Uli. Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg, 2012.

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Persson, Eva. Regiocontrol in copper(I)-catalyzed allylic substitution reactions with Grignard reagents: Mechanistic and synthetic aspects. Uppsala: Acta Universitatis Upsaliensis, 1995.

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Dawson, Graham John. Studies on the stereoselective palladium catalysed allylic substitution reaction. 1995.

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Baldwin, Ian Craig. New methodology involving allylic substitution and conjugate addition reactions. 1996.

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Kazmaier, Uli. Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis. Springer, 2013.

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Capitoli di libri sul tema "Allyic substitution"

Hartwig, John F., e Mark J. Pouy. "Iridium-Catalyzed Allylic Substitution". In Iridium Catalysis, 169–208. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-15334-1_7.

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Jegelka, Markus, e Bernd Plietker. "Iron-Catalyzed Allylic Substitutions". In Asymmetric Synthesis II, 333–41. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2013. http://dx.doi.org/10.1002/9783527652235.ch42.

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Langlois, Jean-Baptiste, e Alexandre Alexakis. "Copper-catalyzed Enantioselective Allylic Substitution". In Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis, 235–68. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/3418_2011_12.

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Milhau, Ludovic, e Patrick J. Guiry. "Palladium-Catalyzed Enantioselective Allylic Substitution". In Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis, 95–153. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/3418_2011_9.

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Liu, Wen-Bo, Ji-Bao Xia e Shu-Li You. "Iridium-Catalyzed Asymmetric Allylic Substitutions". In Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis, 155–207. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/3418_2011_10.

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Poli, Giovanni, Guillaume Prestat, Frédéric Liron e Claire Kammerer-Pentier. "Selectivity in Palladium-Catalyzed Allylic Substitution". In Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis, 1–63. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/3418_2011_14.

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Begouin, Jeanne-Marie, Johannes E. M. N. Klein, Daniel Weickmann e Bernd Plietker. "Allylic Substitutions Catalyzed by Miscellaneous Metals". In Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis, 269–320. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/3418_2011_15.

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Trost, Barry M., e Matthew L. Crawley. "Enantioselective Allylic Substitutions in Natural Product Synthesis". In Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis, 321–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/3418_2011_13.

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Hornillos, Valentín, Jean-Baptiste Gualtierotti e Ben L. Feringa. "Asymmetric Allylic Substitutions Using Organometallic Reagents". In Progress in Enantioselective Cu(I)-catalyzed Formation of Stereogenic Centers, 1–39. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/3418_2015_165.

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Moberg, Christina. "Molybdenum-Catalyzed and Tungsten-Catalyzed Enantioselective Allylic Substitutions". In Transition Metal Catalyzed Enantioselective Allylic Substitution in Organic Synthesis, 209–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/3418_2011_11.

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Atti di convegni sul tema "Allyic substitution"

Brunel, Jean, Martin Smith e Sebastien Reymond. "Enantioselective Palladium Catalyzed Allylic Substitution with New Multichiral Centers Monophosphine Ligands". In The 4th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2000. http://dx.doi.org/10.3390/ecsoc-4-01841.

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