Spelling suggestions: "subject:"neck reaction"" "subject:"beck reaction""
31 |
Reações de arilação de Heck com sais de arenodiazônio : estudos metodológicos e aplicações nas sínteses de compostos bioativos / Heck arylations with arenediazonium salts : methodological studies and application on bioactive compounds synthesisPrediger, Patrícia, 1984- 20 August 2018 (has links)
Orientador: Carlos Roque Duarte Correira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-20T23:15:33Z (GMT). No. of bitstreams: 1
Prediger_Patricia_D.pdf: 29103926 bytes, checksum: bd694717759d7b58fda99bfb77a7fa06 (MD5)
Previous issue date: 2012 / Resumo: O presente trabalho foi centrado na arilacao de Heck-Matuda de diferentes olefinas com sais de arenodiazonio e a aplicacao dos produtos arilados na sintese de compostos bioativos. O trabalho esta dividido em dois capitulos: 1) Reacoes de acoplamento de Heck-Matsuda entre aminas alilicas e sais de arenodiazonio e suas aplicacoes nas sinteses de compostos bioativos. 2) Estudos da reacao de Heck-Matsuda em liquidos ionicos e suas aplicacoes na sintese de derivados C-azanucleosideos, potenciais compostos antituberculose. Com relacao a primeira parte do trabalho, foi desenvolvida uma metodologia abrangente para a reacao de Heck-Matsuda entre alilaminas e sais de arenodiazonio. Foram empregados diversos derivados de aminas alilicas e diferentes sais de arenodiazonio contendo grupamentos doadores, retiradores de eletrons e grupos volumosos. Para todos os casos foram obtidos rendimentos de bons a excelentes, em alta regio- e estereosseletividades em favor do produto ¿×- arilado de configuracao trans. Adicionalmente, a aplicacao deste protocolo forneceu os compostos bioativos naftifina, abamina, abamina SG, alverina e cloridrato de cinacalcet, tendo como etapa-chave a reacao de Heck altamente seletiva. A segunda parte do trabalho envolveu as reacoes de Heck-Matsuda entre a ftalimida alilica e sais de diazonio liquidos ionicos. Nestas reacoes, foram obtidos rendimentos e seletividades semelhantes aos observados com o solvente convencional benzonitrila. Alem disso, foram estudadas reacoes com geracao in situ de sal de hexafluorfosfato de arenodiazonio em [bmim] [PF6], seguida pela reacao de Heck-Matsuda em procedimento ¡§one pot¡¨. Por fim, foram realizadas as sinteses de dois derivados de C-azanucleosideos, tendo como etapa-chave a reacao de Heck-Matsuda entre um enecarbamato endociclico e sal de arenodiazonio. Estes compostos terao suas atividades antituberculose avaliadas pelo grupo de pesquisa do professor Mourey em Toulouse, na França / Abstract: The present work was focused in the Heck-Matsuda arylation of several olefins with arenediazonium salts and in the application of the arylated products as intermediates in the syntheses of bioactive compounds. The work is divided in two chapters: 1) Heck-Matsuda reactions between allyl amines and arenediazonium salts and their applications in the synthesis of bioactive compounds, 2) Studies of the Heck-Matsuda reaction in ionic liquids and its application to the synthesis of Cazanucleosides, which are potential antituberculosis compounds. Regarding the first part of this work, a comprehensive methodology for the Heck-Matsuda reaction between allylamines and arenediazonium salts was developed. Several allyl amines derivatives and differents arenediazonium salts were sucessfully employed. Both electron donating and withdrawing groups, as well as bulky substituents, were well tolerated in the diazonium salt. In all cases good to excellent yields and high regio- and stereoselectivities in favor of the ¿×-trans arylated products were obtained. Additionally, some of the adducts prepared by this highly selective Heck reaction were employed as intermediates in the total synthesis of the bioactive compounds naftifine, abamine, abamine SG, alverine and cinacalcet hydrochloride. The second part of this work adressed the Heck-Matsuda reaction between allylic phthalimide and arenediazonium salts in ionic liquids. Under the investigated conditions, the yields and selectivities were similar to those previous achieved with the conventional solvent benzonitrile. In addition, we evaluated the in situ generation of the 4-fluorbenzenediazonium hexafluorophosphate salt in [bmim][PF6], followed by the Heck-Matsuda reaction in a one pot procedure. Finally, we carried out the synthesis of two C-azanucleosides using the Heck-Matsuda reaction with an endocyclic enecarbamate as the key step. As a further development of this work, these compounds will be evaluated regarding their potential antituberculosis activity by Professor Mourey's research group in Toulouse, France / Doutorado / Quimica Organica / Doutora em Ciências
|
32 |
Reações de Heck de acrilatos substituidos com sais de arenodiazonio em solventes organicos e liquidos ionicos. Aplicação na sintese da paroxetina, da nocaina, da indatralina e da sertralina / Heck reaction of substituted acrylates with arenediazonium salts in organic solvents and ionic liquids. Application to the synthesis of paroxetine, nocaine, indaline and sertralinePastre, Júlio Cezar, 1979- 08 July 2009 (has links)
Orientador: Carlos Roque Duarte Correia / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T14:22:36Z (GMT). No. of bitstreams: 1
Pastre_JulioCezar_D.pdf: 10159507 bytes, checksum: 4f4f32c2c414df354e1d53179d9ebe18 (MD5)
Previous issue date: 2009 / Resumo: Neste trabalho, efetuou-se um estudo da reação de Heck de acrilatos substituídos com sais de arenodiazônio. Um protocolo estereosseletivo para a preparação de acrilatos b,b-diarilssubstituidos foi desenvolvido, baseando-se na arilação Heck do cinamato de metila com sais de arenodiazônio, catalisada por Pd(OAc)2, em metanol. A diastereosseletivade da reação de Heck apresentou uma acentuada dependência com a natureza eletrônica do sal de arenodiazônio empregado. A metodologia ainda forneceu uma rota conveniente para 3-arilindanonas e 4-ariltetralonas, permitindo as sínteses formais totais da (±)-indatralina (4 etapas, 54 % de rendimento global) e da (±)-sertralina (7 etapas, 49 % de rendimento global). A extensão da metodologia para acrilatos mais substituídos (inclusive para acrilatos cíclicos) foi feita com sucesso para a maioria dos casos e os adutos de Heck foram obtidos em bons rendimentos e seletividades, independente do padrão de substituição do sal de arenodiazônio empregado. Esta metodologia foi aplicada à síntese total da (±)-paroxetina (8 etapas, 15 % de rendimento global) e da (±)-nocaína (6 etapas, 20 % de rendimento global). Verificou-se ainda que a reação de arilação de Heck empregando sais de arenodiazônio ocorre de maneira eficiente em meios reacionais alternativos, como PEG e líquidos iônicos. Uma série de líquidos iônicos quirais inéditos do tipo piridínio, imidazolínio e imidazólio foi preparada e testada, não revelando nenhuma incidência no curso estereoquímico da reação. Os resultados obtidos demonstram o enorme potencial sintético do emprego de sais de arenodiazônio em reações de Heck, constituindo uma metodologia bastante versatil em Síntese Orgânica. / Abstract: In this work, we present a study of the Heck reaction of substituted acrilates with arenediazonium salts. A stereoselective protocol for the preparation of b,b-disubstituted acrylates in good yields by means of a Heck-Matsuda reaction was accomplished. The method employs a base- and ligand-free Heck reaction of methyl cinnamate using arenediazonium salts as electrophiles. The Heck reaction displays a remarkable electronic dependence regarding the diastereoselectivity of the arylation process, which correlates with the electronic nature of the arenediazonium salts employed. The overall methodology provides a convenient route to 3-arylindanones and 4-aryltetralones allowing the concise formal total syntheses of the therapeutically important psychoactive compounds (±)-indatraline (4 steps, 54 % global yield) and (±)-sertraline (7 steps, 49 % global yield). The methodology was also successfully extended to more substituted acrylates and the Heck adducts were obtained in good to excellent yields, regardless of the substitution pattern of the arenediazonium salt employed. This methodology was applied to the total synthesis of (±)-paroxetine (8 steps, 15 % global yield) and (±)nocaine (6 steps, 20 % global yield). We also verified that the Heck reaction using arenediazonium salts occurs in an efficient way in alternative reaction media, like PEG and ionic liquids. A series of new chiral ionic liquids was prepared and evaluated in the Heck reaction. In spite the overall performance of the Heck reaction, in all the cases studied no asymmetric induction was detected. Our results demonstrate the enormous synthetic potential of the Heck reaction using arenediazonium salts, constituting a versatile methodology in Organic Synthesis. / Doutorado / Quimica Organica / Doutor em Ciências
|
33 |
Synthesis of Resveratrol and Its Analogs, Phase-Transfer Catalyzed Asymmetric Glycolate Aldol Reaction, and Total Synthesis of 8,9-Methylamido-GeldanamycinLiu, Jing 16 July 2007 (has links) (PDF)
The phytoalexin resveratrol and its acetyl analogs have been made using a decarbonylative Heck reaction. The acid chloride derived from 3,5-dihydroxybenzoic acid was coupled with suitable protected 4-hydroxystyrene in the presence of palladium acetate and N,N-bis-(2,6-diisopropylphenyl)-4,5-dihydro imidazolium chloride to give the substituted stilbene in good yield as the key step. Human HL-60 cell assays showed the 4'-acetyl resveratrol variant improved activity (ED50 17 μM) relative to resveratrol (24 μM). Cinchona phase-transfer catalysts (PTC) were developed for glycolate aldol reactions to give differentially protected 1,2-diol products. Silyl enol ether of diphenylmethoxy-2,5-dimethoxyacetophenone reacted to generate benzhydryl-protected products. O-Allyl trifluorobenzyl cinchonium hydrodifluoride (20 mol %) catalyzed the addition of the silyl enol ether to benzaldehyde to give aldol product as a single syn-product in 76% yield and 80% ee. Recrystallization enriched the product to 95% ee, and a Baeyer-Villiger reaction transformed the product into useful ester intermediates. A novel unnatural product, 8,9-Methylamido-Geldanamycin, has been designed and synthesized. Using a convergent route, the total synthesis of the molecule involved only 27 longest linear steps. New synthesis methodologies, including auxiliary controlled asymmetric anti-glycolate aldol, syn-norephedrine aldol, and selective p-quinone formation, were used.
|
34 |
Ligand-Assisted Catalysis Using Metal SNS ComplexesKhanzadeh, Atousa 08 January 2024 (has links)
In molecular transition metal catalyst architectures, ligand design plays a crucial role in enhancing the efficiency of catalytic reactions. Selected ligands can play a bifunctional role in ligand-assisted catalysis, providing first coordination sphere basic sites and facilitating formation of multinuclear species through monomer bridging, as well as through their electronic and steric effects. This research addresses the underutilization of SNS complexes in various catalytic cycles. Our aim is to expand their activity in different cycles, unlocking untapped reactivity. Specifically, we focus on SNS ligands with soft thiolate and hard amido donors, comparing their catalytic performance in diverse coupling reactions. This comparative study provides insights into the suitability of these ligands with different transition metals, contributing to the understanding of ligand-assisted catalysis. Chapter 1 introduces these concepts and outlines the relevant catalytic reactions studied herein.
To gain a deeper understanding of the chemistry involved, a comparative analysis of the reactivity differences between transition metal complexes with similar coordination structures is conducted. This investigation is crucial as it provides valuable insights into the design of suitable ligands for transition metal catalysts. Specifically, Chapters 2 and 3 of this thesis delve into a comparison of the reactivity of coordination complexes with identical metal centers and similar ligands, or even the same molecular formula, in catalysis.
In the second chapter, we introduce a new cobalt (II) complex bearing an (SNS) amido ligand for the bifunctional hydroboration of carbonyls. Following an unsuccessful attempt to mono-protonate the amido donor in the bis(amido) complex Co(SᴹᵉNSᴹᵉ)₂ (2.1) treatment with 1 equivalent of 1,3-bis(1-adamantyl)imidazolium chloride (IAd•HCl) resulted in the liberation of one protonated ligand, affording CoᴵᴵCl(SᴹᵉNSᴹᵉ)(a-IAd) (2.2) with an "abnormally" coordinated IAd ligand, i.e., specifically bound through C4 instead of C2 of the imidazole ring. Compound 2.2 exhibited excellent catalytic activity in the hydroboration of aldehydes, displaying high substrate tolerance under mild reaction conditions and short reaction times. Stoichiometric reactions of 2.2 with pinacolborane (HBpin) revealed a bifunctional catalyst activation step, generating free SNS-amine, ClBpin and the active cobalt dihydride catalyst. Generation of an analogous catalyst with a normally coordinated IAd ligand showed poor reactivity in the hydroboration of aldehydes and was unable to effect ketone hydroboration.
In Chapter 3, two tetranuclear copper(I) complexes bearing thiolate [Cu(SNSᴹᵉ)]₄ (3.1) and amido [Cu(SNSᴹᵉ)]₄ (3.2) SNS ligands are synthesized and their catalytic activity in a base-free azide-alkyne cycloaddition is compared. Complex 3.1 (1 mol%) demonstrated excellent reactivity for performing this 'click' reaction in water, exhibiting a broad substrate scope and enabling the production of various triazole compounds, including bioactive compound 3.16, which holds potential as an anti-cancer drug. DFT calculations suggested a proton shuttle role for the thiolate donor in conversion of the Cu-coordinated terminal alkyne to the key Cu-alkynyl intermediate. On the other hand, complex 3.2 exhibited reactivity similar to copper chloride. This observation was attributed to the basic nature of the amido ligand, which undergoes protonation by the coordinated alkyne C-H bond, with subsequent dissociation of the SNS-amine from the copper. Without a ligand to stabilize the copper in the less stable +1 oxidation state, a disproportionation reaction occurs, leading to catalyst deactivation.
Chapter 4 introduces two palladium(II) thiolate complexes: PdI(κ³-SNSᴹᵉ) (4.1) exhibits catalytic activity in promoting the Heck cross-coupling reaction, while Pd(κ²-SNSᴹᵉ)₂ (4.2) affords no coupling product. In concert with triethylamine base, catalyst 4.1 efficiently produces olefin products with excellent yields, even at low catalyst loadings, and exhibits broad substrate tolerance over a 5 h reaction period. In contrast, the limited catalytic activity of 4.2 can be rationalized by proposing the formation of a Pd(N₂S₂) complex through ligand imine coupling at elevated temperatures, a reaction reported previously for Ni and Co analogs. The tetra-coordinated ligand formed through this isomerization occupies critical coordination sites around the metal, thereby preventing oxidative addition of the organohalide substrate, a key step in the Heck reaction mechanism. This work sheds light on the divergent catalytic behaviors of these two intriguing complexes.
Finally, in Chapter 5 we assess what has been learned and identify relevant implications for further work.
|
35 |
Etude théorique de réactions de Heck intramoléculaires / Theoretical study of intramolecular Heck reactionsGrüber, Raymond 20 June 2014 (has links)
L'ouverture de cycle aromatique catalysée par le palladium a été récemment observée par une équipe de l'ENSTA. Ce type de réactivité du palladium n’a jamais été observé auparavant et entre en compétition avec l’activation C-H classique. Ce travail de thèse a consisté à étudier ces réactions d'un point de vue théorique pour mieux en comprendre les mécanismes.Nous avons tout d'abord cherché la fonctionnelle permettant la meilleure description de la compétition entre la complexation azote/alcène en comparant plus de soixante fonctionnelles à des calculs CCSD(T)/CBS. Nous avons retenu la fonctionnelle GGA BP86.Nous avons ensuite étudié la réaction de Heck intramoléculaire à partir de la N-allyl-2-iodo-aniline. Nous avons justifié que l'indole soit le produit majoritairement obtenu, et montré que l'azote ne joue pas de rôle sur la régiosélectivité. Cependant, dans certains cas, l'azote inhibe la réaction en piégeant le complexe de palladium. Une étude théorique a montré que le facteur prépondérant de cette inhibition est la population électronique de l'azote et non l'hybridation du carbone benzylique.L'ouverture du furane a été ensuite considérée. Parmi tous les mécanismes proposés, notre étude théorique a montré que la voie principale est celle de la β-alkoxyelimination, potentiellement assistée par la trialkylamine présente dans le milieu.Enfin, nous avons étudié l'ouverture du benzylfurfurylaniline. Le mécanisme est similaire à celui observé pour l'ouverture du furane jusqu'à la régénération du complexe de palladium catalytique. En effet, dans le ce cas, la base azotée joue le rôle d'un donneur de proton. / Aromatic cyclic compound opening catalyzed by palladium has been recently observed by ENSTA team. That kind of reactivité for palladium has not been shown before and is in competition with the C-H activation. This work studies theses reactions from a theoretical point of view to better understand the mechanisms. We first look for the functional who gives the best description of the competition between the nitrogen/alkene complexation comparing more than sixty functionals with CCSD(T)/CBS calculation. We choose at last the GGA functional BP86.We then study the intramolecular Heck reaction starting from the N-allyl-2-iodo-aniline. We justified that the indole moiety was the major product and showed that the nitrogen plays no rôle in the regioselectivity.However, in some cases, the nitrogen inhibits the reaction by trapping the palladium complex. A theoretical study showed that the main factor for this inhibition was the population of nitrogen lone pair and not the hybridation of the benzylic carbon.Furan opening was then considered. Between all the mechanisms proposed, our theoretical study showed that the main way is the β-alkoxyelimination, potentially assisted by the trialkylamine present in the environment.Finally, we have studied the benzylfurfurylaniline opening. The mechanism is similar to the one observed for the furan opening until the regeneration of the palladium complex. Indeed, in that case, the base plays the rôle of a proton donor.
|
36 |
Palladium-Catalysed Carbon–Carbon Coupling Reactions : Focusing on Microwave Heating, Low Catalyst Concentrations, Aqueous Conditions, Regioselectivity and Medicinal Chemistry ApplicationsArvela, Riina K January 2009 (has links)
It is widely accepted that palladium is one of the most useful catalysts in organic chemistry, and many palladium(0)-catalysed carbon–carbon bond-forming reactions have been developed over the years. In addition, the ever-growing need for more environmentally benign processes in the chemical industry has driven scientists to look for greener options while developing new methodologies for organic synthesis. This thesis describes a series of studies on Suzuki and Heck coupling reactions in water and the application of palladium(0) catalysis to the development of new HIV-1 integrase inhibitors. The previously described 'transition-metal-free Suzuki-type coupling' reaction was shown to take place due to sub-ppm levels of palladium contaminants present in the commercially available sodium carbonate base. Based on this finding, a new, microwave-assisted Suzuki protocol utilizing ppb/ppm levels of palladium in water was developed. This methodology was adapted to terminal Heck coupling, although the scope of the protocol was found to be rather limited. Finally, both Suzuki and Heck reaction processes were successfully scaled up to 100 mmol using an automated batch stop-flow microwave apparatus. As the methodologies utilizing ultralow palladium concentrations were not applicable to aryl chlorides, attention was shifted towards palladium on carbon. This simple catalyst, together with microwave heating employing simultaneous cooling, was found to be beneficial in the Suzuki coupling of aryl chlorides with phenylboronic acid in water. Ligand-controlled internal arylation of ethylene glycol vinyl ether with aryl halides was shown to be possible in water alone without any additives. Reactions were run under air, using conventional heating and the products formed were isolated as aryl methyl ketones in good to excellent yields. The electron-rich (dippp)2Pd complex was shown to be beneficial for the microwave-assisted internal arylation of some aryl chlorides. Furthermore, the active role of the hydroxyl group of ethylene glycol vinyl ether in the formation of a cationic intermediate leading to internal Heck coupling product was elucidated. Finally, to demonstrate the usefulness of palladium(0) catalysis in the development of new pharmaceutical entities, a series of HIV-1 integrase inhibitors was synthesised and evaluated in strand transfer assays and in vitro. Based on the results and docking studies performed, valuable information related to the structure–activity relationship was obtained.
|
37 |
Synthesis and Evaluation of N,P-Chelating Ligands in Asymmetric Transition-Metal-Catalyzed Reactions : Ir-Catalyzed Asymmetric Hydrogenation and Pd-Catalyzed Asymmetric Intermolecular Heck ReactionTolstoy, Päivi January 2009 (has links)
This thesis describes synthesis of new chiral N,P ligands and their evaluation in two types of asymmetric transition-metal catalyzed reactions. The first part of the thesis describes studies in iridium-catalyzed asymmetric hydrogenation. A new class of chiral N,P ligands, imidazole-phosphines, was synthesized and evaluated in the Ir-catalyzed asymmetric hydrogenation of olefins (Paper I). The new ligands proved to be highly efficient and enantioselective in the reaction. Because the substrate scope of Ir-catalyzed asymmetric hydrogenation is still limited to certain types of test substrates, new substrate classes with importance in medicinal and materials chemistry were investigated. Vinyl fluorides were efficiently hydrogenated to fluorine-containing chiral centers by the iridium catalysts with imidazole-phosphine ligands (Paper I). To obtain CF3-bearing chiral centers, we hydrogenated CF3-substituted olefins (Paper II). Ir-catalyzed asymmetric hydrogenation was highly enantioselective for the functionalized CF3-substituted olefins and the resulting chiral products can be valuable in design of materials such as LCD screens. Ir-catalyzed asymmetric hydrogenation was also evaluated as a route to diarylmethine chiral centers (Paper III). A wide range of new chiral compounds possessing a diarylmethine chiral center was obtained. The second part of the thesis deals with asymmetric intermolecular Heck reaction utilizing N,P ligands. The N,P ligand class of thiazole-phosphines was evaluated in the Heck reaction (Paper IV) and gave high enantioselectivity. Further, the intermolecular Heck reaction was examined using computational and experimental studies (Paper V). This study led to a better understanding of the enantioselectivity in the reaction.
|
38 |
Palladium-Catalyzed Oligocyclizations of Some 2-Bromotetradec-1-ene-7,13-diynes Under Heck Reaction Conditions / Palladium-katlysierte Oligocyclisierungen einiger 2-Bromotetradec-1-ene-7,13-diine unter Heck-ReaktionsbedingungenTokan, Wajdi Mohammad Izzat 30 January 2003 (has links)
No description available.
|
39 |
A new approach to the benzoporphyrins towards dye sensitized solar cells /Deshpande, Rohitkumar Ashok. January 2010 (has links)
Title from first page of PDF document. Includes bibliographical references (p. 154-156).
|
40 |
Synthèse et pharmacomodulations de composés naturels issus de plantes / Synthèse et pharmacomodulations de composés naturels issus de plantesDumonteil, Geoffrey 15 December 2015 (has links)
Les motifs polyènes constituent une fonction importante parmi les composés organiques et sont présents dans de nombreux composés naturels sous la forme de diènes 1,3-conjugués. Il est donc essentiel de mettre au point des méthodes permettant d’accéder à ces diènes tout en portant un regard attentif à l’impact environnemental. Au cours de ces travaux, nous avons pu synthétiser un composé naturel ayant une incidence sur le diabète de type II : l’acide abscissique. L’étape clef conduisant au succès de cette synthèse est la réaction de Heck. A partir de ces résultats, nous avons mis au point une méthode robuste et efficace pour obtenir divers composés diéniques (E,Z) et triéniques (E,E,Z) en s’affranchissant d’utiliser des ligands ou un solvant. Les composés ainsi obtenus sont envisagés comme potentiels analogues de l’acide abscissique et sont engagés dans diverses réactions afin d’essayer d’obtenir l’acide carboxylique correspondant ou un bioisostère de ce dernier. En parallèle, nous avons mis au point une voie d’accès à des composés de type benzo[d]thiazole substitués en position 2 par un groupement N-aryle ou N-alkyle. Cette méthodologie de synthèse s’inscrit dans un contexte d’écocompatibilité par l’utilisation d’une catalyse au diiode. / Polyene units constitute an important function from organic compounds and are present in many natural products in the form of 1,3-conjugated dienes. It is therefore essential to develop methods to access these dienes while wearing a careful look at the environmental impact. During this work, we were able to synthesize a natural compound which has activity on type II diabetes: the abscisic acid. The key step leading to the success of this synthesis is the Heck reaction. From these results, we have developed a robust and efficient method to obtain various diene compounds (E, Z) and trienes (E, E, Z) without ligand or solvent. The compounds thus obtained are considered as potential analogues of the abscisic acid and are involved in various reactions in order to obtain the corresponding carboxylic acid or its bioisostere. In parallel with this synthesis application, we have developed a pathway to obtain benzo[d]thiazole compounds substituted in position 2 with an N-aryl or N-alkyl. This synthetic methodology is part of a context of environmental compatibility by using iodine catalyst.
|
Page generated in 0.0839 seconds