This thesis describes research efforts dedicated to the development of palladium(II)-catalyzed oxidative Heck and Heck/Suzuki domino reactions, and the applications of a new microwave heating technology, purpose-built for continuous flow in organic synthesis. Paper I describes the development of a ligand-modulated approach for attaching aryl groups to a chelating vinyl ether. By switching the ligand being used, selectivity for the arylation could be shifted to obtain three different outcomes: internal α- or terminal β-arylation, as well as a serendipitously discovered domino α,β-diarylation process. The latter was proposed to be an effect of para-benzoquinone, effectively acting as a stabilizing π-acidic ligand with the ability to suppress β-hydride elimination. Paper II explores the performance of a new microwave heating technology in combination with continuous flow. The novel nonresonant microwave applicator allowed rapid heating of common laboratory solvents and reaction mixtures above their boiling points with stable and reproducible temperature profiles. The technology was successfully applied to small-scale method development and subsequent scale-out of palladium-catalyzed reactions, heterocycle synthesis and classical organic transformations such as the Fischer indole synthesis. Paper III focuses on developing regioselective oxidative decarboxylative Heck reactions with electron-rich olefins. Successful internal α-arylations were achieved using various olefins and ortho-substituted aromatic acids. The mechanism was also studied by ESI-MS analysis. Key cationic organopalladium intermediates were identified, as well as an unexpected palladium(II)-complex which was isolated and characterized. Its experimentally deduced structure was in accordance with the lowest energy minimum found by DFT calculations. Preliminary findings suggested that the complex acts as a catalyst trap. Paper IV studies the mechanism of the reaction in Paper III by means of DFT calculations. Reductive elimination was identified as the rate-determining step when using a linear enamide as the olefin, due to its propensity to form low energy chelates. Its chelating properties also played a key role in the stability of the isolated palladium(II)-complex. The complex, which can act as a catalyst trap, was characterized by X-ray crystallography.

Orientador: Carlos Roque Duarte Correia / Acompanha Anexo denominado V.2. Paginação continua / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-12T12:04:47Z (GMT). No. of bitstreams: 1 Garcia_ArielLazaroLlanes_D.pdf: 15520800 bytes, checksum: 2744757a92f3045d187a1c68320729d5 (MD5) Previous issue date: 2008 / Resumo: A reação de arilação de Heck-Matsuda é um procedimento sintético valioso e extremamente versátil para a formação de ligações carbono-carbono, baseada no acoplamento de uma olefina com um sal de arenodiazônio na presença de uma espécie organometálica de paládio zerovalente. Recentemente, a utilização desta reação tem ganhado espaço na arte de sínteses totais, demonstrando a viabilidade da mesma. Neste trabalho, apresentamos o desenvolvimento de metodologias novas e flexíveis para a síntese eficiente de vários produtos naturais e sintéticos com propriedades farmacológicas importantes, utilizando a reação de arilação de Heck-Matsuda como etapa chave. No total, foram sintetizados 21 compostos finais, incluindo: prolinas e pirrolidinas poliidroxiladas racêmicas e quirais, Radicamina B e outros a-C-ariliminociclitóis quirais análogos das Radicaminas A e B, Rolipram, ácidos b-aril-g-aminobutíricos análogos do Baclofeno, e um precursor chave de Prepolicitrina A e Policitrina A. Os compostos sintetizados, assim como seus respectivos intermediários de reação, foram plenamente caracterizados e os resultados obtidos foram comparados com aqueles reportados na literatura quando aplicável. Dados analíticos e espectroscópicos satisfatórios foram obtidos em todos os casos. / Abstract: The Heck-Matsuda arylation reaction is a valuable and extremely versatile synthetic procedure for carbon-carbon bond formation, based on the coupling of an olefin with an arenediazonium salt in the presence of a zerovalent palladium organometallic specie. Recently, the use of this reaction has been gaining space in total syntheses, demonstrating its viability. In this work, we presented the development of new and flexible methodologies for the efficient synthesis of several natural and synthetic products with important pharmacologic properties, using the Heck-Matsuda arylation reaction as a key stage. Totally, a set of 21 final compounds were synthesized, including: racemic and chiral polyhydroxylated prolines and pyrrolidines, Radicamine B and other chiral C-aryl-iminocyclitols analogues of Radicamines A and B, Rolipram and b-aryl-g-aminobutyric acids analogues of Baclofen, and a key precursor of Prepolycitrin A and Polycitrin A. The synthesized compounds, as well as their respective reaction intermediates, were entirely characterized and the obtained results were compared with those reported in the literature when applicable. Satisfactory analytical and spectral data were obtained in all cases. / Doutorado / Quimica Organica / Doutor em Ciências

Nous avons réalisé la synthèse de thiazoles, sélénazoles, thiéno[2,3-d]thiazoles et thiéno[2,3-d][1,3]sélénazoles, ce dernier étant préparé facilement à partir de cyanamide et de sulfure de carbone. Nous avons de cette manière pu synthétiser des 4-amino-1,3-thiazoles et 1,3-sélénazoles substitués en position 2 et 5 en deux étapes. Appliqué ces hétérocycles, les 4-halogéno-1,3-thiazoles et 1,3-sélénazoles ont été synthétisés par la méthode de Doyle. La labilité des halogènes dans les dérivés précédents a permis de préparer de nouveaux thiéno[2,3-d]thiazoles et [1,3]sélénazoles. La détermination du potentiel antiprolifératif de ces composés a permis de mettre en évidence deux composés, présentant des IC50 de l’ordre du micromolaire sur les lignées cellulaires cancéreuses : MCF-7, PC-3, Hs683, U373, SKMEL-28 et A549. Un composé surtout a montré une activité d’inhibition de Na+/K+-ATPase et de l'oncogène Ras. Par ailleurs dans un second sujet, nous nous sommes intéressés à la mise au point d’une synthèse des deux isomères (alpha et bêta) de 4-butoxylvinyl-coumarines, -thiocoumarine et -2-quinolones par couplage de Heck. Nous avons ainsi pu montrer que suivant le substituant présent en position 4 des hétérocycles le couplage était régiosélectif. Ces dérivés butoxyvinyliques se caractérisaient par leur caractère diénique et nous avons étudié leur réactivité, stéréoséléctivité et régiosélectivité avec différents diénophiles dans des réactions de cycloaddition de Diels-Alder. Parmi tous les composés polyhétérocycliques ainsi préparés, nous avons identifié des composés tétracycliques à noyau quinonique qui présentent un potentiel anticancéreux par des valeurs d’IC50 sur l’inhibition des phosphatases CDC25 et sur plusieurs lignées de cellules tumorales / We performed the synthesis of thiazoles, selenazoles, thieno[2,3-d]thiazoles and thieno[2,3-d][1,3] selenazoles which are easily prepared from cyanamide and carbon disulfide. By this way, we have synthesized 4-amino-1,3-thiazoles et 1,3-selenazoles substituted in position 2 and 5 in two steps. Used these heterocycles, 4-halogeno-1,3-thiazoles et 1,3-selenazoles were synthesized by Doyle’s method. Lability of halogens in previous derivatives allowed to prepare new thieno[2,3-d]thiazoles and [1,3]selenazoles. Determination of the antiproliferative activity of these compounds has brought out two compounds, showing IC50 values in micromolar range on investigated cancer cell lines: MCF-7, PC-3, Hs683, U373, SKMEL-28, and A549. One particular compound showed a high activity of anti-Na+/K+-ATPase and anti-ROS. In addition in the second subject, we were interested in the development of the synthesis of two isomers (alpha and beta) of 4-butoxylvinyl-coumarins, -thiocoumarin and -2-quinolones by Heck coupling. We showed that, depending on the substituent in the position 4 of the heterocycle, the coupling was regioselective. These butoxyvinylic derivatives, characterized by dienic character, were studied for their reactivity, stereoselectivity and regioselectivity with several dienophiles in Diels-Alder cycloaddition. Among all the polyheterocyclic compounds prepared, we have identified the tetracyclic compounds with quinonic ring which have potential anticancer activity by inhibition of CDC25 phosphatase and on several tumor cell lines

CAPÍTULO I. Sales de Hierro e Imidazolio Sustituidas con Grupo Acilo para el Acoplamiento Oxidativo-Tionación de Aminas. En el capítulo I, se ha llevado a cabo el acoplamiento oxidativo de aminas mediado por un catalizador de hierro, para la preparación de tioamidas, de forma eficiente y selectiva en una reacción multicomponente. En la misma, se han utilizado dos aminas diferentes, fosfato de sodio y azufre elemental, bajo calentamiento por microondas. Durante el estudio se ha observado la importancia del catalizador, formado por tetracloroferratos de imidazolio, en el acoplamiento oxidativo y posterior formación del enlace C-S. Esta metodología ha permitido la utilización tanto de bencilaminas primarias y alquilaminas, con diversas propiedades electrónicas, como de derivados de piperidina, demostrando la importancia de esta ruta sintética en la preparación de importantes intermedios sintéticos de productos naturales. CAPÍTULO II. Sistemas Catalíticos Formados por Paladio y Sales de Imidazolio Sustituidas con Grupos Acilo. En el capítulo II, se han sintetizado diferentes sales de imidazolio mono- y di-funcionalizadas con un grupo amido como precursores de sistemas catalíticos en combinación con acetato de paladio(II), usándolos en la reacción de acoplamiento de Heck-Matsuda. A partir del estudio comparativo, se puede concluir que la presencia de un único grupo amido en el precursor del sistema catalítico, formado con una relación 1:1 metal/ligando, es más beneficioso durante el proceso, tal y como se observa en los análisis por espectroscopía UV/Vis. CAPÍTULO III. Cloruro de 1,3-Bis(carboximetil)imidazolio como Catalizador sin Metales para la Síntesis de Quinolinas y Acridinas. En el capítulo III, se ha utilizado el cloruro de 1,3-bis(carboximetil)imidazolio, como catalizador heterogéneo para la preparación, libre de metales y sin uso de disolventes, de quinolinas y acridinas. Esta metodología, sencilla y eficaz para la síntesis de heterociclos con nitrógeno, ha permitido el empleo de diversas cetonas y 2-aminoarilcetonas como precursores, siendo posible la reacción en escala de multigramo. Asimismo, se ha demostrado la aplicabilidad del proceso llevando a cabo la transformación de algunos compuestos a las correspondientes quinolilchalconas mediante una reacción tándem. Además, se ha llevado a cabo el estudio de reciclabilidad del catalizador (hasta 8 ciclos) en la reacción modelo sin observar pérdida de su actividad, remarcando su robustez. Por último, se ha comprobado la sostenibilidad del proceso calculando el factor-E para la formación de quinolinas y la reacción tándem. CAPÍTULO IV. Formación de Enlaces C-C y C-S Catalizada por Cloruro de 1,3-Bis(carboximetil)imidazolio: Síntesis de Tiofenos. En el capítulo IV, se ha empleado el cloruro de 1,3-bis(carboximetil)imidazolio como catalizador para la síntesis de 2,4-diariltiofenos, a través de una autocondensación sulfurativa de la acetofenona. En este proceso, se han estudiado diferentes acetofenonas y cicloalcanonas como precursores, demostrando la simplicidad y eficiencia del proceso para la formación de tiofenos. Además, se ha podido llevar esta reacción a escala de multigramo, siendo, desde el punto de vista de la sostenibilidad, una ruta sintética atractiva.

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.

Les fluoroalcènes sont d'un grand intérêt en chimie médicinale en raison de leur utilisation possible en tant qu'isostères de la liaison peptidique. L'utilisation de la réaction de Heck en vue de complexifier la structure d'alcènes fluorés peu substitués n'a jamais été étudiée de façon approfondie. Seule une étude théorique révèle que suivant les conditions réactionnelles, une élimination β-F peut être favorisée par rapport à une élimination β-H. Ainsi, il serait possible de contrôler le produit de la réaction. Nous nous sommes donc intéressés à synthétiser divers fluoroalcènes, aussi bien mono- que difluorés, dans le but de les soumettre à différentes conditions de Heck.

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.

Organometallic chemistry is highly dependent upon the ligands which are employed on a metal's surface. These ligands control steric bulk and electronics of the metal center which can change the reactivity of the organometallic complex. Ligands that are standard in organometallic chemistry include phosphine ligands. These phosphine ligands have been utilized in the field since the 1960's and have shaped the development of many key organometallic catalysts. Phosphine ligands are easily functionalized and highly reactive. This increased reactivity, however, causes severe limitations as phosphine ligands are often unstable under standard benchtop conditions and must be handled both air and moisture free environments. To combat some of these issues new ligand types have emerged such as N-heterocyclic carbene ligands. These ligands are found to possess similar reactivity in terms of electron and steric influences but can be prepared and used on the benchtop. In this work we highlight a dual N-heterocyclic carbene/phosphine ligand which is obtained from an accessible 2-phosphinoimidazole. These 2-phsophinoimidazole ligands can undergo a transformation in the presence of a proton source. The proton source will cause the disassociation of the C-P bond forming a NHC-phosphine complex. Addition of a metal source to the NHC-phosphonium complex causes a NHC/phosphine metal complex, which upon further investigation was found to be catalytically active. This activity was tested in various cross coupling reactions which include Suzuki, Heck, and Sonogashira. Highlights of these results include the extreme functionalization of these 2-phosphinioimidazole ligands which can produce new aryl groups on the NHC, a free N-H bond on the imidazole which can be deprotonated or influence intermolecular forces with substrates, replacing the moieties on the phosphine, and finally the ability to transform in situ with the addition of a common alcohol. Each of these functionalization's are explained below along with their reactivity to isolate a wide variety of substrates. In addition to the work above a collaboration with Rio Tinto and the Madsen Lab at BYU is discussed. This work involves the concerns of land managers and their ability to restore landscapes that have been destroyed through a variety of issues including fire, mining, and invasive species. These ecological pressures cause land managers to search for native plants to seed on a landscape. Issues arise when using natives, however, because of their inability to quickly germinate and establish on a landscape. This is caused by dormancy issues where an antagonistic relationship between gibberellic acid and abscisic acid where the overproduction of one over the other results in dormant native plants. We have invented a methodology to use slow releasing polymers to hijack this system and deliver gibberellic acid to a seed causing it to germinate regardless of external stimuli. Our results show significant improvement in native Penstemon species with no side effects to the plant growth and establishment.

Yes / The first example of an intramolecular hydroarylation of 1,6-en-α-chloro-enamides was achieved by a palladium-catalysed ligand-free reductive Heck cycloisomerisation with no competing Heck-cyclised by-product.

Le 21e siècle est le berceau d’une conscientisation grandissante sur les impacts environnementaux des processus utilisés pour synthétiser des molécules cibles. Parmi les avancées qui ont marqué ces dernières décennies, il est également question de réduction de déchets, de conservation de l’énergie et de durabilité des innovations. Ces aspects constituent les lignes directrices de la chimie verte. De ce fait, il est impératif de développer des stratégies de synthèse dont les impacts environnementaux sont bénins. Dans ce mémoire nous présentons la synthèse, la caractérisation et l’étude des propriétés catalytiques en milieu aqueux d’un ligand composé d’une unité -cyclodextrine native, d’une unité imidazolium et d’une chaine alkyle à 12 carbones. Ce ligand hybride s’auto-assemble dans l’eau sous forme de micelles, permettant ainsi d’effectuer en sa présence des couplages de Suzuki-Miyaura dans l’eau, avec de bons rendements. La fonctionnalisation de la face primaire de la -cyclodextrine par un noyau alkyl-imidazolium, précurseur de ligand de type carbène N-hétérocyclique, a permis le développement d’un système catalytique vert et hautement recyclable. Dans un deuxième temps, nous présentons l’utilisation du même ligand hybride dans des couplages de Heck dans l’eau, démontrant ainsi la versatilité du ligand. / Chemistry keeps evolving in new directions. Research has provided improved methodologies for the design and synthesis of targeted molecules. At the same time, the 21st century is witnessing increasing concern about the environmental impacts of chemical wastes. A new philosophy of chemical research and engineering has emerged, known as «Green chemistry». This concept encourages the design of products, processes and technologies that minimize the use and generation of hazardous substances. Therefore, there is an urge to develop environmentally friendly process to convert molecules into product of interest. In the present thesis, we describe the synthesis, characterization and catalytic properties of a novel alkylimidazolium-modified β-cyclodextrin (-CD). Our strategy was to construct a single amphiphilic bimodal ligand by the combination of a mass transfer unit (-CD), covalently bound to a ligand moiety (alkylimidazolium, an N-heterocyclic carbene (NHC) precursor) for aqueous catalysis. First, we demonstrated that the introduction of a dodecyl chain on the imidazolium moiety attached to the primary face of a native β-CD allows the formation of a highly active micellar self-assembled catalytic system in neat water with remarkable recyclable properties for the Suzuki–Miyaura coupling. In addition, we studied the versatility of this self-assembled bimodal system by performing Heck coupling in neat water.