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Palladium-Mediated C-H ActivationsHenderson, William Howell 15 December 2011 (has links)
No description available.
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Estudos para transformações quimicas em sistemas sesquiterpenicos do tipo bisabolano / Studies for chemical transformations in bisabolene sesquiterpene systemsHardy, Lucas Drezza, 1981- 12 August 2018 (has links)
Orientador: Lucia Helena Brito Baptistella / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-12T12:46:19Z (GMT). No. of bitstreams: 1
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Previous issue date: 2007 / Resumo:O a-(-)-bisabolol (1) é um sesquiterpeno bisabolano isolado de óleos essenciais de uma grande variedade de plantas, e muito conhecido principalmente por suas atividades farmacológicas. Rotas sintéticas visando a obtenção da (+)-hernandulcina e do acetato do (1S)-1-hidroxi-óxido de bisabolol A, outros sesquiterpenos naturais do tipo bisabolano com atividade adocante e antimalária, respectivamente, tiveram como etapas iniciais tentativas de oxidações alílicas sobre a olefina endocíclica do (-)-1, as quais forneceram diversos produtos. Como meio de diminuir a formação dos produtos laterais frente a estas oxidações, bem como favorecer a formação de derivados cíclicos do (-)-1, úteis quando se visa a síntese do acetato do acetato do (1S)-1-hidroxi-óxido de bisabolol A, a cadeia lateral hidroxílica g,d-insaturada do (-)-1 foi ciclizada utilizando como eletrófilos o iodo e bromo. Em oposição ao que desejávamos, em todas as ciclizações testadas foi verificada a formação majoritária dos derivados tetraidrofuranicos (THF), atribuida, em função dos dados obtidos ao longo do trabalho, a fatores estruturais do substrato e do meio de reação. Testes de oxidações sobre os derivados tetraidrofuranicos (THF) e tetraidropiranicos (THP) de (-)-1 isolados, permitiram verificar que a formação dos derivados oxidados desejados ocorria apenas sobre os derivados THP. Após esta constatação, vários testes visando expansão do anel THF a THP, bem como metodologias para obtenção seletiva dos derivados THP a partir de (-)-1 foram conduzidos, e alguns bons resultados foram obtidos. Adicionalmente, propos-se, ao final do trabalho, uma nova rota para obtenção dos derivados THP a partir de (-)-1, baseada na utilização do linalool como precursor das ciclizações. Paralelamente ao trabalho, diversos compostos obtidos foram submetidos a estudos de atividade antiproliferativa frente a linhagens de celulas tumorais, que permitiram observar que a funcionalização do anel p-mentânico de (-)-1 e um dos fatores responsáveis pela atividade apresentada pelos compostos. / Abstract: The a-(-)-bisabolol (1) is a bisabolene sesquiterpene isolated from the essential oil of several plants, and its pharmacological activities are well known. Synthetic studies envisaging (+)-hernandulcin and (1S)-1-hydroxi-oxide bisabolol A acetate, natural bisabolane sesquiterpenes with sweetener and antimalarial activities, respectively, had been initiated using endocyclic allylic oxidation reactions, which lead to a mixture of products. In order to minimize the formation of by-products and to obtain cyclic derivatives of (-)-1, useful as intermediates for the synthesis of (1S)-1-hidroxi-oxido de bisabolol A, the hydroxylic g,d-unsaturated system of the a-bisabolol was submitted to cyclization reactions using iodine and bromine as electrophiles. In opposition with the expectations, all reactions led to the formation of the THF derivatives as the major products, and it was attributed to the structural features of the substrate and to the reaction conditions. Allylic oxidation essays on the isolated THF and THP derivatives were successfully performed only with the six member ring isomers. Several reactions aiming the THF ring expansion, as well as other methods envisaging the selective preparation of the THP derivative from (-)-1, some of them leading to good results, were also carried out. In addition to these studies, a new synthetic route for the preparation of tetrahydropyran derivatives was proposed from linalool and the initial essays were conduced. Some new compounds obtained in this research project were also submitted to antiproliferative essays. / Mestrado / Quimica Organica / Mestre em Química
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Oxidação alílica de alcenos catalisada por nanopartículas de óxido de cobalto suportadas / Allylic oxidation of alkenes catalyzed by supported cobalt oxide nanoparticles.Silva, Fernanda Parra da 31 March 2011 (has links)
Este trabalho compreende a síntese e caracterização de um novo catalisador magneticamente recuperável de CoO para oxidação alílica de alcenos. O catalisador foi preparado através da deposição de nanopartículas (de tamanho entre 2-3 nm) do metal cataliticamente ativo em nanopartículas de magnetita revestidas por sílica. A natureza magnética do suporte permitiu a fácil separação do catalisador do meio reacional após o termino das reações pela simples aproximação de um ímã na parede do reator. O catalisador pôde ser completamente separado da fase líquida, fazendo com que a utilização de outros métodos de separação como filtração e centrifugação, comumente utilizados em sistemas heterogêneos líquidos, fossem completamente dispensados. O catalisador foi inicialmente testado em reações de oxidação do substrato modelo cicloexeno e mostrou seletividade para a produção do produto alílico, cicloex-2-en-1-ona, que é reagente de partida de grande interesse para a síntese de diversos materiais na indústria química. As reações de oxidação foram realizadas utilizando-se apenas O2 como oxidante primário, dispensando o uso de oxidantes tóxicos como cromatos ou permanganatos, que não são recomendados do ponto de vista ambiental. O catalisador sintetizado mostrou ser reutilizável em sucessivos ciclos de oxidação, destacando-se o aumento da seletividade para a formação da cetona alílica conforme o catalisador perde atividade. A lixiviação da espécie ativa para o meio reacional, problema comum na catálise heterogênea, não foi observada. Um estudo cinético mostrou que mesmo no inicio da reação o catalisador tem seletividade para a ocorrência de oxidação alílica em detrimento da reação de oxidação direta que dá origem ao produto epóxido. Em todos os tempos estudados o produto principal da reação foi sempre a cicloexenona. Os estudos também revelaram que CoO é a espécie mais ativa quando comparado com Co2+, Co3O4 e Fe3O4 nas mesmas condições reacionais. O catalisador de CoO foi empregado na oxidação de monoterpenos mostrando alta seletividade para a formação dos produtos alílicos, resultando em derivados oxigenados altamente valiosos para a indústria de fragrâncias. / This master thesis describes the synthesis and characterization of a magnetically recoverable CoO catalyst for allylic oxidation of alkenes. The catalyst was prepared through the deposition of the catalytic active metal nanoparticles of 2-3 nm on silica-coated magnetite nanoparticles. The magnetic nature of the support allowed the easy separation of catalyst from the reaction medium after the completion of the reaction by simply placing a magnet on the reactor wall.The magnetic separation technique used was able to completely isolate the solid from the liquid phase, making the use of other separation methods such as filtration and centrifugation, commonly used in liquid heterogeneous systems, unnecessary.The catalyst was initially tested in the oxidation of cyclohexene, as a model substrate, and showed high selectivity to the formation of the allylic product, cyclohex-2-en-1-one, an interesting starting reactant for many reactions in the chemical industry. The oxidation reactions were performed using O2 as primary oxidant, eliminating the use of toxic oxidants such as chromate or permanganate, which are not environmentally friendly. The synthesized catalyst was found to be reusable in successive runs, with the increasing selectivity to the allylic ketone as the catalyst lost its activity. The leaching of active species to the reaction medium, a common problem in heterogeneous catalysis, was not observed. A kinetic study showed that even at initial times the catalyst is selective for the allylic oxidation despite the direct oxidation, which leads to the formation of the epoxy product. For all reactions studied in different times, the product was always cyclohexenone. The studies also revealed that CoO is the most active species when compared to Co2+, Co3O4 and Fe3O4 in the catalytic conditions studied. The CoO catalyst was used in the oxidation of monoterpenes and showed high selectivity for the allylic products, giving oxygenate derivatives of highly value for flagrance industry.
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Oxidação alílica de alcenos catalisada por nanopartículas de óxido de cobalto suportadas / Allylic oxidation of alkenes catalyzed by supported cobalt oxide nanoparticles.Fernanda Parra da Silva 31 March 2011 (has links)
Este trabalho compreende a síntese e caracterização de um novo catalisador magneticamente recuperável de CoO para oxidação alílica de alcenos. O catalisador foi preparado através da deposição de nanopartículas (de tamanho entre 2-3 nm) do metal cataliticamente ativo em nanopartículas de magnetita revestidas por sílica. A natureza magnética do suporte permitiu a fácil separação do catalisador do meio reacional após o termino das reações pela simples aproximação de um ímã na parede do reator. O catalisador pôde ser completamente separado da fase líquida, fazendo com que a utilização de outros métodos de separação como filtração e centrifugação, comumente utilizados em sistemas heterogêneos líquidos, fossem completamente dispensados. O catalisador foi inicialmente testado em reações de oxidação do substrato modelo cicloexeno e mostrou seletividade para a produção do produto alílico, cicloex-2-en-1-ona, que é reagente de partida de grande interesse para a síntese de diversos materiais na indústria química. As reações de oxidação foram realizadas utilizando-se apenas O2 como oxidante primário, dispensando o uso de oxidantes tóxicos como cromatos ou permanganatos, que não são recomendados do ponto de vista ambiental. O catalisador sintetizado mostrou ser reutilizável em sucessivos ciclos de oxidação, destacando-se o aumento da seletividade para a formação da cetona alílica conforme o catalisador perde atividade. A lixiviação da espécie ativa para o meio reacional, problema comum na catálise heterogênea, não foi observada. Um estudo cinético mostrou que mesmo no inicio da reação o catalisador tem seletividade para a ocorrência de oxidação alílica em detrimento da reação de oxidação direta que dá origem ao produto epóxido. Em todos os tempos estudados o produto principal da reação foi sempre a cicloexenona. Os estudos também revelaram que CoO é a espécie mais ativa quando comparado com Co2+, Co3O4 e Fe3O4 nas mesmas condições reacionais. O catalisador de CoO foi empregado na oxidação de monoterpenos mostrando alta seletividade para a formação dos produtos alílicos, resultando em derivados oxigenados altamente valiosos para a indústria de fragrâncias. / This master thesis describes the synthesis and characterization of a magnetically recoverable CoO catalyst for allylic oxidation of alkenes. The catalyst was prepared through the deposition of the catalytic active metal nanoparticles of 2-3 nm on silica-coated magnetite nanoparticles. The magnetic nature of the support allowed the easy separation of catalyst from the reaction medium after the completion of the reaction by simply placing a magnet on the reactor wall.The magnetic separation technique used was able to completely isolate the solid from the liquid phase, making the use of other separation methods such as filtration and centrifugation, commonly used in liquid heterogeneous systems, unnecessary.The catalyst was initially tested in the oxidation of cyclohexene, as a model substrate, and showed high selectivity to the formation of the allylic product, cyclohex-2-en-1-one, an interesting starting reactant for many reactions in the chemical industry. The oxidation reactions were performed using O2 as primary oxidant, eliminating the use of toxic oxidants such as chromate or permanganate, which are not environmentally friendly. The synthesized catalyst was found to be reusable in successive runs, with the increasing selectivity to the allylic ketone as the catalyst lost its activity. The leaching of active species to the reaction medium, a common problem in heterogeneous catalysis, was not observed. A kinetic study showed that even at initial times the catalyst is selective for the allylic oxidation despite the direct oxidation, which leads to the formation of the epoxy product. For all reactions studied in different times, the product was always cyclohexenone. The studies also revealed that CoO is the most active species when compared to Co2+, Co3O4 and Fe3O4 in the catalytic conditions studied. The CoO catalyst was used in the oxidation of monoterpenes and showed high selectivity for the allylic products, giving oxygenate derivatives of highly value for flagrance industry.
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Development of Novel Methods to Prepare Nitrogen and Oxygen HeterocyclesWray, Brenda Caroline 22 July 2011 (has links)
No description available.
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Synthesis of nitrogen containing heterocycles and polyfunctionalized compounds from N-tert-butanesulfinyl alkyl, alkenyl and homopropargyl amine derivativesSirvent, Ana 24 September 2021 (has links)
Esta tesis describe el estudio de la aplicación en síntesis de N-terc-butanosulfinil derivados de alquil, alquenil, homoalil y homopropargil aminas como intermedios para acceder a moléculas orgánicas de mayor complejidad. Por un lado, se ha estudiado la adición de compuestos organomagnesianos y organolíticos a N-terc-butanosulfinil iminas, y los distintos derivados de aminas que se obtienen como resultado se han usado como precursores de alcaloides pirrolodínicos y piperidínicos, así como para acceder a anillos tipo azepano. Por otro lado, también se presentan aplicaciones en síntesis de N-terc-butanosulfinil homoalil y homopropargil aminas, que pueden participar en reacciones de oxidación allílica y cicloadiciones [2+2+2], respectivamente, para dar lugar a compuestos polifuncionalizados, en el caso de los derivados de homoalil aminas, y derivados de 9-amino-9, 10-dihidrofenantrenos y 1,2,3,4-tetrahidroisoquinolinas, en el cado de los derivados de homopropargil aminas.
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Synthesis of constrained tricyclic nucleosides and the core of nagilactone BGiacometti, Robert 08 1900 (has links)
Cette thèse décrit deux thèmes principaux: 1) la conception, la synthèse, et l'évaluation biophysique des nucléosides tricycliques, et 2) la synthèse de nagilactone B, un produit naturel norditerpenoïde dilactone de la famille de produits naturels “podolactone”.
Le premier chapitre décrit la stratégie de design rationnel des nucléosides nommé “restriction conformationnelle double” basée sur les études de modélisation structurales des duplex ADN–ARN modifiés. Cette stratégie implique un blocage du cycle furanose dans une configuration de type N- ou S, et une restriction de la rotation torsionelle autour de l’angle γ. La première contrainte a été incorporée avec un pont méthylène entre l’oxygène en position 2′ et le carbone 4′ du nucléoside. Cette stratégie a été inspirée par les acides nucléiques bloqués (ou “locked nucleic acid”, LNA). La deuxième contrainte a été réalisée en ajoutant un carbocycle supplémentaire dans l'échafaud de l’acide nucléique bloqué. Les défis synthétiques de la formation des nucléotides modifiés à partir des carbohydrates sont décrits ainsi que les améliorations aux stabilités thermiques qu’ils apportent aux duplex oligonucléïques dont ils font partie.
Chapitres deux et trois décrivent le développement de deux voies synthétiques complémentaires pour la formation du noyau de nagilactone B. Ce produit naturel a des implications pour le syndrome de Hutchinson–Gilford, à cause de son habilité de jouer le rôle de modulateur de l’épissage d’ARN pré-messager de lamine A. Ce produit naturel contient sept stereocentres différents, dont deux quaternaires et deux comprenant un syn-1,2-diol, ainsi que des lactones à cinq ou six membres, où le cycle à six ressemble à un groupement α-pyrone. La synthèse a débuté avec la cétone de Wieland-Miescher qui a permis d’adresser les défis structurels ainsi qu’explorer les fonctionnalisations des cycles A, B et D du noyau de nagilactone B. / The present thesis comprises two major themes: 1) the design, synthesis, and biophysical evaluation of conformationally restricted tricyclic nucleosides for antisense applications, and 2) strategic approaches for synthesizing the core of nagilactone B, a norditerpenoid dilactone from the podolactone family of natural products.
Guided by structural studies of modified DNA–RNA duplexes, Chapter One focuses on a proposed dual-conformational-restriction strategy, in which two modes of conformational restriction are incorporated into a single nucleotide modification: 1) locking the furanose ring in an N- or S-type configuration and 2) restricting rotation around backbone torsion angle γ. The first constraint was incorporated by way of a 2′,4′-anhydro bridge that is found in the scaffold of locked nucleic acid (LNA), while the second was realized by annealing an additional carbocyclic ring to the modified nucleoside. The synthetic challenges associated with preparing these highly constrained molecules from carbohydrate-derived starting materials are described, in addition to the corresponding improvements in duplex thermal stability they provide to oligonucleotide sequences containing them.
Chapters Two and Three describe complementary approaches for the synthesis of the core of nagilactone B, a natural product with implications for Hutchinson–Gilford progeria syndrome, as a consequence of its ability to act as a modulator of splicing events leading to lamin A. This natural product contains seven stereogenic centers overall, including a syn-1,2-diol moiety, a γ-lactone, and a pair of quaternary stereocenters, which are complemented by the presence of an α-pyrone moiety. To address the synthesis of these structural features, the utility of the Wieland–Miescher ketone was explored with an emphasis on synthesizing rings A, B, and D of the core of nagilactone B.
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Fractionnement par cristallisation extractive à froid des acides gras libres et des triglycérides de l'huile de Nephelium Lappaceum L. (Ramboutan) : oxygénation et enrichissement en acides gras particuliers / New crystallization separation and densification processes of saturated and monounsaturated fatty acids by gelation / degelling of saturated fatty acids and allylic hydroperoxidation of monounsaturated fatty acids of Nephelium Lappaceum L. oil (Rambutan)Douniama-Lonn, Gré Véronique 17 November 2018 (has links)
Dans cette étude, les fruits du Nephelium Lappaceum L. (ramboutan) ont été récoltés en Mars 2015 à Boko, dans la zone sud de la République du Congo. Plante à graines oléagineuses avec un noyau riche en huile (36 %), particulièrement composée d’acides gras saturés et monoinsaturés à longues chaines : C16:0 4,84 %, C18:0 5,48 %, C18:1 45,62 %, C18:2 2,70 %, C20:0 26,53 %, C20:1 9,27 % et C22:0 2,64 %. L’huile de ramboutan a été hydrolysée par voie enzymatique en présence de lipase Candida rugosa, les acides gras libres sont obtenus avec un ratio acides gras saturés (AGS)/acides gras monoinsaturés (AGI) de 0,67. La disponibilité des acides gras saturés et monoinsaturés des familles en C20 et C22 a stimulé nos investigations vers l’élaboration des shortenings et biotensioactifs à haut point de fusion. Deux stratégies ont été mises en place à partir des concentrats en acides gras libres issus de l’hydrolyse enzymatique de l’huile de ramboutan en présence de lipase de Candida rugosa. La première a consisté à la cristallisation à froid des acides gras saturés par la technologie de gélification/dégélification. On observe à l’issu de ce procédé une séparation physique du mélange d’acides gras en deux fractions. Une étude thermique des fractions solide et fluide a été effectuée et a montré que les AGS (To = 15, 86 °C ; Tf = 18,49 °C) refroidissent plus vite, mais fondent moins vite que les AGI (To = -19, 46 °C, Tf= 3,87 °C). Les teneurs des AGI passent de 55,6 % après hydrolyse à 63,53 % dans la fraction fluide et celles des AGS passent de 39,1 % après hydrolyse à 45,13 %. Les résultats de la SFC indique une teneur en AGS de 25,98 % dans la fraction fluide mais de 38,24 % dans la fraction solide ; Et le rendement massique de la fraction fluide passent de 16% à 55 % et de 84 % à 45 % respectivement de la fraction fluide et la fraction solide. La deuxième stratégie a consisté à réaliser l'insertion allylique de l'oxygène singulet dans les acides gras libres monoinsaturés à longues chaines C18:1 et C20:1. Elle est réalisée dans un milieu émulsionné constitué d'un système multiphase NaOH/H2O2/Na2MoO4. Le produit de réaction, au moyen de la GC, montre la présence des acides gras non conventionnels, deux isomères d’hydroperoxydes d’acides gras respectifs de chaque AGMI (C18:1 et C20:1) de conformation trans. Il en résulte une augmentation de la teneur en acides gras saturés à longues chaines C20: 0 (26,21% à 56,46%) et C22 (2,48 % à 3,77 %). Le produit de cette réaction présente un ratio AGS/ AGT (acides gras totaux): 0,82. La valorisation séquencée des acides gras de l'huile de noyau de ramboutan permet de proposer deux plateformes de biomolécules shortenings à haut point de fusion: Une plateforme de composition bien définie en acides gras saturés C20:0 et C22:0 et une autre constituée par un bulk en acides gras saturés C20:0-C22:0 et acides gras insaturés monohydroxyperoxydés trans. Les investigations sur l'hydroperoxydation des acides gras insaturés ont révélé un intérêt particulier sur l'impact du radical hydroxy peroxyde sur le mouvement de la configuration trans et cis dans ces acides gras modifiés en présence de glycidol en monoesters de glycérol et d'acides gras hydroxy peroxydes insaturés cis. C'est une autre plateforme de synthèse originale de biotensioactifs hydroxy peroxydes insaturés cis nouveaux qu'offre la valorisation séquencée des concentrats d'acides gras insaturés de l'huile de ramboutan. / In this study, the fruits of Nephelium Lappaceum L. (Rambutan) were harvested in Boko, in the southern area of the Republic of Congo. Oilseed plant with an oil-rich core (36 %), particularly composed of long chain fatty acids: C16:0 4.84 %, C18:0 5.48 %, C18:1 45.62 %, C18:2 2.70 %, C20:0 26.53 %, C20:1 9.27 % and C22:0 2.64 %. Rambutan oil was hydrolyzed enzymatically in the presence of lipase Candida rugosa, the free fatty acids are obtained with a ratio of saturated fatty acids (AGS)/monounsaturated (AGI) of 0.67. The availability of saturated and monounsaturated fatty acids of the C20 and C22 families stimulated our investigations towards the development of shortenings and biotensioactives with a high melting point. Two strategies have been implemented using free fatty acid concentrates derived from the enzymatic hydrolysis of rambutan oil in the presence of Candida rugosa lipase. The first was to achieve the cold crystallization of saturated fatty acids by gelation / defrosting technology. At the end of this process, a physical separation of the fatty acid mixture into two fractions is observed. A thermal study of the solid and fluid fractions was carried out and showed that the AGS (To = 15, 86 °C, Tf = 18.49 °C) cool faster, but melt slower than the AGI (To = -19 46 °C, mp = 3.87 °C). The contents go from 55.6% after hydrolysis to 63.53 % of AGI in the fluid fraction and 39.1 % after hydrolysis to 45.13 % of AGS. The results of the SFC indicate an AGS content of 25.98 % in the fluid fraction but of 38.24 % in the solid fraction ; And the mass yield of 16 % to 55 % and 84 % to 45 % respectively of the fluid fraction (enriched in AGI, in particular in MUFA) and the solid fraction (enriched with AGS). The second strategy was to perform the allyl insertion of singlet oxygen in long-chain monounsaturated free fatty acids C18:1 and C20:1, carried out in an emulsified medium consisting of a multiphase NaOH / H2O2/Na2MoO4 system. The reaction product, using GC, shows the presence of unconventional fatty acids, two isomers of respective fatty acid hydroperoxides of each trans-conforming MUFA (C18:1 and C20:1) and an increase in saturated fatty acids content with long chain C20:0 (26.21 % to 56.46 %) and C22:0 (2.48 % to 3.77 %). The product of this reaction has an AGS/AGT ratio of 0.82. The sequential evaluation of the fatty acids of the Ramboutan core oil makes it possible to propose two platforms of biomolecules shortenings with a high melting point: A platform with a well defined composition of saturated fatty acids C20:0 and C22:0 and another constituted by a bulk of C20:0-C22:0 saturated fatty acids and transmonohydroxyperoxide trans unsaturated fatty acids. Investigations on the hydroperoxidation of unsaturated fatty acids have revealed a particular interest on the impact of hydroxyperoxide radical on the movement of the trans and cis configuration in these fatty acids modified in the presence of glycidol in monoesters of glycerol and hydroxyperoxide fatty acids unsaturated cis. This is another novel synthesis platform of new cis-unsaturated hydroxyperoxyd biotensiatives offered by the sequenced recovery of unsaturated fatty acid concentrates from rambutan oil.
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