A obtenção de moléculas enantiomericamente puras ou enriquecidas tem se demonstrado um desafio em química orgânica sintética. Nesse âmbito, a biocatálise aparece como uma importante ferramenta sintética. Neste trabalho, desenvolveu-se uma metodologia para a obtenção de 6-hidróxioct-7-inoato de metila, 5-hidróxihept-6-inoato de metila, e 4-hidróxihex-5-inoato de metila enantiomericamente enriquecidos via resolução cinética enzimática. Primeiramente foram investigadas variáveis como temperatura, tempo, quantidade de doador de acila, solvente e enzima adequada para a reação. Em uma segunda etapa do trabalho, foram desenvolvidas seqüências reacionais onde os hidroxiésteres originariam moléculas bioativas Utilizando o 5-hidróxihept-6-inoato de metila, após três etapas reacionais, foi possível sintetizar intermediários sintéticos avançados das moléculas bioativas goniotalamina e argentilactona. De maneira análoga, após algumas etapas reacionais, o 4-hidróxihex-5-inoato de metila originou os feromônios buibuilactona, japonilura e 4-hexanolida / The synthesis of enantiomerically pure or enriched molecules has been an important challenge in synthetic organic chemistry. Among a variety of disciplines dedicated to achive this goal, biocatalysis appears as an important synthetic tool. Herein, we developed a methodology to obtain methyl 6-hydroxyoct-7-ynoate, methyl 5-hydroxyhept-6-ynoate and methyl 4-hydroxyhex-5-ynoate enantiomerically enriched by an enzymatic kinetic resolution. Reaction conditions such as temperature, reaction time, amount of acyl donor, solvent and enzyme were screened, in order to obtain high yields and enantioselectivities. In the second part of our work, synthetic pathways were developed where the hydroxyesters lead to bioactive molecules. Using methyl 5-hydroxyhept-6-ynoate, after three steps, advanced synthetic intermediates for the synthesis of the bioactive molecules, such as goniothalamine and argentilactone, were prepared. In the same way, methyl 4-hydroxyhex-5-ynoate was submitted to a reaction sequence leading the pheromones buibuilactone, japonilure and 4-hexanolide.

Neste trabalho foram estudadas reações de substituição nucleofílica alifática de seis substratos halogenados, na presença de sais quaternários de amônio quirais (catalisadores por transferência de fase), derivados de alcalóides naturais. O sistema usado durante os trabalhos foi o sólido-líquido, sendo utilizado o tolueno como solvente do substrato halogenado. Os eletrófilos escolhidos para este trabalho foram, em sua grande maioria, compostos halogenados na posição alfa à carbonila e o nucleófilo foi o fenilmercapteto de sódio. A estrutura do substratos, as condições de reação e o tipo de catalisador foram variados visando-se avaliar qual a melhor condição de interação entre o catalisador e o substrato, usando-se como parâmetro comparativo o excesso enantiomérico obtido em cada caso. Os substratos foram também colocados para reagir na ausência de catalisador (\"branco de reação\") para avaliar a possibilidade de haver reações não catalisadas competindo com a reação enantiosseletiva. Tais reações diminuiriam a enantiosseletividade do processo, o que tomou imprescindível determinar sua extensão. Métodos de análise do excesso enantiomérico dos produtos de reação obtidos, por CLAE utilizando fase estacionária quiral e/ou RMN de 1H na presença de reagentes de deslocamento quirais, foram desenvolvidos para cada caso. Os resultados experimentais permitiram propor e discutir um modelo de associação catalisador/tiolato/eletrófilo, baseado em interações do tipo π-π e ligação de hidrogênio. / The main focus of the present work was the investigation of some aliphatic nucleofilic substitution reactions of halogenated compounds in the presence of chiral phase transfer catalyst, in a solid-liquid two phase system, using toluene as solvent. Most electrophiles were carbonylic or carboxylic derivatives bearing a halogen atom in the a-position to the carbonyl group. As for the nucleophile, sodium thiophenolate was employed in all reactions. Factors such as molecular structure of the electrophile, reaction conditions and catalyst were varied in order to optimize product enantiomeric excesses, and to gain an insight into the mode of action of the chiral catalyst in the kinetic resolution. In all cases blank experiments in the absence of the catalyst were performed, considering the possibility of a competitive uncatalyzed reaction as being responsible for lower enantiomeric excesses. Methods for determining the enantiomeric excess, based on HPLC and/or 1H-NMR, were developed for each specific product. The mechanistic and geometrical factors responsible for the kinetic resolution are analyzed in each case. The structure of the catalyst/thiolate/electrofile is discussed in terms of hydrogen bonding and π-π interactions.

Nesta dissertação estão descritos os resultados obtidos sobre a preparação de nanocascas funcionalizadas (nanopartículas ocas) de ouro/prata de diâmetro de 50 nm e imobilização de diferentes lipases (Burkholderia cepacia (BCL) e pâncreas de porco (PPL)). [Obs.: A imagem do esquema pode ser visto no arquivo PDF] Inicialmente as nanocascas de ouro/prata (NSs AgAu) foram sintetizadas e caracterizadas, através de imagens de MEV e MET. Através destas imagens algumas características das NSs AgAu foram elucidadas, como seu tamanho e sua característica oca. Em seguida, a funcionalização das NSs AgAu com diferentes moléculas mercapto-alcanóicas e uma molécula mercapto-amina foi realizada. Depois de funcionalizadas as NSs-funcionalizadas foram ativadas, com glutaraldeído ou EDC, para que assim elas ficassem aptas à imobilização das lipases, via ligação covalente. Para a BCL foi possível imobilizar 0,155-0,282 mg de proteína/3 mg do suporte. No caso da PPL uma menor quantidade de enzima foi imobilizada (0,035-0,048 mg/3 mg do suporte). A atividade da enzima imobilizada foi testada frente à reação de acetilação enantiosseletiva do (R,S)-1-feniletanol com acetato de vinila (RCE, resolução cinética enzimática). Excelentes resultados de conversão (50%) e seletividade (E > 200) foram conseguidos com a BCL imobilizada em todos os suportes. A PPL livre não catalisava a acetilação deste substrato e quando esta enzima foi imobilizada nas diferentes NSs-funcionalizadas, os resultados apresentados para acetilação enantiosseletiva do (R,S)-1-feniletanol com acetato de vinila foram interessantes. Nesse caso conseguimos alcançar conversões de até 4% do substrato R à sua forma acetilada com excelente enantiosseletividade ( > 99% e.e. do produto). Como uma alternativa de demonstrar a atividade enzimática da BCL imobilizada em reação tradicional de hidrólise, o teste da hidrólise do palmitato de p-Nitrofenila pela BCL livre e imobilizada foi realizado. Este teste revelou que a BCL imobilizada nas NSs-funcionalizadas catalisavam a hidrólise do palmitato de p-Nitrofenila mais rápido que a enzima livre, comprovando os bons resultados obtidos na RCE, mostrando que os sistemas onde tínhamos a BCL imobilizada foram mais eficientes que a enzima livre. As NSs AgAu, NSs-funcionalizadas e até as nanocascas contendo as lipases imobilizadas foram caracterizadas por de imagens de MEV e MET, análises de FT-IR e método de Bradford. Outros estudos com os sistemas contendo a BCL imobilizada foram elucidados. Diferentes funcionalizadores de diferentes tamanhos foram utilizados e a influência de cada um deles sobre a atividade enzimática foi estudado. Por exemplo, quando as NSs AuAg foram funcionalizadas com moléculas mercapto-alcanóicas menores, como por exemplo, o ácido mercapto acético, melhores resultados para a RC do (R,S)-1-feniletanol foram conseguidos. As diferentes formas de ativação da NSs-funcionalizadas utilizando glutaraldeído ou EDC, para consequente imobilização da BCL não resultaram em alterações da atividade enzimática na RC, apresentando valores idênticos para RCE. Experimentos para testar a estabilidade dos sistemas contendo a BCL imobilizada também foram feitos. Descobrimos que é possível armazenar a BCL imobilizada nos diferentes sistemas à - 4 °C por até 28 dias. O estudo da reciclagem destes sistemas revelou que por até 3 ciclos os sistemas conseguiram manter 90% da atividade enzimática. / This dissertation presents the results achieved on the preparation of functionalized gold/silver nanoshells (hollow nanoparticles, 50 nm) and immobilization of different lipases (Burkholderia cepacia (BCL) and porcine pancreatic (PPL)). Initially Gold/Silver nanoshells (NSs Ag Au) were synthesized and characterized through SEM and TEM pictures. By these images some characteristics of NSs AgAu were elucidated, as its size and hollow feature. The functionalization NSs AgAu with different mercapto-alkanoic molecules and mercapto-amine molecule was next step performed. After the functionalized NSs-functionalized were activated with glutaraldehyde or EDC, after that they remained suitable for the immobilization of lipases via covalent bond. BCL was possible immobilized 0.155-0.282 mg protein/3 mg of support. And the PPL a smaller amount of enzyme was immobilized (from 0.035-0.048 mg / 3 mg of support). The activity of the immobilized enzyme was assayed by the reaction enantioselective acetylation of (R,S)-1-phenylethanol with vinyl acetate (KR, kinetic resolution). Excellent conversion results (50%) and selectivity (E > 200) were achieved with the immobilized BCL. The free PLP did not catalyzed acetylation of the substrate and when this enzyme was immobilized on NSs-functionalized the results for enantioselective acetylation of (R,S)-1-phenylethanol with vinyl acetate were interesting. In this case we achieve conversions of 4% of the substrate (R) to acetylated form with excellent enantioselectivity (> 99% e.e. of the product). As alternative to demonstrate the enzymatic activity of BCL immobilized on traditional hydrolysis reaction, the hydrolysis of p-nitrophenyl palmitate by free and immobilized BCL was performed. This test revealed BCL immobilized on NSs-functionalized catalyzed hydrolysis of p-nitrophenyl palmitate faster than free enzyme, confirming the good results obtained in KR, showing that systems which had immobilized BCL were more efficient than the enzyme free. The NSs AgAu, NSs-functionalized and Nanoshells containing the immobilized lipases were characterized by SEM and TEM images , FT-IR analysis , the Bradford method. Other studies with systems containing immobilized BCL were elucidated. Different spacers with different sizes were used for functionalized the nanoshells, and the influence of each of the enzymatic activity was studied. For example, when the NSs were functionalized with smaller molecules mercapto-alkanoic and cysteamine best results for the KR (R,S)-1-(phenyl)ethanol were obtained. The different forms of activation of NSs-functionalized using glutaraldehyde or EDC, for subsequent immobilization of BCL did not result in changes in enzyme activity in the KR . Experiments to test the stability of systems containing immobilized BCL were also made . We found it possible to store the BCL immobilized on different systems at - 4 ° C for 30 days. The study of the recycling of these systems was made and by 3 cycles systems maintain 90% of the enzyme activity.

Apresenta-se, nesta tese, a síntese total do alcaloide marinho (+)-trans-triquentrina A. Três abordagens foram investigadas como estratégias sintéticas: uma adição conjugada assimétrica, um acoplamento arílico com um complexo de ferro e uma resolução cinética enzimática. Esta última permitiu finalizar a síntese do produto natural em 20 etapas e com 0,6% de rendimento global. A síntese tem como etapas-chave a resolução cinética de um éster racêmico, mediada pela lipase da Pseudomonas cepacia - que forneceu o (S)-ácido correspondente em excelente excesso enantiomérico - e a contração de anel de um ciclo-hexeno substituído promovida por um sal de tálio(III), fornecendo seletivamente o composto trans-1,3-dimetilciclopentano correspondente. Efetuaram-se testes visando à síntese total da (+)-cis-triquentrina A a partir de um intermediário obtido da etapa de resolução cinética enzimática, que seria comum à síntese das duas moléculas-alvo. Investigou-se a atividade antiproliferativa da (+)-trans-triquentrina A, bem como a de intermediários da síntese e de produtos relacionados. Estes estudos permitiram descobrir compostos com atividade potente frente a linhagens de células tumorais humanas de ovário (GI50=0,31-0,42 µg.mL-1) e de cólon (GI50=0,25 µg.mL-1). / The total synthesis of marine alkaloid (+)-trans-trikentrin A is presented in this thesis. Three approaches were investigated as synthetic strategies: an asymmetric conjugate addition, an aryl coupling with an iron complex and an enzymatic kinetic resolution. The latter allowed the synthesis of the natural product to be achieved in 20 steps and 0.6% overall yield. The synthesis features as key steps a kinetic resolution of a racemic ester, which was mediated by the lipase from Pseudomonas cepacia, leading to the corresponding (S)-acid in excellent enantiomeric excess, as well as a thallium(III)-mediated ring contraction of a cyclohexene derivative that selectively afforded the corresponding trans-1,3- dimethylcyclopentanic compound. Studies toward the total synthesis of (+)-cis-trikentrin A were performed aiming to achieve both natural products from a common intermediate, obtained from the enzymatic kinetic resolution. The antiproliferative activity of (+)-trans-trikentrin A as well as that of intermediates and related products was investigated. Compounds with potent activity against ovarian (GI50=0.31- 0.42 µg.mL-1) and colon (GI50=0.25 µg.mL-1) tumor cell lines were discovered during these studies.

Ausgangspunkte der vorliegenden Arbeit waren stereoselektive Synthesen von Reissert-analogen N-Acylaminohydroperoxiden über chirale N-Acylisochinoliniumsalze. Edukte waren Isochinolin(derivaten), Menthylchloroformiat und Wasserstoffperoxid. Es galt die Konfiguration der erhaltenen Produkte zu beweisen und deren Sauerstoffübertragungspotential zu erforschen. Ein zweites Ziel dieser Arbeit war es, von bekannten Diketopiperazinhydroperoxiden ebenfalls das Sauerstoffübertragungspotential zu überprüfen, weil sie die gleiche N-Acylaminohydroperoxidstruktur aufweisen aber bisher wenig untersucht wurden. Es gelang durch NMR-Untersuchungen und Vergleich mit ähnlichen Reaktionen die Annahme eines stereoselektiven Verlaufes zu widerlegen. Weiterhin wurde gezeigt, dass anstelle von Hydroperoxiden Peroxide vorliegen. Es konnte eine in situ Methode entwickelt werden, um mit dem vorgegebenen Substanzen unter Zusatz eines Metallkatalysators wie Vanadium(V)triisopropylat und Titan(IV)tetraisopropylat eine Sauerstoffübertragung auf Methylphenylsulfid zu erzielen. In Abhängigkeit der eingesetzen Isochinolinderivate gelang eine kinetische Racematspaltung, so dass eine stereoselektive Sulfoxidation möglich wurde. Das günstigste Ergebnis betrug 51 % Sulfoxid bei 73 % Enantiomerenüberschuss. Mit einem bekannten Diketopiperazinhydroperoxid konnte Methylphenylsulfid direkt in 62 % Sulfoxid mit 32 % Enantiomerenüberschuss überführt werden. Dies sind die ersten erfolgreichen stereoselektiven Sulfoxidationen mit N-Acylaminohydroperoxiden. / Starting points of the present work were stereoselective syntheses of Reissert analogous N-acylaminohydroperoxides derived from chiral N-acylisochinoliniumsalts. Starting materials were isochinoline (and derivates), menthylchloroformiate and hydrogen peroxide. It was a matter of proving the configuration of the preserved products and of investigating the oxygen transfer potential. The second purpose of this work was to check the oxygen transfer potential of known diketopiperazinehydroperoxides likewise because they show the same N-acylaminohydroperoxide structure, however, up to now they were only examined scarcely. One succeeded by NMR investigations and comparison with similar reactions in disproving the acceptance of a stereoselective course. Furthermore it was shown that there are peroxides instead of hydroperoxides. We developed an in situ method to achieve with the given substances under addition of a metal catalyst like vanadium(V)triisopropylate and titanium(IV)tetraisopropylate an oxygen transfer to methylphenylsulfide. In dependence of the used isochinoline derivates a kinetic resolution was observed, so that a stereoselective sulfoxidation became possible. The most favorable result amounted to 51% sulfoxide with 73% enantiomeric excess. With a known diketopiperazinehydroperoxide methylphenylsulfide could be directly transfered into 62% sulfoxide with 32% enantiomeric excess. These are the first successful stereoselective sulfoxidations with chiral N-acylaminohydroperoxides.

<p>This thesis describes the synthesis and application of new chiral bicyclic ligands and their application in asymmetric catalysis. The studies involved: [i] The development of novel chiral bicyclic amino sulfur ligands and their use in transfer hydrogenation. [ii] The development of the kinetic resolution of racemic epoxide through the use of chiral lithium amides. [iii] The synthesis and application of chiral bicyclic amine in the organocatalysed epoxidation of alkenes. [iv] Development and application of new chiral diamine ligands in the rearrangement of epoxides into allylic alcohols.</p><p>[i] The preparation of two-series of amino thiol ligands based on the structure of camphor is described, together with their application in the iridium-catalysed asymmetric transfer hydrogenation of acetophenone using isopropanol as the hydrogen source. Excellent activity and good enantioselectivity have been achieved using 2 mol% of chiral ligand in combination with [IrCl(COD)]2.</p><p>[ii] The chiral diamines (1S,3R,4R)-3-(pyrrolidine-1-ylmethyl)-2-aza-bicyclo[2.2.1]heptane and its (2R,5R)-dimethylpyrrolidine derivative were applied to the kinetic resolution of a variety of racemic 5-7 membered cycloalkene oxides with lithium diisopropylamide (LDA) as the bulk base. Using 5 mol% of the chiral diamines, both unreacted epoxides and allylic alcohols could be produced in enantiomeric excess up to 99%.</p><p>[iii] The synthesis of chiral bicyclic amines and their use in the organocatalysed epoxidation of alkene has been described. Using a substoichiometric amount of the chiral amines and aldehydes as ligands precursors, with Oxone® as oxidant, a good activity but moderate enantioselectivity was observed for the epoxidation of trans-stilbene. </p><p>[iv] The preparation of 6-substituted-7-bromo-aza-bicyclo[2.2.1]heptanes via nucleophilic addition of organocopper reagents to 3-bromo-1-azoniatricyclo[2.2.1.0]heptyle bromide has been described. These compounds have been utilised as chiral building blocks in the preparation of novel chiral diamine ligands, which have been successfully applied to the catalysed asymmetric rearrangement of epoxide into the corresponding allylic alcohol.</p>

This thesis describes the synthesis and application of new chiral bicyclic ligands and their application in asymmetric catalysis. The studies involved: [i] The development of novel chiral bicyclic amino sulfur ligands and their use in transfer hydrogenation. [ii] The development of the kinetic resolution of racemic epoxide through the use of chiral lithium amides. [iii] The synthesis and application of chiral bicyclic amine in the organocatalysed epoxidation of alkenes. [iv] Development and application of new chiral diamine ligands in the rearrangement of epoxides into allylic alcohols. [i] The preparation of two-series of amino thiol ligands based on the structure of camphor is described, together with their application in the iridium-catalysed asymmetric transfer hydrogenation of acetophenone using isopropanol as the hydrogen source. Excellent activity and good enantioselectivity have been achieved using 2 mol% of chiral ligand in combination with [IrCl(COD)]2. [ii] The chiral diamines (1S,3R,4R)-3-(pyrrolidine-1-ylmethyl)-2-aza-bicyclo[2.2.1]heptane and its (2R,5R)-dimethylpyrrolidine derivative were applied to the kinetic resolution of a variety of racemic 5-7 membered cycloalkene oxides with lithium diisopropylamide (LDA) as the bulk base. Using 5 mol% of the chiral diamines, both unreacted epoxides and allylic alcohols could be produced in enantiomeric excess up to 99%. [iii] The synthesis of chiral bicyclic amines and their use in the organocatalysed epoxidation of alkene has been described. Using a substoichiometric amount of the chiral amines and aldehydes as ligands precursors, with Oxone® as oxidant, a good activity but moderate enantioselectivity was observed for the epoxidation of trans-stilbene. [iv] The preparation of 6-substituted-7-bromo-aza-bicyclo[2.2.1]heptanes via nucleophilic addition of organocopper reagents to 3-bromo-1-azoniatricyclo[2.2.1.0]heptyle bromide has been described. These compounds have been utilised as chiral building blocks in the preparation of novel chiral diamine ligands, which have been successfully applied to the catalysed asymmetric rearrangement of epoxide into the corresponding allylic alcohol.

Chiral &amp / #945 / -hydroxy and &amp / #945 / -acetoxy enones are important starting materials in the synthesis of many biologically active materials. In this work, enantiomerically pure &amp / #947 / -hydroxy enone and polyoxo cyclohexenones are synthesized starting from 1,3-cyclohexandione. In the first step, 1,3-cyclohexandione is protected under acid catalyzation and 3-methoxy-2-methyl-2-cyclohexen-1-one is obtained. &amp / #945 / &#039 / -Acetoxy enone is obtained by Mn(OAc)3 mediated oxidation which is an attractive alternative to other multi-step procedures in the literature. Enzymatic kinetic resolution is applied to the racemic form of this product and enantiomerically pure &amp / #945 / &#039 / -acetoxy enone and &amp / #945 / &#039 / -hydroxy enone is obtained. In this stage, for the screening of the reaction many enzymes were tried. Reduction of &amp / #945 / &#039 / -hydroxy enone furnished enantiopure &amp / #947 / -hydroxy enone.

The research work reported in the thesis deals with the development of dynamic covalent systems and their applications in evaluation and screening of protein-ligands and enzyme inhibitors, as well as in synthetic methodologies. The thesis is divided into four parts as described below. In part one, synthetic methodologies to access 3-functionalized phthalides and 3-thioisoindolinones using the concept of cascade reactions are demonstrated. Efficient syntheses of the target products are designed and performed in one-pot process under mild reaction conditions.  In part two, phosphine-catalyzed disulfide metathesis for the generation of dynamic carbohydrate system in aqueous solution is demonstrated. In the presence of biological target (Concanavalin A), the optimal dynamic ligand is successfully identified in situ by the 1H STD-NMR spectroscopy. In part three, lipase-catalyzed resolutions of dynamic reversible systems using reversible cyanohydrin and hemithioacetal reactions in one-pot processes are demonstrated. The dynamic systems are generated under thermodynamic control in organic solution and subsequently resolved by lipase-mediated resolution under kinetic control. The resolution processes resulted in the lipase-selected substrates with high structural and stereochemical specificities. In the last part, dynamic fragment-based strategy is presented using β-galactosidase as a model target enzyme. Based on our previous study, the best dynamic inhibitor of β-galactosidase was identified using 1H STD-NMR technique from dynamic hemithioacetal systems. The structure of the dynamic inhibitor is tailored by fragment linking and optimization processes. The designed inhibitor structures are then synthesized and tested for inhibition activities against β-galactosidase. / QC 20110526

Im Rahmen dieser Arbeit wird eine neuartige Deoxygenierungskaskade von Flavanonen bzw. Isoflavanonen via asymmetrischer Transferhydrierung (ATH) beschrieben. Diese Methodik ermöglicht einen einstufigen Zugang zu enantiomerenreinen Flavanen bzw. Isoflavanen aus entsprechenden racemischen Ketonen. Unter Verwendung der ATH-Deoxygenierungskaskade werden hoch enantioselektive Naturstoffsynthesen elaboriert. So erfolgt eine effiziente Darstellung der Flavane Brosimin A, Brosimin B, Brosimacutin L, Kazinol U und 7,3‘-Dihydroxy-4‘-methoxyflavan. Darüber hinaus wird mittels dynamischer kinetischer Racematspaltung die Totalsynthese der Isoflavane Equol, Manuifolin K und Eryzerin D beschrieben.