Orientador: Luiz Carlos da Silva Filho / Resumo: A reação de acilação de Friedel-Crafts é uma das mais importantes reações de formação de ligações carbono-carbono em compostos aromáticos. As reações de acilação de Friedel-Crafts ocorrem basicamente por meio da reação entre compostos aromáticos com haletos de acila ou anidridos na presença de um ácido de Lewis. Assim, neste trabalho foi estudado o uso do pentacloreto de nióbio como ácido de Lewis nas reações de acilação de Friedel-Crafts visando à síntese de corantes sensibilizadores. Os derivados de fluoresceína foram sintetizados a partir de derivados fenólicos e derivados de anidrido, na presença de NbCl5 e sob aquecimento. Os produtos de interesse foram obtidos com rendimentos de 54 a 90% e em curtos tempos reacionais que variaram de 50 a 200 minutos. As fluoresceínas apresentaram absorção e emissão de luz dentro do comprimento de onda do visível, com alta intensidade e altos valores de rendimento quântico de fluorescência (0,60 a 0,93) quando dissolvidos em soluções alcalinas. Os derivados de fluoresceínas foram aplicados na confecção de células solares de Gratzel apresentando eficiências de conversão que variaram de 0,11 a 0,23%. Também foi estudado a aplicação dos derivados de fluoresceínas como corantes iniciadores em reações de fotopolimerização de resinas de dimetacrilato. Estas resinas tem sido largamente utilizadas na odontologia, devido as suas propriedades como baixa toxicidade, baixa solubilidade em água e alta resistência mecânica. As fluoresceínas promoveram... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Friedel-Crafts acylation reaction is one of the most important reactions for the formation of carbon-carbon bonds. The Fridel-Crafts acylation reaction occurs basically by a reaction between aromatic compounds with acyl halides or anhydrides in the presence of a Lewis acid. Thus, in this work it was studied the use of niobium pentachloride as Lewis acid in Friedel-Crafts acylation reaction, aiming the synthesis of sensitizing dyes. The fluorescein derivatives were synthesized from phenolic derivatives and anhydride derivatives, in the presence of NbCl5 and under heating. The products of interest where obtained in yields of 54 to 90% and in short reaction times ranging from 50 to 200 minutes. The fluorescein derivatives presented absorption and emission within the range of visible and with high intensity and high fluorescence quantum yield (0,60 to 0,93) when dissolved in alkaline pH. Due to these good results obtained in the photophysical study, the fluorescein derivatives were applied in Gratzel solar cells, presenting convertion efficiencies that ranging from 0.11 to 0.23%. It has also been studied the application of fluorescein derivatives as initiator dyes in photopolymerization reactions of dimethacrylated resins. This resins have been widely used in dentistry, due this properties as, low toxicity, low solubility in water and high mechanical resistance. The fluoresceins promoted the photopolymerization of dimethacrylated resins with conversion values ranging from 1.2... (Complete abstract click electronic access below) / Doutor

L’acylation de Friedel-Crafts est parmi les réactions les plus fondamentales et les plus utiles pour former des cétones aromatiques. Bien que la mise en oeuvre de ces réactions soit habituellement pénalisante en termes de sous produits formés, de rendement atomique et de quantité de catalyseur utilisée, cette voie est encore largement utilisée dans l’industrie de la chimie fine. Ces dernières années, la prise de conscience de l’impact des activités industrielles sur l’environnement a mené les chimistes à travailler sur de nouvelles voies, moins dangereuses et plus respectueuses de l’environnement.Nous avons considéré ici l’acylation d’un dérivé du benzofurane par un chlorure d’acyle, correspondant à une étape intermédiaire pour la fabrication d’un principe actif pharmaceutique. Dans cette étude, la première proposition a consisté à remplacer les catalyseurs classiques (FeCl3 ou AlCl3) par des catalyseurs solides réutilisables. Dans ce travail, plusieurs catalyseurs (zéolites, résines échangeuses d’ions...) ont d’abord été testés dans des conditions « conventionnelles » , c’est-à-dire en utilisant un solvant organique, afin de déterminer le plus performant, en termes de réactivité, de durée de vie et de réutilisabilité. Une zéolite Y s’est avéré la plus adaptée. Cependant, l’utilisation d’un solvant organique (ici le 1,2-dichlorobenzène) reste discutable et l’utilisation du CO2 supercritique comme solvant a donc été envisagée. Pour cela, nous avons imaginé et dimensionné un réacteur tubulaire à lit fixe de catalyseur fonctionnant sous pression et en continu. Les résultats présentés montrent la faisabilité d’un tel procédé et pose les jalons pour arriver à une ou des solutions pour une meilleure mise en oeuvre industrielle des réactions de Friedel-Crafts. / Friedel-Crafts acylation is among the most fundamental and useful reactions to yield aromatic ketones, but it is one of the less acceptable in terms of unwanted polluting by-products or atom economy because of overconsumption of catalyst which is used in stoichiometric quantities in the conventional process. This route is nevertheless still widely used in the fine chemicals industry. In recent years, awareness of the impact of industrial activities on the environment has lead chemists to work on new chemical routes, less dangerous and more environmentally friendly. We considered here the acylation of a benzofurane derivative by an acid chloride, as an intermediary step for a pharmaceutical product. In this study, one of the first alternative was to replace conventional catalysts (FeCl3 or AlCl3), by reusable solid catalysts. In this work, different catalysts (zeolites, ion-exchange resins...) were first tested in "conventional" conditions, i.e., using an organic solvent (1,2-dichlorobenzene in our case), to determine the best one, in terms of reactivity, lifetime and reusability. The zeolite Y was found the most appropriate. However, the use of an organic solvent still remains questionable and the use of supercritical carbon dioxide as the solvent was also considered. Its inherent properties include non-flammability, mild critical conditions, tuneable solubility near to the critical point and very low environmental impact. The reaction was operated using a specifically designed continuous high pressure fixed bed and results concerning yield and selectivity are presented. These results demonstrate the feasibility of such an approach, which would ultimately yield to better industrial operation of Friedel-Crafts reactions.

Triquentrinas A são produtos naturais marinhos com atividade biológica e alta complexidade estrutural. Estes fatores tornam estes alcaloides e compostos análogos, como os herbindóis, alvos para a síntese total e plataforma para o desenvolvimento de novas metodologias sintéticas. Nesta Dissertação de Mestrado, procurou-se completar a síntese estereosseletiva da (+)-cis-triquentrina A empregando-se intermediários sintéticos protegidos com o grupo benzila que poderão ser usados para a futura prospecção de novos compostos com atividade biológica. A rota proposta baseia-se na obtenção do ácido (S)-3-(1-benzil-4-etil-1H-indol-7-il)butanóico, um intermediário-chave já descrito por Silva e colaboradores no percurso da síntese total da (+)-trans-triquentrina A, e da finalização da síntese de acordo com a abordagem proposta pelo grupo de RajanBabu para conversão do análogo protegido com grupo tosila à (+)-cis-triquentrina A. A resolução enzimática do intermediário-chave com lipase de Pseudomonas cepacia imobilizada em terra diatomácea foi otimizada, resultando em rendimentos de 32% e 99% ee na metade do tempo descrito anteriormente. Na etapa-chave da síntese, o (S)-ácido foi submetido a uma acilação de Friedel-Crafts intramolecular na presença de anidrido trifluoroacético que produziu o produto de ciclização desejado com 40% de rendimento. Na etapa final da síntese, o intermediário sintético protegido com grupo benzila não pode ser convertido à (+)-cis-triquentrina A, empregando-se a metodologia desenvolvida para a redução do composto análogo tosilado, dada a diferença de reatividade imposta pela troca do grupo protetor. As etapas realizadas até o penúltimo intermediário sintético (S)-8, consta com 10 etapas e rendimento global de 1,3%. viii As diferenças eletrônicas e estruturais relacionadas a diferentes grupos protetores poderão ser refletidas em variações na atividade antiproliferativa de indóis relacionados a triquentrinas. Ainda no interesse de preparar moléculas para envio à análises de atividade antiproliferativa preparou-se um composto relacionado à síntese da trans-triquentrina A tendo como etapa-chave uma contração de anel mediada por I(III) em 21% de rendimento, cujo trabalho foi incluído nos anexos. / Trikentrins A are marine natural products with biological activity and high structural complexity. These factors make these alkaloids and analogous compounds, such as herbidoles, targets for total synthesis and platform for the development of new synthetic methodologies. In this Master\'s Dissertation, we attempted to complete the stereoselective synthesis of (+)-cis-trikentrin A using synthetic intermediates protected with the benzyl group that could be used for the future prospection of new compounds with biological activity. The proposed route is based on the preparation of (S)-3-(1-benzyl-4-ethyl-1H-indol-7-yl) butanoic acid, a key intermediate already described by Silva et al., in the course of total synthesis (+)-trans-triquentrin A, and the final part of the synthesis according to the approach proposed by the RajanBabus group for conversion of the protected analogue with tosyl group to (+)-cis-trikentrin A. The enzymatic resolution of the key intermediate with Pseudomonas cepacia lipase immobilized on diatomaceous earth was optimized, resulting in 32% yield and 99% ee in half the time described above. In the key step of the synthesis, the (S)-acid was subjected to an intramolecular Friedel-Crafts acylation in the presence of trifluoroacetic anhydride which yielded the desired cyclization product in 40% yield. In the final step of the synthesis, the synthetic intermediate protected with benzyl group couldnt be converted to (+)-cis-trikentrin A, employing the methodology developed for the reduction of the tosylated analogous compound, given the difference of reactivity imposed by exchange of the protective group. The steps carried out up to the synthetic intermediate (S)-8, consists of 10 steps and overall yield of 1.3%. Electronic and structural differences related to different protective groups may be reflected in variations in the antiproliferative activity of indoles related to trikentrins. A compound related to the synthesis of trans-triquentrin A having as its key step an I(III) mediated ring contraction in 21% yield was also prepared in the interest of preparing molecules for antiproliferative activity analysis, whose work was included in the appendix.