Neste trabalho, avaliou-se o potencial do uso de oxidantes quirais em oxidações enantiosseletivas de compostos orgânicos de boro. É de conhecimento geral que compostos orgânicos de boro, especialmente ésteres e ácidos borônicos são facilmente oxidados por hidroperóxidos em meio básico. No entanto, são escassos na literatura exemplos destas reações de modo enantiosseletivo. A fim de realizar as reações mencionadas, sintetizou-se os hidroperóxidos quirais TADOOH ({(4R,5R)-5-[(hidroperoxidifenil)metil]-2,2-dimetil-1,3-dioxolan-4il}difenilmetanol) e o hidroperóxido quiral derivado de carboidrato, 2,3-dideoxi1-O-oxidanil-4,6-di-O-pivaloil-α-D-eritro-hex-2-enopiranose (di-O-PivOOH). Estes compostos apresentaram resultados interessantes na literatura em oxidações enantiosseletiva de sulfetos orgânicos, em epoxidações de alcenos e em oxidações de Baeyer-Villiger. Inicialmente o potencial oxidativo de ambos hidroperóxidos, bem como a seletividade destes, foi avaliado frente a diversos ésteres borônicos, sendo que somente o TADOOH apresentou resultados promissores. (Ver esquema no PDF) Observou-se uma melhor seletividade do TADOOH frente a ésteres borônicos que possuíam grupos carbonílicos em sua estrutura. Ao submeter o β-boronil-éster, 3-fenil-3-(4,4,5,5-tetrametil-1,3,2-dioxaborolan-2-il)propanoato de etila, à oxidação com o TADOOH em THF utilizando NaOH como base, a -30°C por 1 hora, obteve-se o respectivo álcool com 40% de e.e. Cálculos de DFT para o estado de transição na oxidação dos ésteres borônicos com o TADOOH foram realizados em colaboração com o grupo do Prof. Dr. Ataualpa Albert Carmo Braga. Estes cálculos demonstraram que o estado de transição é estabilizado por uma ligação de hidrogênio não clássica entre o oxigênio da carbonila e umas das ligações C-H dos grupos fenila do TADOOH. Além dos estudos relatados, a reconhecida metodologia de Sharpless na epoxidação assimétrica de alcoóis alílicos foi adaptada para a oxidação enantiosseletiva de ésteres borônicos. Ao trocar o ligante derivado de éster tártarico, normalmente utilizado nas epoxidações de Sharpless, por (-)-efedrina observou-se uma moderada seletividade deste sistema frente ao pinacol l-fenietilboronato. Investigações mais detalhadas demonstraram que a presença do Ti(IV) não era necessária, sendo que a (-)efedrina era a responsável pela ativação e indução quiral nesta reação. / In this work, it was investigated the potential use of chiral oxidants in organic boron compound oxidation. It is known in the literature, that organic boron compounds can be easily oxidized by hydroperoxides. However, an enantioselective approach in literature is scarce. In order to perform these reactions, hydroperoxide TADOOH ({(4R,5R)-5[(hydroperoxydiphenyl)methyl]-2,2-dimethyl-l,3-dioxolan-4-yl}diphenylmethanol) and carbohydrate derived hydroperoxide, 2,3-dideoxy-1-O-oxidanyl-4,6-di-O-pivaloyl-α-D-erythro-hex-2-enopyranose (di-O-PivOOH), have been synthesized. These compounds showed interesting results in several enantioselective oxidations, as like, organic sulfides oxidation, alkenes epoxidation and Baeyer-Villiger oxidations. The oxidative potential of both hydroperoxides, as well as their selectivity, were evaluated against several boronic esters. Only TADOOH has shown promissing results for further studies. (See Scheme on PDF). Boronic esters containing a carbonyl moiety showed better selectivities with TADOOH, for example, the reaction of β-boronyl-ester, ethyl 3-phenyl-3-(4,4,5,5-tetramethyl-l,3,2-dioxaborolan-2-yl)propanoate, gave the correponding alcohol with 40% e.e. DFT calculations for the transition state in the oxidation of the boronic esters with TADOOH were carried out in collaboration with the group of Prof. Dr. Ataualpa Albert Carmo Braga. These calculations have shown that the transition state is stabilized by a non-classical hydrogen bond between the carbonyl oxygen and one of the C-H bonds of the TADOOH phenyl groups. In addition to the studies, the well-known Sharpless protocol for asymmetric epoxidation of allylic alcohols was adapted in the enantioselective oxidation of boronic esters. By replacing the tartaric ester-derived, commonly used in the Sharpless experiments, for (-)-ephedrine moderate selectivity was observed with pinacol 1-phenylethyl boronate. Further investigations showed that the presence of Ti (IV) was not necessary, and (-)-ephedrine was responsible for the activation and chiral induction in this reaction.

microssomas hepático de humanos (HLMs) e biotransformação empregando fungos. Anteriormente aos estudos de biotransformação e metabolismo in vitro, todos os métodos propostos foram validados e os resultados corroboraram de acordo com os guiais oficiais. Inicialmente foi desenvolvido um método para determinação simultânea da OXC e os enantiômeros de seu metabólito em meio de cultura empregando a eletroforese capilar. A separação foi realizada utilizando como eletrólito de análise uma mistura da ?-ciclodextrina fosfatada (P-?-CD) 1% (m/v) como seletor quiral em solução tampão tris-fosfato 10 mmol L-1 pH 2,5. O comprimento efetivo do capilar foi 20 cm, a tensão aplicada foi de ?20 kV e a temperatura de análise foi de 15° C. Para esse método, nenhuma técnica miniaturizada de preparação de amostra foi efetiva na extração desses analitos do meio de cultura. Portanto, optou-se por utilizar extração líquidolíquido empregando metil-terc-butil éter como solvente extrator. Os estudos de biotransformação demonstraram enantiosseletividade na formação da licarbazepina (LIC) a partir da OXC para duas espécies de fungos. A espécie Glomerella cingulata (VA1), biotransformou com 100% de fração enantiomérica (fe) o enantiômero (S)-(+)- LIC enquanto que a espécie Beuveria bassiana (ATCC 7159) metabolizou com fe de 79% o enantiômero (S)-(+)-LIC. Um outro método empregando a eletroforese capilar também foi desenvolvido neste trabalho. Este novo método foi empregado para a análise enantiosseletiva dos metabólitos da diHTBZ após o procedimento de metabolismo in vitro empregando microssomas hepático de humanos para o fármaco TBZ e também foi utilizado para análise dos metabólitos diHTBZ após o procedimento de biotransformação da TBZ empregando fungos. Neste método de EC foi utilizada como eletrólito de análise a carboximetil-?-ciclodextrina (CM-?-CD) 1% (m/v) como seletor quiral adicionada em solução tampão tris-fosfato 80 mmol L-1 pH 2,5. O comprimento efetivo do capilar correspondeu a 20 cm e a tensão aplicada foi de +15 kV. A temperatura de análise foi de 15° C. Entre as técnicas miniaturizadas de preparação de amostras avaliadas para extração destes metabólitos diHTBZ tanto em meio microssomal quanto em meio de cultura líquido, a DLLME foi escolhida. Para tanto, utilizando a matriz de meio microssomal (para aplicação dos estudos de metabolismo in vitro da TBZ) foi empregado 75 ?L de diclorometano como solvente extrator e 150 ?L de acetona como solvente dispersor. Os estudos de metabolismo in vitro demonstraram que o perfil cinético do metabolismo da TBZ corresponde a um comportamento de inibição pelo substrato e trata-se de um metabolismo diastereo- e enantiosseletivo. Estes estudos também demonstraram que os enantiômeros dos diastereoisômeros diHTBZ foram catalisados principalmente pela CYP2C19 e o clearance predito sugere que o metabolismo pelo fígado é a principal via para a eliminação da TBZ. Já, nos estudos de biotransformação com fungos para a TBZ, o método por CE foi utilizado e, assim como para o meio microssomal, as técnicas de microextração foram avaliadas. Novamente, foi escolhida a técnica DLLME como técnica de extração, e também foi utilizado 75 ?L de diclorometano como solvente extrator e 150 ?L de acetona como solvente dispersor. Os estudos preliminares de biotransformação da TBZ demonstraram diastereoisomerismo para todos os fungos avaliados, e, adicionalmente, para algumas espécies de fungos, houve também enantiosseletividade na formação dos isômeros. O fungo Chaetomiun globusum (VR10) metabolizou ambos isômeros da diHTBZ, sendo que a produção dos metabólitos foi diastereosseletiva para a formação majoritária do estereoisômero trans-diHTBZ e enantiosseletividade somente na produção do estereoisômero cisdiHTBZ. As espécies Glomerella cingulata (VA1), Mucor rouxii, e Beuveria bassiana (ATCC 7159), metabolizaram diastereoisomericamente e também enantiosseletivamente ambos metabólitos da diHTBZ, sendo que o fungo da espécie Mucor rouxii apresentou um perfil de metabolização bem interessante, com a formação majoritária dos enantiômeros (E1) dos diastereoisômeros cis- e trans- e formação majoritária do metabólito trans-diHTBZ. Os resultados apresentados nesse trabalho demonstraram que somente a DLLME foi efetiva na extração da TBZ em meio microssomal e em meio de cultura. Para analitos com características bastante básicas, como é o caso da OXC, as demais técnicas de microextração avaliadas não foram eficientes nas condições de análise empregadas nesse estudo devido principalmente à dificuldade de manter estes analitos na forma molecular. Porém, a importância deste trabalho recai sobre os resultados obtidos a partir da aplicação dos estudos estereosseletivos de biotransformação com fungos de ambos os fármacos e, principalmente, nos resultados obtidos do metabolismo in vitro da TBZ que corroboram com dados in vivo da literatura e traz novas informações a respeito do metabolismo deste fármaco / Nowadays miniaturized extraction techniques are widely used in many sectors of analytical chemistry because they present several advantages such as: the ability to extract analytes in levels of trace employing minimal or none amounts of organic solvents; facility of automation and speed in the extraction procedure. New methodologies with the aim of producing pure enantiomers of drugs marketed as racemates are also very promising. In this context, this study aimed to evaluate the miniaturized sample preparation techniques, Solid Phase Microextraction (SPME), Hollow Fiber Liquid Phase Microextraction (HF-LPME) and Dispersive Liquid-Liquid Microextraction (DLLME) in extraction of drugs and their metabolites: oxcarbazepine (OXC) and tetrabenazine (TBZ) from complex matrices such as microsomal medium and liquid culture medium for subsequent application in stereoselective in vitro metabolism using human liver microsomes (HLMs) and in biotransformation studies employing fungi as catalytic agent. Prior to the biotransformation and the in vitro metabolism studies, all the proposed methods were validated and the results were in agreement with the official guidelines. Initially, an enantioselective capillary electrophoresis method was developed for the simultaneous determination of OXC and its metabolites in liquid culture medium. The chiral separation was carried out using phosphated ?-cyclodextrin (P-?-CD) 1% (w/v) as the chiral selector in tris-phosphate 10 mmol L-1 pH 2.5 buffer solution. The effective length of the capillary was 20 cm, the applied voltage was ?20 kV and the temperature of analysis was 15 °C. For this method, no miniaturized sample preparation technique was effective in extracting these analytes from the culture medium. Therefore, liquid-liquid extraction using methyl tert-butyl ether as solvent extractor as employed. The biotransformation studies showed enantioselectivity in the formation of licarbazepine (LIC) by two fungus species. The specie Glomerella cingulata (VA1) biotransformed OXC with 100% of enantiomeric fraction (EF) for the (S)-(+)-LIC enantiomer while the fungus Beuveria bassiana (ATCC 7159) metabolized with EF of 79% for the (S)-(+)-LIC enantiomer. Next, another method by capillary electrophoresis was also developed in this work. This new method was employed for the enantioselective analysis of diHTBZ metabolites after in vitro microsomal metabolism of the drug TBZ. Additionally, this method was used to analyze the diHTBZ metabolites after TBZ biotransformation by fungi. The chiral separation of diHTBZ metabolites was performed by using carboxymethyl-?-cyclodextrin (CM-?-CD) 1% (w/v) as the chiral selector added to trisphosphate buffer solution 80 mmol L-1 pH 2.5. The effective length of the capillary was 20 cm and the applied voltage was +15 kV. The analysis temperature was 15 °C. Among the miniaturized sample preparation techniques evaluated for the extraction of diHTBZ metabolites from both matrices, human liver microsomal and in liquid culture medium, DLLME showed to be the most adequate. Therefore, using microsomal medium as matrix 75 ?L dichloromethane as solvent extractor and 150 ?L acetone as disperser solvent was used. The in vitro metabolism of TBZ showed a kinetic profile of inhibition by substrate and demonstrated a diastereo- and enantioselective metabolism. These studies showed also that the enantiomers of the diastereomers of the diHTBZ were catalyzed mainly by CYP2C19 and the predicted clearance suggests that the metabolism by the liver is the major pathway for the elimination of TBZ. For the last, for fungal biotransformation studies with TBZ, 75 ?L was used as extracting solvent of dichloromethane and 150 ?L acetone as solvent disperser for the DDLME procedure. Preliminary biotransformation studies TBZ demonstrated a diastereoisomerism for all evaluated fungi, and additionally for some species of fungi, showed enantioselectivity in the formation of isomers. The fungus Chaetomiun globusum (VR10) metabolized both isomers of diHTBZ, and the production of metabolites was diastereoselective with majority formation of the trans-stereoisomer diHTBZ and enantioselectivity only in the production of cis-stereoisomer diHTBZ. The species Glomerella cingulata (VA1), Mucor rouxii, and Beuveria bassiana (ATCC 7159), metabolized diastereomerically and also enantiosselectivelly both metabolites of diHTBZ. The fungus Mucor rouxii showed an interesting biotransformation profile, with the majority training enantiomers (E1) of cis- and trans- diastereoisomers and majority formation of trans-diHTBZ metabolite. The results presented in this study showed that only DLLME was effective in extracting the TBZ from microsomal and liquid culture medium. For analytes with very basic features such as the OXC, the other evaluated microextraction techniques were not effective under the conditions employed in this study due mainly to the difficulty of keeping these analytes in the molecular form.

The research presented herein is concerned with the exploration of the rhodium catalysed addition of organoboron reagents. Chapter 1 firstly introduces the area of organoboron reagents, focussing on the applications of potassium alkenyl trifluoroborate reagents. Secondly, an extensive discussion of the rhodium catalysed conjugate addition of organboron reagents demonstrates its utility as a key coupling step in recent syntheses. Chapter 2 describes synthetic methods towards alkenylboron reagents and describes the synthesis of functionalised and enantiopure alkenyl trifluoroborate salts. Chapter 3 discusses the rhodium catalysed addition of potassium alkenyl trifluoroborate salts to α,β-unsaturated compounds. A gas chromatography study addresses issues concerning protodeboronation and highlights the potential for olefin transposition. A new rhodium catalysed olefin transposition reaction has been thoroughly investigated and applied using the synthesised potassium alkenyl trifluoroborate salts. Chapter 4 describes the synthesis of biologically relevant, enantiopure dihydropyranones for use as acceptors in the rhodium catalysed conjugate addition reaction. The hetero-Diels-Alder reaction is employed to synthesise the dihydropyranones. Rhodium catalysed conjugate addition of arylboronic acids and potassium alkenyl trifluoroborates is utilised to concisely assemble late stage intermediates of natural products including diospongin B. Chapter 5 describes the synthesis and characterisation of the compounds discussed in chapters 2, 3 and 4.

microssomas hepático de humanos (HLMs) e biotransformação empregando fungos. Anteriormente aos estudos de biotransformação e metabolismo in vitro, todos os métodos propostos foram validados e os resultados corroboraram de acordo com os guiais oficiais. Inicialmente foi desenvolvido um método para determinação simultânea da OXC e os enantiômeros de seu metabólito em meio de cultura empregando a eletroforese capilar. A separação foi realizada utilizando como eletrólito de análise uma mistura da ?-ciclodextrina fosfatada (P-?-CD) 1% (m/v) como seletor quiral em solução tampão tris-fosfato 10 mmol L-1 pH 2,5. O comprimento efetivo do capilar foi 20 cm, a tensão aplicada foi de ?20 kV e a temperatura de análise foi de 15° C. Para esse método, nenhuma técnica miniaturizada de preparação de amostra foi efetiva na extração desses analitos do meio de cultura. Portanto, optou-se por utilizar extração líquidolíquido empregando metil-terc-butil éter como solvente extrator. Os estudos de biotransformação demonstraram enantiosseletividade na formação da licarbazepina (LIC) a partir da OXC para duas espécies de fungos. A espécie Glomerella cingulata (VA1), biotransformou com 100% de fração enantiomérica (fe) o enantiômero (S)-(+)- LIC enquanto que a espécie Beuveria bassiana (ATCC 7159) metabolizou com fe de 79% o enantiômero (S)-(+)-LIC. Um outro método empregando a eletroforese capilar também foi desenvolvido neste trabalho. Este novo método foi empregado para a análise enantiosseletiva dos metabólitos da diHTBZ após o procedimento de metabolismo in vitro empregando microssomas hepático de humanos para o fármaco TBZ e também foi utilizado para análise dos metabólitos diHTBZ após o procedimento de biotransformação da TBZ empregando fungos. Neste método de EC foi utilizada como eletrólito de análise a carboximetil-?-ciclodextrina (CM-?-CD) 1% (m/v) como seletor quiral adicionada em solução tampão tris-fosfato 80 mmol L-1 pH 2,5. O comprimento efetivo do capilar correspondeu a 20 cm e a tensão aplicada foi de +15 kV. A temperatura de análise foi de 15° C. Entre as técnicas miniaturizadas de preparação de amostras avaliadas para extração destes metabólitos diHTBZ tanto em meio microssomal quanto em meio de cultura líquido, a DLLME foi escolhida. Para tanto, utilizando a matriz de meio microssomal (para aplicação dos estudos de metabolismo in vitro da TBZ) foi empregado 75 ?L de diclorometano como solvente extrator e 150 ?L de acetona como solvente dispersor. Os estudos de metabolismo in vitro demonstraram que o perfil cinético do metabolismo da TBZ corresponde a um comportamento de inibição pelo substrato e trata-se de um metabolismo diastereo- e enantiosseletivo. Estes estudos também demonstraram que os enantiômeros dos diastereoisômeros diHTBZ foram catalisados principalmente pela CYP2C19 e o clearance predito sugere que o metabolismo pelo fígado é a principal via para a eliminação da TBZ. Já, nos estudos de biotransformação com fungos para a TBZ, o método por CE foi utilizado e, assim como para o meio microssomal, as técnicas de microextração foram avaliadas. Novamente, foi escolhida a técnica DLLME como técnica de extração, e também foi utilizado 75 ?L de diclorometano como solvente extrator e 150 ?L de acetona como solvente dispersor. Os estudos preliminares de biotransformação da TBZ demonstraram diastereoisomerismo para todos os fungos avaliados, e, adicionalmente, para algumas espécies de fungos, houve também enantiosseletividade na formação dos isômeros. O fungo Chaetomiun globusum (VR10) metabolizou ambos isômeros da diHTBZ, sendo que a produção dos metabólitos foi diastereosseletiva para a formação majoritária do estereoisômero trans-diHTBZ e enantiosseletividade somente na produção do estereoisômero cisdiHTBZ. As espécies Glomerella cingulata (VA1), Mucor rouxii, e Beuveria bassiana (ATCC 7159), metabolizaram diastereoisomericamente e também enantiosseletivamente ambos metabólitos da diHTBZ, sendo que o fungo da espécie Mucor rouxii apresentou um perfil de metabolização bem interessante, com a formação majoritária dos enantiômeros (E1) dos diastereoisômeros cis- e trans- e formação majoritária do metabólito trans-diHTBZ. Os resultados apresentados nesse trabalho demonstraram que somente a DLLME foi efetiva na extração da TBZ em meio microssomal e em meio de cultura. Para analitos com características bastante básicas, como é o caso da OXC, as demais técnicas de microextração avaliadas não foram eficientes nas condições de análise empregadas nesse estudo devido principalmente à dificuldade de manter estes analitos na forma molecular. Porém, a importância deste trabalho recai sobre os resultados obtidos a partir da aplicação dos estudos estereosseletivos de biotransformação com fungos de ambos os fármacos e, principalmente, nos resultados obtidos do metabolismo in vitro da TBZ que corroboram com dados in vivo da literatura e traz novas informações a respeito do metabolismo deste fármaco / Nowadays miniaturized extraction techniques are widely used in many sectors of analytical chemistry because they present several advantages such as: the ability to extract analytes in levels of trace employing minimal or none amounts of organic solvents; facility of automation and speed in the extraction procedure. New methodologies with the aim of producing pure enantiomers of drugs marketed as racemates are also very promising. In this context, this study aimed to evaluate the miniaturized sample preparation techniques, Solid Phase Microextraction (SPME), Hollow Fiber Liquid Phase Microextraction (HF-LPME) and Dispersive Liquid-Liquid Microextraction (DLLME) in extraction of drugs and their metabolites: oxcarbazepine (OXC) and tetrabenazine (TBZ) from complex matrices such as microsomal medium and liquid culture medium for subsequent application in stereoselective in vitro metabolism using human liver microsomes (HLMs) and in biotransformation studies employing fungi as catalytic agent. Prior to the biotransformation and the in vitro metabolism studies, all the proposed methods were validated and the results were in agreement with the official guidelines. Initially, an enantioselective capillary electrophoresis method was developed for the simultaneous determination of OXC and its metabolites in liquid culture medium. The chiral separation was carried out using phosphated ?-cyclodextrin (P-?-CD) 1% (w/v) as the chiral selector in tris-phosphate 10 mmol L-1 pH 2.5 buffer solution. The effective length of the capillary was 20 cm, the applied voltage was ?20 kV and the temperature of analysis was 15 °C. For this method, no miniaturized sample preparation technique was effective in extracting these analytes from the culture medium. Therefore, liquid-liquid extraction using methyl tert-butyl ether as solvent extractor as employed. The biotransformation studies showed enantioselectivity in the formation of licarbazepine (LIC) by two fungus species. The specie Glomerella cingulata (VA1) biotransformed OXC with 100% of enantiomeric fraction (EF) for the (S)-(+)-LIC enantiomer while the fungus Beuveria bassiana (ATCC 7159) metabolized with EF of 79% for the (S)-(+)-LIC enantiomer. Next, another method by capillary electrophoresis was also developed in this work. This new method was employed for the enantioselective analysis of diHTBZ metabolites after in vitro microsomal metabolism of the drug TBZ. Additionally, this method was used to analyze the diHTBZ metabolites after TBZ biotransformation by fungi. The chiral separation of diHTBZ metabolites was performed by using carboxymethyl-?-cyclodextrin (CM-?-CD) 1% (w/v) as the chiral selector added to trisphosphate buffer solution 80 mmol L-1 pH 2.5. The effective length of the capillary was 20 cm and the applied voltage was +15 kV. The analysis temperature was 15 °C. Among the miniaturized sample preparation techniques evaluated for the extraction of diHTBZ metabolites from both matrices, human liver microsomal and in liquid culture medium, DLLME showed to be the most adequate. Therefore, using microsomal medium as matrix 75 ?L dichloromethane as solvent extractor and 150 ?L acetone as disperser solvent was used. The in vitro metabolism of TBZ showed a kinetic profile of inhibition by substrate and demonstrated a diastereo- and enantioselective metabolism. These studies showed also that the enantiomers of the diastereomers of the diHTBZ were catalyzed mainly by CYP2C19 and the predicted clearance suggests that the metabolism by the liver is the major pathway for the elimination of TBZ. For the last, for fungal biotransformation studies with TBZ, 75 ?L was used as extracting solvent of dichloromethane and 150 ?L acetone as solvent disperser for the DDLME procedure. Preliminary biotransformation studies TBZ demonstrated a diastereoisomerism for all evaluated fungi, and additionally for some species of fungi, showed enantioselectivity in the formation of isomers. The fungus Chaetomiun globusum (VR10) metabolized both isomers of diHTBZ, and the production of metabolites was diastereoselective with majority formation of the trans-stereoisomer diHTBZ and enantioselectivity only in the production of cis-stereoisomer diHTBZ. The species Glomerella cingulata (VA1), Mucor rouxii, and Beuveria bassiana (ATCC 7159), metabolized diastereomerically and also enantiosselectivelly both metabolites of diHTBZ. The fungus Mucor rouxii showed an interesting biotransformation profile, with the majority training enantiomers (E1) of cis- and trans- diastereoisomers and majority formation of trans-diHTBZ metabolite. The results presented in this study showed that only DLLME was effective in extracting the TBZ from microsomal and liquid culture medium. For analytes with very basic features such as the OXC, the other evaluated microextraction techniques were not effective under the conditions employed in this study due mainly to the difficulty of keeping these analytes in the molecular form.

A hidroxicloroquina (HCQ) é um importante fármaco quiral usado, principalmente, no tratamento de artrite reumatóide, lupus eritematoso sistêmico e malária e cujas propriedades farmacocinéticas e farmacodinâmicas são estereosseletivas. Em relação às propriedades farmacocinéticas, alguns estudos prévios indicam que o metabolismo estereosseletivo parece ser função da espécie estudada, o que implica na necessidade de métodos seletivos para a determinação de seus enantiômeros em materiais biológicos. Assim, propôs-se o desenvolvimento e a validação de métodos para análise dos enantiômeros do fármaco inalterado e de seus principais metabólitos em frações microssomais de homogeneizados de fígado de ratos e camundongos. Para tanto foram empregadas as técnicas de eletroforese capilar (CE) e de cromatografia líquida de alta eficiência (HPLC). Inicialmente foi desenvolvido um método por HPLC, em uma etapa, para a quantificação dos enantiômeros de dois metabólitos da HCQ, desetilcloroquina (DCQ) e desetilhidroxicloroquina (DHCQ) em microssomas de fígado de ratos e camundongos. A separação foi efetuada utilizando-se a coluna Chiralpak AD-RH e hexano:isopropanol (92:8, v/v) acrescido de 0,1% de dietilamina como fase móvel. O procedimento de extração líquido-líquido foi utilizado para a preparação das amostras. A metodologia desenvolvida resultou na completa resolução dos enantiômeros da HCQ, DCQ e DHCQ e pode ser considerada adequada, visto que os parâmetros de validação mostraram valores dentro dos limites exigidos na literatura. O segundo método desenvolvido permitiu a quantificação dos enantiômeros dos três metabólitos da HCQ: DCQ, DHCQ e bisdesetilcloroquina (BDCQ) em microssomas de fígado de camundongos. A separação foi efetuada utilizando-se um tubo capilar de sílica fundida e solução do eletrólito tris(hidroximetil)aminometano 100 mmol/L, ajustada a pH 9,0 com ácido fosfórico e acrescida de 1% (m/v) de β –CD - sulfatada e 30 mmol/L de β –CD - hidroxipropilada. O procedimento de extração líquido-líquido foi eficiente para remover interferentes e os parâmetros de validação mostraram valores dentro dos limites exigidos na literatura. Os métodos desenvolvidos foram aplicados no estudo in vitro do metabolismo da HCQ em frações microssomais de fígado dos animais, verificando-se que o principal metabólito formado é o (-)-(R)-DHCQ, para ambas espécies estudadas. / Hydroxychloroquine (HCQ) is an important chiral drug used specially in the treatment of rheumatoid arthritis, systemic lupus erythematosus and malaria, with stereoselective pharmacokinetic and pharmacodinamic properties. Concerning these properties, some previous studies indicate that the stereoselective metabolism seems to be a function of the studied species, therefore selective methods are required for the determination of its enantiomers in biological matrix. Thus, the present work reports the development and validation of methods for the analysis of the enantiomers of HCQ and its main metabolites in microsomal fraction of rats and mice liver homogenates. Capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) were used for this purpose. Initially, a one-step HPLC method was developed for the quantification of the enantiomers of two HCQ metabolites, desethylchloroquine (DCQ) and desethylhydroxychloroquine (DHCQ) in microsomal fraction of rats and mice liver homogenates. The separation was performed on a Chiralpak AD-RH column using hexane:isopropanol (92:8, v/v) plus 0.1% diethylamine as the mobile phase. Liquid-liquid extraction procedure was used for sample preparation. The developed methodology resulted in the complete resolution of HCQ, DCQ and DHCQ enantiomers and can be considered suitable because the validation parameters are in accordance with the limits established in the literature. The second developed method allowed the quantification of the enantiomers of the three HCQ metabolites, DCQ, DHCQ and bisdesethylchloroquine (BDCQ) in microsomal fraction of mice liver homogenates. The separation was performed using a fused-silica capillary tube and tris (hydroxymethyl) aminometane 100 mmol/L electrolyte solution, adjusted at pH 9.0 with phosphoric acid, containing 1% (w/v) sulfated- β -CD and 30 mmol/L hydroxypropyl- β -CD. The liquid-liquid extraction procedure was efficient to remove interferents and the validation parameters showed values within accordance to the literature. The developed methods were applied in the in vitro metabolism study of HCQ in microsomal fractions of the liver of the animals and it was verified that the main metabolite formed is (-)-(R)-DHCQ for both animal species studied.

No description available.

The synthesis of enantiomerically pure compounds is of vital importance. Most biologically active natural products are chiral and require asymmetric synthesis, chiral resolution, or the use of naturally chiral starting materials for their preparation. Organocatalytic enantioselective reaction methodology is a continuously growing area in organic chemistry. The use of organocatalysts as a potentially environmentally friendly alternative to metal catalysts is appealing to the pharmaceutical industry. In this dissertation an enantioselective Mannich reaction using an organocatalyst was investigated. The reaction was between a ß-keto ester and an imine electrophile catalyzed by vaulted biphenanthrol (VAPOL) phosphoric acid. The reaction resulted in products with high yields, but low to moderate enantioselectivity and diastereoselectivity. The development of the first Brønsted acid-catalyzed desymmetrization of meso-aziridines was also investigated. This is one of the first instances where a phosphoric acid has been used to catalyze a reaction that did not involve an imine. It was shown that the chiral VAPOL phosphoric acid was an excellent catalyst for the reaction resulting in high yields and enantioselectivities for the chiral ring opened products. It was also shown, for the first time, that a vaulted binaphthol (VANOL) phosphoric acid can also catalyze the ring-opening of meso-aziridines with comparable results to the VAPOL phosphoric acid in some cases. Mechanistic NMR studies were used to probe the reaction, and it is believed that evidence leads one to conclude that a unique mechanism for phosphoric acid-catalysis is followed. The products that can be obtained from this reaction, 1,2-diamines, are of high value for synthetic chemists. They have been used as chiral auxiliaries, ligands, and precursors to natural products.

The development of enantioselective reaction methodology has been at the forefront of research in both academic and industrial research laboratories due to the importance of chiral molecules in biological systems. An emerging area of research in the development of enantioselective reaction methodology has been the development of organocatalytic reactions. Organocatalysis, the use of small, chiral organic molecules as catalysts, has the advantage over traditional Lewis acid catalysis in that the reactions in general produce less toxic by-products. One recent breakthrough in the development of enantioselective methodology has been the development of chiral phosphoric acids as organocatalysts. Chiral phosphoric acids have been shown to be excellent catalysts for a wide variety of reactions. In this thesis chiral phosphoric acid-catalyzed enantioselective reaction methodologies have been developed for the addition of sulfonamides and indoles to imines. The development of Bronsted acid-catalyzed amidation of imines allows for an expedient route for the synthesis of N,N-aminals, which have been incorporated into a wide variety of biologically active compounds. Initial studies were undertaken to determine the practicality of a Bronsted acid-catalyzed method for the addition of amides to N-Boc protected imines. Over 20 achiral Bronsted acids were screened, and it was found that phenylphosphinic acid and trifluoromethanesulfinimide were both excellent catalysts for the addition of amides to a variety of imines giving the respective products in excellent yield. The methodology was extended to the development of an enantioselective method for the addition of sulfonamides to imines. It was found that a chiral phosphoric acid derived from the VAPOL ligand was suitable for this purpose. The developed methodology is capable of tolerating a wide variety of functional groups allowing for the preparation of the N, N-aminal products in excellent yield and enantioselectivities. An enantioselective phosphoric acid-catalyzed aza-Friedel-Crafts reaction between N-benzylindoles derivatives and N-benzoyl protected imines has been developed. A catalyst derived from the BINOL backbone was found to be the optimum catalyst for the enantioselective transformation. The developed methodology was capable of tolerating a wide variety of functional groups and provides an expedient route for the synthesis of chiral 3-indolylmethanamines.

Abstract not available

[Formulae and special characters can only be approximated here. Please see the pdf version of the Abstract for an accurate reproduction.] The kinetics for outer-sphere electron transfer between a series of cobalt(II) poly-aza cage ligand complexes and the iron(III) sarcophagine-type hexa-aza cage complex, [Fe(sar)]3+ (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane), in aqueous solution have been investigated and the Marcus correlation is used to deduce the electron self-exchange rate constant for the [Fe(sar)]3+/2+ couple from these cross-reactions. The deduced electron self-exchange rate constant is in relatively good agreement with the experimentally determined rate constant (k ex calc = 4 ´ 10 5 M -1 s -1 ; k ex obs = 8 ´ 10 5 M -1 s -1 ). The successful application of the Marcus correlation to the electron transfer reactions of the Fe cage complex is consistent with the trend for the Co, Mn, Ni and Ru cage complexes which all follow the pattern of outer-sphere electron transfer reactivity expected from the Marcus-Hush formalism. A comparison of predictions based on the Marcus correlation with the experimentally determined kinetics of an extended series of cross reactions involving cobalt cage complexes with low-spin-high-spin cobalt(III)/(II) couples shows that electron transfer reactions involving large spin changes at the metal centre are not necessarily anomalous in the context of the adiabatic Marcus-Hush formalism. The results of this study also show that for suitable systems, the Marcus correlation can be used to reliably calculate the rates of outer-sphere electron transfer cross-reactions, with reaction free-energy changes spanning the range -6 to -41 kJ mol -1 and many different combinations of initial electronic configurations. Together, these results provide a coherent and internally consistent set of experimental data in support of the Marcus-Hush formalism for outer-sphere electron transfer. The results with the caged metal-ion systems also highlight the special nature of the mechanism of electron transfer in reactions of metal-aqua ions. ¶ A new range of symmetrically disubstituted hexa-aza sarcophagine-type cage ligand complexes are prepared in this study by the base-catalysed co-condensation of formaldehyde and a-methylene aliphatic aldehydes with cobalt(III) tris(1,2-diamine) precursors in acetonitrile solution. Encapsulation reactions based on the condensation of the weak carbon di-acids propanal and decanal with formaldehyde and the cobalt(III) tris(1,2-diamine) precursors, [Co(en)3 ] 3+ (en = 1,2-ethanediamine) and D-lel3 -[Co((R, R)-chxn)3 ] 3+ (chxn = 1,2-cyclohexanediamine), yield unsaturated cobalt(III) cage complexes with an endo-cyclic imine function in each cap. The Co III -coordinated endo-cyclic imine units of the cage ligands are reactive electrophiles that are readily reduced by the BH4 - ion to give the corresponding symmetrically di-substituted hexaamine macrobicyclic cage ligands. The nitromethane carbanion is also shown to add at the endo-cyclic imine function to yield a novel nitromethylated cage ligand complex. The latter reaction introduces a new method for the regioselective functionalisation of cage ligands at sites removed from the more commonly substituted bridgehead positions. The capping of cobalt(III) tris(1,2-diamine)-type complexes with weak CH-acids developed in this study introduces a new and more direct route to symmetrically di-substituted cage ligand complexes. ¶ A new range of cobalt(III) surfactant cage complexes, with linear octyl, dodecyl and hexadecyl hydrocarbon chains built directly into the bridgehead structure of the cage ligand, have been prepared by the base catalysed co-condensation of formaldehyde and long chain aliphatic aldehydes with the tripodal cobalt(III) hexaamine complex, [Co(sen)]3+ (sen = 4,4',4''-ethylidynetris(3-azabutan-1-amine)), in acetonitrile solution. Chiral surfactant cage complexes are obtained by capping reactions beginning with the optically pure L-[Co(sen)]3+ precursor complex. The cobalt(III) cage complexes with octyl to hexadecyl substituents are surface active and reduce the surface tension of water to levels approaching those of organic solvents. The dodecyl substituted cage complex forms micelles in aqueous solution when the concentration of cage complex is > 1 ´ 10 -3 mol dm -3 at 25 °C. The cobalt(III) cage head-group of these surfactants undergoes an electrochemically reversible one-electron reduction to the corresponding cobalt(II) cage complex. The reduction potential of the surfactant head group can be tuned to more positive potentials by replacing the bridgehead hydrocarbon chain substituent with an ether linked hydrocarbon chain. The cobalt(III) surfactant-cage complexes are biologically active and are lethal to the tapeworm Hymenolepis diminuta, and the vaginal parasites, Trichomonas vaginalis and Tritrichomonas foetus. The surfactant cage complexes also cause lysis in red-blood cell membranes at concentrations as low 10 -5 mol dm -3 . Their biological activity is linked to the high head-group charge (3+) and size which cause distortions in biological membranes when the membrane is treated with these molecules. The combination of the chemically reversible outer-sphere redox properties of the cobalt cage head-groups and the chirality of the head group introduces a new and possibly unique series of chiral surfactant coordination complexes which are also redox active. ¶ The chiral carboxylic-acid ionophore, lasalocid A, has been used to promote the selective supramolecular transport and extraction of cobalt(III) hexa-aza cage cations and related tripodal cobalt(III) complexes. The conjugate base anion of lasalocid A forms stoichiometric outer-sphere complexes with the cobalt(III) cage and tripod complexes. These outer-sphere complexes are highly lipophilic and partition strongly from water into a chloroform phase. The extraction of the dissymmetric cobalt(III) complexes by the chiral polyether anion is enantioselective for many systems and results in the partial resolution of initially racemic complexes in the aqueous phase. A strong structural preference was demonstrated by the ionophore for symmetrically disubstituted cobalt(III) hexa-aza cage cations with a D-absolute configuration of the ligand about the metal-ion and an R configuration of the coordinated secondary amine N-H groups. The lasalocid A anion was also shown to promote the transport of the complexes, intact, across a chloroform bulk-liquid membrane against an NH4 + concentration gradient. The transport of the cobalt(III) complexes was also enantioselective and resulted in partial resolution of the initially racemic aqueous phase. The most efficiently transported enantiomer of each complex was also the most efficiently extracted isomer in all systems examined, consistent with a transport process limited by interfacial diffusion. The magnitude of the enantiomer separation obtained in some systems was sufficient to indicate that lasalocid A mediated extraction and transport may become a practical method for the resolution of particular types of kinetically-inert chiral metal-amine complexes.