Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1992.

Abstract available in pdf file.

Abstract available in pdf file.

No description available.

During my research career in Prof. V.J.Hruby's laboratory I worked on two different projects. The first project, which was initiated by the author, was planned to serve the need of our laboratory for a novel method of peptide cyclization. This method was planned to use recent advances in Pd0-catalyzed asymmetric synthesis combined with the structural richness offered by the Baylis-Hillman chemistry which could open new ways to diverse areas of drug design, molecular immunology and chemotherapy. This approach would provide cyclic peptides featuring N-alkylated amino acids that would confer high resistance to degradation by proteases. Because of numerous synthetic problems imposed, this strategy was not of considerable current use in peptide synthesis, especially on solid supports. However, despite a substantial amount of effort invested, this method faced serious drawbacks such as multistep synthesis and side reactions when applied to solid supports. Moreover, recent introduction of microwave technology which has helped to solve a great number of problems has led to a renaissance in the classical lactam and thioester bond cyclizations which overshadowed our quest for a novel methodology. The second project was focused on application of 4-anilidopiperidines for the synthesis of chimeric bioactive peptides. It was an effort towards the development of novel analgesics with reduced toxicity and enhanced potency. This project linked small molecule and multimeric ligand designs that were ongoing in our laboratory at the time. Major accomplishments in this project were made possible by successful resolution of several research challenges. I was able to find a straightforward, convenient and economical approach for the synthesis of novel analogues on a solid support. These developments led to novel compounds which showed substantial increases in their binding affinity relative to corresponding opioid analogues. To illustrate, compounds PET25, 26, 27, 29, 30, 31, and 32 showed high bioactivity and sub-nanomolar binding affinity to opioid receptors. Most of the peptides generated in the second project are still being investigated for their biological activities by our colleagues at the Department of Pharmacology, but the results to date indicate that some highly potent novel compounds have been made.

Orientador: Fernando Antonio Santos Coelho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-17T04:53:06Z (GMT). No. of bitstreams: 1 Ferreira_BrunoRicardoVilacha_D.pdf: 6759229 bytes, checksum: 694bc9385b15888a01afa4ea8d62f945 (MD5) Previous issue date: 2010 / Resumo: Esse trabalho descreveu o uso de adutos de Morita-Baylis-Hillman como substratos para reações mediadas por paládio. Inicialmente, desenvolvemos uma estratégia eficiente para preparar a-benzilcetoesteres a partir de adutos de Morita-Baylis-Hillman. A reação de Mizoroki-Heck foi empregada nessa estratégia e esses compostos foram obtidos em elevados rendimentos e seletividades. Além disso, os paladaciclos de Nájera foram usados com sucesso pela primeira vez como catalisadores nessa reação. Em seguida, os derivados a-(4-hidroxibenzil)-b-cetoesteres obtidos dessa reação foram tratadas com um reagente de iodo hipervalente para fornecer novas espirocicloexadienonas em bons rendimentos (21- 60%). Inúmeros grupos funcionais mostraram ser toleráveis. As atividades biológicas contra bactérias Gram-positivas mostraram que esses compostos são mais ativos que a meticilina. A segunda parte desse trabalho reportou o uso de adutos de MBH em reações de ciclocarbonilação para sintetizar 3-alquenil-ftalídeos. Nesse método, o uso de grupos de proteção no grupo hidroxila não era necessário e as seletividades observadas foram acima de 95:05 E/Z. Quando os derivados de adutos de MBH-nitro o-halogenados foram utilizados, obtivemos indanonas e, neste caso, propomos que uma reação de Heck intramolecular e favorecida. Na sequência, os adutos de MBH foram tratados com o sistema Pd/norborneno para formar compostos policíclicos. Quando os ácidos borônicos foram utilizados, isolamos compostos em baixo rendimento a partir de um processo de arilação tandem. Na última parte dessa tese os adutos de MBH também foram empregados para preparar 4 fragrâncias. Essa estratégia direta e simples originou esses compostos em bom rendimento global (34-41%) / Abstract: This work described the use of the Morita-Baylis-Hillman adducts as substrates for palladium-mediated reactions. Initially, we have developed an efficient strategy to prepare a-benzyl-b-ketoesters from MBH adducts. This strategy was based on a Mizoroki-Heck reaction and the a-benzyl-b-ketoesters were obtained in high yields and selectivities. Moreover, Nàjerapalladacycles were successfully used for the first time as catalyst in this reaction. The a-(4-hydroxybenzyl)-b-ketoesters derivatives obtained in this reaction were treated with hypervalent iodine reagent to give new spirocyclohexadienones in good yields (21-60%). Several functional groups showed to be well-tolerated. Preliminary biological essays against Gram-positive bacteria showed that these compounds are more active than the meticiline. In the second part of this work we described the use of the MBH adducts in a cyclocarbonylation reaction to synthesize 3-alkenyl-phthalides. In this method no protecting group were necessary to the MBH secondary hydroxyl group and selectivities up to 95:5 E/Z were observed. On the other hand, when the o-halogenated nitro-MBH adducts derivatives were used we obtained indanones and this case an intramolecular Heck reaction seems to be favored. In the sequence the MBH adducts were treated with a Pd/norbornene system to form polycyclic compounds. When boronic acids were utilized, compounds from a tandem arylation process were isolated in low yield. In the last part of this thesis, the MBH adducts were used as substrates to the synthesis of 4 differents fragrances in three steps and overall yield ranging from 34-41% / Doutorado / Quimica Organica / Doutor em Quimica

Orientador: Fernando Antonio Santos Coelho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-26T02:39:26Z (GMT). No. of bitstreams: 1 Ullah_Hamid_D.pdf: 4284540 bytes, checksum: 3371acfc6c696bf069405b0e69378616 (MD5) Previous issue date: 2014 / Resumo: Esse trabalho de doutorado visou explorar o potencial sintetico da reacao de Morita-Baylis- Hillman (MBH) na preparacao de intermediarios sinteticos, que possam ser utilizados na sintese total de produtos naturais. Na primeira parte deste trabalho, realizamos estudos para a sintese total do alcaloide (})-Plicamina e de outros alcaloides, isolados de plantas da familia das Amaryllidaceae, estruturalmente semelhantes. Desenvolvemos uma nova abordagem sintetica para esse trabalho, que culminou com o estabelecimento de uma nova metodologia para a preparacao de ¿À-hidroxi-¿¿-amino esteres. A ozonolise, oximacao e subsequente reducao do aduto de Morita-Baylis-Hillman sililado, proveniente do bromopiperonal, forneceu um ¿À-hidroxi-¿¿-aminoester, com estereoquimica relativa anti, e elevada diastereosseletividade. Esse foi transformado em um intermediario avancado (¿À-hidroxi-¿¿-aminoester N-alquilado) para a sintese do alcaloide, ja que possui todos os grupos funcionais necessarios para atingir o alvo final. Na segunda parte desse trabalho, avaliamos o escopo da nova metodologia de sintese de ¿À-hidroxi-¿¿-aminoesteres. Essa metodologia, simples e direta, permitiu a preparacao de diferentes ¿À-hidroxi-¿¿-aminoesteres, com elevada diastereosseletividade em 4 etapas e bons rendimento globais. Esse e o primeiro exemplo de sintese ¿À-hidroxi-¿¿-aminoesteres, a partir de adutos de Morita-Baylis- Hillman (MBH) / Abstract: This work of doctorate explored the synthetic potential of Morita-Baylis-Hillman (MBH) reaction in the preparation of synthetic intermediates that could be utilized in the synthesis of natural products. In the first part of this work we performed studies towards the total synthesis of (±)-Plicamin and the other structurally related alkaloids, isolated from the plants of the Amaryllidaceae family. We developed a new synthetic approach, which culminated with the establishment of the new methodology for the preparation of â-hydroxy-á-amino esters. The ozonolysis, oxymation and subsequent reduction of the silylated Morita-Baylis-Hillman adduct, obtained from bromopiperonal, furnished a â-hydroxy-á-aminoester, with a relative stereochemistry anti, in high diastereoselectivity. This was transformed further to an intermediate (N-alkylated â-hydroxy-á-aminoester), which has almost all the necessary functional groups to allow the synthesis of the target alkaloid. In the second part of this work we evaluated the scope of the new methodology of the synthesis of â-hydroxy-á-aminoester. This simple and direct methodology allowed us the preparation of different â-hydroxy-á-aminoesters, with high diastereoselectivities, in four steps with good global yield. Additionally, this work demonstrates a first example the synthesis of â-hydroxy-á-aminoesters from the Morita-Baylis- Hillman (MBH) adducts / Doutorado / Quimica Organica / Doutor em Ciências

Orientador: Fernando Antonio Santos Coelho / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T14:15:24Z (GMT). No. of bitstreams: 1 Pirovani_RodrigoVezula_M.pdf: 4861337 bytes, checksum: 988b7727a8446980e41ff275bc8c0875 (MD5) Previous issue date: 2009 / Resumo: A (+)-Plicamina, um alcalóide que pertence à família Amaryllidaceae, foi isolado em 1999. Este alcalóide é o primeiro produto natural de sua classe com dois átomos de nitrogênio na sua estrutura. Esta nova estrutura química conduziu a criação de uma nova subclasse do grupo das Tazetinas. Como parte de um programa de pesquisa voltada para a síntese de produtos naturais e fármacos, descrevemos a síntese de uma isoquinolina funcionalizada para ser utilizada como um intermediário na síntese total racêmica da Plicamina. Dois diferentes métodos sintéticos foram testados, e alguns intermediários avançados foram preparados em rendimentos globais moderados. Na segunda parte deste trabalho, uma nova estratégia foi descrita para a síntese de polifuncionalizadas espirocicloexadienonas. Nossa estratégia foi baseada na associação de uma reacao Heck intermolecular entre um aduto de Morita-Baylis-Hillman e iodophenol usando como catalizador um paladaciclo Nájera. Assim, os a-hidroxibenzil-b-cetoésteres foram utilizados como substratos para uma oxidação fenólica mediada por composto de iodo hipervalente, obtendo as espirocicloexadienonas em duas etapas a partir dos adutos de MBH, com rendimento global de 20-40%. O padrão estrutural espiro está presente em vários produtos naturais biologicamente ativos, especialmente na classe dos alcalóides. / Abstract: The (+)-Plicamine, an alkaloid that belongs to the Amaryllidaceae family, was isolated in 1999. This alkaloid is the first natural product in its class having two nitrogen atoms in the structure. This unusual chemical structure led to the creation of a brand new subclass in the Tazetine Group. As part of a research program directed toward the synthesis of natural products and drugs, we describe the synthesis of a functionalized isoquinoline to be used as an intermediate in a shorter total synthesis of racemic Plicamine. Two different synthetic methods have been tested, and some advanced intermediates have been prepared in moderate overall yields. In the second part of this work, a new strategy for the synthesis of polyfunctionalized spirocyclohexadienones is described. Spiro arrangement is present in several biologically active natural products, especially in the alkaloid class. Our strategy was based on the association of a intermolecular Heck reaction between a Morita-Baylis-Hillman adduct and a iodophenol using a Najera palladacycle as catalyst. The a-hydroxybenzyl-b-ketoesters were used as substrates for a phenolic oxidation mediated by a hypervalent iodine compounds. Spirocyclohexadienones compounds were afforded in two steps from the MBH' adducts in 20-40% overall yield. / Mestrado / Quimica Organica / Mestre em Química

Orientador: Fernando Antonio Santos Coelho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-15T03:19:35Z (GMT). No. of bitstreams: 1 Abella_CarlosAlbertoMiranda_D.pdf: 8234084 bytes, checksum: 0320b741bad5e28b8ad206ec73935836 (MD5) Previous issue date: 2009 / Resumo:O capítulo 1 relata os intermediários atingidos visando à síntese do alcalóide (±)-8-a-etoxiprecrivelina. Obteve-se um intermediário com todos os grupos funcionais necessários para atingir o alvo. A adição de metilamina sobre o aduto de Morita-Baylis-Hillman sililado proveniente do bromopiperonal levou ao produto de adição syn com elevada diastereosseletividade que foi racionalizada através de cálculos teóricos. Através de uma mudança na rota sintética inicialmente proposta, foi possível inserir um álcool secundário necessário através de uma reação de ozonólise seguida de redução quimiosseletiva. Dada a ausência na literatura deste tipo de reação sobre olefinas de adutos de Morita-Baylis-Hillman com anéis aromáticos, realizaram-se testes com adutos possuindo diferentes demandas eletrônicas no anel aromático os quais foram obtidos na sua maioria com sucesso. O capítulo 2 descreve a aplicação de uma metodologia desenvolvida no nosso grupo de pesquisa visando a síntese de alcalóides indolizidínicos a partir de lactamas bicíclicas polifuncionalizadas. Estas últimas foram obtidas nas suas formas racêmicas e quiral. O aldeído quiral sintetizado não racemizou nas condições empregadas na síntese do aduto de Morita-Baylis-Hillman, o qual foi obtido de forma majoritária como anti. Os diastereoisômeros foram separados e o majoritário ciclizado para fornecer a lactama bicíclica. A primeira parte do capítulo 3 relata as tentativas de usar bases de Tröger como catalisadores na reação de Morita-Baylis-Hillman, as quais se mostraram infrutíferas. Na segunda parte do mesmo capítulo, o mecanismo de reação de formação de bases de Tröger foi estudado por ESI-MS usando tanto formaldeído como urotropina como fontes de metileno. Os intermediários chaves foram caracterizados via ESI-MS/MS e determinou-se que o mecanismo envolve uma seqüência de reações de substituição eletrofílica aromática / Abstract: Chapter 1 describes the intermediates obtained towards the total synthesis of (±)-8-a-ethoxyprecriwelline. An intermediate with all required functionalities was obtained in order to achieve the target. Methylamine addition on silylated Morita-Baylis-Hillman adduct obtained from bromopiperonal gave mostly the syn diastereoisomer which was rationalized by the use of theoretical calculations. By means of changing the original synthetic proposal, it was possible to introduce a necessary secondary alcohol through an ozonolysis reaction followed by chemoselective reduction. Since there was no evidence of this kind of reaction on olefin of Morita-Baylis-Hillman adducts with aromatic ring in the literature, some test were done with adducts having different electronic requirements on the aromatic ring, and most were successfully obtained. Chapter 2 shows the application of a methodology developed in our research group envisaging the synthesis of indolizidinic alkaloids from polyfunctionalized bicyclic lactams. The latter were obtained in its racemic and chiral form. The chiral aldehyde synthesized didn' t racemize in the conditions used in the synthesis of Morita-Baylis-Hillman adduct, which was obtained as the anti as the major diastereomer. Both diastereomers were separated and the major one was cyclized to produce the bicyclic lactam. The first part of chapter 3 tells the tentative of use of Tröger' s bases as catalyst in the reaction of Morita-Baylis-Hillman, which didn' t prove useful. In the second part of the same chapter, the mechanism of formation of Tröger' s bases was studied by ESI-MS using formaldehyde as well as urotropine as the source of methylene. Key intermediates were characterized by ESI-MS/MS and it was found that the mechanism involves a sequence of electrophilic aromatic substitution reaction / Doutorado / Quimica Organica / Doutor em Ciências

The natural product 2 crotonyloxymethyl-(4R,5R,6R)-4,5,6-trihydroxy-cyclohex-2-enone (COTC) was isolated from the microorganism Streptomyces griseosporeus in 1975. It was shown to exhibit 'cytotoxic and cancerostatic activity'. The simplified synthetic analogue 2-crotonyl-oxymethyl-cyclohex-2-enone (COMC) has been shown to exhibit potent anti tumour activity against murine and human tumours in cell culture. For several years, the Whitehead research group at the University of Manchester have focused on the synthesis of COTC and COMC analogues in an attempt to produce compounds with enhanced cytotoxicity. In this thesis, the syntheses of several polyfunctionalised cyclohexenones are described. These compounds are analogues of COTC and COMC which also bear structural resemblance to the antheminone and carvotacetone natural products. Initially, the syntheses of six novel compounds from the chiral pool starting material (-)-quinic acid are described. The first four synthetic steps of each sequence were carried out by slight modification of procedures previously reported by the Whitehead research group. As part of the synthetic strategy, the diastereoselective conjugate addition of carbon nucleophiles to several polyfunctionalised cyclohexenones was investigated. The cytotoxicity of four of the synthetic analogues towards A549 non small cell lung cancer cells was investigated by use of an MTT assay. Two of the analogues were found to be more cytotoxic then COMC. The most effective synthetic analogue had an IC50 value of 2.2 μM. This analogue was more cytotoxic than similar molecules that had previously been synthesised by members of the Whitehead research group. Based on the results of the MTT assay, another two analogues were designed and their synthesis from (-)-quinic acid is described. The cytotoxicity of these analogues has yet to be assessed. In summary, the general synthetic strategies developed in this thesis will provide easy access to new analogues of the natural products, enabling the development of new cytotoxic compounds.