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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Estudos sobre a síntese de furanoeliangolidos a partir da reação de Diels-Alder / Studies about synthesis of furanoheliangolies from Diels-Alder reaction

Susimaire Pedersoli 06 February 2006 (has links)
O objetivo deste trabalho foi iniciar o estudo de uma nova metodologia sintética para a obtenção do sistema 11-oxabiciclo[6.2.1]undecano, o esqueleto estrutural básico de uma classe de produtos naturais conhecidos como furanoeliangolidos. A abordagem sintética proposta envolveria a formação de um composto bicíclico através da reação de Diels-Alder com derivados de furano, seguida pela formação de um hexanel e, finalmente, ruptura de uma ligação central para formação do sistema macrocíclico. Além disso, a reação de Diels-Alder entre derivados de furano e acetileno dará origem a compostos que apresentam como esqueleto estrutural o sistema 7-oxabiciclo[2.2.1]heptano, que podem ser utilizados como material de partida para a síntese de diversos produtos naturais. Iniciamos este estudo com a reação de Diels-Alder entre o 3,4-dimetoxi-2-metil furano e o bromopropiolato de metila, onde foi obtido o produto 85, que após algumas modificações deu origem ao composto 92. Entretanto, após inúmeras tentativas não conseguimos transformar o composto 92 no triciclo desejado. Para evitar essas transformações que se mostraram problemáticas, resolvemos estudar a reação de Diels-Alder entre derivados de furano e benzoquinonas 2,5-dissubstituídas, que dará origem aos adutos devidamente funcionalizados para serem transformados no derivado do sistema 11-oxabiciclo [6.2.1]undecano. No entanto, após o estudo dessas reações de cicloadição, observamos que elas têm o equilíbrio fortemente deslocado no sentido dos materiais de partida. Por esse motivo, a continuidade desta metodologia sintética mostrou ser inviável. Iniciamos então, um estudo da reação de Diels-Alder entre os diverso derivados de furanos e acetilenos. Após o estudo dessas reações de Diels-Alder foi possível verificar que a maioria dos adutos derivados dos furanos é instável no meio reacional. Os melhores resultados obtidos nessas reações de Diels-Alder foram usando o acetilenodicarboxilato de dimetila como dienófilo. Os adutos obtidos são intermediários importantes e bem funcionalizados, que podem ser utilizados na continuidade do estudo de desenvolvimento de nova metodologia sintética para a obtenção do sistema 11-oxabiciclo[6.2.1]undecano / The aim of this work was to start the study of a new methodology to synthesize the 11-oxabicycle[6.2.1]undecane system, the main carbon skeleton of the furanoheliangolides. The proposed synthetic approach involves the preparation of a bicyclic compound through a Diels-Alder reaction with furan derivatives, followed by formation of a six membered ring and, finally, cleavage of the central bond to obtain of the macrocyclic system. The Diels-Alder reaction between furan and acetylene derivatives gives a compound with the 7-oxabicyclico[2.2.1]heptane system, that is a potential starting material for the synthesis of several natural products. We started this study with the Diels-Alder reaction between the 3,4-dimethoxy-2-methylfuran and methyl bromopropiolate, and obtained the product 85 that after some modifications furnished the compound 92. However, after various attempts we were unable to convert the compound 92 into the desired tricycle. We have then decided to study the Diels-Alder reaction between furan and 2,5-disubstituted benzoquinone derivatives, that could furnish the adducts properly functionalized to be transformed in the 11-oxabicyclico[6.2.1]undecane system. However, we observed that the equilibrium is strongly shifted towards the starting materials in these cycloaddition reactions. This methodology has thus showed to be impracticable. As a third alternative, we affected the study the Diels-Alder reaction between the furans derivatives and the acetylenes. The adducts obtained present 7-oxabicyclico[2.2.1]heptane system that could be used to synthesizes of structural skeleton of furanoheliangolide.
32

Návrh změny procesu výroby odlitků se zaměřením na zvýšení produktivity práce, kvality a úsporu nákladů / Suggestion of change in production process of castings with focus on increase of productivity of labour, quality and costs saving

Balcarová, Hana January 2009 (has links)
This diploma work is focused on evaluation of opportunities to improvement and modernization of production process of castings in company ŽĎAS a.s. As base are in theoretical part informations about business process management and change management (Deming's improvement cycle, theory of constraints, reengeneering, concept of quality management). Practical part analyses concrete opportunity to modernization of molding section and compares it with technology which is now used.
33

Sintese e atividade biologica de analogos furanicos da goniotalamina / Synthesis and biological activity of furan analogues of goniothalamin

Marquissolo, Cilene 07 July 2009 (has links)
Orientador: Ronaldo Aloise Pilli / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T13:10:56Z (GMT). No. of bitstreams: 1 Marquissolo_Cilene_M.pdf: 4919703 bytes, checksum: f834b50c778a98043d8f699e6b2947b9 (MD5) Previous issue date: 2009 / Resumo: Este trabalho tem como objetivo preparar análogos furânicos da goniotalamina 31, 32 e 33 em suas duas formas enantioméricas, utilizando-se a alilação catalítica e assimétrica nas condições de Keck e a reação de metátese de olefinas para fechamento de anel. Estes análogos foram obtidos em bons rendimentos e excelentes razões enantioméricas. Estes novos compostos foram submetidos a testes de atividade antiproliferativa frente a nove linhagens de células tumorais e a bioensaios in vitro contra a forma tripomastigota do Trypanosoma cruzi e contra a forma promastigota de Leishmania major e Leishmania brasiliensis. No que diz respeito à atividade antiproliferativa, exceto para as linhagens de melanoma e cólon, os compostos testados apresentaram maior potência do que o controle positivo, doxorrubicina. Adicionalmente, os compostos 31, 32 e 33 mostraram-se mais ativos que a goniotalamina (1), exceto para as linhagens de mama e ovário. Os bioensaios de citotoxicidade com células não infectadas (LLC-MK2) mostraram que os compostos apresentaram baixa citotoxicidade. Com relação à atividade tripanocida, embora o composto (S)-31 tenha se apresentado como o composto mais ativo, mostrou alta citotoxicidade em células não-infectadas. (S)-32 é o composto que apresenta atividade mais interessante contra T. cruzi, além do menor valor de citotoxicidade e alto índice de segurança. Para a atividade leishmanicida, o análogo (S)-31 apresentou-se como o composto mais ativo para ambas as espécies de Leishmania, mostrando-se cerca de 6,5 vezes mais ativo que o controle positivo para Leishmania brasiliensis e cerca de 14,6 vezes para Leishmania major. Os ensaios de citotoxicidade revelaram valores de concentração superiores aos valores de IC50, indicando baixa toxicidade. Para Leishmania brasiliensis e Leishmania major, (R)-31 e (S)-31 mostraram-se como os compostos mais ativos e apresentaram bons índices de segurança. O análogo 33 não apresentou atividade expressiva em nenhum dos testes realizados indicando que a presença do grupo nitro ligado ao anel furânico é de grande importância para as atividades biológicas avaliadas / Abstract: This work describes the preparation of furan analogues of goniothalamin (compounds 31, 32 and 33) in both enantiomeric forms through the utilization of Keck asymmetric allylation and ring-closing methatesis reaction. These analogues were prepared in good overall yield and excellent enantiomeric ratio. These novel compounds were evaluated as antiproliferative agents against a panel of nine cancer cell lines and in vitro bioassays against the tripomastigote form of Trypanosoma cruzi and promastigote form of Leishmania major and Leishmania brasiliensis. Compounds 31-33 were more potent than the positive control (doxorubicin) in the antiproliferative experiments, except for melanoma and colon cancer cells. Additionally compounds 31-33 were more active than goniothalamin (1), except for breast and ovary cancer cells. Regarding their tripanocidal activity, compound (S)-31 was shown to be very toxic to non-infected cells despite its being highly active. Compound (S)-32 was the most promising one against T. cruzi due to its low toxicity and high insurance level. As to the leishmanicidal activity, the analogue (S)-31 was shown to be the most active for both Leishmania species investigated being 6,5 times more active than the positive control for Leishmania brasiliensis and about 14,6 times for Leishmania major, The citotoxicity assays revealed low toxicity against non-infected cells. For Leishmania brasiliensis and Leishmania major (R)-31 and (S)-31 were shown to be more active one and also displayed the best insurance level. Analogue 33 did not display any significant biological activity in our assays indicating that the nitrofuran moiety is very important for the biological activities investigated / Mestrado / Quimica Organica / Mestre em Química
34

Résines thermodurcissables et nanocomposites époxydes renouvelables à base de furanne pour les applications de revêtement / Renewable furan-derived epoxy thermosets and nanocomposites for coating applications

Marotta, Angela 25 January 2019 (has links)
La recherche scientifique concernant les polymères biosourcés augmente rapidement pendant les dernières années, poussée par des croissantes préoccupations écologiques et économiques, ainsi que par l'incertitude sur la disponibilité future de ressources pétrochimiques limitées. Durabilité est un mot-clé de ce processus. Dans ce cadre, des produits respectueux de l'environnement, y compris des molécules et des additifs eco-compatibles, sont maintenant recherchés pour remplacer les polymères à base de pétrole par ceux dérivés de matières premières naturelles.Les résines époxydes sont des polymères thermodurcissables très polyvalents, extrêmement résistants à la corrosion, à l'humidité et aux produits chimiques, avec une bonne force d'adhérence à la plupart des matériaux et un faible retrait lors du durcissement. En raison de leurs températures de transition vitreuse élevées et de leur excellente résistance mécanique, les résines époxydes sont largement utilisées dans une large gamme d'applications, telles que l'électronique, les adhésifs structuraux, les composites pour l'aérospatiale et les revêtements protecteurs.Actuellement, plus des deux tiers des résines époxydes sont à base de diglycidyl éther de Bisphénol A. Dans cette industrie, la tendance à remplacer les matériaux dérivés du pétrole par des matériaux biosourcés est également liée à la nécessité de remplacer le bisphénol A (BPA), une molécule controversée, reconnu comme un perturbateur endocrinien et une substance reprotoxique. En particulier en application comme revêtement, l'utilisation de BPA présente un risque pour les utilisateurs d'aliments et de boissons conditionnés dans des récipients traités avec des résines époxydes. Les effets de la contamination du corps humain causée par le BPA sont le diabète, maladies cardiovasculaires, modification des enzymes hépatiques et les lésions de l'appareil reproducteur. Pour ces raisons, cette molécule a été interdite dans de nombreux pays pour la fabrication de produits pour enfants, ainsi qu'en France et au Canada de tous les matériaux en contact direct avec les aliments. La nécessité de développer de nouvelles résines époxy est donc urgente.Les molécules bio-dérivées développées depuis maintenant présentent des structures chimiques les plus diverses, chacune d’elles produisant des propriétés différentes des polymères finaux. Les caractéristiques particulières des résines époxydes sont liées à la structure aromatique de ses composants. Les molécules aromatiques présentes dans les matières premières naturelles proviennent principalement de la lignine, un des principaux constituants des parois cellulaires naturelles. Cependant, pour extraire des fragments aromatiques de la lignine, des procédés difficiles et consommateurs d’énergie sont nécessaires. Un substitut précieux des molécules aromatiques, facilement récupérables du glucose, sont les molécules furaniques ; leur validité a été étayée par plusieurs études.À la lumière de ce qui précède, les travaux présentés ici sont focalisés sur la production de résines époxyde à base de furane comme substitut potentiel de DGEBA dans l’industrie du revêtement de boîtes de conserve. Le cycle complet du matériau a été étudié : des synthèses de monomères époxydes furaniques ont été proposées, puis des thermodurcis époxydes ont été obtenus et caractérisés à la fois dans leurs propriétés chimiques et physiques (étude de la cinétique de durcissement, des propriétés mécaniques et thermiques). En outre, l’application des matériaux thermodurcissables époxydes proposés comme revêtement interne des boîtes de conserve a été testée. / Research on bio-based polymers is rapidly increasing in last years, pushed by growing environmental and economic concerns, as well as by the uncertainty about future availability of finite petrochemical resources. Sustainability is a keyword in this process. In this frame, products that are respectful towards the environment, including eco-compatible building blocks and additives, are now researched to replace petroleum-based polymers with those derived from naturally occurring feedstocks. Epoxy resins are very versatile thermosetting polymers, extremely resistant to corrosion, moisture and chemicals, with good adhesive strength toward most materials (wettability) and low shrinkage upon curing. Due to their high glass transition temperatures and excellent mechanical strength, epoxy resins are widely employed in a broad range of applications, such as electronics, structural adhesives, aerospace composites and protective coatings. More than two-thirds of epoxy resins nowadays are based on diglycidyl ether of bisphenol A. In this industry the trend to replace petrol-derived materials with bio-based ones is related also to the necessity to substitute the Bisphenol A (BPA), a controversial building block recognized as an endocrine disrupter and reprotoxic substance. In particular in application as coating, the use of BPA results in hazard for customers of food and beverage products packed into containers treated with epoxy resins. The effects of human body contamination caused by BPA are diabetes, cardiovascular diseases, altered liver enzymes and reproductive apparatus damages. For these reasons, this molecule has been banned in many countries for the manufacturing of child products, and in France and Canada from all the materials in direct contact with food. The necessity to develop new epoxy resins results therefore urgent.Bio-derived molecules since now developed show the most various chemical structure, each of them producing different properties of final polymers. Peculiar characteristic shown by epoxy resins are related to the aromatic structure of its components. Aromatic molecules present in natural feedstock are mainly derived from lignin, one of the principal constituents of natural cell walls. However, to extract aromatic moieties from lignin, difficult and energy consuming processes are required. A valuable replacement of aromatic molecules, easily recoverable from glucose, are furanic molecules; their validity has been supported by several studies. In the light of the above, the work here presented is focused on production of furanic bio-based epoxy resins as potential substitute of DGEBA in can coating industry. The complete cycle of the material has been studied: the synthesis of furanic epoxy monomers and epoxy thermosets, the characterization of their chemical and physical properties (study of curing kinetics, mechanical and thermal properties). Furthermore, the application of bio-based epoxy thermosets as cans internal lining has been evaluated. Experimental results demonstrated that the obtained resins have good potential to be proposed as good alternatives to the traditional BPA-containing epoxy resins.
35

I. Progress Toward Leiodelide A II. Palladium-Catalyzed Reactions of Enol Ethers

Lauer, Matthew Gregory January 2012 (has links)
No description available.
36

An Investigation of Gold(I) Catalyzed Cycloaddition Reactions

Conyers, Ryan C. 19 April 2013 (has links)
No description available.
37

Etude théorique de réactions de Heck intramoléculaires / Theoretical study of intramolecular Heck reactions

Grüber, Raymond 20 June 2014 (has links)
L'ouverture de cycle aromatique catalysée par le palladium a été récemment observée par une équipe de l'ENSTA. Ce type de réactivité du palladium n’a jamais été observé auparavant et entre en compétition avec l’activation C-H classique. Ce travail de thèse a consisté à étudier ces réactions d'un point de vue théorique pour mieux en comprendre les mécanismes.Nous avons tout d'abord cherché la fonctionnelle permettant la meilleure description de la compétition entre la complexation azote/alcène en comparant plus de soixante fonctionnelles à des calculs CCSD(T)/CBS. Nous avons retenu la fonctionnelle GGA BP86.Nous avons ensuite étudié la réaction de Heck intramoléculaire à partir de la N-allyl-2-iodo-aniline. Nous avons justifié que l'indole soit le produit majoritairement obtenu, et montré que l'azote ne joue pas de rôle sur la régiosélectivité. Cependant, dans certains cas, l'azote inhibe la réaction en piégeant le complexe de palladium. Une étude théorique a montré que le facteur prépondérant de cette inhibition est la population électronique de l'azote et non l'hybridation du carbone benzylique.L'ouverture du furane a été ensuite considérée. Parmi tous les mécanismes proposés, notre étude théorique a montré que la voie principale est celle de la β-alkoxyelimination, potentiellement assistée par la trialkylamine présente dans le milieu.Enfin, nous avons étudié l'ouverture du benzylfurfurylaniline. Le mécanisme est similaire à celui observé pour l'ouverture du furane jusqu'à la régénération du complexe de palladium catalytique. En effet, dans le ce cas, la base azotée joue le rôle d'un donneur de proton. / Aromatic cyclic compound opening catalyzed by palladium has been recently observed by ENSTA team. That kind of reactivité for palladium has not been shown before and is in competition with the C-H activation. This work studies theses reactions from a theoretical point of view to better understand the mechanisms. We first look for the functional who gives the best description of the competition between the nitrogen/alkene complexation comparing more than sixty functionals with CCSD(T)/CBS calculation. We choose at last the GGA functional BP86.We then study the intramolecular Heck reaction starting from the N-allyl-2-iodo-aniline. We justified that the indole moiety was the major product and showed that the nitrogen plays no rôle in the regioselectivity.However, in some cases, the nitrogen inhibits the reaction by trapping the palladium complex. A theoretical study showed that the main factor for this inhibition was the population of nitrogen lone pair and not the hybridation of the benzylic carbon.Furan opening was then considered. Between all the mechanisms proposed, our theoretical study showed that the main way is the β-alkoxyelimination, potentially assisted by the trialkylamine present in the environment.Finally, we have studied the benzylfurfurylaniline opening. The mechanism is similar to the one observed for the furan opening until the regeneration of the palladium complex. Indeed, in that case, the base plays the rôle of a proton donor.
38

Síntese e avaliação de derivados furânicos, tetraidrofurânicos e pirrólicos com potencial atividade  tripanocida / Synthesis and evaluation of furan, tetrahydrofuran and pyrrole derivatives with potential trypanocidal activity

Hartmann, Ana Paula 13 July 2015 (has links)
A Doença de Chagas é causada pelo Trypanosoma cruzi, e possui duas fases clínicas, sendo o tratamento com o fármaco benznidazol eficaz somente na fase aguda, porém com diversos efeitos adversos ao longo do período do tratamento. Desta forma, consórcios vêm sendo estabelecidos entre \"governo - universidade - indústria\", com auxilio de capital nacional e estrangeiro para o desenvolvimento de novos fármacos. Apesar de diversas ferramentas disponíveis para o planejamento de novos compostos, a busca por produtos naturais ainda desperta interesse de muitos pesquisadores. Diversos trabalhos vêm descrevendo estudos de síntese e atividade tripanocida de lignanas, as quais merecem destaque, veraguensina (17) e grandisina (18). Devido à falta de tratamento e a alta toxicidade dos agentes disponíveis, este trabalho tem como objetivo sintetizar análogos dessas lignanas, relacionados a derivados de tetraidrofurânicos, furânicos, pirrólicos e de seus intermediários e testa-lasfrente à atividade tripanocida e citotóxica. O planejamento sintético envolveu a geração de derivados 1,4-diaril-2-butino-1,4-diol (28a-t) a partir da reação de condensação entre fenil carbinol (26) e aldeídos arílicos (27a-t) com diferentes padrões de substituiçõescom diversos grupos funcionais. Estes intermediários, obtidos em rendimentos moderados, foram convertidos aos correspondentes 1,4-diaril-1,4-diidroxílicos (30a-g), pela reação de redução em dióxido de platina e, posteriormente, oxidados a 1,4-diaril-1,4-dicetonas (29a-g). A partir da formação dos intermediários 29 e 30, os produtos de interesse, 2,5-diaril-furano (32a-g) e 2,5-diaril-tetraidrofurano (31a-g) foram preparados empregando reações de ciclização na presença de ácidos tríflico e trifluoroacético, respectivamente. Os intermediários e produtos obtidos em rendimentos de moderado a bom, totalizando 48 compostos, foram avaliados em ensaios de atividade tripanocida, envolvendo a cepa Tulahuen de T. cruzi, bem como ensaios de citotoxicidade. Considerando as cinco séries sintetizadas (28, 29, 30, 31 e 32), vale destacar que a maioria apresentou compostos com potente atividade tripanocida, a partir de 1,4 ?M, superior ao fármaco disponível benznidazol (7,9 ?M) e, adicionalmente, não apresentaram citotoxicidade em ensaios realizados por citometria de fluxo. / Chagas\' disease is caused by the Trypanosoma cruzi, whichhas two clinical stages. The treatment with the benznidazole is effective only in the acute stage, although with several side effects throughout the treatment period. Therefore, consortia are being established between \"government - university - industry\", with national and foreign financial support for drug discovery development. In spite of many available tools to design new compounds, the search for natural products still arouse interestfor a great number of researchers. Several papers have described studies of synthesis and trypanocidal activity of lignans, being veraguensin (17) and grandisin (18) worth to mention. Due to the lack of treatment and the high toxicity of the available drugs, this research has the aimto synthesize analogues from the above lignans, such astetrahydrofuran, furanic, pyrrolic derivatives and their intermediates,and test their trypanocidal activity and cytotoxicities. The synthetic strategy was based on the synthesis of 1,4-diarylacetylene-1,4-glycols (28a-t) via condensation reaction between phenyl carbinol (26) and substituted aryl aldehydes (27a-t) with several functional groups at different positionsof the aromatic ring. These intermediates, obtained in moderate yields, were converted to their corresponding 1,4-diaryl-1,4-dihydroxyl derivatives (30a-g) by the reduction reaction using platinum dioxide and, subsequently, oxidized to 1,4-diaryl-1,4-diketones (29a-g). From the synthesis of the intermediates 29 and 30, products of interest, 2,5-diaryl-furan (32a-g) and 2,5-diaryl-tetrahydrofuran (31a-g) were prepared from the cyclization reaction in the presence of the triflic and trifluoracetic acids, respectively. The intermediates and products, obtained in moderate to good yields, in a total of 48 compounds, were assessed in trypanocidal assays, using T. cruzi Tulahuen strain,as well as cytotoxicity assays. Considering the five synthesized series (28, 29, 30, 31 e 32), it is worth noting that the majority of the compounds showed potent trypanocidal activity from 1.4 ?M, higher than the available benznidazole (7,9 ?M) and, additionally, they were not cytotoxicin Flow Cytometry assays.
39

Synthesis and molecular modelling of bio-based polyamides

Cousin, Thibault 19 March 2013 (has links) (PDF)
In the current context of oil resources rarefaction, the development of biobased polymers is of major importance. The present work focused on the development of a biobased amorphous polyphthalamide, based on furan-2,5-dicarboxylic acid. The first part of the study was devoted to the development of a molecular modelling protocol that could calculate the glass transition temperature of polyphthalamides with accuracy. In order to do this, model polyphthalamides based on isophthalic, terephthalic acid and hexamethylene diamine were synthesized and characterized as well as simulated. By comparison between simulated and measured Tg, the protocol was validated. In a second part of the study, this protocol was applied to FDCA based polyphthalamides. These PPA were also synthesized. It was found that the PA 6-F undertakes a decarboxylation, preventing it from reaching high a molar mass. It was also found that the mechanical and thermal properties decrease as the amount of FDCA in the copolymers increases.
40

Total Synthesis Of Palmerolide A, Dihydroconduritols And Lentiginosine

Pawar, Amit Balkrishna 03 1900 (has links) (PDF)
The thesis entitled “Total synthesis of palmerolide A, dihydroconduritols and lentiginosine” is divided into two chapters. First chapter of the thesis describes the formal total synthesis of bioactive marine macrolide palmerolide A. Palmerolide A was isolated by Baker and co-workers from an Antarctic tunicate Synoicum adareanum. Palmerolide A is a 20-membered macrolactone containing five chiral centers and seven unsaturations. Palmerolide A was found to be potent and selectively cytotoxic against human melanoma cancer cell lines and was also shown to inhibit vacuolar V-ATPase. In section A, enantioselective formal total synthesis of palmerolide A is described. key steps in the synthesis involve Jung non-aldol aldol reaction to construct the C16-C23 fragment 1 and oxidation of a chiral furyl carbinol to assemble the C1-C15 fragment 2. Scheme 1: Synthesis of C16-C23 fragment of palmerolide A. Scheme 2: Formal total synthesis of palmerolide A In section B, enantiospecific formal total synthesis of palmerolide A is presented from chiral pool tartaric acid. This approach is based on coupling of the three fragments viz. C1-C8 enoic acid fragment 3, C9-C15 vinyl stannane fragment 4 and the C16-C23 vinyl iodide fragment 1. The C1-C8 enoic acid fragment 3 is synthesized from L-threotol obtained from L-tartaric acid, while synthesis of the C9-C15 fragment 4 involved the elaboration of a γ-hydroxy amide derived from the bis-Weinreb amide of tartaric acid. Stille coupling of the vinyl iodide 1 obtained by Jung non-aldol aldol process with the vinyl stannane 4 delivered the C9-C23 unit. Esterification of this unit with the enoic acid 3 followed by zinc mediated Boord olefination and RCM furnished the macrolactone which is further elaborated to palmerolide A. Scheme 3: Synthesis of C1-C8 fragment of palmerolide A. Scheme 4: Enantiospecific formal total synthesis of palmerolide A. Section A of the second chapter deals with the enantiospecific synthesis of dihydroconduritols E and F from tartaric acid. Conduritols are 1,2,3,4-cyclohex-5-ene tetrols and are shown to be inhibitors of glycosidase. A number of derivatives of conduritols were found to possess various biological activities. Enantiospecific synthesis of dihydroconduritol E and F is accomplished from tartaric acid employing the Boord type fragmentation and ring closing metathesis as the key steps. Scheme 5: Enantiospecific synthesis of dihydroconduritols E and F Section B of the second chapter describes the enantiospecific total synthesis of ()lentiginosine. Lentiginosine is a dihydroxylated indolizidine alkaloid isolated from leaves of the plant Astragalus lentiginosus. Lentiginosine is the most powerful and competitive inhibitor (IC50 5µg/mL) of amyloglucosidase known so far. Key transformation in the synthesis include the in situ reduction and cyclization of a dihydroxyazide derived from the γ-hydroxy amide prepared from tartaric acid amide. (for structural formula pl see the abstract file.)

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