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1
Wright, Edward Andrew. "π-Allyltricarbonyliron lactones in asymmetric synthesis." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621938.
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2
Edwards, M. I. "Asymmetric synthesis of lignan lactones from meso compounds." Thesis, Swansea University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636768.
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The purpose of this research was to form (2S, 3R)-2,3bis(3,4-dimethoxybenzyl) butyrolactone. A brief review of the main classes of lignans, their biosynthesis, biological activity and clinical utility is given in the first chapter. The main chemical synthesis routes to such compounds are also provided covering the six most commonly used routes including the Stobbe condensation. An overview of the use of meso compounds for the production of chiral synthons and use of the 'meso trick' to enhance yields during chiral induction to meso substrates are discussed in chapter two. Construction of the basic C18 lignan skeleton in chapter three is achieved via a double Stobbe condensation with preferential formation of the E-isomer at each stage. In the first step the Stobbe product is reduced to give the maleic anhydride. This resisted further reduction but reduction of the dimethyl maleate successfully gave the meso succinic anhydride with no d/l isomer formation. The formation of the target compound is described in chapter four. Reaction of the meso substrate with (+)-α-methylbenzylamine proceeded with chiral induction in 81% d.e. The use of chiral alcohols including 1-methol, 1-α phenyl ethylalcohol and S-(+)-methyl mandelate has also been examined showing widely varying diastereoselectivities. Conversion of (2S, 3R, αR)-N-(α-phenylethyl)- 2,3-bis(3,4-dimethoxybenzyl)butanedioic acid monoamide to the target dibenzyl butyrolactone has been readily achieved by reduction to the corresponding alcohol prior to lactonisation. Racemisation of (2S, 3R)-2,3-bis(3,4-dimethoxybenzyl) butyrolactone under basic conditions and comparison of the optical rotation values obtained with those in the literature allowed the absolute stereochemistry to be assigned. The attempted formation of picrostegane type lignans by non phenolic oxidative coupling is also described.
3
Harsh, Philip R. "Applications of asymmetric allylation reactions towards natural product synthesis." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=6029.
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Thesis (M.S.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains vi, 78 p. : ill. Includes abstract. Includes bibliographical references (p. 37-38).
4
Oh, Seongho. "Optimization and extensions of the nucleophile catalyzed aldol-lactonization (NCAL) process for bicyclic beta-lactone synthesis: applications to piperidine, pyrrolidine, and gamma-lactam-fused beta-lactones." Texas A&M University, 2003. http://hdl.handle.net/1969.1/3961.
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The intramolecular nucleophile catalyzed aldol-lactonization (NCAL) process
was optimized successfully. A variety of C9-acylated cinchona alkaloids were
synthesized and used for NCAL reactions with non-activated aldehydes. New
pyridinium salts, derivatives of MukaiyamaÂs reagent, led to marked improvements in
efficiency for the catalytic, asymmetric NCAL process while maintaining high
enantioselectivity. Larger scale versions of the catalytic, asymmetric NCAL reaction
were also developed allowing practical access to chiral bicyclic b-lactones. As an
extension of the intramolecular NCAL process, pyrrolidine and piperidine fused blactones
were synthesized. Simple g-lactam fused b-lactones were synthesized as a
model study for omuralide, salinosporamide A, and derivative synthesis. Synthesis of asubstituted
aldehyde acids was extensively studied but steric effects from both acid and
amine moieties led to great difficulties in this approach.
5
Soltani, Omid. "Photochemical preparations of salicylate/resorcylate esters/amides asymmetric synthesis of SCH 351448 /." Access to abstract only; dissertation is embargoed until after 5/16/2007, 2006. http://www4.utsouthwestern.edu/library/ETD/etdDetails.cfm?etdID=168.
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6
Rabiller, Christine. "Nouvelles voies de synthèse de lactones bioactives." Nancy 1, 1994. http://www.theses.fr/1994NAN10339.
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La synthèse enantiospécifique de lactones bioactives, inhibitrices d'une part de l'hmgcoa réductase, et d'autre part des lipases pancréatiques a été entreprise. Dans une première partie, l'accès facile et rapide à des composés de structure didesoxy-2-4-hexopyranose, chiron clé pour la synthèse d'inhibiteurs de la biosynthèse du cholestérol, a été réalisé par transformation stéréospécifique du 1,6-anhydro-beta-d-glucopyranose obtenu par pyrolyse dans de bonnes conditions qui ont été mises au point dans ce travail. Dans la deuxième partie, l'application des méthodes de création de liaison carbone-carbone en c-2 et en c-6 sur un dérivé du glucose, a permis d'ouvrir deux nouvelles voies pour la préparation d'intermédiaires clés de la synthèse de la valilactone, le tetrahydrolipstatine et la tetrahydroexterastine, composes d'intérêt pharmacologique pour le traitement de l'obésité
7
Olabisi, Ayodele O. Wimalasena Kandatege. "The chemistry of L-ascorbic acid derivatives in the asymmetric synthesis of C2- and C3-substituted aldono-gamma-lactones." Diss., Access through your commercial service, 2005. http://il.proquest.com/products_umi/dissertations/.
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Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry."August 2005." Title from PDF title page (viewed on February 6, 2007). Thesis adviser: Kandatege Wimalasena. Includes bibliographic references (leaves 144-163).
8
Otto, Andreas. "Ringtransformationen an chiralena-Alkylidenlactonen." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 1999. http://dx.doi.org/10.18452/14473.
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Ziel dieser Arbeit ist die Synthese neuer optisch aktiver Hydroxyalkylheterocyclen durch Ringtransformationen von chiralen -Alkylidenlactonen. Hierzu wurden letztere gezielten Additionen von Binucleophilen, 1,3-dipolaren Cycloadditionen, Cupratadditionen und Epoxidierungsreaktionen unterworfen. Die erhaltenen Produkte konnten durch weitere gezielte Folgereaktionen, Spaltungen oder Reaktionen mit Nucleophilen zu interessanten enantiomerenreinen Hydroxyalkylheterocyclen umgesetzt werden. Eine Deutung der acyclischen Seitendifferenzierung gelang mit Hilfe des antiperiplanaren Effektes und des inside alkoxy effects. Umsetzungen mit Hydrazinen führten in guten Ausbeuten zu trans-Hydroxyalkyl-3-pyrazolidinonen. Aus Nitromethan und -Alkylidenlactonen erhält man DBU-katalysiert Nitroethyllactone die sich unter hydrogenolytischen Reaktionsbedingungen zu trans-3-Hydroxyalkyl-2-pyrrolidinonen ringtransformieren lassen. Über o-Aminothiophenoladditionen und Ringtransformationen werden enantiomerenreine 3-(2-Hydroxyalkyl-2,3-dihydro-1,5-benzothiazepin-4(5H)-one erhalten, die neuartige Analoga der Pharmaka Dilthiazem und Thiazesim darstellen. Neue D1-Pyrazoline entstehen durch 1,3-dipolare Cycloadditionen von Diazoalkanen an -Alkylidenlactone. Durch photolytische Extrusion von Stickstoff werden neue chirale Cyclopropanderivate erhalten. Enantiomerenreine , -Diaminosäurederivate werden durch hydrogenolytische N-N-Bindungsspaltung der D1-Pyrazoline generiert. Über Epoxidierung der -Alkylidenlactone mittels Dimethyldioxiran und Umsetzung der erhaltenen Oxirane mit verschiedenen N- und S-Nucleophilen und anschließender Ringtransformation, ist ein Zugang zu Benzothiazepin-4(5H) -on, 1,5-Benzodiazepin-2-on, 1,4-Thiazepan-5-on, Thiomorpholin-2-on, 1-Phenyl-2-acetidion sowie über Lithium-Halogenaustausch-Reaktion zu 2-Hydroxy-2-hydroxyethyl- thiochromen-4-on erarbeitet worden. Mit Organokupferverbindungen gelingt hochregioselektiv die 1,4-Addition. Unter Bedingungen der Iodlactonisierung werden aus den Addukten neuartig substituierte -Butyro- und -Valerolactone erhalten.The thesis is focused on the synthesis of new optically active hydroxyalkyl heterocycles by ring-chain-transformation of chiral -alkylidenlactones. The latter were subjected to specific additions of binucleophiles to 1,3-dipolare cycloadditions to addition of cuprates and to epoxidation. The product obtained could be further applied in the synthesis of interesting enantiomerically pure hydroxyalkyl heterocycles by specific reactions like ring-cleavage or reactions with nucleophiles. The acyclic side differentiation could be explained with the help of the antiperiplanar effect and the inside alkoxy effects. Reactions with hydrazines led to trans-hydroxyalkyl-3-pyrazolidinones in good yields. Nitroethyllactones were obtained from -alkylidenlactones and nitromethane under DBU-catalysis. In a following step they are ring-transformed into trans-3-hydroxyalkyl-2-pyrrolidinones by hydrogenation. Enantiomerically pure 2-hydroxyalkyl-2,3-dihydro-1,5-benzothiazepin-4-(5H)ones could be prepared by addition of o-aminothiophenol and following ring-chain-transformation. These compounds represent novel analogs of the drugs Dilthiazem™ and Thiazesim™. Novel D1-pyrazoline results from 1,3-dipolare cycloadditions of -alkylidenlactone with diazoalkanes. New chiral derivatives of cyclopropanes were obtained by photolytic extrusion of nitrogen. Enantiomerically pure ,-diaminoacid derivatives were generated by hydrogenolytic cleavage of the N-N-bond of the pyrazolines. Epoxidation of -alkylidenlactones with dimethyldioxirane and opening of the oxirane ring obtained by various N- and S-nucleophiles provided new methods for the synthesis of benzothiazepin-4(5H)-one, 1,5-benzodiazepin-2-one, 1,4-thiazepan-5-one, thiomorpholin-2-one and 1-phenyl-2-acetidione. 2-Hydroxy-2-hydroxyethyl-thiochromen-4-one could be obtained by lithium-halogens exchange reaction. The 1,4-additions of organocuprates to -alkylidenlactones succeeded with high regioselectivity. Novel substituted [gamma]-butyro- and -valerolactones were obtained by iodolactonisations of these adducts.
9
Hamze, Khalil. "Baeyer-Villiger monooxygenases d'Acinetobacter : réactions biocatalysées et dédoublements cinétiques dynamiques." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4311/document.
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L'oxydation de Baeyer-Villiger (BV) par voie enzymatique est une méthode efficace pour obtenir de lactones sous forme énantiomériquement pure. Les Baeyer-Villiger Monooxygénases (BVMO) sont ainsi capables d'oxyder de nombreux substrats avec une stéréospécificité remarquable.Nous avons recherché de nouvelles enzymes dans le génome de deux souches appartenant au genre Acinetobacter, A. baylyi ADP1 et A. baumannii AYE. Six gènes ont été clonés dans E. coli. Leur profil de substrat a été étudié en utilisant des cellules entières de ce microorganisme recombinant comme biocatalyseur. Quatre enzymes ont montré une spécificité de substrat similaire, avec une préférence pour les petites cétones cycliques et pour les substituants aryliques. Une de ces enzymes a permis le Dédoublement Cinétique Parallèle Régiodivergent d'une bicyclohepténone et la désymétrisation de cyclobutanones benzyliques avec, dans chaque cas, une énantiosélectivité intéressante car conduisant à des énantiomères rarement obtenus par réaction de BV enzymatique.Dans une seconde partie, des Dédoublements Cinétiques Dynamiques, associant réaction de BV enzymatique et racémisation in situ ont été réalisés avec des cellules entières d'E. coli produisant la Cyclohexanone Monooxygenase (CHMO) issue d'A. calcoaceticus. La racémisation de cyclohexanones α-substituées, habituellement difficilement racémisables, a été assurée par l'emploi de solutions tampons à base de sels de phosphate ou de glycine. Les -caprolactones correspondantes ont été isolées sous forme d'esters méthyliques hydroxylés quasi énantiopurs avec des rendements compris entre 70 et 80%Enzyme-mediated Baeyer-Villiger oxidation is nowadays largely recognized as an efficient method to obtain highly optically active lactones. An increasing number of Baeyer-Villiger Monooxygenases from various sources has been found to oxidize a large range of substrates with a good to excellent stereospecificity.Firstly, in order to enlarge the scope of these biotransformations, the genome of two strains of the Acinetobacter genus, A.baylyi ADP1 and A.baumannii AYE was explored. Six genes were expressed in E. coli and the substrate profile of each enzyme was studied using whole cell biotransformations. Four enzymes showed close substrate specificity with a preference for small cyclic ketones and for arylic substituents. Interestingly, one enzyme led to a Kinetic Parallel Regiodivergent Resolution of a bicycloheptenone and desymmetrisation of benzylic cyclobutanones in an enantiocomplementary manner when compared to the most of already known enzymes.The second part of this work describes the implementation of Dynamic Kinetic Resolution processes combining enzymatic BV oxidation and in situ racemization of α-substituted cyclohexanones to afford corresponding lactones in more than 50% yield. Cyclohexanone Monooxygenase (CHMO) from another Acinetobacter strain, A. calcoaceticus, was selected and the reactions were carried out with whole cells of producing CHMO E. coli strain. The racemization of α-substituted cyclohexanones, usually slowly racemized under basic conditions, was ensured by the use of containing phosphate salts or glycine buffer solutions. Several corresponding -caprolactones were isolated after methylation as enantiopure hydroxy methyl esters in 70-80% yield
10
David, Hamon Catherine. "Synthese asymetrique de lactones : application a la serie des acides meviniques, inhibiteurs de la biosynthese du cholesterol." Poitiers, 1988. http://www.theses.fr/1988POIT2203.
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La compactine et la mevinoline sont des inhibiteurs de l'hmg-coa reductase, enzyme qui transforme l'hmg-coa en acide mevalonique dans une des premieres etapes de la biosynthese du cholesterol. Ces inhibiteurs sont caracterises par un squelette decalinique lie a un systeme lactonique dont la presence est indispensable a l'activite biologique. La preparation d'analogues necessite de disposer d'un synthon chiral qui peut etre obtenu a partir d'un sucre de la serie d. Plusieurs methodes de desoxygenation en positions 2 et 4 a partir de sucres divers (glucose, mannose, galactose) ont ete etudiees. Elles reposent sur l'hydrogenolyse de derives halogenes ou soufres. C'est ainsi qu'en utilisant l'anhydro-1,6 d-glucose la lactone recherchee est tenue en seulement 6 etapes
11
Aybey, Asuman. "Synthesis Of Chiral Lactones Via The Baeyer Villiger Oxidation Of Cyclic Aromatic Acetoxy Ketones Novel Annulation Reactions Of 2-propynyl-1,3-dicarbonyl Compounds To Form Pyrroles Addition Of Acyl Phosphonates To Diethyl Cyanophosphonate (depc)." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12610293/index.pdf.
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Chiral Baeyer-Villiger (BV) oxidation of cyclic ketones allows rapid access to asymmetric lactones as valuable intermediates in organic chemistry and frequently encountered precursors in enantioselective synthesis. In the first part, BV oxidation of functionalized ketones, especially cyclic 
-hydroxy and acetoxy ketones is described which could be a straightforward route to the &
#61537
-hydroxy lactones and &
#61537
-hydroxyalkanoic acid derivatives. The &
#61537
-acetoxylation of indanone, tetralone and chromanone derivatives by using Mn(OAc)3 followed by the enzyme catalyzed kinetic resolution of acetoxy ketones gives both of the enantiomers of &
#61537
-acetoxy ketones in good chemical and optical yields. The Bayer-Villiger oxidation of &
#61537
-acetoxy ketones with m-CPBA, CF3SO3H, and CH2Cl2, at rt gives the corresponding lactones without racemization. The phenyl moiety migrates selectively in order to form lactones. The mild hydrolysis of lactones affords phenolic &
#61537
-hydroxycarboxylic acid derivatives. Because of the high importance of pyrrole derivatives which exist in the structure of many natural products possessing biological activity beside their valuable feature of being versatile building blocks in organic synthesis and important starting materials for various synthetic transformations, a convenient method for the synthesis of 1,2,3,5-tetrasubstituted pyrrole derivatives starting from 1,3,-dicarbonyl compounds throuh acid catalyzed cyclization reaction is presented in the second part of the thesis. Alkylation of 1,3-dicarbonyl compound with propargyl bromide followed by one step cyclization with the introduction of primary amines in the presence of catalytic amount of trifluoroacetic acid (TFA) affords the corresponding pyrrole derivatives in high yields. The third part of the thesis describes the cyano-phosphorylation of various alkyl and aryl phosphonates in the presence of diethyl cyanophosphonate (DEPC) as the phosphorylating agent under the promotion of the KCN catalyst. Reaction of acyl phosphonates with DEPC forms the phosphonocyanohydrin-O-phosphates which are the important starting materials of quaternary &
#945
-hydroxy carboxylic acid and phosphonate containing &
#946
-aminoalcohol derivatives.
12
Hollowood, Christopher John. "π-allyltricarbonyliron lactone complexes in asymmetric synthesis." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620305.
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Cox, Liam Robert. "π-Allyltricarbonyliron lactone complexes in asymmetric synthesis." Thesis, University of Cambridge, 1997. https://www.repository.cam.ac.uk/handle/1810/275281.
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The thesis is divided into seven chapters. The first reviews methods of preparation of tricarbonyliron complexes of organic molecules, with particular emphasis on their synthesis in enantiomerically enriched form. Chapter two describes the use of these complexes in controlling the stereochemical outcome of reactions carried out on functional groups appended to the organic ligand. The third chapter describes methods of releasing the organic ligand in a stereoselective manner. Chapter four outlines an example of 1,5-induction of chirality in the diastereoselective allylation of ketone groups appended to the allyl ligand of π-allyltricarbonyliron lactone complexes. Attempts at manipulating incorporated side-chain functionality in these complexes are discussed in Chapter five. The Mukaiyama aldol reaction provides a powerful tool for stereoselective C-C bond formation. The use of π-allyltricarbonyliron lactone complexes bearing methyl ketone-derived silyl enol ether functionality in an asymmetric Mukaiyama aldol reaction is discussed in Chapter six. This reaction provides a novel example of 1,7-induction of chirality.
14
Fernandez, Anne-Marie. "Préparation de γ-butyrolactones γ-alkylées optiquement pures à partir de l'acide L-tartrique. Application à la synthèse totale de la L-bioptérine." Rouen, 1996. http://www.theses.fr/1996ROUES025.
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Une nouvelle méthode pour la préparation de gamma-butyrolactones optiquement pures est proposée. Une stratégie de synthèse donnant accès à deux types de chirons carbonylés (cétones et aldéhyde) a permis le développement de deux réactions hautement stéréosélectives créant ainsi un troisième centre stéréogénique : la réduction des cétones, (2R, 3R)-2,3-dipivaloxy-4-oxo alcanoates de méthyle par le borohydure de sodium dans le méthanol mène aux alcools correspondants (4R), avec des ee>98%, précurseurs des (2R,3S,4R)-2,3-dipivaloxy-4-alkylbutyrolactones. L'addition d'organomagnésiens sur l'aldéhyde (2R,3R)-4-oxo-2,3-dipivaloxy butanoate de méthyle conduit de façon spontanée aux (2R,3S,4S)-2,3-dipivaloxy-4-alkylbutyrolactones avec des ee>98%, épimères des précédentes. Les étapes de lactonisation et de déprotection ont donné accès aux (2R,3S,4R) et (2R,3S,4S)-2,3-dihydroxy-4-alkylbutyrolactones optiquement pures. Certaines de ces lactones ont permis les synthèses formelles de quatre produits naturels : (3R, 4R)-quercus lactone, (-)-avénaciolide, (+)dodécanolactone, (+)-tétrahydrocérulénine enfin, une nouvelle synthèse totale de la L-bioptérine, important composé intervenant comme cofacteur d'enzymes dans de nombreuses réactions biologiques, est effectuée à partir de l'acide L-tartrique via le 5-déoxy-l-arabinose issu de la (2R,3S,4S)-2-3-dihydroxy-4-méthylbutyrolactone.
15
Harter, Jürgen. "π-allyltricarbonyliron lactone complexes : versatile tools for asymmetric synthesis." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603808.
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The opening chapter will give an introductory review of the chemistry of p-allyltricarbonyliron lactone complexes, in which their preparation and behaviour towards a variety of reagents is described. The utility of those complexes in organic synthesis to date will be outlined, with particular focus on controlling the stereochemical outcome of reactions carried out on functional groups appended to the organic ligand. In a further chapter, a synthetic route towards the total synthesis of the neutral product decarestrictine D will be described. Model studies will highlight the potential feasibility of employing the iron template in a route towards this target. In the following chapter, the synthesis of novel complexes with the side-chain attached to the C-2 position on the core allyl system will be discussed. Conformational analysis of these complexes employing modern NMR techniques will be outlined and studies on some addition attempt and the synthetic utility of these new compounds will be disclosed. Another chapter will describe the synthesis of chiral iron enoate ester complexes. Furthermore, the outcome of a variety of additions and cycloadditions into this new enoate ester functionality will be discussed. In a further chapter, the formal total synthesis of the natural product (-)-gloeosporone will be described. This route employs a 1,7 Mukaiyama aldol addition on a suitable iron lactone complex, a stereoselective reduction in the appended side-chain and a novel decomplexation step with lithium naphthalenide.
16
Hutt, Jean. "Synthese d'analogues de la vitamine d::(3) : synthese chirale de composes polyhydroxyles." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13326.
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La transformation de la cfarvone en quatre diastereoisomeres precurseurs du cycle a des dihydrovitamines et dihydrotachysterols est decrite dans la premiere partie. Par couplage d'un acetylure derive des cycles c/d de la vitamine d::(3) avec la cetone precurseur du cycle a, puis sa formation du systeme dienique a l'aide de titane a basse valence nous avons obtenu des dihydrotachysterols majoritairement. D'un autre cote, l'utilisation de sulfoxydes optiquement actifs dans l'intention de creer des centres hydroxyles chiraux et son application a la synthese du fragment polyhydroxyle de l'amphotericine b et du l-arabinitol est decrite dans la deuxieme partie. Les trois etapes-cles de cette methodologie sont: reduction stereospecifique d'un beta-cetosulfoxyde; condensation stereospecifique; cis-hydroxylation d'un beta-hydroxysulfoxyde
17
Chemla, Philippe. "Reactions diastereospecifiques de dienones fer-tricarbonyle : applications a la synthese d'alcools fonctionnalises optiquement purs." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13049.
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La methode de synthese utilisee permet d'acceder avec de bons rendements, a des composes de haute purete optique et de configuration donnee: alpha et gamma aldols et une delta -lactone fonctionnalisee en position 5. Des hydrocarbures optiquement actifs dont le centre asymetrique est eloigne de toute fonction, ont egalement ete synthetises par cette voie
18
Pale, Patrick. "Synthese et reactivite d'epoxyalcools acetyleniques chiraux : application a la synthese de cyclopropanes et d'heterocycles fonctionnalises." Reims, 1988. http://www.theses.fr/1988REIMS012.
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TALAGA, PATRICE. "Synthese et activite biologique de tolerogenes potentiels." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13101.
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Essais d'induction de tolerance aux haptenes de type alpha-methylene gamma butyrolactones (amgbl) responsables de nombreuses allergies de contact. Synthese de differents tolerogenes potentiels hydrosolubles de la forme lactone-derives lysinyl et lactone-derives cysteinyl. Etude de l'induction asymetrique observee lors de l'addition de michael d'un dipeptide (voc-cys-ala-ome) a differentes amgbl. Observation d'un parallelisme entre cette induction asymetrique et l'enantioselectivite de la reponse immunitaire dans le phenomene de l'allergie croisee
20
Azevedo, Mariangela Burgos Martins de. "Synthèse énantiosélective de (gamma)-butyrolactones : ()-méthylénolactocine, (-)-acide protolichestérinique, (-)-blastmycinolactol, (+)-blastmycinone, (-)-NFX-2 et (+)-antimycinone." Université Joseph Fourier (Grenoble ; 1971-2015), 1995. http://www.theses.fr/1995GRE10116.
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La cycloaddition du dichlorocetene avec des éthers d'enols chiraux conduit à des cyclobutanones fonctionnalisées avec une diastéréosélectivité élevée. Cette réaction est basée sur la différenciation des faces de la double liaison de l'oléfine chirale. Des intermédiaires de pureté enantiomerique élevée, comme les gamma-butyrolactones, sont obtenus à partir des cycloadduits. Au cours de ce travail, nous avons effectué les premières synthèses enantioselectives des produits naturels suivants: la (moins)-methylenolactocine et l'(moins)-acide protolichesterinique. Ces alpha-méthylène-gamma-butyrolactones possèdent des propriétés antibiotiques et antitumorales importantes. Dans cette partie du travail une réaction d'alpha-méthylation de gamma-butyrolactones a été mise au point. Dans un deuxième temps, nous avons effectué la synthèse asymétrique d'un certain nombre de gamma-butyrolactones beta-oxygénées: (moins)-blastmycinolactol, (plus)-blastmycinone, (moins)-nfx-deux et (plus)-antimycinone, composés issus des antibiotiques antimicynones a(trois) et a(un) respectivement
21
PETIT, YVES. "Synthese d'hydroxy-2 esters enantiomeriquement purs a partir d'amino-2 acide : etude stereochimique de l'addition 1,4 d'organometalliques sur des systemes insatures-2,3 hydroxy-4." Paris 6, 1987. http://www.theses.fr/1987PA066578.
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Davoren, Jennifer Elizabeth. "Studies towards the asymmetric total synthesis of solandelactone oxylipins: the total synthesis of solandelactone E." Thesis, 2006. http://hdl.handle.net/2152/2709.
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Morris, Kay A. "Applications of B-Lactones: Utility of Spiroepoxy-B-Lactones and Development of a Double Diastereoselective Nucleophile Catalyzed, Aldol-Lactonization Process Leading to !-Lactone Fused Carbocycles and Tetrahydrofurans." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-08-8405.
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Natural products continue to inspire synthetic chemists to develop novel
methodologies to provide efficient and expedient syntheses of the target molecules.
Haterumalide NA aroused our interest and prompted development of four differing
methodologies. Three of the strategies pursued involved use of B-lactone scaffolds as
intermediates. Extensions of the nucleophile catalyzed, aldol-lactonization (NCAL)
reaction were also pursued and targeted toward alternative natural product targets.
The reactivity of the unexpectedly stable strained spirocycle, spiroepoxy-B-
lactone, was explored. Spiroepoxy-B-lactones exhibited a wide range of reactivity, but
largely rearranged to tetronic acids. The desired reaction manifold remained inaccessible
and led to application of the NCAL process to tetrahydrofuran-fused B-lactones. Several
tetrahydrofuran-fused B-lactones were prepared, which displayed low
diastereoselectivity. The diastereoselectivity could be somewhat improved in a double
diastereoselective NCAL process with varied solvent systems, yet the carbocyclic
analogues gave much more promising results. The use of carbocycle-fused !-lactones
ultimately culminated in a double diastereoselective NCAL process, and overall led to improvements in diastereoselectivities from 1:1-2 up to >19:1. Further expansion of the
substrate scope for the NCAL process was studied for application to bridged tricyclic B-
lactones, access to carbocycle-fused y-lactones, and towards development of a dynamic
kinetic resolution NCAL process.
With our interest aimed at haterumalide NA, a modified Negishi cross coupling
between zincates and dichloroolefins was also revisited. The stringent anhydrous
reaction conditions led to reexamination of initial leads, which provided user-friendly
anhydrous conditions by utilizing commercially available anhydrous solvent. However,
application was implemented solely to a simplified model system.
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Dornan, Peter. "Transition Metal Catalysis: Construction of Chiral Lactones, Ketones, Sulfoxides and 6-deoxyerythronolide B." Thesis, 2013. http://hdl.handle.net/1807/35807.
Full textAbstract:
The products of organic synthesis affect countless aspects of our everyday lives, from our medicines to our fuels, plastics and more. The discovery of new methods for organic synthesis is of paramount importance if we are to find greener and more efficient ways to synthesize commodity and fine chemicals, and lower the impact of the chemical industry on our environment. The aim of my doctoral thesis is to discover fundamentally new enantioselective transformations using transition metal catalysis, which can be applied to the synthesis of pharmaceutical agents, natural products or other fine chemicals.
Hydroacylation is the atom economical addition of an aldehyde C–H bond across an unsaturated functional group such as an olefin or ketone. Theoretical studies on an intramolecular ketone hydroacylation catalyzed by rhodium were performed. The insights gained from this mechanistic study were then applied to the development of an asymmetric olefin hydroacylation using ethers, sulfides and sulfoxides as directing groups.
Motivated by a desire to discover new catalysts with high activity and selectivity in rhodium catalyzed transformations, a chiral tridentate sulfoxide ligand was designed and synthesized. This ligand was found to be highly enantioselective in rhodium catalyzed 1,4-addition reactions. The use of allylic sulfoxides in a dynamic kinetic resolution was then investigated. The sulfoxide was found to direct a rhodium catalyzed olefin hydrogenation with simultaneous substrate racemization through a rhodium π-allyl pathway.
Progress was made towards the total synthesis of a complex polyketide natural product, 6-deoxyerythronolide B. The key macrocyclization step was achieved in a model system by ring closing metathesis, and future work will be directed at completing the synthesis of the natural product.
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Khan, Hasan. "Asymmetric Synthesis of Lactones and Lactams: Rhodium Catalysis in the Hydroacylation of Ketones and the Hydrogenation of Cyclic Dehydropeptides." Thesis, 2013. http://hdl.handle.net/1807/35862.
Full textAbstract:
Organic synthesis allows access complex materials in the context of fine chemicals, pharmaceuticals, and natural products, but many contemporary methods are wasteful – the focus is on the target rather than the process. Stoichiometric reagents, protecting groups, and multi-step processes are often involved to synthesize moieties such as chiral lactones and lactams, which are prevalent in biologically-relevant molecules like antibiotics (for example, the macrolides, typified by erythromycin) and cyclic peptides (such as cyclosporin and gramicidin). We have developed a rhodium-catalyzed lactonization of prochiral keto-aldehydes to access chiral lactones in a mild and atom-economical fashion, and a synthesis of cyclic peptides from achiral dehydropeptides using asymmetric rhodium-catalyzed hydrogenation to set the chirality in the peptide. In this fashion, we avoid using expensive and wasteful activating agents, protecting groups, and a host of other drawbacks endemic in lactonizations and peptide synthesis. This dissertation details: 1) the development of asymmetric rhodium-catalyzed hydroacylation, elucidation of the mechanism of this transformation through experimental and theoretical analyses, and the synthesis of chiral benzoxazecinones using this method, and 2) the synthesis of prochiral linear dehydropeptides, efficient cyclization of these molecules, and asymmetric reduction of multiple enamides in a highly enantio- and diastereoselective manner to access cyclic peptides.
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Olabisi, Ayodele O. "The chemistry of L-ascorbic acid derivatives in the asymmetric synthesis of C2- and C3-substituted aldono-gamma-lactones." Diss., 2005. http://hdl.handle.net/10057/540.
Full textAbstract:
The antioxidant and redox properties of L-ascorbic acid are closely associated with the electron rich 2, 3-enediol moiety of the molecule and therefore selective functionalization of the 2- and 3-OH groups is essential for the detailed structure-activity studies. Reactions of 5- and 6-OH protected ascorbic acid with electrophilic reagents exclusively produce the corresponding 3-O-alkylated products under mild basic conditions due to the high nucleophilicity of the C-3-OH. Based on the density functional theory (B3LYP) electron density calculations, a novel and general method was devised for the direct alkylation of the 2-OH group of ascorbic acid with complete regio- and chemo-selectivity. A complete spectroscopic analysis of two complementary series of 2- O -acetyl-3- O -alkyl and 2- O -alkyl-3- O -acetyl ascorbic acid derivatives was carried out to define their spectroscopic characteristics and to resolve common inconsistencies in the literature.
The asymmetric approach to the synthesis of natural products or other biologically active compounds is impeded by low abundance of natural sources as well as a limited number of efficient synthetic methods. Nevertheless, carbohydrate-based systems such as the aldono-1,4-lactones (also known as aldono-γ-lactones) which generate a host of chiral compounds have been particularly rewarding in this respect. This study shows a practical approach using 5,6- O -isopropylidene-L-ascorbic acid (ketal of L-ascorbic acid) as a single common starting material for facile asymmetric synthesis of protected, optically pure and functionalized aldono-1,4-lactones derivatives, valuable in the synthesis of derivatives of various pharmacologically active agents for structure-activity studies. The practicality of this new approach is demonstrated by the convenient synthesis of a series of thermal Claisen-rearranged products of 5,6- O -isopropylidene-3- O -allyl-L-ascorbic acid and 5,6- O -isopropylidene-2- O -allyl-L-ascorbic acid as the corresponding 5,6- O -isopropylidene-2-allyl-3-keto-L-galactono-γ-lactone and 5,6- O -isopropylidene-3-allyl-2-keto-L-galactono-γ-lactone respectively. The synthetic routes are economical, efficient, diastereospecific, and proceed in high yields."August 2005."
Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry.
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Jeong, Won Boo [Verfasser]. "Asymmetric methodologies for the construction of 5,7,5- and 6,6,6-tricyclic sesquiterpene lactones towards the synthesis of Arglabin / vorgelegt von Won Boo Jeong." 2007. http://d-nb.info/985286229/34.
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Hu, Chu Chen, and 胡聚成. "Intramolecular Cyclization of Tungsten Alkynyl Complexes and Bicyclic Lactones Asymmetry Synthesis." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/94071570455283060763.
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