Dissertations / Theses on the topic 'Nitrone cycloaddition'
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Henderson, A. J. "Studies towards solid-phase nitrone cycloaddition reactions." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.603957.
Williams, Simon Frederick. "The intramolecular nitrone cycloaddition route to alkaloids." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328912.
Alkayar, Ziad Tariq Ibrahim. "Synthesis of iboga alkaloids using cascade cyclisation, nitrone cycloaddition." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/16898/.
Erhard, Thomas. "Totalsynthese von (±)-Codein durch 1,3-dipolare Cycloaddition." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-69013.
Lopes, Tiago Luiz. "Modificação do produto natural (-)-∝- Bisabolol." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/97/97136/tde-22082013-112422/.
The (-)-?-bisabolol is a natural product available in a large quantity in Brazil. It is extracted of several specimens of trees and has recognized biological activity that made it a so interesting product for cosmetic and pharmaceutic industries. The research has as mean goal the modification of (-)-?-bisabolol a natural product. The modification has intended, improve the biological activity or create new biological activity. The methods applied always consider condition to protect the environment (Green Chemistry). The research has three main parts: amino reduction, oxidation and cycloaddition. The first part based on the reaction to synthesize the imines (N-benzylphenilmethanoamine) and with the amine reduction synthesis the secondary amine. A second part was oxidizing the secondary amines and bisabolol. The third part is a research about cycloaddition. The amines oxidation (dibenzylamine e 1,2,3,4-tetrahydroisoquinoline) gave the nitrones [N-benzylidenebenzylamine N-oxide and 3,4-dihydroisoquinoline N-oxide] respectively. The Bisabolol oxidation (epoxidation reaction) gave a mix of bisabolol oxide: The Bisabolol oxide B, 1-methyl-1-[5-(4-methyl-3-ciclohexenyl)tetrahydro-2-furanyl]ethyl alcohol and The Bisabolol oxide A, (3S)-2,2,6-trimethyl-6-(4-methyil-3-ciclohexenyl) tetrahydro-2H-3-piranol. The alilic oxidation from Bisabolol also was achieved and gave the tetrahydro-2,2,6-trimethyl-6-(4-methyl-3-cyclohexen-1-yl)-4H-pyran-4-one. The cycload-dition [1+2] between diclorocarbene and bisabolol gave, 4-(2,2-dicloro-3,3-dimethylciclopropil)-2-(7,7-dicloro-6-methylbiciclo[4.1.0]hept-3-yl)-2-butanol. The cycloaddition [2+3] with nitrones (3,4-dihydroisoquinoline N-oxide) and dipolarophile (butyl vinyl ether) gave the isoxazolidine 1,5,6,10b-tetrahydro-2H-isoxazolol[3,2-a]isoquinoline-2-yl butyl ether.
Nguyen, Thanh Binh. "Nouveaux Développements Méthodologiques pour la Cycloaddition 1,3-Dipolaire de Nitrones." Phd thesis, Université du Maine, 2008. http://tel.archives-ouvertes.fr/tel-00382503.
• l'étude de la réactivité des N-alcényloxazolidin-2-ones en tant que nouveaux dipolarophiles aza-substitués en cycloaddition 1,3-dipolaire à demande inverse vis-à-vis de nitrones.
• la mise en jeu de nitrones aspartiques originales en cycloaddition vis-à-vis de différents alcènes pour fournir des précurseurs d'aspartates α-substitués par une chaîne fonctionnelle.
Dans un premier temps, nous avons mis au point deux méthodes inspirées de celles de la littérature en partant d'une oxazolidin-2-ones pour synthétiser les N-alcényloxazolidin-2-ones: (i) vinylation cupro-catalysée utilisant un bromure d'alcényle, (ii) condensation avec un aldéhyde. Ces méthodes simples, générales, directes et à hauts rendements nous ont permis d'accéder aux N-alcényloxazolidin-2-ones de structure diverse.
Ces N-alcényloxazolidin-2-ones ont montré une grande réactivité en tant que dipolarophile vis-à-vis de diverses nitrones dans différentes conditions : thermiques (avec/sans solvant) et promues par TMSOTf. Les 5-aza-isoxazolidines diversement substituées originales ont été obtenues avec des rendements élevés mais de faibles stéréosélectivités. Cette limitation − due à l'instabilité configurationnelle des nitrones activées et à la flexibilité conformationnelle des N-alcényloxazolidin-2-ones − a été résolue par utilisation de la nitrone chirale à géométrie fixe de Tamura : les adduits trans-β sont obtenus avec d'excellents sélectivités
La tranformation des adduits issus de la N-benzyl-α-carbonyloxyéthylnitrone en dérivés aspartates carboxy-différenciés a été ensuite étudiée par une séquence en deux étapes (i) ouverture du cycle isoxazolidinique en aspartimide via N-quaternarisation par benzylation (ii) attaque chimiosélective d'un hétéronucléophile sur la fonction amide. Les aspartates carboxy-différenciés ont été obtenus avec de bons rendements, des excès énantiomériques élevés en version non-racémique, et un grand degré de diversité fontionnelle en ω (ester, amide, acide).
L'étude a été étendu à la cycloaddition 1,3-dipolaire des N-vinyloxazolidin-2-ones β,β-difluorées originales avec la N-benzyl-α-carbonyloxyéthylnitrone : les 4,4-difluoro-5-aza-isoxazolidines sont obtenues avec de bons rendements malgré une faible stéréosélectivité probablement due à un mécanisme non-concerté.
Notre étude a été complétée par l'accès à des dérivés d'α-aminoacides α,α-disubstitués via cycloaddition 1,3-dipolaire mettant en jeu de nouvelles nitrones aspartiques d'une stablilité configurationnelle inédite. Ce type de nitrones − préparé facilement par addition d'une N-benzylhydroxylamine sur un acétylènedicarboxylate – a montré une grande réactivité vis-à-vis d'une large gamme d'alcènes de différents natures électroniques. Les adduits issus des éthers vinyliques ont été obtenus avec de hauts sélectivités trans. L'extension asymétrique utilisant soit un éther vinylique chiral , soit une nitrone chirale a été effectuée et a permis l'obtention facile des adduits diastéréomériquement enrichis. A partie de ces adduits, un premier accès réussi aux dérivés aminoacides α,α-disubstitués a été réalisé en trois étapes. La diversification de cette méthodologie a été effectuée en utilisant une nitrone aspartique carboxy-différenciée.
Chigrinova, Mariya. "Development of New Bioorthogonal Strain-Promoted Alkyne-Nitrone Cycloaddition Methodology for Applications in Living Systems." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31281.
Oukani, El Hassan. "Synthèse de sucres à longue chaîne par réaction de cycloaddition 1,3 dipolaire." Nancy 1, 1995. http://www.theses.fr/1995NAN10065.
Wang, Lianjie. "New biobased chemicals from HMF and GMF : Applications of Morita-Baylis-Hillman reaction and nitrone 1,3-dipolar cycloaddition." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI026.
The design of new fine chemicals from biomass and platform molecules has recently become a very active field of research. 5-Hydroxymethylfurfural (HMF) is considered as one of the most promising renewable building blocks derived from carbohydrates, due to the rich chemistry offered by its high level of functionality. Its glucosylated analogue glucosyloxymethylfurfural (GMF), though much less available, is also an interesting biobased furanic aldehyde able to provide a range of novel architectures which include a remaining full carbohydrate moiety. The present thesis is a contribution to the use of these two building blocks for the design of novel fine chemicals, using notably two reactions, namely the Morita-Baylis-Hillman reaction, and the cycloaddition of nitrones. The application of these strategies for designing novel surfactants was also investigated. First, we investigated the MBH reaction of HMF and GMF with cycloalkenones using pure water as solvent. New functionalized scaffolds have been prepared in mild and safe conditions with remarkable atom-economy by this route for the first time. Then we investigated the possibility to run MBH reactions of HMF and GMF with acrylates or other alkenes in absence of any solvent. The 1,3-dipolar cycloaddition reactions of nitrones obtained from HMF and GMF offer novel synthetic routes towards biobased isoxazolidines. The sequence “nitrone formation-cycloaddition reaction” can be performed either in a multicomponent approach or in a stepwise one. In the last part, we addressed the possibility to use these two routes for the design of novels biobased surfactants, in the frame of a collaboration with Prof Véronique RATAJ and Dr Fermin ONTIVEROS of the CISCO team of the UCCS research unit in Lille. Preliminary results on their surfactants properties have been obtained, and indicate a real interest of these compounds which exhibit easily adjustable properties based on simple structural variations, and which are obtained in an easy straightforward and original synthetic sequence
Ben, Ayed Achich Kawther. "Synthèse énantiosélective d'aminoacides disubstitués polyfonctionnels via cycloaddition dipolaire d'α-carboxy cétonitrones." Thesis, Le Mans, 2016. http://www.theses.fr/2016LEMA1013/document.
During this thesis, we were interested to develop two different ways of 1,3 dipolar cycloaddition to reach enantiopure disubstituted polyfunctionnal amino acids.We have described in a first part the diastereoselective 1,3-dipolar cycloaddition between an aspartic nitrone and chiral vinyl ethers. The aspartic ketonitrone and vinyl ether of (R) or (S) stericol led to high diastreocontrols. This control is due to the stability of the nitrone under (E) geometry which favors the exo approach, facially controlled by the dipolarophile. The chemoselective N-deprotection of this adduct leads to a diastereo- and enantiomerically pure isoxazolidine which affords the target DAA after N-acylation and N-O ring opening by a dismutative pathway. In a second part, we describe the synthesis of isoxazolidines obtained by organocatalytic enantioselective 1,3-dipolar cycloaddition between an alanine-derived nitrone and an enal or an ynal as the dipolarophile. With enals β-substituted by alkyl groups, good diastereoselectivities and ees were obtained in the presence of the MacMillan catalyst. These organocatalyzed conditions can be applied to a range of carboxy ketonitrones, and to different enals, provided an appropriate choice of the co-acid. Ynals show no reactivity under these organocatalytic conditions, although they lead regioselectively to polyfunctional quaternary isoxazolines under thermal conditions.Our study was achieved by the access of polyhydroxylated amino acids derived from opening adducts obtained by the enantioselective route using enals as dipolarophiles. This study allows to envisage the enantioselective synthesis of analogs of myriocin
Kalu, Chimdi E., Noah Lyons, Abbas G. Shilabin, and Chimdi Kalu. "Synthesis and Evaluation of 1,2,4-oxadiazolidinones: The Search for Potential non-β-lactam β-lactamase Inhibitors." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/159.
Dasser, Mohammed. "Réactions de cycloadditions en série glucidique." Nancy 1, 1989. http://www.theses.fr/1989NAN10144.
Wang, Xianheng. "Synthesis of five-membered cyclic nitrones and their applications in preparation of isoxazolidines and substituted pyrrolidines." Berlin Logos-Verl, 2008. http://d-nb.info/992551595/04.
Richmond, Edward. "An asymmetric pericyclic cascade approach to oxindoles." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/4459.
Shpak-Kraievskyi, Pavlo. "Nouvelles méthodologies pour la synthèse asymétrique de peptides aldéhydiques β3-C-terminaux et de dérivés d’acides aminés disubstitués via hétérocycloaddition." Thesis, Le Mans, 2013. http://www.theses.fr/2013LEMA1002/document.
Peptide aldehydes are known as protease inhibitors and precursors for many biologically active compounds. Methods for their synthesis involve classically the transformation of a precursor (Weinreb amide, ester, alcohol, acetal) into an aldehyde as one of the final steps to prevent epimerization of the carbon α to the aldehyde. By contrast, β-peptide aldehydes, more stable to epimerization, have been relatively unexplored. They are usually obtained by homologation of the corresponding amino acid despite low yielding steps, an epimerization problem and low number of accessible amino acids. Therefore, new synthetic access to β-peptide aldehydes is still a challenging problem. On the basis of previous work in our team concerning [4+2] and [3+2] diastereoselective cycloadditions, we have developed during this PhD thesis new strategies for the asymmetric access of β-amino acid derivatives by two complementary ways :1) Original six-membered heterocycles 6-ATO (6-alkoxy-tetrahydrooxazinone ) were prepared by a highly stereoselective heterocycloaddition reaction with good yields and de. These cycloadducts were transformed via transacetalisation into both «mixed» and «symmetrical» aminoacetals. Moreover, these new acetals are ideal intermediates for further peptide coupling, leading ultimately to monosubstituted β3-C-terminal peptide aldehydes. 2) By another approach five-membered heterocycles 5-AISO (3,3’-disubstituted 5-alkoxy-isoxazolidines) were obtained via 1,3-dipolar cycloaddition between α-keto ester nitrones and vinyl ether. These compounds were successfully used as precursors of disubstituted β-amino aldehydes after transprotection of the nitrogen atom and N-O cleavage of the isoxazolidine ring. Asymmetric extension of the cycloaddition step was studied by enantioselective and diastereoselective pathways, thus opening unprecedented entry to enantioenriched disubstituted β3,β3-C-terminal peptide aldehydes
Quillin, H. K. "Synthetic applications of 1,3-dipolar cycloadditions." Thesis, University of Southampton, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235278.
Shpak-Kraievskyi, Pavlo. "Nouvelles méthodologies pour la synthèse asymétrique de peptides aldéhydiques β3-C-terminaux et de dérivés d'acides aminés disubstitués via hétérocycloaddition." Phd thesis, Université du Maine, 2013. http://tel.archives-ouvertes.fr/tel-00793512.
Hughes, Christine Merricc. "Nitrile oxide cycloaddition chemistry /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phh8929.pdf.
Martin, Jason Neil. "Chiral imidazoline nitrones for cycloaddition reactions." Thesis, Open University, 2000. http://oro.open.ac.uk/58065/.
Viceriat, Audrey. "Cycloaddition [3+2] de cétènes avec des aziridines." Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAV049/document.
This thesis work focuses on a new type of [3+2] cycloaddition of ketenes with aziridines. Aziridines are good precursors of zwitterionic 1,3-aza-dipoles, by selective C-N bond cleavage catalyzed by Lewis acid. We have found that ketenes react with the 1,3-dipole generated by addition of lithium iodide to the aziridine, efficiently providing the gamma-lactams. This new cycloaddition could be extended to a one-pot simple transformation of imines to gamma-lactams. The synthesis is compatible with a wide range of aromatic imines and stable ketenes. Finally, a one-pot catalytic asymmetric synthesis of enantioenrichied gamma-lactams have been developed starting from olefins, involving an asymmetric nitrene aziridination
Fox, Martin Edward. "Intramolecular cycloaddition reactions of nitrones and hydroxylamines." Thesis, University of Cambridge, 1992. https://www.repository.cam.ac.uk/handle/1810/272243.
McKay, Craig. "Alkyne-Nitrone Cycloadditions for Functionalizing Cell Surface Proteins." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/23585.
Blackwell, Mark Leslie. "Palladium catalysed reactions of allenes and nitrone cycloadditions." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424606.
Louis, Chantal. "Cycloadditions 1,3-dipolaires asymétriques nitrones-sulfoxydes vinyliques." Doctoral thesis, Universite Libre de Bruxelles, 1996. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212435.
MacKenzie, Douglas Allan. "Strain-Promoted Alkyne-Nitrone Cycloadditions: Developing Bioorthogonal Labelling Strategies." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32733.
Ghose, S. "Cycloaddition reactions of nitroalkenes." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384381.
Smith, Julian Robert. "Nitrones in organic synthesis : #beta#-lactams from the cycloaddition of nitrones with copper acetylides." Thesis, University of Exeter, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328470.
Dawson, Claire E. "A cycloaddition route to heterocyclic triones." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243698.
Katkova, Olga. "Photochemical isomerization and stereoselective thermal cycloaddition reactions of conjugated nitrones." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=bgsu1123003688.
Roseblade, Stephen. "Intramolecular asymmetric nitrone cycloadditions in the synthesis of β amino acids." Thesis, University of Bristol, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251146.
Cano-Soumillac, Céline. "Synthèse de pharmacophores par cycloaddition [3+2] à partir de carbohydrates." Poitiers, 2004. http://www.theses.fr/2004POIT2287.
We describe herein the development of a novel methodology propitious to the asymmetric synthesis of new families of molecules with potential pharmacological interest. Our strategy involves the 1,3-dipolar cycloaddition reaction as key step: indeed, this reaction allows the creation of new bonds and asymmetric centres in a single step. Easily accessible and inexpensive unsaturated sugars are employed as precursors in this reaction, taking advantage of the existing chiral centres. We describe the regio- and stereoselective synthesis of isoxazolidines, a class of molecules of structural analogy with Sceletium alkaloids such Mesembrine. The use of microwaves in the context of the [3+2] cycloaddition reaction using carbohydrates was also explored. The major improvements are reduced time of reaction and higher yields due to reduced side products. Finally, we describe the synthesis of pyranopyrrolidinic bicyclic systems obtained in good yields and high regio- and stereoselectivity
Cai, Qiang. "Etudes et synthèse stéréosélective par cycloaddition de nouvelles isoxazolidines à potentiel pharmacologique." Poitiers, 2007. http://www.theses.fr/2007POIT2348.
This work demonstrates that the cycloaddition of nitrones with alcoxyacrylates is regio- and stereoselective, giving 5-alcoxy-isoxazolidines in good yields. This reaction is generally reversible: heating cis isoxazolidine in C3-C4 (kinetic product) give a cycloreversion to starting materials and a new cycloaddition allows accumulation of trans isoxazolidine (thermodynamic product). The reaction thus becomes diastereoselective. Cycloadditions performed under micro-waves, which are used also for the synthesis of nitrones, provide excellent results, with reduced preparation times while essentially avoiding use of solvents. Use of chiral groups on the ether function leads to enantioselectivity in the case of protected glucoside auxiliaries. Indicating that reversilility is at all levels. It has been demonstrated also that the cycloaddition can also be performed in an intramolecular fashion, providing original bridged isoxazolidines. The isoxazolidine cycle can undergo tandem opening and recyclizing reactions, providing directly original lactones. A controlled opening reaction gives access to plurifunctional beta-amino esters, considered as starting molecules towards more complex strutures and potentially useful compounds
Charles, Mark David. "Synthetic studies toward a total synthesis of morphine." Thesis, University of Sussex, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272077.
Karlsson, Staffan. "Asymmetric 1,3-Dipolar Cycloaddition Reactions of Azomethine Ylides, Thiocarbonyl Ylides, and Nitrones." Doctoral thesis, KTH, Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3524.
This thesis describes the development of methods for thepreparation of chiral non-racemic substituted pyrrolidines,tetrahydrothiophenes, and isoxazolidines. This has beenaccomplished by using asymmetric intermolecular 1,3-dipolarcycloaddition reactions of azomethine ylides, thiocarbonylylides and nitrones, respectively, with variousdipolarophiles.
The asymmetry in these reactions was introduced using twodifferent approaches: a diastereoselective approach (i.e. usingdipolarophiles linked to chiral auxiliaries and/or usingenantiomerically pure ylides) and an enantioselective approach(i.e. the reacting partners are achiral and the reaction iscatalysed by an enantiomerically pure catalyst). Thus, usingthe former approach, 3,4-disubstituted pyrrolidines andtetrahydrothiophenes were obtained in high diastereofacialselectivities (up to 90:10 dr). Using the latter approach,bicyclic fused isoxazolidines were obtained in up to 93%ee.
Some of the cycloadducts obtained from these reactions weretransformed into enantiopure known precursors of somebiologically active compounds{[(3R,4R)-4-(hydroxymethyl)pyrrolidin-3-ol andoctahydrocyclopenta[c]pyrrol- 3a-ylmethylamine dihydrobromide}and an active stereoisomer of a sex pheromone component of apine sawfly [the acetate of (2S,3R,7R,9S)-3,7,9-trimethyl-2-tridecanol]. The synthetic utility of these1,3-dipolar cycloaddition reactions was also demonstrated bythe syntheses of some new enantiopure organocatalysts whichwere found to be useful in some 1,3-dipolar cycloadditionreactions of nitrones with a,b-unsaturated aldehydes.
Yip, Carol. "Intramolecular 1,3-dipolar cycloadditions of norbornadiene-tethered nitrile oxides." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0016/MQ55731.pdf.
Zhu, Kaicheng. "Total synthesis of (+)-SCH 351448 and rhodium catalyzed stereoselective nitrene/alkyne cycloaddition cascade." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12900.
SCH-351448 is a 28-membered C2-symmetric macrocyclic metabolite isolated from the fermentation broth of a Micromonospora microorganism. This macrodiolide selectively activates transcription of the low-density lipoprotein receptor (LDL-R) promoter, which is important in the treatment of people with high cholesterol levels. The biological potential as well as the intriguing structure of this natural product prompted us to initiate synthetic studies towards its preparation. A convergent, enantioselective total synthesis of (+)-SCH 351448 was achieved. The tetrahydropyran ring systems in both fragments were constructed through our organosilane-based [4+2]-annulation methodology. Olefin cross metathesis was utilized in the union of two advanced fragments to generate the monomeric subunit. A metal-template directed macrodimerization strategy was examined but proved unsuccessful. Thus, the macrodiolide was assembled through a two-step sequence involving dioxinone ring-opening with concomitant esterification followed by DMC/DMAP mediated macrolactonization. Due to the prevalence of nitrogen-containing heterocycles in many natural products and pharmaceutical agents, the development of efficient methods for N-incorporation has remained at the forefront of synthetic research. Transition metal-catalyzed nitrene chemistry, an effective method to incorporate N-containing functionality into simple organic substrates, has become an attractive field for direct carbon-nitrogen bond formation. Of particular interest in this area is the metallonitrene/alkyne cycloaddition cascade reaction, a process in which nitrenes formed from sulfamate esters undergo addition to alkynes. In light of this, homopropargylic ethers, derived from chiral allenylsilanes in high yields and levels of diastereoselectivity , were converted into sulfamate esters bearing an internal alkyne. The generated sulfamate esters then underwent a metallonitrene cycloaddition and a subsequent highly stereoselective dearomative cyclopropanation, which resulted in unique tetracyclic norcaradiene-like products with two contiguous quaternary stereocenters. After subsequent opening of the sulfamate ester ring, the norcaradiene scaffold rearranged via a 6π electrocyclic ring opening process to form a fused tricyclic cycloheptatriene.
Cessford, Alastair G. "1,3-Dipolar cycloaddition reactions of triene-conjugated nitrile ylides and diazoalkanes." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/14299.
Feraldi-Xypolia, Alexandra. "Synthesis of trifluoromethylated nitrogen-containing heterocycles." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066444/document.
The introduction of a fluorine atom in an organic compound can have major impact on the compounds chemical and physico-chemical properties, therefore influencing its biological activity. Moreover, heterocycles represent an important class of compounds for the pharmaceutical and agrochemical industry, given that 70% of the biologically-active molecules possess a heterocyclic moiety. Therefore, the development of synthetic methods which allow access to trifluoromethylated heterocycles represent a challenge in organic chemistry. The work presented in this manuscript is focused on the synthesis of nitrogen containing heterocycles possessing a CF3 group at the α position to the nitrogen. More specifically, a variety of substituted α-(trifluomethyl)pyrrolidines and substituted α (trifluomethyl)piperidines were obtained by the ring contraction of (trifluoromethyl)piperidines and (trifluoromethyl)azepanes respectively via an aziridinium intermediate. The regioselective attack of the nucleophile on the aziridinium is induced by the CF3 group present on the intermediate. Furthermore, a diversity of functionalized α-(trifluoromethyl)pyridazines were obtained by a [2+1]/[3+2] cycloaddition sequence between a terminal alkyne, a difluorocarbene and (trifluoromethyl)diazomethane
Hostetler, Katherine J. "The photochemistry and 1,3-dipolar cycloadditions of 4-azidopyridine-N-oxide." Virtual Press, 2005. http://liblink.bsu.edu/uhtbin/catkey/1328115.
Department of Chemistry
Wan, Hayley. "A generic parallel combinatorial strategy to water tolerant asymmetric catalysis." Thesis, Durham University, 2003. http://etheses.dur.ac.uk/3084/.
Amos, David Thomas 1975. "Synthesis of nitrogen heterocycles via the intramolecular [4+2] cycloaddition of iminoacetonitriles." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/30015.
Vita.
Includes bibliographical references.
Iminoacetonitriles have been shown to function as aza dienophiles in intramolecular Diels-Alder reactions, affording substituted quinolizidines and indolizidines. The cycloadducts are formed with a high preference for an exo-orientated cyano group due to the a-amino nitrile anomeric effect. The substrates for these [4+2] cycloadditions are prepared from readily available alcohols via a Mitsunobu reaction with the previously unknown N-cyanomethyltriflamide (HN(Tf)CH₂CN) followed by cesium carbonate promoted elimination of trifluoromethanesulfinate. The a-amino nitrile cycloadducts are versatile synthetic intermediates and can be elaborated via alkylation, reduction, and nucleophilic addition chemistry to provide a variety of substituted and functionalized nitrogen heterocycles. Initial investigations have been undertaken to explore the use of this methodology in the total synthesis of alkaloid natural products.
by David Thomas Amos.
Ph.D.
Pepper, Adrian Gordon. "Asymmetric synthesis using acyl-nitroso cycloadditions : applications to natural product synthesis." Thesis, University of Salford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314011.
Katkova, Olga A. "Photochemical Isomerization and Stereoselective Thermal Reactions of Conjugated Nitrones." Bowling Green State University / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1123003688.
Morin, Marie. "Applications of new phosphorus-based 1,3-dipolar cycloaddition reagents in nitrogen heterocycle synthesis." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117088.
Cette thèse décrit l'étude du phospha-Münchnone, une nouvelle classe de 1,3-dipôle. Il a été démontré précédemment que ces 1,3-dipôles peuvent être facilement générés à partir des imines, des chlorures d'acides et de composés organophosphorés et peuvent être utilisés dans des réactions de cycloadditions 1,3-dipolaires. Le but de cette recherche est à la fois de comprendre la réactivité de ces dipôles et de les exploiter dans des réactions de cycloadditions avec des alcynes et des alcènes pour synthétiser des pyrroles et des 2-pyrrolines de façon hautement régio-, diastéréo- et énantiosélective. Le Chapitre 2 focalise sur la compréhension des facteurs qui contrôlent la régiosélectivité des réactions de cycloadditions 1,3-dipolaires avec les phospha-Münchnones et les alcynes ainsi qu'avec des hétérocycles mésoioniques analogues, les Münchnones et les Münchnones-imines. Malgré que chacun de ces 1,3-dipôles soit reconnu pour sa participation aux réactions de cycloadditions 1,3-dipolaires, aucune règle générale concernant les facteurs qui contrôlent la régiosélectivité n'a été encore établie jusqu'à maintenant. Grâce à l'étude des cycloadditions de ces trois 1,3-dipôles avec une gamme d'alcynes asymétriques électron pauvres et électron riches, et par la comparaison des comportements de ces 1,3-dipôles, des tendances au niveau de la régiosélectivité en fonction du potentiel d'ionisation de l'alcyne ont pu être observées. Conjointement avec le Pr. Houk et le Dr. Krenske à L'UCLA, des calculs DFT ont été réalisés et fournissent une explication logique sur les différents comportements de ces dipôles. De plus, ces 1,3-dipôles présentent des régioselectivités divergentes qui peuvent être exploitées pour la synthèse d'une variété de pyrroles avec de hautes sélectivités grâce au choix du réactif approprié. Cette étude permet également la prédiction de la régiosélectivité pour une large gamme d'alcynes. Dans le Chapitre 3, l'effet de l'unité organophosphorée sur la structure, la réactivité et la régiosélectivité du phospha-Münchnone est étudié. Les études aux rayons-X cristallographiques démontrent le rôle important de l'unité PR3 sur l'état fondamental et la réactivité de ces 1,3-dipôles. De plus, les résultats de l'étude théorique du Chapitre 2 sont exploités pour varier de façon logique les substituants du phosphore afin d'améliorer la régiosélectivité des cycloadditions d'alcynes sans modifier les substituants du produit final. Dans le Chapitre 4, la cycloaddition du phospha-Münchnone avec des alcènes est explorée. Différents phosphites et phosphonites sont testés pour leur capacité à participer aux cycloadditions intramoléculaires d'alcènes, et les résultats optimaux sont obtenus avec le (2-catechyl)PPh. Les 2-pyrrolines polycycliques sont générées dans des réactions de cycloadditions rapides, de façon modulaires et à partir de réactifs facilement accessibles : des imines contenant un alcène, des chlorures d'acyles et des phosphonites. De plus, la réaction procède avec une haute régio- et diastéréosélectivité. L'utilité de cette réaction a été étendue à d'autres produits, avec la réduction in situ des 2-pyrrolines en pyrrolidines, et avec l'oxydation en pyrroles. Dans le Chapitre 5, une nouvelle façon de contrôler l'énantiosélectivité des réactions de cycloadditions 1,3-dipolaires est décrite. Grâce à l'utilisation d'un phosphite substitué par un groupement (R)-BINOL, un nouveau phospha-Münchnone peut être synthétisé avec l'avantage d'être facilement accessible, modulaire, et ne requiert aucune étape supplémentaire pour installer ou enlever le fragment chiral. Cela offre une approche simple pour contrôler la chiralité des réactions de cycloadditions 1,3-dipolaires et générer des pyrrolines et des pyrrolidines polycycliques avec trois ou quatre centres stéréogènes de façon « one-pot » et jusqu'à 99% ee.
Lieou, kui Evelyn. "Nouvelles cétonitrones à partir de bêta-N-hydroxyamino alpha-diazoesters issus de l'addition nucléophile d'alpha-diazoesters sur des nitrones : application à la synthèse de nouveaux iminosucres." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAV027.
This manuscript reports the synthesis of bicyclic iminosugars bearing a quaternary carbon at their ring junction from polyalkoxylated ketonitrones. Firstly we have studied the nucleophilic addition of α-diazoesters to nitrones. The expected β-N-hydroxyamino α-diazoesters were successfully obtained by using lithium bis(trimethylsilyl)amide as base in THF at -78 °C. Treatment of these hydroxylamines with different metal catalyst induced 1,2-hydride shift and lead to unprecedented ketonitrones. To promote this transformation, silver triflate and tetrakis acetonitrile copper hexafluorophosphate were the most effective catalyst and ten new α-alkoxymethylcarbonyl cyclic ketonitrones were prepared. Their reactivity as 1,3-dipoles in cycloaddition reactions with various dipolarophiles was investigated. Cycloadducts obtained from the reaction between these ketonitrones and allyl alcohol or homoallyl alcohol were coverted into the corresponding pyrrolizidines or indolizidines by a molybdenum-catalyzed N-O bond cleavage. Subsequent modifications (ester reduction and benzylic ethers hydrogenolysis) gave acess to six new bicyclic iminosugars which are substituted at their ring junction. Among these molecules, the inhibitory activity evaluation revealed two potent and selective inhibitors of α-glucosidases
Plefka, Oliver. "1,3-Dipolare Cycloaddition von N2O an hochreaktive Mehrfachbindungen." Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-70667.
Sancibrao, Pierre. "Cycloadditions de nitroso Diels-Alder asymétriques et régiosélectives : une nouvelle voie synthétique d'hétérospirocycles." Thesis, Paris 11, 2012. http://www.theses.fr/2012PA112417.
During this research, we were interested in the synthesis of enantiopur heterospiranic bicycles. We therefore developed a new synthetic route towards the synthesis of molecules with different spirocyclic structures. This novel synthetic route features a nitroso Diels-Alder cycloaddition as key step. The total control of the stereoselectivity and the regioselectivity of the reaction, rarely described in the literature, have been specifically studied during this work. This study allows us to have a better understanding of this reaction. Two different approaches have been developed in this work. They both led to total control of the regioselectivity of this cycloaddition. Cycloadditions performed by reactions using a nitrosopyridine dienophile and catalyzed by a chiral source of copper allows the synthesis of cycloadducts precursor of azaspirocycles with a modest enantioselectivity. Cycloadditions using a chloronitroso chiral dienophile derived from xylose allowed the synthesis of oxaspiraniques precursors with enantioselective excess of at least 95%. The last approach was finally validated by the synthesis of various spiroethers and spirolactones through N-O bond cleavage an intramolecular cyclizations. Finally, the vinyl triflate function of the spirolactones and spiroethers was engaged in Suzuki couplings to introduce molecular diversity at a late stage allowing the synthesis of 9 different spiranic structures including 5 enantioenriched
RIGOLET, SEVERINNE. "Cycloaddition 3 + 2 de methylenelactames avec les nitrones. Structure et reactivite des spiroheterocycles. Ouverture selective du cycle isoxazolidinique." Besançon, 1999. http://www.theses.fr/1999BESA2003.
Tangara, Salia. "Synthèse d'aziridinyl iminosucres à partir de nitrones et évaluation de leur activité inhibitrice de glycosidases." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAV053.
Our team has recently described the synthesis of new indolizidine and quinolizidine iminosugars, which revealed to be potent and selective α-glucosidase inhibitors (nanomolar IC50). These original molecules exhibit a quaternary center at the ring junction and a D-gluco configuration. With the aim to define the mode of interaction of these molecules with glycosidases, we engaged in the synthesis of analogues containing an aziridine moiety included in a 1-azabicyclo[4.1.0]heptane scaffold.Our synthetic approach towards aziridinyl iminosugars involves a stereoselective 1,3-dipolar cycloaddition between carbohydrate-derived cyclic ketonitrones and alkynes, and a stereoselective Baldwin rearrangement into 2-acylaziridines. The latter (if polybenzylated) were converted into aziridinyl iminosugars through diastereoselective reduction of their ketone function and deprotection under Birch conditions. In the case of polyacetylated acylaziridines, the final iminosugars were obtained by reduction with hydrides.Using this strategy, we have prepared 7 aziridinyl iminosugars, and 5 polyhydroxylated isoxazolines. All these new iminosugars were evaluated as glycosidase inhibitors, and they revealed to be modest (micromolar IC50) but selective inhibitors of α-glucosidases. Their complexes with a crystalline bacterial α-glucosidase allowed crystallographic elucidation of their mode of interaction with this enzyme at the molecular level
Liang, Shengwen. "Nitrene Transfer Reactions Mediated by Transition Metal Scorpionate Complexes." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1339005115.