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Tesi sul tema "Alkylation"
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1
Myers, K. A. "Alkylation of mitochondrial DNA". Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234216.
Testo completo
2
Feilden, Andrew David. "Alkylation of salicylic acids". Thesis, University of York, 1997. http://etheses.whiterose.ac.uk/14177/.
Testo completoAbstract (sommario):
The work described in this thesis has been directed at the development of a novel synthetic route to alkylsalicylic acids. Associated reactions have also been studied. The primary aim has been the synthesising of alkylsalicylic acids possessing an alkyl chain containing more than eight carbon atoms. In addition, a limited study has also been carried out into the sulfurisation of alkylphenols. Both the alkylsalicylic acids and the sulfurised aJkylphenols are used as oil additives. They both act as detergents, keeping an engine clean and neutralising any acids formed in the engine as a result of oxidation processes. Chapter Icontains a general introduction to oil additives, principally the overbased detergents, and an introduction to Friedel-Crafts chemistry, which is the basic reaction employed in the alkylation of salicylic acid. Chapter 2 introduces the alkylation of salicylic acid employing concentrated sulfuric acid as the catalyst, and using simple model compounds to demonstrate the feasibility of the approach. The effect of varying the alkylating substrate to produce an alkylsalicylic acid with an alkyl chain containing at least eight carbon atoms is explored in Chapter 3. Optimization of the alkylation reaction and the effect of altering a number of the reaction parameters (e.g. temperature, catalyst and reaction duration) on the yield and product distribution for a range of alkylating substrates is set out in Chapter 4. The work contained in Chapter 5 concentrates on the synthesis and rearrangement of the esters of salicylic acid and investigates the possibility that the esters are intermediates in the alkylation reaction. Chapter 6 is concerned with the industrial implications of the alkylation of salicylic acid. It concentrates in particular on the synthesis using industrially available alkenes and the scale-up of the reaction. An insight into the sulfurisation of alkylphenols, and the attempted identification of products formed in the industrial process, can be found in Chapter 7. Finally, the experimental details for Chapters 2 to 7 are contained in Chapter 8.
3
Klein, Rosalyn. "Asymmetric α-alkylation reactions". Thesis, Rhodes University, 2000. http://hdl.handle.net/10962/d1006710.
Testo completoAbstract (sommario):
A novel camphor-derived hydroxy ketal 138 has been developed as a crural auxiliary, and used to prepare a series of six carboxylic esters of increasing steric bulk. The α-benzylation of this series of esters was achieved with diastereoselectivities of 59 - 83％ d. e. and in 39 - 48％ material yield. These results compared very favourably with those obtained in earlier studies using a regioisomeric analogue as the chiral auxiliary. Computer.modelling studies of the putative enolate intermediate has provided some insight into the possible mode of electrophilic attack at the α-carbon and the roles of the ketal protecting group and the lithium cation in these asymmetric transformations. In a related investigation, based on earlier work, a camphor-derived imino lactone has provided convenient access to α-alkyl α-amino acids, the imino lactone serving as a masked glycine equivalent. Using straight chain primary alkyl iodides [RI; R = Me, Et, Pr, Bu, CH₃(CH₂)₄ and CH₃(CH₄)₅], alkylation of the potassium enolate of the camphor-derived imino lactone was effected with 54 - 89％ d.e. and in 54 - 87％ material yield. Four novel alkylated derivatives were synthesised using isopropyl iodide, sec-butyl iodide and allyl iodide, the latter reagent resulting in both the monoallylated and diallylated products. While very good diastereoselectivities were achieved (83 - 88％ d. e.) in these reactions, the material yields from reaction with the secondary alkyl iodides were low (31- 35％) due, presumably, to their decreased electrophilicity. Computer modelling studies of the enolate were carried out and support the hypothesis of endo attack by the electrophile on the enolate intermediate. These studies also indicate the possibility of coordination of the postassium cation to the endocyclic ester oxygen, thus effectively anchoring the bulky cation away from the reaction site.
4
Bisnaire, Michel M. J. "Iron-mediated allylic alkylation reactions". Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5797.
Testo completoAbstract (sommario):
In this work it will be shown that Fe(CO)$\sb2$(NO)$\sb2$ mediated allylic alkylation reactions proceed via an intermediate which is neither an $\eta\sp3$-allyliron complex nor an $\eta\sp2$-allyliron complex. Rather, (Fe(CO)(NO)$\sb2$DMM)$\sp-$Na$\sp+$ has been identified as the catalytic intermediate. This provides the first evidence of an interaction between the nucleophile and the metallic center in reactions involving iron nitrosyl complexes. The study of the Fe(CO)$\sb3$(NO)$\sp-$Na$\sp+$, geranyl acetate, and NaDMM system was studied in order to elucidate the catalytically active species. Although it was determined that Fe(CO)$\sb3$(NO)$\sp-$Na$\sp+$ served as the precursor of a catalytic species X, the nature of X remains unknown.
5
Walsh, Kelly Ann. "The alkylation of aromatic amines". Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/7659.
Testo completoAbstract (sommario):
N-alkylated anilines can be obtained in moderate yields from aniline and methyl formate in the presence of Rh$\sb6$(CO)$\sb $ and KI after 72 hours at 180-200$\sp\circ$C. Ru$\sb3$(CO)$\sb $ gave similar results to the unpromoted rhodium carbonyl system. Formanilide and N-methylformanilide were also formed in the reaction. The (HCr(CO)$\sb5$) -anion in the form of its PPN$\sp+$ and Et$\sb4$N$\sp+$ salts also catalysed this reaction (under hydrogen) but was selective to the formanilide products. The presence of an electron donating group on the aromatic ring favoured the formation of alkylated products in the presence of bis(triphenylphosphine)iminium (PPN$\sp+$) hydridochromiumpenta-carbonyl. Several possible mechanisms were tested and the nature of the polynuclear catalysts investigated.
6
El, Gihani Moharem Taha. "Aspects of some alkylation reactions". Thesis, Loughborough University, 1995. https://dspace.lboro.ac.uk/2134/10420.
Testo completoAbstract (sommario):
Friedel-Crafts reactions of the (-)-8-phenylmenthyl and (+ )-trans-2-(acumyl) cycJohexyl aryl hydroxy acetates catalysed by trimethylsilyl triflate (TMSOTf) and equivalents in the presence of electron rich heterocycles gave the expected diarylacetates in high de 88%, via a planar cation. The interaction of trifluoromethanesulfonic (triflic) acid (TfOH) with either bistrimethylsilyl -acetamide (BSA) or -urea (BSU) can be used to generate stoichiometric amounts of trimethylsilyl triflate (TMSOTf) "in situ" , the system can be used efficiently to remove triflic acid from TMSOTf and to generate catalytic amounts of TMSOTf from TfOH for use in a range of trimethylsilyl triflate (TMSOTf) catalysed reactions. Similarly the interaction of fluorosulfonic acid (FSA) with either bis-trimethylsilyl -acetamide (BSA) or -urea (BSU) can be used to generate catalytic amounts of trimethylsilylfluorosulfonate (TMSOFs) "in situ" for use in a wide range of reactions as an alternative to trimethylsilyltriflate (TMSOTf) Scandium(III) trifluoromethanesulfonate and copper(II) trifluoromethanesulfonate can be used to catalyse aromatic alkylation with arylhydroxyacetates. Scandium(III) trifluoromethanesulfonate also proved to be a recyclable catalyst for these reactions. A number of Pictet-Spengler cyclisation reactions were also catalysed by Scandium(III) trifluoromethanesulfonate and copper(II) trifluoromethanesulfonate. Mannich reactions of a number of caJix[4jresorcinarene derivatives with (R)-(+)-amethylbenzylamine under alkaline conditions lead to the formation of single diastereomeric tetrakis(l,3-dihydrobenzoxazine) derivatives in high yields; the reactions using the (S)-(-)-a-methylbenzylamine afford the enantiomers. The products react with protic acids to afford equilibrium mixtures of diastereomers.
7
Evans, Louise Anne. "Ion-pairing in allylic alkylation". Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.529850.
Testo completo
8
Loaring, Huw W. "Alkylation studies on the gibberellins". Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338439.
Testo completo
9
Latieule, Sylvie. "Alkylation aliphatique sur solide acide". Paris 6, 1994. http://www.theses.fr/1994PA066740.
Testo completoAbstract (sommario):
La reaction d'alkylation isobutane/butene-1 a ete etudiee a basse temperature, en utilisant un catalyseur a base d'acide sulfurique concentre, depose sur silice. L'etude bibliographique de la reaction constitue le premier chapitre de cette these. La premiere partie est consacree aux aspects mecanistiques de la reaction, aux catalyseurs d'alkylation et aux procedes industriels. Les themes suivants sont developpes dans la deuxieme partie: activite catalytique, mise en evidence du role des sulfates de butyle et etudes cinetiques. Le second chapitre presente le systeme catalytique utilise et decrit les modes operatoires. Le chapitre iii propose un mecanisme pour l'etage d'initiation du catalyseur, a l'issue d'une etude sur le role des sulfates de butyle secondaires et tertiaires. Le chapitre iv demontre que la reaction cinetiquement limitante de l'alkylation est une reaction de volume pendant la periode d'initiation et une reaction interfaciale a l'etat de regime. Le chapitre v est consacre a l'effet de l'acidite sur la selectivite de l'alkylat. Une modelisation permettant de prevoir la selectivite en trimethylpentanes, a t = -5c, pour une large gamme de granulometries et de compositions de phase acide, est proposee. L'effet de l'acidite sur les reactions secondaires de degradation de l'alkylat a egalement ete evoque, dans le cadre d'une etude cinetique sur la degradation du trimethylpentane-2,2,4
10
Chumbhale, V. R. "Alkylation reactions over synthetic zeolites". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1992. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/5828.
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11
Zhu, Jia Liang. "Reductive alkylation of Ã-cyano ketones". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq39611.pdf.
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12
Knowles, Haydn Scott. "The light activated alkylation of glycine". Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341492.
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13
Al-Matar, Hamad M. "Alkylation of [60]- and [70]fullerenes". Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326917.
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14
Ortega-Martínez, Aitor. "Synthesis of 3,3-disubstituted 2-oxindoles by deacylative alkylation and photocatalytic alkylation of olefins by zinc-sulfinates". Doctoral thesis, Universidad de Alicante, 2018. http://hdl.handle.net/10045/77351.
Testo completoAbstract (sommario):
La tesis doctoral está dividida en una introducción general y cuatro capítulos. En la introducción general, se describen diferentes productos naturales y derivados sintéticos que contienen un núcleo de oxindol en su estructura junto a comentarios sobre sus actividades biológicas. Además, también están incluidas diversas metodologías de síntesis para la síntesis de estos derivados de oxindol junto a una explicación general sobre el proceso de alquilación desacetilativa. Los capítulos se han desarrollado con una breve introducción, una propuesta de objetivos, comentarios y discusión de los resultados obtenidos en las investigaciones finalizando con las conclusiones obtenidas. El Capítulo 1 trata sobre la síntesis de 2-oxindoles 3,3-disustitutidos a través de un proceso de alquilación desacetilativa utilizando halogenuros de alquilo. El Capítulo 2 describe la alilación y la alilación desacetilativa catalizada por paladio de los derivados de 2-oxindol utilizando alcoholes alílicos no activados. En el Capítulo 3 está incluida la síntesis de 3-fluoro-2-oxindoles combinando las metodologías descritas en los dos anteriores capítulos. Finalmente, en el Capítulo 4, se desarrolla la alquilación fotocatalizada de olefinas electrofílicas a través de sulfinatos de zinc bencílicos y alquílicos.
15
Fretz, Samuel J. "Reductive alkylation of benzoates containing benzylic oxygen". Connect to resource, 2010. http://hdl.handle.net/1811/45479.
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16
Graham, Ronald Joseph. "The conformationally controlled alkylation of 15-hexadecanolide". Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27459.
Testo completoAbstract (sommario):
The 16-membered lactone 17was synthesized and alkylated to yield a 4:1 ratio of 20 and 19 respectively. The product ratio was rationalized by molecular mechanics calculations on 18.
A new polar map convention was developed for conformational analysis of cyclohexadecane.[See Thesis for Diagram]Science, Faculty of
Chemistry, Department of
Graduate
17
Hewitt, C. N. "Studies of the natural alkylation of lead". Thesis, Lancaster University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355056.
Testo completo
18
Klair, Sukhbinder S. "Stereoselective enolate alkylation of acyl dithiane oxides". Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314512.
Testo completo
19
Hodgson, Anne. "Asymmetric alkylation of substituted beta-keto esters". Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292828.
Testo completo
20
Hodgson, Anne. "Asymmetric alkylation of substituted p-keto esters". Thesis, University of Bath, 1991. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760613.
Testo completo
21
Chighine, Alessandra. "Microwave-assisted alkylation reactions employing O-alkylisoureas". Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/13374.
Testo completoAbstract (sommario):
In recent years, the use of microwave irradiation to accelerate chemical reactions has become increasingly popular. A protocol for the synthesis of esters via reaction of carboxylic acids with O-alkylisoureas under microwave heating was studied. Efficient processes were developed using pre-formed O-alkylisoureas or via an in-situ formation sequence starting from primary and secondary alcohols. It was demonstrated that under these microwave conditions ester formation with primary and secondary alcohols proceeded in good yields and, in the latter case, with clean inversion of configuration of the esters. O-alkylisoureas were used as reactive intermediate also in the alkylation of substituted phenols. A PASP procedure was also developed by employing pre-formed polymer-supported isoureas, and by an efficient “catch and release” esters formation procedure in which alcohols are caught on resin as isoureas by reaction with immobilised carbodiimide, and released as ester by subsequent treatment with a carboxylic acid. Polymer-supported isoureas were also employed in the synthesis of 2-oxazolines.
22
Carmali, S. "New bis-alkylation reagents for protein conjugation". Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1462963/.
Testo completoAbstract (sommario):
Bis-alkylation for disulfide-bridging PEGylation has emerged as a valid strategy for protein conjugation. Proteins can be efficiently modified to add a three-carbon methylene bridge between the two sulfurs in a disulfide bond. The so-called C3 bis-sulfone reagent is a linear poly (ethylene glycol) (PEG) that has been functionalised at one terminus with a latently reactive bis-alkylation moiety capable of undergoing sequential Michael reactions. Latency is achieved by utilising leaving groups that must undergo elimination to unmask an ,-unsaturated double bond needed for Michael addition. Structural modifications of these reagents are thought to alter the solvent availability or electrophilic character of the Michael acceptor to modulate conjugation reactivity with a protein. It was therefore hypothesised that by modifying the structure of C3 bis-sulfone reagent, it would be possible to obtain reagents with different reactivity. This variable reactivity can then be exploited with bifunctional reagents to allow the preparation of protein-protein conjugates in an efficient manner. Several synthetic targets and strategies were examined to prepare different types of di-PEG and multifunctional reagents for protein conjugates. A small family of di-PEG bis-alkylating reagents with different molecular weights was prepared and the conjugation efficiency was compared to linear C3 PEG reagents of the same overall molecular weight. Molecular dynamic studies were used to understand how the PEG chain affected the linker reactivity. Results showed that PEG-linker interactions were found to be less pronounced for reagents that contained two 10 kDa PEG chains (di-PEG2×10) when compared to a linear C3 reagent with a single PEG of 20 kDa (PEG20) with the same overall molecular weight. While the presence of a second PEG chain was found to influence conjugation efficiency, the modification of the bis-alkylating Michael acceptor in C3 reagent was also explored as a means to vary reactivity. Acetylenic ketones were examined as bis-Michael acceptors in the preparation of two C1 reagents with distinct structural features (aliphatic and aromatic). An aliphatic C1 reagent was prepared without leaving groups but was found to have less reactivity when compared to an aromatic C3 reagent. Semi-empirical studies suggested that this lower reactivity could be attributed to less electron-withdrawing aliphatic structure and to stereoelectronic effects. Aliphatic C1, while less reactive was found to undergo a double Michael addition and consequently allowed re-bridging of a reduced disulfide. In contrast, aromatic C1 required leaving groups to modulate the higher reactivity observed but was not found to re-bridge a reduced disulfide. The C3 bis-sulfone reagent is known to undergo elimination much more slowly at slightly acidic pH values. This is important because conjugation will not proceed until elimination has occurred. The need for elimination was used as a basis for the synthesis of hetero-bifunctional reagents that could be used for hetero-functional protein-protein conjugates, such as bispecific Fab-PEG-Fab conjugates. For potential scalability, effort was focused on preparing mono-sulfone-PEG-bis-sulfone hetero-bifunctional reagents (MpB reagents) that could be utilised in a one-pot reaction sequence to give hetero-functional protein conjugates. Reactions using the MpB reagent showed the potential to allow the sequential conjugation of two Fab molecules by altering the pH conditions of the reaction mixture in a single reaction vessel. This variable reactivity can provide a synthetic platform for controlled sequential conjugation that can allow the efficient preparation of protein-protein conjugates.
23
Mordacque, Olivier Michel André. "Selective alkylation of phenols using solid catalysts". Thesis, University of York, 2003. http://etheses.whiterose.ac.uk/14186/.
Testo completoAbstract (sommario):
Alkylphenols are important industrial chemicals used in a wide range of applications. In particular, 2,6-ditertbutylphenol is an indispensable building block for anti-oxidants and light protective agents. A new solid catalyst was prepared, characterised and tested for the alkylation of phenols with alkenes in an attempt to reduce the environmental hazards associated with the aqueous wastes generated by the homogeneously catalysed alkylation reactions. The new silica gel supported aluminium phenolate catalyst was prepared by a two steps procedure, first grafting of an aluminium precursor such as aluminium trichloride or triethyl aluminium onto silica mainly through reaction with the support silanol groups, then exchange of the aluminium ligand with phenol. Catalysts exhibited mainly Lewis acidity and two types of active sites were detected. The new catalyst was successfully applied in the phenol - isobutene alkylation system. Catalysts exhibited an ortho- selectivity for the introduction of the first tertbutyl group. The selectivity of the second alkylation could be tuned by varying reaction conditions (reaction temperature, catalyst amount, alkene addition methods) and catalyst characteristics (support surface pre-treatment temperature, aluminium precursor and loading). Hence high yields of 2,4-ditertbutylphenol or moderated yields of 2,6-ditertbutylphenol were obtained. Alkylation of phenol with other alkenes and cresols alkylations were successfully catalysed by the new silica gel supported aluminium phenolate catalyst with the same selectivity. However, the diorthopropylphenol was the main dialkyl products when using propene as alkylating agent. "Greening" of the catalyst preparation by reducing the amount of solvent used was carried out without changing the selectivity and the activity of the catalyst. Reusability of the catalyst was investigated and a decrease of activity was observed. Storage of the catalyst was possible for a long time but activity and selectivity were affected.
24
BODIBO, JEAN-PAULIN. "Alkylation et acylation du phenol sur zeolithes". Poitiers, 1991. http://www.theses.fr/1991POIT2336.
Testo completoAbstract (sommario):
L'objectif de ce travail est de montrer que des catalyseurs zeolithiques peuvent etre substitues aux solutions acide corrosives et dangereuses souvent utilisees pour la synthese d'aromatiques fonctionnels. Les reactions modeles choisies sont d'une part l'alkylation du phenol par le methanol, d'autre part le rearrangement de l'acetate de phenyle. Dans chacun des cas le schema reactionnel est etabli et les mecanismes discutes. Tous les produits de l'alkylation du phenol sur une zeolithe hy resultant de reactions d'o- et c-alkylation. L'anisole et les ortho- et para-cresols sont les produits primaires. Leur transformation conduit a des methylanisoles et dimethylphenols mais aussi a des produits permethyles qui ne desorbent pas du catalyseur et qui sont responsables de la desactivation. Les ordres de reaction sont en accord avec un mecanisme de type rideal, l'etape limitante etant la reaction entre le methanol adsorbe sur un site protonique et le phenol adsorbe physiquement dans les pores de la zeolithe. Sur la zeolithe hy, la transformation de l'acetate de phenyle en hydroxyacetophenones se produit par deux mecanismes, l'un intramoleculaire, l'autre bimoleculaire (dismutation) tandis que la zeolithe hzsm-5 elle se produit uniquement par dismutation. Les reactions secondaires dependent de la zeolithe: cyclisation de la 2-acetoxyacetophenone sur hy, formation de produits de condensation du cetene sur hzsm-5; ces produits secondaires sont responsables de la faible stabilite des zeolithes. Cette stabilite est nettement amelioree si l'acetate de phenyle est additionne d'eau ou s'il est remplace par un melange de phenol et d'acide acetique
25
Kankam, Kofi. "Alkylation of Benzene on Immobilized Phosphotungstic Acid". Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etd/3847.
Testo completoAbstract (sommario):
Linear alkylbenzenes (LAB) are key intermediates in the synthesis of linear alkylbenzene sulfonate surfactants that are used in the manufacture of detergents. Production of LAB with traditional Lewis acids as catalysts, such as hydrofluoric acid, results in the formation of large amounts of toxic wastes and corrosion of industrial equipment. Phosphotungstic acid (PTA) has gained much attention in recent years as a solid catalyst for various alkylation reactions. This research work aims to develop a novel material based on PTA-containing silica gel, which can effectively catalyze LAB synthesis. Sol-gel synthesis of silica gel in the presence of PTA and tetraethyl orthosilicate as precursors produced a mesoporous aterial containing covalently embedded PTA clusters. Obtained superacidic catalyst demonstrated high catalytic activity in liquid-phase alkylation of benzene by various alkenes. Covalent embedding of catalytically active HPA clusters prevents their leaching from the catalyst surface, which enabled its excellent catalytic properties.
26
Taylor, Piers. "Aza-enolate alkylation reactions of lactim ethers". Thesis, University of Bath, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425801.
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27
Parham, Karol Renee. "Carbon Alkylation of 2-Phenylthio-1,3-cyclopentanediones". W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539625347.
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28
Cann, Patrice. "Etudes de l'alkylation de Williams et de la réaction de Strecker pour l'obtention d'acides alfa-amino-omega-phosphonocarboxyliques optiquements actifs". Brest, 1998. http://www.theses.fr/1998BRES2018.
Testo completoAbstract (sommario):
L'objectif de ce travail etait de mettre au point de nouvelles voies de syntheses d'acides alfa-amino-omega-phosphonocarboxyliques. Dans la premiere partie, apres un rappel bibliographique des differentes methodes de preparation des acides alfa-aminocarboxyliques, nous avons decrit l'alkylation du synthon de williams, analogue chiral de la glycine, par le 4-(bromomethyl)phenyl methylphosphonate de diethyle qui permet d'acceder apres hydrogenolyse au 4-diethylphosphonomethylphenylalanine avec de bon rendement et une excellente stereoselectivite (ee>96%). La deuxieme partie est consacree a la synthese asymetrique de strecker de l'acide (s)-2-amino-4-phosphonobutanoique ((s)-ap4) en utilisant le (1s, 2r)-2-amino-1,2-diphenylethanol et le (r)-2-amino-2-phenylethanol comme auxiliaires chiraux. Ces syntheses menees dans le chloroforme, sont initiees par la condensation du 2-formylethylphosphonate et du -aminoalcool, qui conduit a la formation de l'isomere e de l'iminoalcool et des deux diastereoisomeres de l'oxazolidine. L'aminonitrile est obtenu par reaction de ce melange tautomerique avec le cyanure de trimethylsilyle. Nous montrons au cours de cette etude que la stereoselectivite de la nitrilation ne depend pas de la proportion des tautomeres. Le cyanure s'additionne sur l'imine qui est en equilibre avec ses deux isomeres cycliques. L'ap4 est obtenu apres clivage de la copule chirale et hydrolyse acide avec des exces enantiomeriques de 64% et 54% lorsqu'on utilise respectivement le 2-amino-1,2-diphenylethanol et le 2-amino-2-phenylethanol.
29
Vergani, Diego. "Shape-selective alkylation of biphenyl over zeolite catalysts /". [S.l.] : [s.n.], 1995. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=11139.
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30
Skiti-Mama, Neliswa. "Novel camphor derivatives as potential asymmetric alkylation auxiliaries". Thesis, Nelson Mandela Metropolitan University, 2008. http://hdl.handle.net/10948/1077.
Testo completoAbstract (sommario):
The investigation has been focussed on the synthesis and characterisation of camphor-derived chiral auxiliaries that incorporate two camphor skeletons and an evaluation of their stereodirecting potential in ester α-benzylation reactions. Two regioisomeric camphorquinone-derived monoketals were synthesised and identified by 1D- and 2D-NMR, and X-ray crystallography. The stereo-directing potential of the alcohols that resulted from reduction of these ketones as chiral auxiliaries in the alkylation of carboxylate ester derivatives has been studied. The diastereoselectivities shown by NMR spectroscopy range from 14- 30 % d.e. for (1R,2 S, 3R) -2 ,2-[ (1R, 2 S, 3R) -bornane-2,3-dioxy] - bornan-3-ol and 68-74 % d.e. for (1R, 2S ,3R) -3 ,3-[ (1R, 2S ,3R) - bornane-2, 3 -dioxy]bornan-2-ol with selectivities that correlate with the size of the alkyl group in the ester moiety. Trapping of the enolates generated from (1R, 2S ,3R)-2, 2 -[(1R,2 S, 3R) -bornane- 2,3-dioxy]bornan-3-yl propanoate afforded both E- and Z-silyl ketene acetal derivatives in the ratio of 64:36 confirming the formation of both possible enolate structures during enolization. Chiral auxiliaries containing a hemiaminal ether blocking group as well as two chiral alcohols containing monothio-ketal blocking groups have also been synthesised. α-Benzylation of their corresponding propanoate esters afforded the alkylated product with disappointingly low diastereos electivities. Asymmetric reduction of α-keto esters attached to (1R, 2 S, 3R) - 2,2- [ (1R,2 S, 3R) -bornane-2, 3 -dioxy]bornan-3-ol and (1R, 2S ,3R) - 3,3- [ (1R,2 S, 3R) -bornane-2, 3 -dioxy]bornan-2-ol with metal hydrides proceeded with selectivities of up to 30 % d.e. Modelling of the keto ester derivatives at DFT levels provided useful insights into possible conformations adopted by the two α-keto esters and hence the preferred face of attack by metal hydride during reduction.
31
Stephen, Susanna Catherine. "The study of memory effects in allylic alkylation". Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322249.
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32
Lorusso, Patrizia. "Metal catalysed alkylation of carbonyl compounds with formaldehyde". Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/7823.
Testo completoAbstract (sommario):
Formaldehyde is a chemical used widely in the manufacture of building materials. A remarkable example is represented by the Lucite two-step Alpha technology for the large scale production of methyl methacrylate (MMA), the essential building block of all acrylic-based products. Esters and ketones are important intermediates in the manufacture of acrylate esters therefore α-hydroxymethylenation of carbonyl compounds using formaldehyde as a one carbon alkylating agent and subsequent dehydration to the corresponding methylenated derivatives has been explored in the current work. We report a novel catalytic approach for the synthesis of methyl methacrylate (MMA) via one-pot α-methylenation of methyl propanoate (a chemical intermediate of the ALPHA process) with formaldehyde, generated in situ by Ru-catalysed dehydrogenation of methanol. Elucidation of the mechanism involved in the catalytic dehydrogenation of methanol along with the collateral alcohol decarbonylation reaction was gained through a combined experimental and DFT study. The development of an alternative process where anhydrous formaldehyde is produced in situ would provide a simplification over the current second step of the ALPHA technology where the formaldehyde is initially produced as formalin, subsequently dehydrated to afford anhydrous formaldehyde in order to ensure high selectivity to MMA. As an alternative approach, ketones, in particular 3-pentanone and 2-butanone, were targeted as potential substrates in order to overcome some of the problems related to competing reactions that occur at the ester group. Hydroxymethylenation, followed by dehydration and Baeyer-Villager oxidation, possibly catalysed by enzymes to reverse the normal selectivity, leads to the formation of acrylate esters. The catalytic reaction is enabled by a gold carbene hydroxide complex in such a way that the substrate undergoes C-H activation and the nascent metal alkyl acts as a nucleophile towards the electrophilic formaldehyde, supplied in the form of alcoform* (solution of paraformaldehyde in methanol).
33
EJ-JENNANE, KAMAL. "Alkylation et transalkylation des aromatiques sur catalyseurs zeolithiques". Paris 6, 1991. http://www.theses.fr/1991PA066106.
Testo completoAbstract (sommario):
Les performances catalytiques de diverses h-mfi, h-mordenite et h-y, en regime, de rapports si/al variables, sont comparees dans les reactions de dismutation du toluene et d'alkylation du toluene par l'ethylene. Les conditions operatoires utilisees sont proches de la realite industrielle. L'influence du rapport si/al, de la taille des pores sur les proprietes catalytiques, ainsi que l'effet de la formation du coke sur l'activite et la stabilite catalytique ont ete particulierement examines. La cinetique de chacune de ces reactions sur zeolithes a egalement ete etudiee. Les resultats experimentaux montrent que la formation de coke est tres limitee dans les zeolithes a 10 mr, comme la mfi. Dans ce cas, l'activite catalytique de la zeolithe fraiche ou cokee est etroitement liee a son acidite. L'activite catalytique des zeolithes a 12 mr, dotees d'un reseau poreux tridimensionnel, comme la h-y, est principalement limitee par la formation de coke sur les sites acides. Pour les zeolithes a 12 mr, caracterisees par un reseau poreux monodimensionnel, telle que la mordenite, l'activite catalytique est limitee par la formation de coke dans les micropores qui engendre d'une part une inhibition des sites acides et d'autre part des phenomenes de limitations diffusionnelles. Le rapport si/al de la mordenite doit etre eleve de maniere a reduire la formation de coke. Ces observations expliquent pourquoi les valeurs des energies d'activation obtenues pour les reactions de transformation d'aromatiques sont elevees dans le cas des h-mfi (20-29 kcal/mol) et des h-y (18-25 kcal/mol) et faibles dans le cas des mordenites (9-14 kcal/mol). Par consequent, l'intervention de phenomenes de limitations diffusionnelles sur la h-mordenite, lors de la dismutation du toluene, ne permet pas dans ce cas d'acceder aux parametres cinetiques vrais de la reaction. Neanmoins, un effet inhibiteur des pressions elevees en hydrogene sur la formation du coke est mis en evidence. Par contre sur h-mfi, la cinetique de cette reaction est plus facile d'acces, et les resultats obtenus montrent clairement un effet inhibiteur de l'hydrogene sur la vitesse de reaction et confirment que le mecanisme de la reaction de dismutation du toluene est base sur la formation d'un intermediaire carbocation benzylique
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Perfetti, Michael Thomas. "Diastereoselective α-Alkylation of Chiral β-Borylated Esters". Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/30820.
Testo completoAbstract (sommario):
The use of boron in the synthesis and development of asymmetric methodologies and various biological and medicinal compounds has increased significantly over the last decade. This thesis reports the development of a novel diastereoselective reaction for the α-alkylation of chiral β-borylated esters. We propose that standard deprotonation of chiral β-borylated esters with lithium diisopropylamide (LDA) leads to the formation of a boron"ate" intermediate that upon treatment with an alkylation reagent collapses to provide chiral α, β-substituted boronic esters with a high degree of diastereoselectivity. This reaction is powerful in that a wide range of chiral β-borylated ester substrates can be employed that possess varying degrees of substitution and steric bulk. Results show that the reaction is syn-selective and provides yields of up to 60%, with diastereomeric ratios as high as (9.7:1). Additionally, alkylation products from bulkier tert-butyl esters provide higher DR values compared to those of methyl esters that possess the same β-functional groups. Several techniques were utilized to elucidate the mechanism of this reaction including variations of reaction temperature and equivalents of base, and also real-time analysis of the reaction by ¹¹B NMR experiments.Master of Science
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Alezra, Valérie. "Nouvelles voies d'accés à des sérines alpha-substituées énantiopures à partir d'aziridino-esters ou d'oxazolidino-esters". Paris 5, 2000. http://www.theses.fr/2000PA05P614.
Testo completo
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Platon, Alexandru. "Characterization of solid acid catalysts for isobutane/butene alkylation". Online access for everyone, 2004. http://www.dissertations.wsu.edu/Dissertations/Fall2004/a%5Fplaton%5F100104.pdf.
Testo completo
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PATOIS, CARL. "Alkylation-metallation des esters et amides phosphoriques : la 1,3-dimethyl-2-oxo-1,3,2-diazaphospholidine precurseur d'acrylates z". Palaiseau, Ecole polytechnique, 1992. http://www.theses.fr/1992EPXX0005.
Testo completoAbstract (sommario):
L'alkylation-metallation des phosphates par les alkyllithiens permet d'acceder a des carbanions alpha-phosphonyles, qui peuvent etre utilises apres fonctionnalisation comme precurseurs dans la reaction de wittig-horner. Son application a differents composes phosphores cycliques et acycliques est etudiee. La selectivite z:e de la reaction de wittig-horner pour preparer des acrylates est ensuite evaluee en faisant varier l'habillage de l'atome de phosphore. Le choix de diazaphospholidines (bisamides cycliques) permet l'obtention selective d'acrylates z avec de bons rapports z:e (>90:10) dans des conditions specifiques qui ont ete definies: li#+, thf, milieu dilue, rechauffement intermediaire du reactif, basse temperature, emploi eventuel de tetramethylpiperidine. Une comparaison de la selectivite induite est effectuee entre la diazaphospholidine et differents cycles phosphores, ainsi que le reactif de still et gennari (cf#3ch#2o)#2p(o)ch(r)co#2r'
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Horvath, Raymond Frank. "Regiochemical control in alkylation reactions of a-silylallyl carbanions". Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75863.
Testo completoAbstract (sommario):
The reaction of a series of 1,1-disubstituted-1-silacyclo-3-pentenes with butyllithium reagents was studied. This reaction depends critically on the substituent at silicon. 1,1-Dimethyl- or 1,1-diphenyl-1-silacyclo-3-pentene has the propensity to undergo anionic polymerization whereas 1,1-bis(4-tert-butylphenyl)-1-silacyclo-3-pentene was metalated cleanly to give the anion derived from proton abstraction on the cyclopentenyl ring. The regioselectivity of the reaction of the silacyclopentenyl anion with electrophiles was examined and found to be influenced by the steric size of the electrophile. Small electrophiles favor $ alpha$-selection while larger ones show slight $ gamma$-preference.The regiochemistry of reactions of $ alpha$-silylallyl lithium with alkyl halides can be controlled with metal-ion complexing substituents on silicon to give selectively the $ alpha$-substituted allylsilane. The extent of $ alpha$-selection depends significantly on the nature of the ligand and solvent. Allyl (bis(2-ethoxyethyl)aminomethyl) dimethylsilane gives higher $ alpha$-selection than allylsilanes with fewer binding heteroatoms. When the ligand is chiral the alkylation reaction also proceeds stereoselectively. Changing the solvent from tetrahydrofuran to diethyl ether further increases the yield of the $ alpha$-isomer. The synthetic utility of these silyl-ligands was demonstrated by an application to the synthesis of $ alpha$-(E)-bisabolene.
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Miles, Timothy J. "Synthesis of amino alcohols using a reductive alkylation methodology". Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289405.
Testo completo
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Goldsmith, Paul J. "Copper-catalysed allylic alkylation of electron-deficient allylic halides". Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430507.
Testo completo
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PreÌvost, Natacha. "Radical, alkylation and cycloaddition reactions of a 2-alkylideneaziridines". Thesis, University of Exeter, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273005.
Testo completo
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Burguin, Emilie. "Zirconia based solid acids for Friedel-Crafts alkylation reactions". Thesis, University of York, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420266.
Testo completo
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Gouriou, Laure. "Mechanistic studies on metal catalysed asymmetric allylic alkylation reactions". Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406956.
Testo completo
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Tallon, Luka. "Heterogeneous catalysts for the alkylation of amines using alcohols". Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/51110.
Testo completoAbstract (sommario):
This PhD thesis describes the Au-catalysed alkylation of amines using alcohols (AAA). The work was broadly divided into two parts: (i) developing mechanistic and kinetic models for the reaction; and (ii) further catalyst development. The introductory Chapter provides and overview of reported homogeneous and heterogeneous catalysts for the AAA reaction, with a comparison of their scope and limitations. Chapter 2 begins with a summary of a previously reported mechanistic model using Au/TiO2 to catalyse the model reaction of aniline with benzyl alcohol in flow. The Chapter proceeds by comparing the effects of O2 and the use of different H2O concentrations when performing the model reaction. Additionally, the stability and possible deactivation routes of the catalyst is interrogated. In Chapter 3, the results from the mechanistic studies are used to further develop the previously reported kinetic model. The effects of using different preparation techniques and supports on the catalyst structure and activity of Au/TiO2 are detailed in Chapter 4 and 5, respectively. Chapter 6 presents the activities of different metal catalysts for the model reaction. Chapter 7 contains experimental procedures for reactions and catalyst preparation methods.
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Kantner, Terrence. "Bioconjugation strategies through thiol-alkylation of peptides and proteins". Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.675737.
Testo completoAbstract (sommario):
Bioconjugation chemistry generally refers to the covalent derivatisation of biomolecules. Derivatisation of cysteine’s thiol of peptides and proteins is a common method in bioconjugation chemistry as the thiolate is an excellent nucleophile in aqueous conditions. The propensity for thiols to oxidise in an aqueous environment necessitates the need for a disulfide reduction step prior to the addition of ligands derivatised with thiol alkylating linkers. Disulfide reducing agents such as tris(2-carboxyethyl)phosphine (TCEP) and tris(3-hydroxypropyl)phosphine (THPP) are disulfide reducing agents that are often marketed as being non-reactive with thiol alkylating reagents. The reaction of TCEP and THPP with thiol alkylation linkers was therefore investigated. Characterisation of reaction products and mechanistic studies revealed that TCEP and THPP both react with thiol alkylation reagents. A novel protocol was, therefore, developed utilising the Staudinger reaction to oxidise excess TCEP and THPP prior to the addition of thiol alkylating reagents. The protocol offers a simple “one-pot” method for effecting conjugate production via thiol alkylation, without the need for an intermediate purification step for the removal of excess disulfide reducing agents. 4-Vinyl pyridine (4-VP) derivatives were developed and explored as an alternative Michael acceptor class for thiol alkylation of peptides and proteins. The 4-VP derivatives exhibited high reactivity and specificity for thiol alkylation between pH = 7 and pH = 8. A selection of 4-VP linkers were subsequently functionalised with either carbohydrates or polyethylene glycol (PEG) and successfully utilised to produce peptide or protein conjugates via thiol alkylation reactions.
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Shen, Di. "Transition metal catalyzed alkylation and synthesis of biotin derivatives". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:1467ba98-846c-46e6-9620-e4639ed07e43.
Testo completoAbstract (sommario):
Transition Metal Catalyzed Alkylation We have reported methodology for the use of methanol as an alkylation reagent using catalytic rhodium or iridium species for the formation of branched products from methyl ketones. The synthetic utility of the dialkylated products was enhanced by performing a regioselective Baeyer-Villiger oxidation which allowed access to ester products. A range of different phosphine ligands were screened, and sterically hindered and electron rich phosphine ligands were found to favour the formation of enone and methoxy adducts under an O2 atmosphere. This interrupted hydrogen borrowing reaction enabled the in situ addition of a nucleophile to give more complex products. A range of tetrasubsitituted pyridines were then synthesized from 1, 5-dicarbonyl compounds formed in the methylenation/conjugate addition sequence. Finally, deuteration experiments suggest that the reaction proceeds via a monohydride mechanism, and the possibilities for the beneficial effect of O2 were discussed. Synthesis of biotin derivatives The streptavidin-biotin system was chosen for the studies of protein/ligand interactions at molecular level. A series of modified biotin ligands were designed and synthesized to introduce repulsive interations with streptavidin. The protein/ligand complexes were analyzed at high resolution by X-ray crystallography.
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Arias, Maria. "Horizon "soufre zéro" dans les essences par alkylation catalytique". Lyon 1, 2007. http://www.theses.fr/2007LYO10180.
Testo completoAbstract (sommario):
Suite aux nouvelles réglementations imposées par les législateurs pour une meilleure préservation de l'environnement, la réduction du soufre dans les essences, sans perte d'indice d'octane, conduit à considérer aujourd'hui de nouveaux procédés de désulfuration. Dans cette optique, notre travail a été orienté vers l'élimination du soufre par alkylation catalytique, procédé au cours duquel les composés soufrés sont alourdis pour être ensuite séparés des essences par distillation. Pour cela, un ensemble de catalyseurs acides ont été testés dans la réaction modèle mettant en oeuvre le 3-méthylthiophène comme composé soufré, et le 2-méthyl-2-butène comme agent alkylant, ces deux molécules étant représentatives des composés présents dans une esence de FCD. Dans cette étude, parmi de nombreux solides acides tels que les zéolithes (USY, H-Beta et MCM-22), l'acide phosphorique supporté à 11% sur silice (SPA 11) ou l'acide 12-tungstophosphorique supporté sur silice d(40HPW/SiO2), ce dernier a montré la meilleure activité catalytique. Les conditions de préparation de ce catalyseur ont alors été optimisées et celui-ci a été testé sur une essence issue du craquage catalytique. Les résultats confirmant l'intérêt de ce solide pour le traitement de charges réelles nous avons ensuite porté attention à la prévention de la désactivation et à la régénération de ce catalyseur
48
Li, Zhaoyang. "DNA alkylation by active metabolites of Cyclophosphamide and Ifosfamide /". The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192960169091.
Testo completo
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Amos, Jacques. "Anion oxalyle équivalent : Alkylation fonctionnalisante stéréospécifique en série stéroïde". Nancy 1, 1990. http://docnum.univ-lorraine.fr/public/SCD_T_1990_0493_AMOS.pdf.
Testo completoAbstract (sommario):
L'ester glycidique α-chloré dérivé de la 5α-cholestan-3-one se transpose thermiquement pour conduire exclusivement à un cétoester chloré à halogène équatorial. Celui-ci peut être transformé stéréospécifiquement en α-hydroxycétoester à hydroxyle axial, par passage par un époxyéther. Les réactions de l'ester glycidique α-chloré et du cétoester chloré avec les amines fournissent un accès stéréospécifique aux aminocétoesters diastéréoisomères comportant le groupe aminé dans les configurations respectives équatoriales et axialesα-chloroglycidic ester derived from 5α-cholestan-3-one was thermally transposed to yield exclusively a chlorinated cetoester at equatorial halogen. This could be transformed in a stereospecific fashion into hydroxycetoester at axial hydroxyl group via the corresponding epoxyether. The réactions of the amines on α-chloroglycidic ester and the α-chlorocetoester enhance an stereospecific access to the diastereoisomeric aminocetoesters carrying the aminated group in equatorial and axial configuration respectively
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Vijayaraj, M. "Heteroatom alkylation reactions of aromatic compounds over metal oxides". Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2006. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2494.
Testo completo