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Dissertations / Theses on the topic 'Directed Ortho Metalation'

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Published: 4 June 2021

Last updated: 1 February 2022

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1

Timmons, Michael. "Directed Ortho-Metalation of Dimethylarylamines." TopSCHOLAR®, 2002. http://digitalcommons.wku.edu/theses/641.

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Site-specific product(s) from the reaction of benzene derivatives with various reagents is a need of researchers at numerous laboratories, particularly those in the pharmaceutical industry. Such derivatives can be synthesized directly, i.e., by substitution of a proton, using either of two procedures: electrophilic aromatic substitution (EAS) or directed ortho-metalation (DoM). Directed ortho-metalation (DoM) is an alternative aromatic substitution process initiated by organolithium reagents which provides regiospecific substitution exclusively at the ortho- position (equation). The focus of this study is to find hydrocarbon media that will permit the maximum extent of metalation of several dimethylarylamines. The dimethylamine-containing substituents constitute directing metalation groups (DMG's) for the various aryl systems investigated. Maximization of the extents of ortho-lithiation of dimethylaniline [DMG = - N(CH3)2] and dimethylbenzylamine [DMG = -CH2N(CH3)2] have now been achieved using novel combinations of solvent, temperature and increments of catalyst. Studies of substituted dimethylanilines and dimethylbenzylamines containing a second DMG have yielded mixed results. Both metalation condition parameters as well as certain mechanistic aspects are altered by inclusion of a second DMG into these two parent systems.

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2

Woosley, Barry. "Directed ortho Metalation in Hydrocarbon Solvents: Opposing Pi-Resonance Effects." TopSCHOLAR®, 2004. http://digitalcommons.wku.edu/theses/539.

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Hydrocarbon solvents are known to be unreactive toward organolithium reagents and do not typically support ortho-metalation reactions without the aid of a promoter. An exception would be an arene substrate having the capability to bidentate complex to the reactive alkyllithium dimer, which enables ortho-metalation to occur in high yields. A second, more limiting exception, would be that the arene substrate possesses localized lone pairs of electrons, as is the case when the directed ortho metalating group (DMG) is located in the benzyl position. The work reported here centers upon developing a third and larger class of arene substrates that are exceptions to the general rule that metalation in hydrocarbon solvents requires the use of added promoter. When an arene is either 1,2- or 1,4- disubstituted with electron donating DMGs, the lone pairs of electrons on each of the DMG groups are more localized than is the case for a monosubstituted arene. The effect of localization allows the arene to complex more efficiently and therefore metalate. This localization effect we term the Opposing Pi Resonance Effect.

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3

Cai, Xiongwei. "Regiospecific synthesis of alkylphenanthrenes using a combined directed ortho metalation, DoM, (Suzuki-Miyaura cross coupling), directed remote metalation, DreM, methodology." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63276.pdf.

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4

Friesen, Carl. "Directed Ortho-Metalation of the Three Methyl Anisoles in Various Media." TopSCHOLAR®, 1996. http://digitalcommons.wku.edu/theses/870.

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Directed ortho-metalation (DoM) is a very useful alternative to electrophillic aromatic substitution (EAS) for the synthesis of substituted aromatic compounds. DoM is highly regiospecific providing metalation chiefly in the ortho-position. However, lateral (a-) metalation of an alkyl side-chain and ortho-metalation of a second ortho-position can compete. Investigation of the three methylanisoles was therefore undertaken to determine the interplay between these factors and to discover metalation conditions to achieve selectivity. This goal was uniquely achieved for p-methylanisole where conditions were discovered which allowed > 85% ortho-metalation as determined by GC analysis with virturally no competing lateral metalation. Three derivitives of this ortho-lithio intermediate were prepared, each in > 75% yield. Metalation conditions were found that permitted significant descrimination between 2- and 6- position metalation of m-methylanisole. Metalation conditions were also found that permitted regiospecific a-metalation of o-methylanisole.

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5

Macklin, Todd Kristopher. "The development of sulfamates as latent directed metalation groups. Total synthesis of schumanniophytine. Divergent synthesis of substituted chromone 3- and 8-carboxamides." Thesis, Kingston, Ont. : [s.n.], 2007. http://hdl.handle.net/1974/925.

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6

Milburn, Claire Louise Maud Jackson. "The directed ortho metalation reaction of aryl O-carbamates on solid support." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63340.pdf.

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7

Kendall, Christopher Nicholas Owen. "The directed ortho metalation - Suzuki-Miyaura cross-coupling connection, towards the total synthesis of dehydrorabelomycin." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0020/MQ54462.pdf.

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8

Lai, Ping-Shan. "Directed ortho metalation-boronation Suzuki-Miyaura cross coupling leading to synthesis of azafluorenol core liquid crystals." Thesis, Kingston, Ont. : [s.n.], 2007. http://hdl.handle.net/1974/511.

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9

Chauder, Brian Andrew. "Combined directed ortho metalation-transition metal catalyzed coupling reactions for the synthesis of chromenes, ergot alkaloids, and biaryl macrocycles." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ63410.pdf.

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10

Onuska, Nicholas Paul Ralph. "Studies Towards the Synthesis of 2,5-Disubstituted-3-Fluorothiophenes Using a Directed Ortho-Metalation/Nickel-Catalyzed Cross-Coupling Approach." Kent State University Honors College / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1460652408.

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11

Green, Anthony Laine. "The Directed ortho Metalation of pyridine derivatives with in situ boronation and links to the Suzuki-Miyaura cross coupling reaction." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ63310.pdf.

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12

Yin, Chunfeng. "Regiospecific synthesis of chlorodihydroxybiphenyls and synthesis of 3,3'-bisaryl substituted BINOLs by combined directed ortho metalation (DoM) and Suzuki-Miyaura cross coupling." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ63395.pdf.

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13

Nguyen, Quang. "Reinventing Aromatic Substitution: A Novel Look." TopSCHOLAR®, 2013. http://digitalcommons.wku.edu/theses/1292.

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Electrophilic aromatic substitution (EAS) and directed ortho-metalation (DoM) involve the direct substitution of an arene hydrogen. A major drawback involving EAS is the necessity for harsh forcing conditions for the reaction to proceed. Catalysts such as Lewis acids FeBr3 and AICI3 for the introduction of halogens and acyl groups, respectively, are each highly toxic and corrosive. Textbook preparations of aryl iodides classicaly involved the use of iodine and nitric acid. This approach affords only modest yields and does not provide regiospecific substitution of most substituted aromatics because most contain ortho/para directors which afford mixtures of isomers. The novelty of our procedure for the synthesis of the iodinated aromatics is twofold in that regiospecific para-iodination is observed and hydrocarbon media are utilized. Hydrocarbon media are less hazardous and greener than media used for halogenations reported in literature. This procedure always yields derivatives regiospecifically substituted para to an electron donating substituent. Moreover, this method eliminates the need to use hazardous oxidative catalysts. DoM is a reaction regiospecifically substitute an arene hydrogen at the ortho position. The media used in DoM reactions are less hazardous than those required for a variety of EAS reactions. The only problem for this reaction is use of extremely strong bases, alkyllithium reagents, which are known to be air and water sensitive. However, the DoM reaction does eliminate the need to separate ortho/para isomer mixtures so that only a single product is generated. The metalation yields predominantly products regiospecifically substituted ortho-to the direcing metalating group (DMG). With our deficiency catalysis concept and subsequent purificaion methods, relatively pure ortho-lithiated intermediates have been prepared. The study of catalysts/promoters on the derivatization of these intermediates is anticipated to be extremely insightful. For this study, we have shown that highly selective, efficient ortho-lithiation can be achieved by deficiency catalysis utilizing n-BuLi as the only strong metalating base.

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14

Peel, Andrew James. "Group 11 'ate bases : towards an understanding of solid- and solution-state structures." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267910.

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Lithium bis(amido)cuprates are an important class of bimetallic base, which can chemo- and regioselectively metalate aromatic compounds, via directed ortho cupration (DoCu). This thesis begins with an introduction to aspects of the chemistry of organolithium compounds, group 11 organometallic compounds and their lithium 'ate complexes. Examples of such synergic bases are presented and the introduction is concluded with a discussion of lithium bis(amido)cuprate bases, which along with their silver congeners, are the subject of this dissertation. In general, syntheses involve the addition of a lithium amide to a group 11 salt, resulting in the formation of a lithium bis(amido)cuprate or argentate. Structurally focussed work commences with the use of new amide ligands to develop heteroleptic bis(amido)cuprate systems. The reaction of mixtures of lithium amides with CuBr provides a series of novel Lipshutz-type and Gilman cuprates. Interesting structural features are uncovered, which are rationalised in terms of altered steric demands in the newly introduced amide ligands in these systems. CuSCN and CuOCN are investigated as inexpensive and safer alternatives to CuCN in cuprate formation. In the solid state, a series of Lipshutz-type cuprates (TMP)2Cu(SCN)Li2(L) (L = Et2O, THF, THP) are revealed, whose molecular conformations are infuenced by the identity of the Lewis base. However, in benzene solution, in situ conversion of Lipshutz-type to Gilman cuprate is found to occur. Moving to the synthetic setting, derivatisation of chloropyridines is attempted and gives functionalised halopyridines in 51-71 % yield. CuOCN is found to behave quite differently when reacted in the same way as CuSCN, whereby X-ray crystallography reveals structures in which Cu-Li substitution is apparent. The unique reactivity of CuOCN is interpreted with the aid of multinuclear NMR spectroscopy. A new route to Lipshutz-type cuprates is explored by the synthesis of (TMP)2Cu(OCN)Li2(THF) from Gilman cuprate and LiOCN. This avoids Cu-Li substitution. Meanwhile, reaction of lithium N,N-diisopropylamide with CuOCN also avoids metal disorder, to give a novel lithium cuprate-lithium amide adduct. Further advances in our understanding of group 11 'ate complexes are made by introducing silver as a spectroscopically active nucleus in the lithium argentates (TMP)2AgLi and (TMP)2Ag(CN)Li2(THF). In the solid state, these parallel the structures known for Gilman cuprate (TMP)2CuLi and Lipshutz cuprate (TMP)2Cu(CN)Li2(THF), respectively. In solution, NMR spectroscopy reveals features consistent with retention of these structures. Lastly, the formation of mixed Cu-Li aggregates from combining TMPLi and TMPCu in aromatic solvent are investigated. Surprising reactivity is uncovered, in which the aromatic solvent is metalated and incorporated into mixed-metal aggregates. This thesis concludes with a summary of the findings and suggestions for future work, including how the findings presented herein may be transformed into practical improvements to cuprate systems. In particular, the possibility that Gilman cuprate may be activated towards the metalation of aromatic substrates by the addition of sub-stoichiometric or catalytic amounts of a lithium salt additive is explored.

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15

Aissaoui, Regadia. "Réaction de substitution nucléophile aromatique des acides naphtoïques ortho-fluorés/méthoxylés avec les réactifs de Grignards et les organolithiens (SNArAB)." Phd thesis, Université du Maine, 2012. http://tel.archives-ouvertes.fr/tel-00684960.

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Dans ce travail, il est montré que les alkyl/vinyl/aryl lithiens et magnésiens réagissentavec les acides C-1(F/OMe) naphtoïques en l'absence de catalyseur métallique. Cette nouvelleréaction de substitution nucléophile aromatique permet potentiellement de préparer n'importequel biaryle tout en s'affranchissant des étapes de protection et de déprotection de la fonctionacide (CO2H). Les alkyllithiens linéaires et ramifiés réagissent avec la même efficacité que lesalkylmagnésiens même à basse température (-78 °C). Le déplacement d'un fluor ou d'unméthoxy s'effectue avec la même facilité. L'absence d'ortho-lithiation est confirmée par lepiégeage du milieu réactionnel en fin de réaction par l'iodométhane (après addition de n-BuLi,s-BuLi et t-BuLi). Le bromure de vinylmagnésium requiert un chauffage au reflux du THF.La méthode étudiée permet de préparer extrêmement facilement des 1- et 2-phénylnaphtalènes, 1,1'-binaphtalènes et 2,2'-binaphtalènes. Dans les exemples où lesaryllithiens donnent des rendements moyens-faibles en produits de couplage, les réactifs deGrignard sont beaucoup plus efficaces. Le o-tolyllithium, le bromure de o-tolylmagnésium, lebromure de (4-méthoxyphényl)magnésium, le bromure de (2,5-diméthylphényl)magnésium etle bromure de benzo[d][1,3]dioxol-5-ylmagnésium déplacent facilement le groupefluoro/méthoxy en ortho du groupe CO2M pour donner les produits de substitutioncorrespondants alors que la réaction du bromure de (2,6-diméthoxyphényl)magnésium estmoins efficace sans doute en raison de l'encombrement stérique causé par les deux groupesortho-méthoxy. L'acide 1-(2-méthoxyphényl)-2-naphtoïque est un produit particulièrementintéressant. La déprotection du groupe méthoxy suivie d'une cyclisation est réalisée par BBr3pour donner la 6H-naphtho[2,1-c]chromén-6-one qui est isolée avec un rendement de 97 %.Cette lactone est utile pour la préparation de composés atropoisomères optiquement actifsaprès ouverture énantiosélective du cycle lactone selon la technique mise au point parBringmann.

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16

Alessi, MANLIO. "Synthetic Methods and Application Based on Directed ortho Metalation and Suzuki Cross Coupling Strategies." Thesis, 2008. http://hdl.handle.net/1974/1634.

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The Directed ortho Metalation reaction is described in Chapter 1 of this thesis with particular emphasis on its mechanism and synthetic potential. Chapter 2 contains a review of the DoM (Directed ortho Metalation) of pyridine systems and describes the conditions that allow the one-pot DoM (Directed ortho-Metalation)-Boronation-Suzuki-Miyaura cross coupling of pyridines 2.263a-c, 2.351-2.53 (Table 2.9) bearing several DMGs (Directed Metalation Groups) including the synthetically versatile diethyl amide functionality without incurring into commonly observed self-condensation processes. The method avoids the tedious and uncertain isolation of the intermediate boronic acids while offering rapid access to synthetically valuable arylpyridines (2.354a-s, Table 2.9). Selected aryl pyridine carboxamides were used to demonstrate the DoM-DreM (Directed remote Metalation) nexus that furnishes substituted and isomerically diverse azafluorenones 2.380a-d (Table 2.11) with high regioselectivity. The previous discovery of the anionic O→C -vinyl carbamoyl migration of carbamoyl stilbenes stimulated its application in the total synthesis of natural product isoprekinamycin, bearing the unusual diazo group. Chapter 3 of this thesis describes the efficient synthesis of the key stilbene derivative 3.113 and its structural variations whose conversion to the desired naphthols 3.143, 3.144, 3.153 and 3.169 (Table 3.3) is accompanied by extensive decomposition, thus terminating this approach to isoprekinamycin. A modified approach via Z-3.271 (Scheme 3.54) gave the desired naphthyl carbamate intermediates 3.274 and 3.278 (Schemes 3.55 and 3.56, respectively) whose complex DreM reactions prevented the completion of the synthesis but remain under active investigation in our laboratories. Previous studies of the DoM reaction of aryl tetramethyl phosphorodiamidate have shown that unpractical experimental conditions are necessary, thus limiting synthetic application. Chapter 4 of this thesis describes the results concerning the performance of the tetraethyl phosphorodiamidate DMG under standard DoM and DreM conditions, anionic phospha-Fries rearrangement, 1,4 lateral migration, and Suzuki cross coupling which demonstrate synthetic utility and application in synthetic aromatic chemistry.
Thesis (Ph.D, Chemistry) -- Queen's University, 2008-12-16 14:15:09.695

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17

Blackburn, Thomas. "I. PROGRESS IN DIRECTED ortho METALATION II.II. GENERATING CHIRALITY IN PERIODIC MESOPOROUS ORGANOSILICA." Thesis, 2009. http://hdl.handle.net/1974/5238.

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Chapter 1 constitutes a review of current methods of aromatic substitution focusing on Directed ortho Metalation (DoM) and Directed remote Metalation (DreM). The field of mesoporous silica is reviewed in Chapter 2, focusing on the preparation, characterization, and application of mesoporous silicates. Chapter 3 presents an introduction of phosphorus based Directed Metalation Groups (DMGs). The development of the directed ortho metalation (DoM) reaction of the tetraethyl phosphorodiamidate DMG is described. In addition to being one of the most powerful DMGs, migration of the OPO(NEt2)2 group to the ortho and remote positions is demonstrated, constituting new reactions as well as affording new organophosphorus compounds. Attempts to improve the synthetic utility of the DMG led to the discovery and optimization of a two new nickel-catalyzed cross coupling reactions, which is described in Chapter 4. Both the OPO(NEt2)2 and OCONEt2 DMGs are demonstrated to undergo cross coupling reactions with aryl boronic acids. By means of DoM and cross coupling tactics, the concise synthesis of a chiral binaphthol bridged silasesquioxane is described. Chapter 5 explores new methods to prepare chiral periodic mesoporous organosilica (PMO) materials using this monomer. PMOs are prepared by the co-condensation of a relatively small amount of chiral binaphthyl dopant which acts to twist the bulk prochiral biphenylene framework.
Thesis (Master, Chemistry) -- Queen's University, 2009-09-25 11:38:25.029

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18

MORRISON, MATTHEW. "A Convenient Synthesis of Pyrrolnitrin and Related Halogenated Phenylpyrroles." Thesis, 2009. http://hdl.handle.net/1974/5265.

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This thesis details a straightforward synthetic route to the antifungal compound pyrrolnitrin 1.2, along with several analogous halogenated phenylpyrroles. The proposed synthetic protocol involved the Suzuki-Miyaura cross-coupling of appropriately halogenated pyrrole pinacolboronate esters and aryl compounds. In the efforts towards preparing the cross-coupling partners, we report a regiospecific and high yielding synthesis of a 3-chloro pyrrole compound 2.14, its brominated analog 2.16, an iodinated analog 2.17, and the corresponding pinacolboronate ester 2.18. We also report a generalized reaction sequence (lithiation/carboxylation/Schmidt reaction/oxidation) for the preparation of halogenated benzoic acids, anilines and nitrobenzenes. In particular, we synthesized the desired halogenated nitrobenzene coupling partner 3.27 in excellent yield. We were also able to show that the conditions employed in this sequence were mild enough to allow preparation of the 2-bromo-6-iodo compound 3.33. Once the coupling partners were prepared, we developed the optimal conditions for our Suzuki-Miyaura cross-coupling reactions. In doing so, we were able to prepare our target compound 1.2 and several halogenated analogs in good yields. We also prepared brominated and deuterated arylpyrroles 4.27 and 4.28, respectively, for future use in mechanistic studies of the pyrrolnitrin biosynthetic enzymes, PrnB, Prn C and PrnD. This required preparation of the corresponding brominated and deuterated pyrrole pinacolboronate esters 4.24 and 4.26.
Thesis (Master, Chemistry) -- Queen's University, 2009-09-29 13:58:35.186

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