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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Hypervalent Iodine Reagents in Metal-Free Arylations and Vinylations : Investigation of Suitable Coupling Partners and Synthesis of New Reagents

Stridfeldt, Elin January 2017 (has links)
This thesis concerns the development of metal-free reactions to obtain carbon-heteroatom and carbon-carbon bonds. This is achieved by transferring carbon ligands from hypervalent iodine reagents to suitable nucleophiles. The bulk of the work presented herein concerns arylation of oxygen and nitrogen nucleophiles, using the well-known diaryliodonium salts as aryl sources. In the first project, O-arylation of the oxime ethyl acetohydroxamate was studied. It was found that electron-poor as well as electron-rich aryl moieties could be transferred successfully to this nucleophile. Furthermore, the protocol could be extended to a sequential one-pot synthesis of benzo[b]furans. This method allowed for a fast synthesis of the natural product stemofuran A and formal syntheses of other natural products. In a successive project, O-arylation of hydroxide and aliphatic alkoxides was investigated. It is known that electron-poor aryl moieties can be transferred to these nucleophiles in moderate to high yields. However, combined with more electron-rich diaryliodonium salts, a large amount of side products were formed. These were suppressed upon addition of aryne traps, suggesting that aryne pathways are competing with the desired ligand coupling. It was also observed that secondary alcohols were oxidized to the corresponding ketones. The mechanism for this oxidation was investigated and aryne pathways could be excluded. Instead we suggest that the carbinol hydrogen gets deprotonated via an internal mechanism, after the alkoxide has coordinated to the iodonium salt. Highly sterically congested alkyl aryl ethers could be obtained in high yields by combining tertiary alcohols with ortho-blocked diaryliodonium salts.  Next, N-arylation of secondary acyclic amides was studied using acetanilide as the model substrate. This procedure was suitable for transfer of electron-poor as well as ortho-substituted aryl moieties, but attempts to transfer very electron-rich aryl groups were unsuccessful. On the other hand, the amides displayed a complementary reactivity, allowing phenylation of electron-rich amides.  In the final project, a one-pot synthesis of the cyclic iodonium reagent vinylbenziodoxolone is presented. These compounds have not been explored as reagents earlier. Initial screenings showed that the vinyl moiety could be transferred to nitrocyclohexane with opposite regioselectivity compared to the acyclic analogue of the reagent. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.</p>
2

Metal-Free O- and C-Arylation with Diaryliodonium Salts

Lindstedt, Erik January 2017 (has links)
This thesis concerns the development of metal-free applications using diaryliodonium salts. The first project describes an arylation protocol of allylic and benzylic alcohols in aqueous media. The method proceeds under mild conditions and the ether products were obtained in moderate to good yields. The methodology was also expanded to include arylation of phenols, giving diaryl ethers in good to excellent yields. In the second project, an arylation method that included a wider range of aliphatic alcohols was developed. The scope of accessible alkyl aryl ethers was studied and included a comparative study of phenylation and nitrophenylation of various alcohols. Finally, a formal metal-free synthesis of butoxycain was performed, illustrating the applicability of the developed method. The third project focused on the limitations and side reactions occurring in Chapter 2 and 3. First, an approach to access symmetric diaryl ethers via arylation of hydroxide was presented. This reaction gave rise to a number of side products, which we hypothesized to originate from aryne-type intermediates. A mechanism for the formation of these side products was suggested, supported by trapping and deuterium labeling experiments. Oxidation of the alcohol to the corresponding ketone was also observed and the mechanism of this interesting side reaction was investigated. The latter was suggested to proceed via an intramolecular oxidation without the involvement of radicals or arynes. The fourth project covers a method to synthesize highly sterically congested alkyl aryl ethers via arylation of tertiary alcohols using diaryliodonium salts. The method displayed a broad scope of tertiary alcohols and was also suitable for fluorinated alcohols. The final project detailed in this thesis deals with C-arylation with diaryliodonium salts, showcasing nitroalkanes as well as a nitro ester as suitable nucleophiles for metal-free arylation. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>
3

Development of Iridium-Catalyzed Skeletal Transformations of Aryl Ethers through Carbon-Carbon Bond Formation / イリジウム触媒を用いたアリールエーテルの炭素-炭素結合形成を伴う骨格変換反応の開発

Kusaka, Satoshi 25 July 2022 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第24148号 / 工博第5035号 / 新制||工||1786(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 杉野目 道紀, 教授 大江 浩一, 教授 中尾 佳亮 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
4

Mn(III)porfirinas sintéticas como modelos químicos do Citocromo P-450: a O-desalquilação oxidativa de aril éteres substituídos como modelos de drogas por iodosilbenzeno / Synthetic Mn(III)porphyrins as cytochrome P-450 mimic: oxidative O-dealkylation of aryl substituted ethers by iodosylbenzene as drug models

Felipucci Neto, Carlos Alberto 03 October 2007 (has links)
Reações de O-desmetilação oxidativa estão entre as várias oxidações realizadas pelas enzimas do citocromo P-450. Entretanto, poucos estudos de O-desmetilação catalisadas por enzimas do citocromo P-450 ou modelos químicos baseados em metaloporfirinas sintéticas têm resultado em dúvidas acerca do mecanismo da O-desmetilação destes compostos orgânicos. Neste trabalho, foi estudada a O-desmetilação oxidativa, com PhIO, do benzil metil éter e alguns de seus derivados para substituídos (com os grupos doadores de elétrons -OCH3 e -CH3 e os grupos retiradores -NO2 e -Cl) catalisada pelas Mn(III)P [Mn(TPP)]Cl, [Mn{T(4-N-MePy)P}](PF6)5, [Mn(TMP)]Cl, [Mn(TDCSPP)]Cl e [Mn(TFPP)]Cl para verificar o efeito destes diferentes catalisadores na conversão e seletividade de produtos da O-desmetilação oxidativa e avaliar o efeito dos diversos substituintes citados no mecanismo de O-desalquilação. Inicialmente, realizou-se o estudo das oxidações catalíticas do metil benzil éter. Todas as reações catalisadas pelas MnP se mostram seletivas, sendo que o benzaldeído foi o produto comum a todas as oxidações. A melhor condição encontrada foi 1:50:1224 (catalisador/oxidante/substrato). Em relação às reações com os substratos contendo os substituintes na posição -para, as reações de oxidações catalíticas do p-metóxibenzil metil éter por PhIO não se mostraram tão seletivas quanto as do metil benzil éter, mostrando claramente que o grupo metóxi alterou a reatividade do aril éter original. Mesmo assim, o p-metoxibenzaldeído ainda foi o produto principal, sendo a conversão ao álcool p-metoxibenzílico observada em escala menor. Já com o substrato p-nitrobenzil metil éter, novamente o efeito provocado pelo substituinte na posição para no anel benzênico pôde ser percebida na distribuição final dos produtos, sendo que houve seletividade total para a formação de p-nitrobenzaldeído em detrimento ao álcool p-nitrobenzóico. Em relação aos dois últimos substratos da série proposta, metil p-metilbenzil éter e metil p-clorobenzil éter, de um modo geral, as reações realizadas com o p-clorobenzil metil éter não se mostraram tão seletivas quanto as do metil p-nitrobenzil éter, mostrando que o grupo cloro aumentou a reatividade do cloroéter em relação ao éter com o substituinte nitro- original. Mesmo assim, o p-clorobenzaldeído foi o produto principal, sendo a conversão ao álcool p-clorobenzílico observada em menor escala. Em relação às reações de oxidação do p-metilbenzil metil éter, observou-se que os resultados experimentais são semelhantes aos encontrados para o metil benzil éter. Esses resultados corroboram o principal mecanismo proposto para os sistemas modelo do citocromo P-450 que envolve abstração inicial do átomo de hidrogênio, o mecanismo por recombinação de oxigênio. / O-dealkylation oxidative reactions are among the several oxidations accomplished by the cytochrome P-450 enzymes. However, few studies on O-dealkylation catalyzed by such enzymes or chemical models based on synthetic metalloporphyrins have resulted in doubts concerning the mechanism of these reactions involving organic compounds. In this work, we studied the oxidative O-dealkylation by PhIO of benzyl methyl ether and some of its para-substituted derivatives (with the electron donor groups -OCH3 and -CH3 and the electronwithdrawing groups -NO2 and -Cl) catalyzed by the following Mn(III)P: [Mn(TPP)]Cl, [Mn{T(4-N-MePy)P}] (PF6)5, [Mn(TMP)]Cl, [Mn(TDCSPP)] Cl, and [Mn(TFPP)]Cl. Our aim was to verify the effect of these different catalysts on the conversion yields and product selectivity, as well as evaluate the effect of the several substituents on the ether on the O-dealkylation mechanism. We initially studied the catalytic oxidation of methyl benzyl ether. All the reactions catalyzed by the various MnPs were selective, and benzaldehyde was the product common to all oxidations. The best reaction condition was catalyst/oxidant/substrate molar ration = 1:50:1224. As for the reactions with the substituted substrates, the catalytic oxidation of p-methoxybenzyl methyl ether by PhIO was not as selective as the ones of methyl benzyl ether, clearly showing that the methoxy group affects the reactivity of the original aryl ether. Nevertheless, p-methoxybenzaldehyde was still the main product, being the conversion to p-methoxybenzylic alcohol observed in minor amount. With the substrate p-nitrobenzyl methyl ether, the effect of the electronwithdrawing substituent in the para- position of the aromatic ring could be observed in the final product distribution once again, and total selectivity toward the formation of p-nitrobenzaldehyde to the detriment of p-nitrobenzoic alcohol was observed. In relation to the two last substrates of the proposed series, the methyl p-methylbenzyl and methyl p-chlorobenzyl ethers, the reactions accomplished with p-chlorobenzyl methyl ether were not as selective as the ones carried out with methyl p-nitrobenzyl ether, showing that the chloro group increased the reactivity of the chloro-ether in relation to the ether with the original nitro- substituent. Even so, p-chlorobenzaldehyde was the main product, being the conversion to the p-chlorobenzylic alcohol observed in smaller amount. Concerning the oxidation reactions of p-methylbenzyl methyl ether, the experimental results were similar to those obtained in the case of methyl benzyl ether. These results corroborate the main mechanism proposed for the cytochrome P-450 model systems, which involves initial hydrogen atom abstraction, followed by oxygen rebound.
5

Mn(III)porfirinas sintéticas como modelos químicos do Citocromo P-450: a O-desalquilação oxidativa de aril éteres substituídos como modelos de drogas por iodosilbenzeno / Synthetic Mn(III)porphyrins as cytochrome P-450 mimic: oxidative O-dealkylation of aryl substituted ethers by iodosylbenzene as drug models

Carlos Alberto Felipucci Neto 03 October 2007 (has links)
Reações de O-desmetilação oxidativa estão entre as várias oxidações realizadas pelas enzimas do citocromo P-450. Entretanto, poucos estudos de O-desmetilação catalisadas por enzimas do citocromo P-450 ou modelos químicos baseados em metaloporfirinas sintéticas têm resultado em dúvidas acerca do mecanismo da O-desmetilação destes compostos orgânicos. Neste trabalho, foi estudada a O-desmetilação oxidativa, com PhIO, do benzil metil éter e alguns de seus derivados para substituídos (com os grupos doadores de elétrons -OCH3 e -CH3 e os grupos retiradores -NO2 e -Cl) catalisada pelas Mn(III)P [Mn(TPP)]Cl, [Mn{T(4-N-MePy)P}](PF6)5, [Mn(TMP)]Cl, [Mn(TDCSPP)]Cl e [Mn(TFPP)]Cl para verificar o efeito destes diferentes catalisadores na conversão e seletividade de produtos da O-desmetilação oxidativa e avaliar o efeito dos diversos substituintes citados no mecanismo de O-desalquilação. Inicialmente, realizou-se o estudo das oxidações catalíticas do metil benzil éter. Todas as reações catalisadas pelas MnP se mostram seletivas, sendo que o benzaldeído foi o produto comum a todas as oxidações. A melhor condição encontrada foi 1:50:1224 (catalisador/oxidante/substrato). Em relação às reações com os substratos contendo os substituintes na posição -para, as reações de oxidações catalíticas do p-metóxibenzil metil éter por PhIO não se mostraram tão seletivas quanto as do metil benzil éter, mostrando claramente que o grupo metóxi alterou a reatividade do aril éter original. Mesmo assim, o p-metoxibenzaldeído ainda foi o produto principal, sendo a conversão ao álcool p-metoxibenzílico observada em escala menor. Já com o substrato p-nitrobenzil metil éter, novamente o efeito provocado pelo substituinte na posição para no anel benzênico pôde ser percebida na distribuição final dos produtos, sendo que houve seletividade total para a formação de p-nitrobenzaldeído em detrimento ao álcool p-nitrobenzóico. Em relação aos dois últimos substratos da série proposta, metil p-metilbenzil éter e metil p-clorobenzil éter, de um modo geral, as reações realizadas com o p-clorobenzil metil éter não se mostraram tão seletivas quanto as do metil p-nitrobenzil éter, mostrando que o grupo cloro aumentou a reatividade do cloroéter em relação ao éter com o substituinte nitro- original. Mesmo assim, o p-clorobenzaldeído foi o produto principal, sendo a conversão ao álcool p-clorobenzílico observada em menor escala. Em relação às reações de oxidação do p-metilbenzil metil éter, observou-se que os resultados experimentais são semelhantes aos encontrados para o metil benzil éter. Esses resultados corroboram o principal mecanismo proposto para os sistemas modelo do citocromo P-450 que envolve abstração inicial do átomo de hidrogênio, o mecanismo por recombinação de oxigênio. / O-dealkylation oxidative reactions are among the several oxidations accomplished by the cytochrome P-450 enzymes. However, few studies on O-dealkylation catalyzed by such enzymes or chemical models based on synthetic metalloporphyrins have resulted in doubts concerning the mechanism of these reactions involving organic compounds. In this work, we studied the oxidative O-dealkylation by PhIO of benzyl methyl ether and some of its para-substituted derivatives (with the electron donor groups -OCH3 and -CH3 and the electronwithdrawing groups -NO2 and -Cl) catalyzed by the following Mn(III)P: [Mn(TPP)]Cl, [Mn{T(4-N-MePy)P}] (PF6)5, [Mn(TMP)]Cl, [Mn(TDCSPP)] Cl, and [Mn(TFPP)]Cl. Our aim was to verify the effect of these different catalysts on the conversion yields and product selectivity, as well as evaluate the effect of the several substituents on the ether on the O-dealkylation mechanism. We initially studied the catalytic oxidation of methyl benzyl ether. All the reactions catalyzed by the various MnPs were selective, and benzaldehyde was the product common to all oxidations. The best reaction condition was catalyst/oxidant/substrate molar ration = 1:50:1224. As for the reactions with the substituted substrates, the catalytic oxidation of p-methoxybenzyl methyl ether by PhIO was not as selective as the ones of methyl benzyl ether, clearly showing that the methoxy group affects the reactivity of the original aryl ether. Nevertheless, p-methoxybenzaldehyde was still the main product, being the conversion to p-methoxybenzylic alcohol observed in minor amount. With the substrate p-nitrobenzyl methyl ether, the effect of the electronwithdrawing substituent in the para- position of the aromatic ring could be observed in the final product distribution once again, and total selectivity toward the formation of p-nitrobenzaldehyde to the detriment of p-nitrobenzoic alcohol was observed. In relation to the two last substrates of the proposed series, the methyl p-methylbenzyl and methyl p-chlorobenzyl ethers, the reactions accomplished with p-chlorobenzyl methyl ether were not as selective as the ones carried out with methyl p-nitrobenzyl ether, showing that the chloro group increased the reactivity of the chloro-ether in relation to the ether with the original nitro- substituent. Even so, p-chlorobenzaldehyde was the main product, being the conversion to the p-chlorobenzylic alcohol observed in smaller amount. Concerning the oxidation reactions of p-methylbenzyl methyl ether, the experimental results were similar to those obtained in the case of methyl benzyl ether. These results corroborate the main mechanism proposed for the cytochrome P-450 model systems, which involves initial hydrogen atom abstraction, followed by oxygen rebound.
6

A modular synthesis of processable and thermally stable semi-fluorinated aryl ether polymers via step-growth polymerization of fluoroalkenes

Shelar, Ketki Eknath 13 May 2022 (has links)
Tailored fluoropolymers remain the leading choice for a wide variety of advanced high-performance applications, including electronic/optical and energy conversion, owing to their unique blend of complementary high-performance properties. Amorphous semi-fluorinated polymers exhibit improved solubility and melt processability when compared to traditional perfluoropolymers. A leading class of semi-fluorinated aryl ether polymers includes perfluorocyclobutyl (PFCB), perfluorocycloalkenyl (PFCA), and fluoroarylene vinylene ether (FAVE) polymers. Monomers containing aromatic trifluorovinyl ethers (TFVE) are used to synthesize PFCB polymers via radical-mediated [2+2] cyclodimerization. On the other hand, FAVE and PFCA polymers are polymerized via base-mediated nucleophilic addition/elimination of bisphenols with TFVE monomers and decafluorocyclohexene respectively. The use of different monomer cores (aromatic, aliphatic, contorted, and renewable) should help to develop general structure/property relationships for this versatile and expanding approach to semi-fluorinated aryl ether polymers. The enchainment of polycyclic aromatic hydrocarbon (PAH) cores with functional fluorocarbon groups (or segments) recently afforded a new class of semi- fluorinated polymers in the continuing quest for novel organic materials for potential applications in optoelectronic, gas-separation, and advanced composites. Chapter 2 details the incorporation of commercially available acenaphthenequinone was achieved to afford PFCB aryl ether polymers with excellent solubility, high thermal stability, and film-forming capability. Chapter 3 represents base-promoted nucleophilic addition/elimination of commercial bisphenols with TFVE-triphenylene monomers affording FAVE aryl ether polymers possessing excellent solution processability, high thermal stability and photostability. In addition, triphenylene-enchained FAVE polymers exhibit extreme thermal-oxidative photostability and emit blue light after heating in air at 250 °C for 24 h. Further, time-dependent density functional theory (TD-DFT) computations were performed to understand electronic polymer structures. In one case, post-polymerization Scholl coupling converted the central triphenylene core to afford a hexabenzocoronene containing semi-fluorinated polymer with new optoelectronic properties. Chapter 4 demonstrates synthesis and characterization of renewable semi-fluorinated polymers obtained using aliphatic diol isosorbide. This renewable diol readily polymerizes with bis-TFVE derivatives of bisphenol A and 6F to provide high molecular weight thermoplastics exhibiting excellent solubility and tough, transparent film-forming capability. Finally, Chapter 5 presents synthesis of TFVE enchained corannulene which gave blue-light emission and outstanding processability. Synthesis and characterization, including the new materials' optical, thermal, and electronic properties, is presented.
7

Step-growth polymerization of perfluoro-vinyl ether, -cycloalkenes, and -acyclic alkenes with bisphenols containing variable polycyclic aromatic cores

Mukeba, Karl Mpumbwa 13 May 2022 (has links) (PDF)
This dissertation reports the synthesis and characterization of semi-fluorinated polymers derived from the polymerization of bisphenols with fluoroalkenes. A series of diverse bisphenols were chosen from popular commercial bisphenols and new polycyclic aromatic hydrocarbon (PAH) derived bisphenols requiring synthesis. Step-growth condensation polymerization of bisphenols with three different fluoroalkene types was performed while probing polymerization conditions and the structure/properties relationship of the resulting fluoropolymers. The fluoroalkene monomers were chosen from bis(trifluorovinyloxy)biphenyl (TFVE), perfluorocyclohexene (PFCH), and perfluoro acyclic monomers, namely, perfluoro(4-methyl-2-pentene) and 1-perfluoroheptene to undergo this chemistry. This work is divided into four parts based on the polymerization methodology. The first section focuses on the development of a new class of fluorinated arylene vinylene ether (FAVE) and their chain extended polymers prepared via base-catalyzed step-growth polymerization of PAH bisphenols with the TFVE monomer. These reactions afforded polymers containing controlled terminal and enchained fluoroalkenylenes for latent reactivity such as post polymerization functionalization, chain extension, and/or crosslinking. In general, these PAH cores resulted in polymers with improved thermal properties The second portion describes the investigation of step-growth addition/elimination polymerizations of PAH bisphenols and PFCH to prepare a new class of fluoropolymers containing alternating rigid PAH linkages and enchained PFCH vinylene ether moieties in the backbone. The third section covers the preparation and characterization of semi-fluorinated poly(aryl ether sulfone)s by nucleophilic addition/elimination reactions of PFCH with sulfone bisphenols. From commercially bisphenols combined with PAH bisphenols, we introduced the industrially valuable and property enhancing diaryl sulfone unit in a series of semi-fluorinated copolymers. This modular approach greatly expands access to partially fluorinated aryl ether sulfone polymers intended for high performance applications in optoelectronics, separation/purification membranes, and composites. Finally, in the fourth section, a new class of semifluorinated polymers was synthesized via nucleophilic addition/elimination reactions of acyclic perfluoroalkenes with bisphenols. In particular, environmental concerns for biopersistent and highly regulated perfluorooctanoic acid (PFOA) is the driver for using perfluoroheptene, which is derived cleanly by the decarboxylation of these pollutants in one step. This provided a new class of semi-fluorinated materials with promising properties including thermal stable, processability, and transparent film formation.

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