| 1. |
- Bielawski, Marcin, 1981-
(författare)
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Diaryliodonium Salts : Development of Synthetic Methodologies and α-Arylation of Enolates
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes novel reaction protocols for the synthesis of diaryliodonium salts and also provides an insight to the mechanism of α-arylation of carbonyl compounds with diaryliodonium salts. The first chapter gives a general introduction to the field of hypervalent iodine chemistry, mainly focusing on recent developments and applications of diaryliodonium salts. Chapter two describes the synthesis of electron-rich to electron-poor diaryliodonium triflates, in moderate to excellent yields from a range of arenes and iodoarenes. In chapter three, it is described that molecular iodine can be used together with arenes in a direct one-pot, three-step synthesis of symmetric diaryliodonium triflates. A large scale synthesis of bis(4-tert-butylphenyl)iodonium triflate is also described, controlled and verified by an external research group, further demonstrating the reliability of this methodology. The fourth chapter describes the development of a sequential one-pot synthesis of diaryliodonium salts from aryl iodides and boronic acids, furnishing symmetric and unsymmetric, electron-rich to electron-poor diaryliodonium tetrafluoroborates in moderate to excellent yields. This method was developed to overcome the regiochemical limitations imposed by the reaction mechanism in the protocols described in the preceding chapters. Chapter five describes a one-pot synthesis of heteroaromatic iodonium salts under similar conditions described in chapter two. The final chapter describes the reaction of enolates with chiral diaryliodonium salts or together with a phase transfer catalyst yielding racemic products. DFT calculations were performed, which revealed a low lying energy transition state (TS) between intermediates, which is believed to be responsible for the lack of selectivity observed in the experimental work. It is also proposed that a [2,3] rearrangement is preferred over a [1,2] rearrangement in the α-arylation of carbonyl compounds. The synthetic methodology described in this thesis is the most generally applicable, efficient and high-yielding to date for the synthesis of diaryliodonium salts, making these reagents readily available for various applications in synthesis.
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| 2. |
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| 3. |
- Bielawski, Marcin, 1981-
(författare)
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Efficient and High-Yielding Routes to Diaryliodonium Salts
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis summarizes three novel and general reaction protocols for the synthesis of diaryliodonium salts. All protocols utilize mCPBA as oxidant and the acids used are either TfOH, to obtain triflate salts, or BF3•Et2O that gives the corresponding tetrafluoroborate salts in situ. Chapter two describes the reaction of various arenes and aryl iodides, delivering electron-rich and electron-deficient triflates in moderate to excellent yields. In chapter three, it is shown that the need of aryl iodides can be circumvented, as molecular iodine can be used together with arenes in a direct one-pot, three-step synthesis of symmetric diaryliodonium triflates. The final and fourth chapter describes the development of a sequential one-pot reaction from aryl iodides and boronic acids, delivering symmetric and unsymmetric, electron-rich and electron-deficient iodonium tetrafluoroborates in moderate to excellent yields. This protocol was developed to overcome mechanistic limitations existing in the protocols described in chapter two and three. The methodology described in this thesis is the most general, efficient and high-yielding existing up to date, making diaryliodonium salts easily available for various applications in synthesis.
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| 4. |
- Destouni, Georgia, 1961-, et al.
(författare)
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Needs and means to advance science, policy and management understanding of the freshwater system : A synthesis report
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fragmented and inconsistent understanding of the freshwater system limits our ability to achieve water security and sustainability under the human-driven changes occurring in the Anthropocene. To advance system-level understanding of freshwater, gaps and inconsistencies in knowledge, data, representations and links of processes and subsystems need to be identified and bridged under consideration of the freshwater system as a continuous whole. Based on such identification, a freshwater system conceptualization is developed in this report, which emphasizes four essential, yet often neglected system aspects:i) Distinction of coastal divergent catchments.ii) Four main zones (surface, subsurface, coastal, observation) of different types of freshwater change.iii) Water pathways as system-coupling agents that link and partition water change among the four change zones.iv) Direct interactions with the anthroposphere as integral system pathways across the change zones.We explain and exemplify some key implications of these aspects, identifying in the process also distinct patterns of human-driven changes in large-scale water fluxes and nutrient loads.The present conceptualization provides a basis for common inter- and trans-disciplinary understanding and systematic characterization of the freshwater system function and its changes, and of approaches to their modeling and monitoring. This can be viewed and used as a unifying checklist that can advance science, policy and management of freshwater and related environmental changes across various scales and world regions.
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| 5. |
- Di Tommaso, Ester Maria, et al.
(författare)
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Ortho-Functionalization of Azobenzenes via Hypervalent Iodine Reagents
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Ortho-functionalized azobenzenes are much sought-after molecular switches. They may be tuned to absorb in the visible range of light and in many cases, the Z-isomers have very high thermal half-lives. However, methods to introduce substituents in ortho-position are still rare. This work presents the synthesis of azobenzenes with an iodine(III) moiety in the ortho-position. This novel class of diaryliodonium salts is demonstrated to efficiently arylate oxygen, nitrogen, carbon and sulfur nucleophiles under metal-free conditions. Selective transfer of the azobenzene moiety to the nucleophile gives access to an unprecedented range of ortho-substituted azobenzenes. In addition, the structure of these versatile reagents has been analyzed by X-ray crystallography and their photo-switching properties were investigated by NMR and UV-vis spectroscopy.
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| 6. |
- Di Tommaso, Ester Maria, 1991-
(författare)
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Synthetic and Mechanistic Studies with Iodine(III) Reagents
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the development of metal-free transformations and mechanistic studies on the reactivity of two classes of hypervalent iodine reagents: diaryliodonium salts and vinylbenziodoxolones (VBX). Recently, they have been recognized as valuable synthetic reagents with broad applicability in organic synthesis. Moreover, hypervalent iodine reagents are non-toxic compounds and sustainable alternatives to heavy metals. In Chapter 1, an overview of hypervalent iodine(III) compounds is provided, with emphasis on the reagents that have been used in the thesis. First, the synthesis and general reactivity of diaryliodonium salts is described. Vinylbenziodoxolones are presented as a novel class of iodine(III) compounds that are powerful electrophilic vinylating reagents. Finally, a brief description of density functional theory and computational methods used in this thesis are outlined. The synthesis and applications of azobenzene-derived diaryliodonium salts is the topic of Chapter 2. The novel iodonium reagents were employed in chemoselective arylation reactions with a wide range of C, N, O and S-nucleophiles under mild and metal-free conditions. In Chapter 3, a mild and transition metal-free vinylation of thiols and mercapto heterocycles using vinylbenziodoxolones reagents is presented. The method allows the synthesis of a wide variety of S-vinylated products with complete chemo-, regio- and stereoselectivity. In Chapter 4, the first mechanistic investigation of VBX vinylations is presented. By exploiting the use of NMR analysis, deuterium labelling and DFT calculations, the observed regio- and stereochemical outcome of the vinylations of sulfur and phosphorous nucleophiles with VBX reagents has been rationalized. A transition metal-free, photocatalyzed C-vinylation method using VBX reagents is described in Chapter 5. The reactions proceed under mild conditions and the method tolerates a series of functional groups that lead to straightforward access to corresponding alkenes in good to high yields with high stereoselectivity.
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| 7. |
- Huang, Xiao, 1987-
(författare)
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Conducting Redox Polymers for Electrode Materials : Synthetic Strategies and Electrochemical Properties
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Organic electrode materials represent an intriguing alternative to their inorganic counterparts due to their sustainable and environmental-friendly properties. Their plastic character allows for the realization of light-weight, versatile and disposable devices for energy storage. Conducting redox polymers (CRPs) are one type of the organic electrode materials involved, which consist of a π-conjugated polymer backbone and covalently attached redox units, the so-called pendant. The polymer backbone can provide conductivity while it is oxidized or reduced (i. e., p- or n-doped) and the concurrent redox chemistry of the pendant provides charge capacity. The combination of these two components enables CRPs to provide both high charge capacity and high power capability. This dyad polymeric framework provides a solution to the two main problems associated with organic electrode materials based on small molecules: the dissolution of the active material in the electrolyte, and the sluggish charge transport within the material. This thesis introduces a general synthetic strategy to obtain the monomeric CRPs building blocks, followed by electrochemical polymerization to afford the active CRPs material. The choice of pendant and of polymer backbone depends on the potential match between these two components, i.e. the redox reaction of the pendant and the doping of backbone occurring within the same potential region. In the thesis, terephthalate and polythiophene were selected as the pendant and polymer backbone respectively, to get access to low potential CRPs. It was found that the presence of a non-conjugated linker between polymer backbone and pendant is essential for the polymerizability of the monomers as well as for the preservation of individual redox activities. The resulting CRPs exhibited fast charge transport within the polymer film and low activation barriers for charge propagation. These low potential CRPs were designed as the anode materials for energy storage applications. The combination of redox active pendant as charge carrier and a conductive polymer backbone reveals new insights into the requirements of organic matter based electrical energy storage materials.
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| 9. |
- Jalalian, Nazli, 1982-
(författare)
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Development and Applications of Hypervalent Iodine Compounds : Powerful Arylation and Oxidation Reagents
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The first part of this thesis describes the efficient synthesis of several hypervalent iodine(III) compounds. Electron-rich diaryliodonium salts have been synthesized in a one-pot procedure, employing mCPBA as the oxidant. Both symmetric and unsymmetric diaryliodonium tosylates can be isolated in high yields. An in situ anion exchange also enables the synthesis of previously unobtainable diaryliodonium triflates.A large-scale protocol for the synthesis of a derivative of Koser’s reagent, that is an isolable intermediate in the diaryliodonium tosylate synthesis, is furthermore described. The large-scale synthesis is performed in neat TFE, which can be recovered and recycled. This is very desirable from an environmental point of view.One of the few described syntheses of enantiopure diaryliodonium salts is discussed. Three different enantiopure diaryliodonium salts bearing electron-rich substituents are synthesized in moderate to high yields. The synthesis of these three salts shows the challenge in the preparation of electron-rich substituted unsymmetric salts.The second part of the thesis describes the application of both symmetric and unsymmetric diaryliodonium salts in organic synthesis. A metal-free efficient and fast method for the synthesis of diaryl ethers from diaryliodonium salts has been developed. The substrate scope is wide as both the phenol and the diaryliodonium salt can be varied. Products such as halogenated ethers, ortho-substituted ethers and bulky ethers, that are difficult to obtain with metal-catalyzed procedures, are readily prepared. The mild protocol allows arylation of racemization-prone a-amino acid derivatives without loss of enantiomeric excess.A chemoselectivity investigation was conducted, in which unsymmetric diaryliodonium salts were employed in the arylation of three different nucleophiles in order to understand the different factors that influence which aryl moiety that is transferred to the nucleophile.
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| 10. |
- Jalalian, Nazli, et al.
(författare)
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Room temperature, metal-free synthesis of diaryl ethers with use of diaryliodonium salts
- 2011
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Ingår i: Abstracts of Papers, 242nd ACS National Meeting & Exposition, Denver, CO, United States, August 28-September 1, 2011. - : American Chemical Society.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Diaryl ethers are common structural features in numerous natural products and biol. active compds. Despite more than a century of immense focus on finding efficient synthetic routes to this compd. class, diaryl ethers remain difficult to obtain. Routes that are catalytic in copper have been developed, but high catalyst loadings, excess reagents, elevated temps. and long reaction times are still needed. Pd-catalyzed cross-couplings of phenols and aryl halides at temps. up to 100 °C have recently been reported to give high yields of diaryl ethers. Diaryliodonium salts are non-toxic alternatives to transition metals in the synthesis of diaryl ethers and we have recently developed effective synthetic routes to these salts. Herein we report a fast, high-yielding synthesis of diaryl ethers. The reaction conditions are mild, metal-free, and avoid the use of halogenated solvents, additives, or excess reagents. Precautions to avoid air or moisture are not needed. The scope includes ortho- and halo-substituted diaryl ethers, which are difficult to obtain by metal-catalyzed protocols .
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