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  • 1.
    Ahlford, Katrin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rhodium-catalyzed asymmetric transfer hydrogenation of ketones. Ligand development and mechanistic investigation2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 2.
    Ahlsten, Nanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalysed enol formation from allylic alcohols: Isomerisation, C−C and C−F bond formations 2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes the isomerisation of allylic alcohols into enols and enolates catalysed by transition metal complexes. The transformation has been used to prepare both unsubstituted and α-substituted carbonyl compounds. Significant attention has been given to the mechanistic aspects of the reactions.

    In the first part of this thesis, an environmentally benign procedure for the redox isomerisation of allylic alcohols into ketones is described. The reaction takes place in water and at room temperature using a cationic rhodium complex in combination with water-soluble phosphines. A variety of allylic alcohols could be isomerised in high yields using this procedure.

    The second part describes the combination of an allylic alcohol isomerisation with a C−C bond formation, catalysed by a rhodium complex. In this way, allylic alcohols were coupled with aldehydes and N-tosyl imines forming aldol and Mannich-type products. In addition, homoallylic and bishomoallylic alcohols were for the first time isomerised into the corresponding enolates and coupled using this methodology.

    In the third part of this thesis, the isomerisation of allylic alcohols was coupled with a C−F bond formation using an iridium complex and electrophilic fluorinating reagents. This novel transformation was used to convert allylic alcohols into single regioisomers of α-fluoroketones. The reaction is tolerant to air and water and takes place at room temperature.

    All of the reactions described take place under mild conditions, are operationally simple, and utilise catalysts formed in situ from commercially available metal complexes and ligands.

  • 3.
    Aydin, Juhanes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Fine-tuning of the catalytic activity and selectivity of palladium pincer complexes2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is focused on optimization of the catalytic properties of so-called pincer complexes. This work involved synthesis of a large variety of palladium pincer complexes, which were applied in various organic transformations. Optimization of the catalytic properties (also called fine-tuning) was directed to increase the catalytic activity as well as the chemo- and stereo-selectivity of the complexes. This could be achieved by varying the heteroatoms in the terdentate pincer ligand, by changing the electronic properties of the coordinated aryl moiety and by implementing chiral functionalities in the pincer complexes.

    In the cross-coupling reaction of vinyl epoxides and aziridines with organoboronic acids the chemoselectivity of the reaction could be increased by employment of pincer complexes instead of commonly used palladium(0) catalysts. Furthermore, application of a methoxy substituent in the aromatic subunit of the complex considerably increased the activity of the pincer complex catalyst.

    Fine-tuning of the stereoselectivity in electrophilic allylation reactions was achieved using a wide variety of BINOL and biphenanthrol based pincer complexes. The synthesis of these highly stable chiral palladium complexes was accomplished by using an efficient modular approach. The highest enantioselectivity (85% ee) was obtained by applying biphenanthrol based pincer complexes.

    We have presented the first palladium pincer complex catalyzed condensation of sulfonimines with isocyanoacetate. Variation of the heteroatoms in the terdentate ligand of the complex strongly influenced the stereoselectivity of the catalytic transformation. The highest stereoselectivity was obtained by using phosphine based pincer complexes. We have also succeeded to isolate and fully characterize the key intermediate of this reaction.

  • 4.
    Bartholomeyzik, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-Catalyzed Oxidative Carbocyclization/Functionalization of Allenynes2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Palladium catalysis has emerged as an outstanding tool in synthetic organic chemistry for the mild and selective formation of carbon-carbon and carbon-heteroatom bonds. This thesis has been directed towards the extension of palladium(II)-catalyzed carbocyclization chemistry under oxidative conditions. An oxidative carbocyclization/functionalization methodology utilizing boron-containing transmetalation reagents was exploited to convert 1,5-allenynes into either arylated or borylated carbocycles. Two protocols were developed that use minimal amounts of Pd(OAc)2, stoichiometric para-benzoquinone as the oxidant and either bis(pinacolato)diboron or different arylboronic acids under mild conditions. A wide substrate scope is applicable to both methods. When the allenyne substrate bears a propargylic hydrogen, two isomeric functionalized carbocycles can be formed. By controlling the reaction conditions the reaction can be directed towards either of these two isomeric products. Kinetic isotope effect studies suggest that the mechanism leading to the different products proceeds through allylic or propargylic C-H bond cleavage, respectively. Moreover, it was observed that water has an interesting effect on the product selectivity when arylboronic acids are used in the oxidative carbocyclization of allenynes.

  • 5.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Building molecular complexity via tandem Ru-catalyzed reactions of allylic alcohols2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 6.
    Bielawski, Marcin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Efficient and High-Yielding Routes to Diaryliodonium Salts2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    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.

  • 7.
    Buitrago, Elina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal catalyzed reduction of ketones2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 8.
    Daver, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Quantum Chemical Modelling of Biomimetic Phosphoesterase Complexes2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Phosphoesterases are a class of enzymes that catalyze hydrolysis of phosphoester bonds. They facilitate the modification of nucleic acid sequences, as well as the breakdown of rest products of warfare agents and insecticides. In this thesis, three biomimetic complexes that perform the same tasks are studied using density functional theory.

    Two of the catalysts contain a dizinc core while the third binds an Fe(III) ion and a Mn(II)ion. These complexes catalyze the hydrolysis of the phosphodiester substrate bis-(2,4)-dinitrophenyl phosphate (BDNPP). The substrate is analogous to the phosphoric link between two nucleotides in DNA, and the system is thus a model for cleaving bonds between nucleotides.

    By means of computational modelling, the reaction mechanisms are investigated in detail. Different binding modes of the substrates to the catalysts are considered and several mechanistic proposals are evaluated. Conclusions are drawn on the basis of free energy barriers calculated for the different mechanisms.

    In all studied reactions, a hydroxide bridging the metals becomes terminally coordinated to one of the zinc ions and then attacks the phosphorus center in a nucleophilic fashion. Leaving group dissociation takes place without a barrier.

    One of the catalysts was also studied binding a model substrate for RNA, namely hydroxy-2-isopropyl p-nitrophenyl phosphate (HPNP). The hydroxide was found to act as a base, activating the alcohol moiety of the substrate which in turn performs the nucleophilic attack on the phosphorus center.

    Common for all studied systems is that the catalyst-product complex is calculated to be the most stable species. Hence, this complex is suggested to be the resting state of the catalytic cycle. The free energy barriers of the reactions are associated with going from the catalystproduct complex of one catalytic cycle to the transition state for nucleophilic attack in the next. Calculated barriers are in good agreements with experiments.

  • 9.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric Organocatalytic Aldol and Mannich Reactions Catalyzed by Amino Acid-Derivatives and Small Peptides with a Primary Amine Functionality2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 10.
    Engström, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Protein engineering of enzymes for improved enantioselectivity and application of engineered enzymes in organic synthesis2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 11.
    Engström, Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Carbohydrate dynamics and interactions studied by NMR spectroscopy2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The combination of NMR spectroscopy and molecular dynamics (MD) simulations are powerful tools in the studying of bioorganic molecules in solution. In this thesis two such studies are presented with focus on the NMR aspect. The caffeine association to sugars (D-glucose and sucrose) was investigated by NMR titrations and NOESY experiments in paper I. The observations from the NMR experiments confirmed MD simulations showing that the binding occurs by a face-to-face interaction between the aromatic surface of the caffeine and axial protons of the sugar ring. Different sugar molecules and residues have different preferences regarding which side of the sugar ring that are involved in the binding. The sucrose residues bind with only one ring face each whereas β-D-glucopyranose has two sides of similar binding probability and the α-D-glucopyranose has something in between. The MD simulations showed that the driving force of the binding is partly driven by hydration effects that favor the enthalpy of the system. A new approach to calculate NMR relaxation parameters (that is dependent on molecular motions) from computational simulations is presented in paper II. Each sugar residue is assumed to be a rigid unit connected by flexible joints in the approach, thus the name diffusive chain model (DCM). The simplified model together with a stochastic simulation approach lowers the computational cost which makes it possible to acquire long enough trajectories to the calculations of spin relaxation parameters. Two case studies with slightly different methodologies are presented. In one of them, spin relaxation parameters are reproduced for the human milk oligosaccharide LNF-1 in a feasible way by the use of Brownian dynamics.

  • 12.
    Fontana, Carolina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural studies of glycans by NMR spectroscopy2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 13.
    Frigell, Jens
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Towards Carbasugar-Based Mimics of Mycobacerial Arabinogalactan2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 14.
    Híresová, Renáta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Studies on Nucleotide Analogues Containing P-S-C Bond2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 15.
    Ilchenko, Nadia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development of Catalytic ElectrophilicTrifluoromethylation and Fluorination Methods2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is focused on development of new catalytic, electrophilic fluorination and trifluoromethylation methods of alkenes. These reactions were carried out using hypervalent trifluoromethyl and fluoroiodine reagents.

    The first project involved copper catalyzed oxytrifluoromethylation of terminal alkenes and alkynes. In this reaction the employed hypervalent iodine underwent a formal addition to C-C multiple bonds. Subsequently, we have also shown that under similar reaction conditions in the presence of B2pin2 as additive quinones can smoothly undergo C-H trifluoromethylation.

    We also developed a cyanotrifluoromethylation reaction of styrenes, which proceds in the presence of copper cyanide and PCy3 as additive. This reaction allows addition of both trifluoromethyl and cyanofunctionality to the styrene, creating two new carbon-carbon bonds.

    The interesting substituent effects and the acceleration of B2pin2 and PCy3 additives inspired us to further investigate the mechanism for the above trifluoromethylation reactions. The Hammett studies showed that the oxytrifluoromethylation reactions are slightly accelerated by electron donor substituents. The C-H trifluoromethylation does not show deuterium isotope effect. Both B2pin2 and PCy3 accelerated the trifluoromethylation reactions but the extent of the acceleration was dependent on the reaction type and on the substituent effects.

    Inspired by our trifluoromethylation results, we have also studied the silver-mediated difluorination of styrenes in the presence of an electrophilic hypervalent iodine based fluorine source. We obtained over 50% of the difluorinated product which suggests that one fluorine atom comes from the fluoroiodine reagent and the other one from BF4-. A phenonium ion intermediate has been proposed to be involved in the mechanism of the difluorination reaction.

  • 16.
    Jalalian, Nazli
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis and applications of diaryliodonium salts2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 17.
    Janson, Pär G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Metal-catalyzed oxidative formation of C-CF3 and C-O bonds in alkenes and alkynes2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 18.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-catalyzed oxidativecarbocyclization: Functionalization with Boron-Containing Reagents2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 19.
    Johnston, Eric
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Biomimetic oxidation methods: Efficient reoxidation of palladium and ruthenium by the use of a hybrid electron transfer catalyst.2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 20.
    Kalek, Marcin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-catalyzed C-P Bond Formation. Mechanistic Investigations and synthetic Studies2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 21.
    Karlsson, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Oxidation Methods. Use of inexpensive and environmentally friendly Oxidants in organic Synthesis.2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 22.
    Kerdphon, Sutthichat
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    N-Heterocyclic Carbene-Phosphine Iridium Catalyzed Alkylation Reactions and Asymmetric Hydrogenation of Ketones2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is focused on hydrogen transfer reactions using N-heterocyclic carbenephosphine iridium catalysts and is divided in two parts. The first part describes the use of achiral N-heterocyclic carbene-phosphine iridium complexes catalyzing the methylation of ketones and alkylation of amides using alcohols as the electrophile. In Chapter 2, the N-heterocyclic carbene-phosphine iridium complexes that have been developed in the Andersson group was employed as catalysts for the methylation of ketones. These reactions were found to take place under mild conditions with low catalyst loading (1.0 mol%) to furnish the desired methylated products in up to 98% isolated yield. The achiral N-heterocyclic carbene-phosphine iridium complexes were also found to catalyze the N-alkylation of amides with alcohols, as presented in Chapter 3. It was discovered that the reactivity of the catalysts was highly dependent on the structure of the catalyst. At optimum reaction conditions, the best catalyst could be used with a wide range of substrates at low catalyst loading (0.5 mol%) to afford the desired product up to 98% isolated yield.

    The second part of this thesis details the preparation of chiral N-heterocyclic carbenephosphine iridium complexes and their use in the asymmetric hydrogenation of ketones (Chapter 4). These catalysts were successfully used in the asymmetric hydrogenation of ketones at room temperature under base-free conditions and led to full conversion of chiral alcohol products in 30 min with high enantiomeric excess (up to 96%).

  • 23.
    Krumlinde, Patrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development of novel chemoenzymatic dynamic kinetic resolutions2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 24.
    Kärkäs, Markus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bio-inspired metal complexes: Their synthesis and application in light-driven water oxidation and organic transformations2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 25.
    Landström, Jens
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Carbohydrates - conformation, dynamics and interactions2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 26.
    Larsson, Johanna M
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-catalyzed C-H functionalization of alkenes under oxidative conditions2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The unique properties of high oxidation state palladium have been used to develop new catalytic alkene C-H functionalization reactions. A Heck-type coupling based on the reactivity of palladium catalysts and diaryliodonium salts has been developed with broad synthetic scope and tolerance for functional groups that are ordinarily reactive in Pd0/PdII catalysis, for example, allylic acetates and aryl bromides. Poisoning experiments and DFT studies suggest that a PdII/PdIV cycle is operating. The first catalytic allylic C-H silylation method has also been developed utilizing commercially available hexamethyldisilane as silyl source and iodine(III) reagents as oxidants.

  • 27.
    Lee, Bao-Lin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development of metal complexes for water oxidation2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In the course of developing a water oxidation catalyst, five metal complexes have been synthesised, characterised and studied for catalytic activity. Three of them are dinuclear complexes (Ru, Co and Cu) of 2,6-bis[(2-hydroxybenzyl)-(2-pyridylmethyl)aminomethyl]-4-methylphenol (H3bbpmp). The fourth is a dimeric ruthenium complex with a ligandcontaining imidazoles and phenols. The fifth is a dinuclear manganese complex with benzimidazoles and carboxylates coordinating to the metal atoms.

    All complexes were characterised by cyclic voltammetry, UV/Vis spectroscopy, ESIMS and their catalytic activities were investigated. Furthermore, all dinuclear complexes were characterised by single crystal X-ray diffraction and EPR studies were performed on the dimeric ruthenium complex and the dinuclear manganese complex.

    The potential of the three complexes of H3bbpmp as catalysts for oxidation of organic compounds was investigated and it was found that the ruthenium complex catalyses the oxidation of alcohols to the corresponding ketone or aldehyde using (diacetoxyiodo)benzene as oxidant. The cobalt complex functions as an electron transfer mediator in a coupled catalytic system for allylic oxidation using oxygen gas. The oxidation of 3,5-di-tert-butylcatechol to the corresponding ortho-quinone with oxygen gas using the copper complex proved that it can be considered as a model of catecholase.

    The dimeric ruthenium complex and the manganese complex proved to catalyse water oxidation when using stoichiometric amounts of the oxidant Ru(bpy)3(PF6)3. Furthermore, both catalyse the oxidition of water photochemically using Ru(bpy)2(deeb)(PF6)3 as photosensitiser and Na2S2O8 as electron acceptor.

  • 28.
    Lihammar, Richard
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chemoenzymatic Dynamic Kinetic Resolution of Functionalized Secondary Alcohols2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Dynamic kinetic resolution (DKR) is the combination of a kinetic resolution with an in situ racemization and is a powerful method for obtaining optically active compounds. In this thesis various secondary alcohols are transformed to their corresponding enantiomerically enriched acetates by employing immobilized lipases as resolution catalysts and transition metal complexes as racemization catalysts.

    In the first part 3-hydroxypiperidines and 3-hydroxypyrrolidines are transformed to their corresponding acetates in high yields and high enantiomeric excesses using the DKR method. This was the first report of DKR on these types of N-heterocycles. It was found that the immobilization method used has a significant impact on the enzyme selectivity and reactivity.

    In the second part, cyclic allylic alcohols are investigated as substrates for DKR. After optimization, the amount of enone by-product could be reduced to <10% and a range of allylic alcohols could be converted to enantiomerically pure allylic acetates in high ee. The possibility of further transformation of an iodo-substituted substrate was investigated and initial results obtained are promising. Electron-rich allylic alcohols are not suitable for this method due to competing formation of homo coupled ether.

    DKR has also been applied in the total synthesis of Duloxetine, the active species of the pharmaceutical CymbaltaTM. CymbaltaTM is administered as a drug against physical disorder like depression, stress urinary incontinence, and obsessive compulsive disorder. By performing a sixs tep synthesis, utilizing DKR in the enantiodetermining step, Duloxetine could be isolated in an overall yield of 37% and an enantiomeric excess above 96%.

  • 29.
    Lind, Maria E.S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Quantum Chemical Modeling of Asymmetric Enzymatic Reactions: Applications to Limonene Epoxide Hydrolase and Arylmalonate Decarboxylase2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis, density functional theory has been employed to study the reactionmechanisms of two enzymes with possible applications in asymmetric biocatalysis.To reproduce and rationalize the stereoselectivity of the enzymes, quite large cluster models that account for the chiral environment of the active site have been used.

    In the first study, the enantioselectivity of the wild-type limonene epoxidehydrolase and two groups of mutants thereof, that show either (R,R)- or (S,S)-selectivity, were investigated. Using the cluster approach, the enantioselectivity for each variant of the enzyme was calculated and the results are in good agreement with the experimental data. It was found that the enantioselectivity of the enzyme variants is controlled by the steric hindrance introduced or relieved bythe different mutations.

    The second study concerns the reaction mechanism and stereoselectivity of arylmalonate decarboxylase. The calculations support the proposed two-step mechanism, in which decarboxylation and protonation of the substrate occur separately. The stereoselectivity of the enzyme is governed by repulsive steric interactions between the substrate and the residues that deffine a large and a small cavity in the active site. Depending on the size of the substrate, the selectivity was found to be determined already at the binding of the substrate or in the subsequent transition state.

    The results presented in this thesis demonstrate that the quantum chemical cluster approach for modeling enzymes is indeed a very valuable tool in the study of asymmetric biocatalysis.

  • 30.
    Lindstedt, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of Aryl Ethers: Metal-Free Arylation of Alcohols using Diaryliodonium Salts2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis contains two parts showing different metal-free methods to synthesize aryl ethers using hypervalent iodine reagents, more specifically diaryliodonium salts. The first part describes arylation of benzylic and allylic alcohols and phenols in water using the easily accessible base sodium hydroxide. Chemoselectivity of phenols in aqueous media is discussed and limitations of the reaction are presented.

    The second part describes an arylation of aliphatic alcohols at room temperature with short reaction time and no excess of reagents are required. The scope of the methodology was investigated and showed that electron-deficient iodonium salts worked efficiently, but unfortunately electron-rich was not compatible with the reaction conditions. The methodology was applied in a formal synthesis of Butoxycaine.

  • 31.
    Liu, Jianguo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric hydrogenation of allylic alcoholsusing iridium catalysts2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The first part of this thesis is focussed on the enantioselective iridium catalyzeda symmetric hydrogenation of allylic alcohols. The study involved the preparation of a range of allylic alcohols. These allylic alcohols were then hydrogenated, using iridium catalysts that have been previously prepared, to produce chiral alcohols with high yields and excellent enantioselectivity. The selectivity model of the reaction was used to accurately predict the absolute configuration of the hydrogenated products.

    The second part of the thesis was directed on the application of iridium catalyzed asymmetric hydrogenation of allylic alcohols in the synthesis of a late-stage intermediate of Aliskiren. A total of three synthetic routes were evaluated. The best synthesis relies on asymmetric hydrogenation of an allylic ester and an allylic alcohol as key-steps. Full conversion and 94% ee for the allylic alcohol were achieved. The late-stage intermediate of Aliskiren was successfully synthesized in eight steps.

  • 32.
    Lundberg, Helena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Amidst the green Metal-catalyzed amide formation from carboxylic acids2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes novel methods for transition metal-catalyzed transformation of non-activated carboxylic acids to amides. It was found that 2-10 mol% of zirconium(IV) chloride or 10-20 mol% titanium(IV) isopropoxide catalyzed the formation of a range of secondary and tertiary amides in good to excellent yields (61-99%) in THF at 70-100°C, with molecular sieves present as water scavengers. The protocols proved to be suitable for gram scale preparation of amides, where a straight-forward work-up procedure was used for the isolation of the amide products. Furthermore, it was found that ammonium carbamates were suitable equivalents for gaseous ammonia and dimethylamine, in the group (IV) metal-catalyzed amidation of structurally different carboxylic acids, resulting in good to excellent yields (61-99%) of primary and N,N-dimethyl amides.

  • 33.
    Lundborg, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Carbohydrate Structural Studies. Towards Automatic Structure Determination.2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 34.
    Malmgren, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Unsymmetrical Diaryliodonium Salts: Development and Chemoselectivity studies2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The first part describes a chemoselectivity study on diaryliodonium salts where oxygen, nitrogen and carbon nucleophiles have been arylated. Twelve different unsymmetric phenyl(aryl)iodonium salts were designed with a systematic variation of the steric and electronic properties of the aryl group. The chemoselectivity varies greatly between the nucleophiles but several “dummy” aryl groups were identified where selective transfer of the phenyl moiety was consequently observed. HRMS studies of the salts revealed an interesting ligand exchange between the aryl groups of the iodine under certain conditions. This will aid the understanding of the mechanism operating in diaryliodonium salt arylation reactions. The results will facilitate the design of catalytic systems employing diaryliodonium salts, as well as help in search for applications with polymer-bound salts.

    The second part of the thesis describes the development of a new synthetic route towards unsymmetric diaryliodonium salts containing one heteroaryl moiety. The substrate scope of the facile one-pot protocol involves salts containing dummy groups with large steric bulk as well as electron-rich aryl groups. The utility of the salts are demonstrated in the arylation of both phenols and malonates where selective transfer of the heteroaryl moiety was consistently observed

  • 35.
    Manta, Bianca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Quantum Chemical Studies of Enzymatic Reaction Mechanisms: Investigations of Cytosine Deaminase and ω-Transaminase2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis, density functional theory is used to study the reaction mechanisms of two dierent enzymes. Quantum chemical cluster models of the active sites were designed using available crystal structures. In this approach only the active site residues are considered and the effects of the surroundings are accounted for by a coordinate-locking scheme and a polarizable continuum model.

    The enzymes studied are cytosine deaminase (CDA) from Escherichia coli and ω-transaminase from Chromobacterium violaceum (Cv-ωTA). CDA is a zinc-dependentenzyme that catalyzes the hydrolytic deamination of cytosine into uracil and ammonia. Cv-ωTA carries out the interchange of amino and keto groups by utilizing the cofactor pyridoxal-5’-phosphate (PLP). The calculations provide optimized geometries and energies of transition states and intermediates, which are analyzed and used to construct a potential energy prole for the reaction and to identify the rate-limiting step. Each theoretical investigation provides a detailed description of the catalytic mechanism and establishes the roleof important active site residues.

    In the rst study (Paper I), it was found that a glutamate and an aspartate residue assist in the proton transfer events throughout the reaction. In the second study (Paper II), it was found that the lysine residue, which in the holo enzyme binds the cofactor PLP, assists in several proton transfer events once it has been replaced by the amino substrate. It was also found that the water substrate can be utilized as a proton shuttle before it is consumed at a later stage in the reaction mechanism.

    Apart from the detailed chemical insight, the results in this thesis confirmthat density functional theory together with cluster models of active sites is a very useful approach for studying diverse enzymatic reaction mechanisms.

  • 36.
    Nagendiran, Anuja
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalysis: Applications of dynamic kinetic resolution in total synthesis and developments of novel methodologies using heterogeneous Pd catalysts2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The first part of the thesis describes a general and efficient route for the enantioselective synthesis of various α-substituted ketones and their corresponding lactones. The two key steps in this synthesis are the ruthenium and CALB-catalyzed dynamic kinetic resolution (DKR) which provided the exocyclic acetates in high yields and excellent enantioselectivity and the subsequent Cu-catalyzed α-allylic substitution giving the corresponding α-substituted products with inversed stereochemistry in high yields. This synthetic route was applied to the synthesis of the naturally occurring (R)-10-methyl-6-undecanolide, via subsequent oxidative cleavage and Baeyer-Villiger oxidation.

    In the second part, a new microwave-assisted methodology using a heterogeneous Pd nanocatalyst for Suzuki cross-couplings and hydrogenation of alkenes is presented. The catalytic system proved to be compatible with a wide range of functional groups and heteroatoms. In general, excellent yields were obtained within 45 min for the Suzuki cross-couplings and within 30 min for the hydrogenation reactions. The catalyst exhibited high recyclability with a low leaching in both cases.

    A novel method to prepare γ-alkylidene lactones from alkynoic acids mediated by a heterogeneous Pd(II) catalyst is described in the last part of the thesis. The protocol proved to be highly stereo- and regioselective, affording the 5-exo-dig lactone as the single product in all cases. In general, internal alkynes were cyclized in high to excellent yields within 3 hours using 0.3 mol% of catalyst loading. For internal alkynes, the catalyst loading had to be increased to 0.5 mol% along with prolonged reaction times and elevated temperatures in order to obtained high yields. The catalyst showed some recyclability with low leaching.

  • 37.
    Nordin, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Computational Studies of Transition Metal-Catalyzed Asymmetric Transfer Hydrogenation Reactions2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis is based on two studies dealing with the computational investigation of asymmetric transfer hydrogenation reactions, in which hydrogen is transferred from a donor molecule (e.g. alcohol) to a substrate (ketone), via mediation of a metal-ligand catalyst complex. The catalysts, employing either rhodium or ruthenium in combination with pseudo-dipeptideligands, enantioselectively reduce acetophenone into the secondary alcohol. Stereochemically pure secondary alcohols are important intermediates in the synthesis of many pharmaceutical, agricultural and fine chemistry products. The demand for developing effective, mild and reproducible methods for making these alcohols is high.

    The present studies were made using density functional theory calculations, aiming at explaining the sources of enantioselectivity in the reactions. The calculations reproduce the trends in enantioselectivity quite satisfactorily. In the analysis of the obtained free energy graphs and the optimized geometries several factors that contribute to the enantioselectivity are identified

  • 38.
    Olsson, Christina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Construction of binaphthylic ligands via a chiral tether2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 39.
    Olsson, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of oligosaccharides corresponding to the inner core LPS of Neisseria Meningitidis and mechanistic details in glycosylations using a novel bicyclic N-acetylglucosamine donor2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 40.
    Olsson, Vilhelm J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Innovative catalytic protocols for synthesis and selective allylation by organoboronates and other metallorganic species2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 41.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Conformational studies of carbohydrates: MD simulation and NMR spectroscopy2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis describes various aspects of conformational studies of carbohydrates, from development of the methods by which experimental parameters are gathered to the application of NMR spectroscopy and MD simulation for the analysis of a disaccharide. Paper I describes the use of site-specific 13C labeling as a tool to resolve spectral overlap of 1H frequencies in a trisaccharide, allowing the measurement of important crossrelaxation rates and long-range couplings which were previously obscured. The newly acquired parameters are found to support the conformational equilibrium proposed in a previous study of the molecule. Paper II describes a problem in the J-HMBC experiment that occurs when there are large homonuclear 13C scalar couplings present, a situation typically occurring when studying labeled compounds. By introducing a constant-time element to the pulse-program, the interference by one-bond homonuclear 1JC,C couplings is shown to be suppressed when applied to site-specifically labeled disaccharides. The last project, paper III, concerns the conformation and dynamics of the disaccharide β-L-Fucp-(1→6)-α-D-Glcp-OMe, showing the difficulties associated with the flexible nature of (1→6) linkages. The molecule is found to have significant flexiblity in both the ω and ψ torsions. A three-state equilibrium is found for ω, while ψ has two states connected by a low barrier. The force field parm22/SU01 is able to reproduce and explain the experimental parameters reasonably well, but it is concluded that some of the states have slightly incorrect torsion angles and that the populations are not correctly represented.

  • 42.
    Pershagen, Elias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development and applications of lanthanide-based luminescent probes2012Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 43.
    Persson, Andreas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-catalyzed carbocyclizations. Moving from enallenes to aza-enallenes.2010Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 44.
    Pu, Maoping
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dynamical Analysis of Chemical Activity of Sterically Encumbered Lewis acid/base Pairs2014Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Denna licentiatavhandling behandlar dynamisk analys av kemiska reaktioner som involverar en stökiometrisk blandning av steriskt hindrade Lewis-baser (LB) och Lewis-syror (LA) molekyler - så kallade frustrerade Lewis-par (FLP). Ett verktyg för dynamisk beskrivning av kemiska reaktioner är “ab initio molecular dynamics” (AIMD)-simuleringnar tillsammans med beräkningen av “minimal energy paths” (MEP) på “potential energy surfaces” (PES). Syftet är att ta hänsyn till både interatomära krafter och rörelsen hos atomerna vid ändliga temperaturer. Vi har kunnat visa att FLP-reaktioner (kemiska reaktioner som involverar LB/LA-par) inte sker enligt MEP på grund av att grundantaganden som gjorts i “transitition state theory” inte är uppfyllda. Exempel på analyserade kemiska reaktioner är fångandet av den primära växthusgasen CO2 och splittring av H2. Genom en synergistisk kombination av dynamiska analyser och PES-beräkningar, får vi en ny insikt i mekanismerna och kan därmed göra kvantitativa förutsägelser för framtida experiment.

  • 45.
    Rabten, Wangchuk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development of Ruthenium Complexes for Water Oxidation2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Development of a methodology to combat the world energy crisis can be one of the greatest challenges now facing mankind. Our research is focused on the development of versatile catalysts (WOCs) that oxidize water into molecular oxygen at neutral pH, driven by the mild one-electron oxidant [Ru(bpy)3]3+, using natural photosynthesis a sa model.

    The first part of the thesis describes the unexpected generation of a mononuclear Ru complex from a hexadentate ligand, which was envisioned to accommodate two metal atoms. The study of this mononuclear catalyst clearly demonstrated the importance of having strongly electron donating functional groups and their effect on catalytic water oxidation.

    The second part of thesis presents the preparation of a mononuclear Ru complex, which contains two amide groups in the ligand scaffold and the superior reactivity of this complex in catalytic water oxidation under neutral condition. When mild one-electronoxidant [Ru(bpy)3]3+ was employed, TONs of ∼ 6000 and TOFs of ∼20s-1 were achieved, which are the highest values reported so far, using this type of oxidant

  • 46.
    Ramstadius, Clinton
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of Biologically Active Carbohydrate Mimics - Carbasugars and Pseudodisaccharides2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 47.
    Rönnols, Jerk
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of oligosaccharides and conformational analysis by NMR spectroscopy2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The first part of this thesis describes investigations of the conformations of six N-linked pseudodisaccharides (Paper I), which were synthesized as glycosidase inhibitor candidates, and 10 β-D-xylopyranoside derivatives bearing hydrophobic aglycons (Paper II), by NMR spectroscopic methods. In paper I the ring conformations of 2- and 3-amino-α-D-altropyranosides, and ω torsions of altrosides, glucosides and mannosides were described, in neutral and protonated states. Occurrences of the conformations 4C1, oS2 and 1C4 were found for the altrosides, with large differences from the neutral to charged state observed for the 2-linked structures.

    The studied xylosides were found to predominantly reside in 4C1 conformation, with some population of 2So (˜5%), with exception of a 3-deoxygenated compound, which was found to be in equilibrium between the 4C1 and 1C4 conformations, and two epimerized compounds. The 3-deoxy compound was studied in further detail. The equilibrium was found to differ with temperature, and an estimate of the activation energy is presented.

    The second part describes synthesis towards N-glycan oligosaccharides with various fucosylation patterns. The synthesis involves a safe route to a glycosyl azide, a high-yielding conversion of the azide to acetyl amide and a stereoselective β-mannosylation performed by preactivation of the mannosyl donor. The synthesis of an orthogonally protected core trisaccharide is described.

  • 48.
    Sandström, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural Determination and Directed Evolution of Candida antarctica Lipase A for Increased Enantioselectivity2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 49.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development of Multi-Component Reactions using Catalytically Generated Allyl Metal Reagents2008Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This licentiate thesis is based on the development of catalytic reactions for the synthesis and application of organometallic reagents. By use of palladium pincer-complex catalysts, we have developed an efficient procedure for the synthesis of allylboronates starting from allylic alcohols. These reactions were further extended by including various one-pot multi-component reactions, using the in situ generated allylboronates. Furthermore, novel unsymmetrical palladium pincer-complexes were synthesized and studied in auto-tandem catalysis.

  • 50.
    Skantz, Linnéa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of oligosaccharides of the Lewis blood group antigen family2007Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
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