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  • 1.
    Ahlford, Katrin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rhodium-catalyzed asymmetric transfer hydrogenation of ketones. Ligand development and mechanistic investigation2008Licentiate thesis, comprehensive summary (Other academic)
  • 2.
    Ahlsten, Nanna
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal-catalysed enol formation from allylic alcohols: Isomerisation, C−C and C−F bond formations 2011Licentiate thesis, comprehensive summary (Other academic)
    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
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Fine-tuning of the catalytic activity and selectivity of palladium pincer complexes2007Licentiate thesis, comprehensive summary (Other academic)
    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
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium(II)-Catalyzed Oxidative Carbocyclization/Functionalization of Allenynes2013Licentiate thesis, comprehensive summary (Other academic)
    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
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Building molecular complexity via tandem Ru-catalyzed reactions of allylic alcohols2009Licentiate thesis, comprehensive summary (Other academic)
  • 6.
    Buitrago, Elina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal catalyzed reduction of ketones2010Licentiate thesis, comprehensive summary (Other academic)
  • 7.
    Daver, Henrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Quantum Chemical Modelling of Biomimetic Phosphoesterase Complexes2015Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 8.
    Dziedzic, Pawel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Asymmetric Organocatalytic Aldol and Mannich Reactions Catalyzed by Amino Acid-Derivatives and Small Peptides with a Primary Amine Functionality2008Licentiate thesis, comprehensive summary (Other academic)
  • 9.
    Engström, Karin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Protein engineering of enzymes for improved enantioselectivity and application of engineered enzymes in organic synthesis2010Licentiate thesis, comprehensive summary (Other academic)
  • 10.
    Engström, Olof
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Carbohydrate dynamics and interactions studied by NMR spectroscopy2013Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 11.
    Fontana, Carolina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Structural studies of glycans by NMR spectroscopy2012Licentiate thesis, comprehensive summary (Other academic)
  • 12.
    Frigell, Jens
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Towards Carbasugar-Based Mimics of Mycobacerial Arabinogalactan2008Licentiate thesis, comprehensive summary (Other academic)
  • 13.
    Híresová, Renáta
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Studies on Nucleotide Analogues Containing P-S-C Bond2008Licentiate thesis, comprehensive summary (Other academic)
  • 14.
    Ilchenko, Nadia
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of Catalytic ElectrophilicTrifluoromethylation and Fluorination Methods2014Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 15.
    Jalalian, Nazli
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis and applications of diaryliodonium salts2010Licentiate thesis, comprehensive summary (Other academic)
  • 16.
    Janson, Pär G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Metal-catalyzed oxidative formation of C-CF3 and C-O bonds in alkenes and alkynes2012Licentiate thesis, comprehensive summary (Other academic)
  • 17.
    Jiang, Tuo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium(II)-catalyzed oxidativecarbocyclization: Functionalization with Boron-Containing Reagents2012Licentiate thesis, comprehensive summary (Other academic)
  • 18.
    Johnston, Eric
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Biomimetic oxidation methods: Efficient reoxidation of palladium and ruthenium by the use of a hybrid electron transfer catalyst.2009Licentiate thesis, comprehensive summary (Other academic)
  • 19.
    Kalek, Marcin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-catalyzed C-P Bond Formation. Mechanistic Investigations and synthetic Studies2008Licentiate thesis, comprehensive summary (Other academic)
  • 20.
    Karlsson, Erik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic Oxidation Methods. Use of inexpensive and environmentally friendly Oxidants in organic Synthesis.2009Licentiate thesis, comprehensive summary (Other academic)
  • 21.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    N-Heterocyclic Carbene-Phosphine Iridium Catalyzed Alkylation Reactions and Asymmetric Hydrogenation of Ketones2015Licentiate thesis, comprehensive summary (Other academic)
    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%).

  • 22.
    Krumlinde, Patrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of novel chemoenzymatic dynamic kinetic resolutions2007Licentiate thesis, comprehensive summary (Other academic)
  • 23.
    Kärkäs, Markus
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bio-inspired metal complexes: Their synthesis and application in light-driven water oxidation and organic transformations2010Licentiate thesis, comprehensive summary (Other academic)
  • 24.
    Landström, Jens
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Carbohydrates - conformation, dynamics and interactions2007Licentiate thesis, comprehensive summary (Other academic)
  • 25.
    Larsson, Johanna M
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-catalyzed C-H functionalization of alkenes under oxidative conditions2011Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 26.
    Lee, Bao-Lin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of metal complexes for water oxidation2011Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 27.
    Lihammar, Richard
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chemoenzymatic Dynamic Kinetic Resolution of Functionalized Secondary Alcohols2012Licentiate thesis, comprehensive summary (Other academic)
    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%.

  • 28.
    Lind, Maria E.S.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Quantum Chemical Modeling of Asymmetric Enzymatic Reactions: Applications to Limonene Epoxide Hydrolase and Arylmalonate Decarboxylase2013Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 29.
    Lindstedt, Erik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Aryl Ethers: Metal-Free Arylation of Alcohols using Diaryliodonium Salts2015Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 30.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Asymmetric hydrogenation of allylic alcoholsusing iridium catalysts2014Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 31.
    Lundberg, Helena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Amidst the green Metal-catalyzed amide formation from carboxylic acids2012Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 32.
    Lundborg, Magnus
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Carbohydrate Structural Studies. Towards Automatic Structure Determination.2009Licentiate thesis, comprehensive summary (Other academic)
  • 33.
    Malmgren, Joel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Unsymmetrical Diaryliodonium Salts: Development and Chemoselectivity studies2013Licentiate thesis, comprehensive summary (Other academic)
    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

  • 34.
    Manta, Bianca
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Quantum Chemical Studies of Enzymatic Reaction Mechanisms: Investigations of Cytosine Deaminase and ω-Transaminase2014Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 35.
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal-catalysis: Applications of dynamic kinetic resolution in total synthesis and developments of novel methodologies using heterogeneous Pd catalysts2013Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 36.
    Nordin, Mikael
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Computational Studies of Transition Metal-Catalyzed Asymmetric Transfer Hydrogenation Reactions2014Licentiate thesis, comprehensive summary (Other academic)
    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

  • 37.
    Olsson, Christina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Construction of binaphthylic ligands via a chiral tether2007Licentiate thesis, comprehensive summary (Other academic)
  • 38.
    Olsson, Johan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of oligosaccharides corresponding to the inner core LPS of Neisseria Meningitidis and mechanistic details in glycosylations using a novel bicyclic N-acetylglucosamine donor2007Licentiate thesis, comprehensive summary (Other academic)
  • 39.
    Olsson, Vilhelm J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Innovative catalytic protocols for synthesis and selective allylation by organoboronates and other metallorganic species2007Licentiate thesis, comprehensive summary (Other academic)
  • 40.
    Pendrill, Robert
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Conformational studies of carbohydrates: MD simulation and NMR spectroscopy2011Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 41.
    Pershagen, Elias
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development and applications of lanthanide-based luminescent probes2012Licentiate thesis, comprehensive summary (Other academic)
  • 42.
    Persson, Andreas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium(II)-catalyzed carbocyclizations. Moving from enallenes to aza-enallenes.2010Licentiate thesis, comprehensive summary (Other academic)
  • 43.
    Pu, Maoping
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dynamical Analysis of Chemical Activity of Sterically Encumbered Lewis acid/base Pairs2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This licentiate thesis is about the dynamics analysis of chemical reactions involving a stoichiometric mixture of sterically hindered Lewis base (LB) and Lewis acid (LA) – the so-called frustrated Lewis pairs (FLPs). The tool for dynamical description of chemical reactions is the ab initio molecular dynamics (AIMD) simulations together with the calculation of minimum energy paths (MEPs) on the potential energy surfaces (PESs). The aim is to take into account both the interatomic forces, computed with the dispersion-corrected density functional theory, and the motion of the atoms at finite (non-zero) temperature. With extensive AIMD/PES simulations, we have exposed and explained transition state theory (TST)/MEP paradigm failures for such important chemical reactions as binding (sequestration) of CO2 and the heterolytic cleavage of H2 by a Lewis base, tBu3P, and a Lewis acid, B(C6F5)3. The insight into dynamical aspects of FLP activity, obtained from a synergistic combination of AIMD and PES calculations, is the basis for qualitative and quantitative predictions which could be useful for future experiments

  • 44.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of Ruthenium Complexes for Water Oxidation2015Licentiate thesis, comprehensive summary (Other academic)
    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

  • 45.
    Ramstadius, Clinton
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Biologically Active Carbohydrate Mimics - Carbasugars and Pseudodisaccharides2009Licentiate thesis, comprehensive summary (Other academic)
  • 46.
    Rönnols, Jerk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of oligosaccharides and conformational analysis by NMR spectroscopy2011Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 47.
    Sandström, Anders
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Structural Determination and Directed Evolution of Candida antarctica Lipase A for Increased Enantioselectivity2009Licentiate thesis, comprehensive summary (Other academic)
  • 48.
    Skantz, Linnéa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of oligosaccharides of the Lewis blood group antigen family2007Licentiate thesis, comprehensive summary (Other academic)
  • 49.
    Slagbrand, Tove
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis covers the development of two new methods for the asymmetric reduction of ketones and ketone intermediates. The protocols developed are based on the use of a ruthenium pseudo-dipeptide catalyst that previously has been shown to be efficient and selective in the asymmetric reduction of carbonyl compounds.

    The first part of this thesis describes the development of an efficient protocol for sequential isomerization and asymmetric reduction of allylic alcohols into saturated chiral alcohols in a one-pot procedure. This transformation has previously been reported at high temperature and with long reaction times, yielding the products in poor enantioselectivity. In the current project, the same transformation was investigated, however, with a significally more active catalyst. As a result we were able to use milder reaction conditions which yielded higher enantioselectivity in comparison to previously published protocols. The scope was investigated and the mechanism was briefly studied.

    The second part of this thesis describes the asymmetric reduction of sterically demanding ketones with the same metal complex as in the first part. It was found that longer reaction times in combination with the use of potassium tert-butoxide facilitate the reduction of sterically hindered ketones, to yield secondary alcohols with high enantioselectivity. The scope and the role of potassium were investigated, and a plausible new transition state was postulated.

  • 50.
    Stridfeldt, Elin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Metal‐Free Arylations of Oxygen and Nitrogen Nucleophiles: Applications of Diaryliodonium Salts2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns development of new methods for metal‐free arylations in organic synthesis. The protocols discussed in the thesis are based on a class of hypervalent iodine compounds called diaryliodonium salts. These reagents are known to transfer aryl moieties to suitable nucleophiles.

    The first part describes O‐arylation of ethyl acetohydroxamate, which serves as a hydroxylamine equivalent. Electron‐rich as well as electron‐poor aryl groups could be transferred from the diaryliodonium salts. The arylation products could then be used as intermediates in a straightforward meta‐free one‐pot synthesis of benzofurans. Using this procedure, various substituted benzofurans were obtained in good yields. Furthermore, this methodology was used to synthesise the natural product Stemofuran A in one single step, starting from commercially available compounds. Three formal syntheses of other bioactive benzofurans were included.

    The second part describes N‐arylation of secondary acyclic amides. The chemoselectivity was explored with unsymmetric diaryliodonium salts, and aryl moieties with ortho‐substituents were preferably transferred. The protocol was suitable for electron‐deficient as well as highly sterically congested diaryliodonium salts. The transfer of electron‐rich aryl moieties was problematic. However, the reactivity for the amide was complementary to that of the salts and electron‐rich amides were phenylated in high yields. Furthermore, the protocol was compatible with benzamides and amides having sterically hindered acyl groups.

    Both arylation protocols discussed in this thesis work at ambient temperature and a variety of counter‐ions of the diaryliodonium salts were tolerated.

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