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  • 1.
    Ahlsten, Nanna
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal-catalysed isomerisation of allylic alcohols: Applications to C−C, C−F and C−Cl bond formation2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The focus of this thesis has been to develop selective and atom-economical methods for carbon-carbon and carbon-heteroatom bond formation, and to some extent improve on existing findings in this area. More specifically, methods for the catalytic generation of enolates from allylic alcohols and their in situ functionalisation with electrophilic reagents are described.  

    In the first part of this thesis, a method for the Rh-catalysed redox-isomerisation of allylic alcohols into carbonyl compounds under environmentally benign conditions is described. The reaction takes place at room temperature, in the absence of acids or bases, using water as the only solvent, and it is applicable to both primary and secondary allylic alcohols.

    The second part describes the combination of an isomerisation reaction of allylic alcohols with a C−C bond formation, catalysed by a rhodium complex. In this way, allylic alcohols were coupled with aldehydes and N-tosylimines to give aldol and Mannich-type products. In addition to allylic alcohols, homoallylic and bishomoallylic alcohols could be used as enolate precursors, and this is the first report where the latter two substrate types have been used in such a reaction.       

    In the remaining parts of the thesis, an iridium-catalysed isomerisation of allylic alcohols has been combined with an electrophilic halogenation step to provide a conceptually new method for the synthesis of α-halogenated carbonyl compounds. In this way, α-fluoro and α-chloroketones have been synthesised as single constitutional isomers, with the regiochemistry of the final products determined by the position of the double bond in the allylic alcohols. The reactions are tolerant to air, run in water-organic solvent mixtures, and proceed at room temperature.

  • 2.
    Alpe, Marianne
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of oligosaccharides related to the capsular polysaccharides of Streptococcus pneumoniae serotype 9 and of Cryptococcus neoformans2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the present investigation, synthesis of oligosaccharides corresponding to structural elements present in the capsular polysaccharides of Streptococcus pneumoniae and Cryptococcus neoformans has been achieved. The first two sections describe the synthesis of spacer-equipped oligosaccharides corresponding to structures from the CPS of Streptococcus pneumoniae serotypes 9N, 9A and 9L, the production of which involved synthetic challenges such as the construction of β-ManNAc and α-GlcA linkages. The former challenge was met by employing azide displacement of a 2-O-triflate substituent on a β-glucoside, whereas the latter task was accomplished utilizing thioethyl glucuronic acid donors in the presence of various promoters. The pentasaccharide product obtained correspond to the complete repeating unit of the CPS of serotype 9A.

    The last two sections of this thesis describe the construction of thioglycoside di- and trisaccharide building blocks containing α-Man, β-Xyl, β-GlcA and 6-O-acetyl motifs, as well as subsequent assembly of these building blocks into oligosaccharides corresponding to the repeating units of the capsular polysaccharide of the yeast Cryptococcus neoformans. The GlcA moiety was introduced via trichloroacetimidate coupling involving the peracetylated glucuronic acid methyl ester donor, after which the subsequent necessary benzylation was performed with the di- and trisaccharides. All of the target oligosaccharides were synthesized as amino-spacer glycosides in order to make conjugation to a carrier protein possible.

  • 3.
    Andersson, Mats
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Determination of the structures of three bacterial polysaccharides and synthesis and use of new spacers for glycoconjugate formation1993Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The first part of this work describes studies on the structures of three bacterial polysaccharides, i.e., the extracellular polysaccharides of Streptococcus pneumoniae type 2 and Butyrivibrio fibrisolvens strain X6C61 and the O-antigenic side-chain of the lipopolysaccharide of Escherichia coli 086.

    The second part describes the synthesis of new spacer molecules for oligosaccharide immobilization and their use in glycoconjugate formation.

  • 4.
    Balan, Daniela
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The three-component aza-Baylis-Hillman reaction: development and application2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The current thesis presents the optimization and generalization of the Baylis-Hillman reaction applied to in situ generated imines, i.e. a three-component aza- Baylis-Hillman reaction. We found that the title reaction proceeds most efficiently in the presence of a combination of catalysts, i.e. 3-hydroxyquinuclidine (0.15 equiv) and titanium isopropoxide (0.02 equiv), together with molecular sieves (4 Å; activated powder; 200 mg/mmol substrate) at ambient temperature.

    Our study of the scope and limitations of this reaction, revealed that arylaldehydes and sulfonamides are the only imine precursors which both generate the corresponding imines in situ and facilitate a further reaction with the Michael acceptor in a Baylis-Hillman fashion. Among the Michael acceptors tested, acrylates and acrylonitrile demonstrate high reactivity, while acrylamides and β-substituted acrylates do not participate in the reaction.

    The optimized conditions applied to the above range of substrates results in good-to-excellent yields of the desired amine-products (53-94%) and very high chemoselectivity (83- >99%). Furthermore, the reaction times observed under these conditions are considerably shorter than those previously reported for the aza-Baylis-Hillman reaction.

    In the development of a stereoselective version of the title reaction, the use of a chiral catalyst proved to be most effective. Thus, an enantiomeric excess up to 74% can be obtained with β-Isocupreidine. With chiral imine precursors or chiral acrylates, the diastereoselectivity attained was poor. No asymmetric induction was observed when chiral Lewis acids were employed as a co-catalyst.

    The α-methylene-β-amino acid derivatives obtained via the three-component aza-Baylis-Hillman reaction were subjected to further transformation. Carbon chain elongation at the olefinic end of the amine-adduct was attempted. For this purpose, the Miyaura borylation protocol could be successfully applied. The subsequent Suzuki-type cross-coupling reaction resulted predominantly in hydrolysis of the boronate intermediate, together with formation of the amine-adduct via β-hydride elimination. The optimal conditions for this latter reaction remain to be found.

    Finally, 2,5-dihydropyrroles have been synthesized from aza-Baylis-Hillman adducts, via a short and efficient route in which the key step is a microwave-assisted ring-closing metathesis of the N-allylated amine-adducts.

  • 5.
    Bartholomeyzik, Teresa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium(II)-Catalyzed Oxidative Carbocyclization/Functionalization of Allenynes2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The selective formation of carbon-carbon bonds constitutes a key transformation in organic synthesis with useful applications in pharmaceutical or material industry. A particularly versatile tool for carbon-carbon as well as carbon-heteroatom bond formation is palladium catalysis, which allows for mild and selective routes even towards complex structures.

    The work in this thesis describes the development and the mechanistic investigation of a palladium(II)-catalyzed oxidative carbocyclization/functionalization methodology, which converts 1,5-allenynes into either arylated or borylated carbocycles. To this end, either boronic acids or B2pin2 are employed and 1,4-benzoquinone serves as the stoichiometric oxidant. These protocols provide access to two products, a cyclic triene and a cyclic vinylallene. Their formation is dependent on the substrate structure as the latter product requires a propargylic C–H bond to be present in the substrate. Based on kinetic isotope effects, mechanisms involving either an initial allenic or propargylic C–H abstraction, respectively, were proposed. Full control of product selectivity to give either trienes or vinylallenes was achieved by modifying the reaction conditions with additives. Using substoichiometric amounts of BF3·OEt2 leads selectively to borylated or arylated vinylallenes. Under arylating conditions the reaction is zero order in allenyne and oxidant, and first order in phenylboronic acid. Transmetalation and, to some extent, propargylic C–H cleavage were found to be turnover-limiting. The selective reaction towards functionalized trienes was achieved by addition of either substoichiometric LiOAc·2H2O (borylation) or excess amounts of H2O (arylation). For the latter case, a kinetic study revealed an unusually slow catalyst activation. Lower concentrations of H2O gave product mixtures, and it was shown that vinylallenes are formed with either boronic acid or boroxine, whereas the formation of trienes requires boronic acid.

  • 6.
    Björklund, Catarina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Design and Synthesis of BACE-1 Inhibitors: Novel Compounds Targeting an Aspartic Protease Important in the Pathogenesis of Alzheimer’s Disease2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with the design and synthesis of protease inhibitors targeting the aspartic protease BACE-1 (β-site APP cleaving enzyme-1), an enzyme important in the pathogenesis of Alzheimer’s disease. The inhibitors are evaluated with respect to inhibition data, in a structure-activity relationship part.

    Alzheimer’s disease is a disabling, progressive and ultimately fatal form of dementia afflicting approximately 40 percent of the population over 80 years, with over 30 million people suffering from Alzheimer’s disease worldwide. This makes Alzheimer’s disease the most common form of dementia. The identification of the amyloid-β peptide (Aβ) as the main constituent of extracellular plaques, which characterize Alzheimer’s disease, suggests that Aβ plays a vital role in the pathology of Alzheimer’s disease. The formation of Aβ occurs when amyloid-β precursor protein (APP) is cleaved by β-secretase (BACE-1) and γ-secretase, which differ in length by 39-42 amino acids. This suggests that β-secretase is a suitable target for the development of therapeutics against Alzheimer’s disease.

    The synthetic work of this thesis comprises development of BACE-1 inhibitors containing a hydroxyethylene (HE) central core transition state isostere. The target molecules were readily synthesized from chiral carbohydrate starting materials. Highly potent inhibitors were produced by varying the substituents coupled to the HE central core. Selecting an aryloxymethyl P1 side-chain and a methoxy P1’ side-chain resulted in exceptionally potent BACE-1 inhibitors that also exhibit high selectivity over cathepsin D. In a further development, the ether oxygen linkage in the P1 side-chain was removed, resulting in a carba analogue, providing improved potency in a cell-based assay.

  • 7.
    Björsne, Magnus
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of potential candidates for therapeutic intervention against the human immunodeficiency virus1995Doctoral thesis, comprehensive summary (Other academic)
  • 8.
    Bogár, Krisztián
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthetic Transformations via Metal- and Enzyme-Catalyzed Dynamic Kinetic Resolution2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with the preparation of a new half-sandwich type ruthenium(II)- catalyst for racemization of optically active secondary alcohols and the development of a highly efficient method in combination with lipases such as Candida antarctica lipase B and Pseudomonas cepacia lipase for dynamic kinetic resolution of various functionalized alcohols under mild reaction conditions.

    It was shown that the RuCl(CO)25-C5Ph5) complex can racemize optically active aliphatic and aromatic secondary alcohols at room temperature in rather short times. Different parameters, such as the nature of the catalyst, catalyst loading and solvent effect were studied. After the optimization steps, the Ru-catalyzed racemization of (S)-1-phenylethanol in the presence of Candida antarctica lipase B was also investigated. The compatibility of the metal- and enzyme-catalyzed reactions led to a highly efficient coupled catalytic system for transformation of racemic alcohols to their enantiomerically pure acetates. This protocol was applied for a wide range of secondary alcohols. It was shown that in the case of allylic alcohols the obtained enantiopure allylic acetates are useful compounds for synthesis of α-methyl carboxylic acids such as (R)-Flurbiprofen and acyloin acetates. Highly selective dynamic kinetic asymmetric transformation of 3,5-piperidine diol to deliver various 3,5-dioxygenated piperidines is also described.

  • 9.
    Borén, Linnéa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantioselective Synthesis of Sec-Alcohol Derivatives and Diols via Combined Ruthenium and Enzyme Catalysis2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The first part of this thesis describes the synthesis of enantiopure secondary alcohol derivatives. These syntheses are carried out via the combination of an enzyme as a resolution catalyst and a ruthenium catalyst as a racemization catalyst, in what is called dynamic kinetic resolution (DKR). By varying the resolution catalyst enantio-complementary processes can be obtained. A lipase (PS-C II) catalyzed DKR of γ-hydroxyamides gave the corresponding (R)-acetates in high yields and with high enantioselectivity. The synthetic usefulness of these obtained (R)-acetates was demonstrated by the synthesis of (R)-5-methyltetrahydrofurane-2-one. A protease (Subtilisin Carlsberg) catalyzed DKR of various secondary alcohols gave the corresponding (S)-acetates in high yields and with high enantioselectivity. In the second part of this thesis the DKR process has been extended into a dynamic kinetic asymmetric transformation (DYKAT) of diols. Various 1,5- and 1,4-diols were transformed into enantiopure diacetates in a lipase (CALB and PS-C II) catalyzed DYKAT. The synthetic utility of the obtained enantiopure diacetates were demonstrated by the synthesis of various enantiopure disubstituted heterocycles.

  • 10.
    Cotton, Hanna
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chiral metallocene ligands for transition metal-catalysed reactions2004Doctoral thesis, comprehensive summary (Other academic)
  • 11.
    Csjernyik, Gábor
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Studies of Biomimtic Oxidations and Racemizations2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with studies of ruthenium-catalyzed hydrogen transfer reactions for oxidations and racemization.

    Through optimisation of the substrate-selective redox catalyst, the electron and proton transfer mediator (a benzoquinone derivative), and the oxygen-activating metal macrocycle a highly efficient biomimetic oxidation of secondary alcohols was obtained. Several alcohols were subjected to the new oxidation protocol and the corresponding ketones were isolated in high yield.

    The deactivation of the oxygen-activating metal macrocycle retarded the aerobic oxidation of primary alcohols. Encapsulation of the metal macrocycle into zeolite, described in chapter 3, proved to be an efficient method to solve this problem and comparable conversion of alcohols was achieved. The immobilization of the oxygen-activating porphyrin to a surface can be an alternative approach to solve the deactivation problem. Therefore as the first step towards studies of immobilized porphyrins on a metal surface (of gold or silver), S-thioacetyl derivatized porphyrins were synthesized; two alternative syntheses are described in chapter 4.

    A new and effecient ruthenium-catalyzed racemization protocol was established by proper ligand tuning. The racemization of the enantiomerically pure alcohols was increased significantly; this work is reported in chapter 5.

  • 12.
    Dziedzic, Pawel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Amino acid-catalyzed synthesis of amino acid derivatives: Application and semi-synthesis of Paclitaxel, Docetaxel and their derivatives2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with different applications of organocatalysis, where amino acid derivatives and small peptides are applied as catalysts. First, the development of environmentally friendly aldol reactions, carried out in aqueous media is illustrated. The corresponding β-hydroxy ketones are formed with ee´s up to 99%. Chapter 3 describes the ability of β3-amino acids to selectively catalyze Mannich-type reactions and govern the formation of products with high anti-selectivity (up to >19:1) and ee´s up to 99%. In the following chapter, an amino acid-catalyzed one-pot three component Mannich reaction between dihydroxyacetone and PMP-protected imines, is presented. The corresponding a,a’-dihydroxy-b-aminoketones are obtained in high yields and with 82-95% ee. Next, an aza-Morita-Baylis-Hillman reaction was investigated where L-proline is the catalyst. The reaction proceeds with excellent chemo- and enantioselectivity to give the corresponding compounds in good yields and with 97-99% ee. Finally, the last part describes development of a proline-catalyzed Mannich reation between N-acyl imines and protected α-hydroxyaldehyes, providing access to different α-hydroxy-β-amino acids in good yields and high enantioselctivity (92-99% ee). The obtained amino acids were further applied in the semisynthesis of paclitaxel and docetaxel derivatives.

  • 13.
    Fontana, Carolina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    NMR spectroscopy in structural and conformational analysis of bacterial polysaccharides2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Carbohydrates constitute one of the three major classes of biomolecules found in all living cells and, unlike nucleic acids and proteins, their polymeric structures are not based on a template. The structural diversity of these molecules confers them an enormous capacity to encode information in biological systems, acting as efficient mediators in the interaction of the cell with the environment. In order to understand the roles of glycans in biological processes it is of key importance to have a detailed understanding of their structures and conformational preferences, and NMR spectroscopy is one of most powerful techniques for the study of these molecules in solution.

    This thesis is focused on the structural and conformational analysis of lipopolysaccharides from Gram-negative bacteria. In the first two projects (Chapter 2 and 3) the structural analyses of the biological repeating units of the O-antigen polysaccharides from E. coli O174ab and O115 are described; in both cases a combination of NMR spectroscopy and gas chromatography techniques were used. Special emphasis was made in the characterization of the O-acetylation patterns observed in the native O-antigen polysaccharide from E. coli O115. Chapter 4 describes the development of a new methodology for the determination of the absolute configuration of monosaccharide components of glycans. This methodology was used in the structural elucidation of the O-antigen PS of E. coli O155 (Chapter 5) that was carried out in a semi-automated manner using the program CASPER and unassigned NMR data. The conformational preferences of O-antigen PS of E. coli O5ac and O5ab are analyzed in Chapter 6, using a combination of NMR spectroscopy and molecular modeling methods. In Chapter 7 the structural analysis is focused on the core region of the LPS, and the structures of the deacylated lipooligosaccharides of three rough mutants of B. melitesis are reported. In several of the aforementioned chapters, the biosynthetic aspects behind the assembly of the respective PSs were examined on the bases of genetic information available in the NCBI and ECODAB databases.  Finally, in Chapter 8, different NMR pulse sequences available for the study of proteins and nucleic acids were evaluated and optimized for the structural analysis of 13C uniformly-labeled oligo- and polysaccharides.

  • 14.
    Franzén, Johan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Carbocyclizations of Allenes with Unsaturated Hydrocarbons2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Palladium-catalyzed reactions of unsaturated hydrocarbons are important processes in organic chemistry especially for the generation of ring systems. This thesis describes the development and mechanistic studies of carbocyclization reactions of allenes with olefins, allyls or 1,3-dienes catalyzed by palladium(0)- and palladium(II)-complexes. These reactions generally exhibit high stereo- and regioselectivity and give rise to stereodefined [n,3,0] bicyclic systems (n=3,4,5,6) in good to excellent yields. The mechanisms for these reactions were investigated with special attention directed to the intramolecular reaction of (π-allyl)palladium(II)-complexes and (π-1,3-diene)palladium(II)-complexes with allenes. It was demonstrated that the carbon-carbon bond formation occurred by nucleophilic attack of the middle carbon atom of the allene on the face of the allyl or 1,3-diene opposite to that of the palladium atom. Further, two new types of oxidative palladium(II)-catalyzed reactions between allenes and olefins or 1,3-dienes have been developed. These cyclizations constitute a new type of carbon-carbon bond forming reaction and there are support for a palladium(II)-catalyzed C-H activation at the allenic moiety rendering a vinylidienepalladium-intermediate followed by carbon-carbon bond formation via insertion of the olefin or 1,3-diene.

  • 15.
    Fryxelius, Jacob
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Design and Synthesis of Ligands for High-Valent Metal Oxidation Catalysts2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes several approaches towards the design of a water oxidation catalyst. Different aspects of coordination and water oxidation chemistry are adressed and result in various syntheses of ligands and their metal complexes.

  • 16.
    González Miera, Greco
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Homogeneous and heterogeneous Cp*Ir(III) catalytic systems: Mechanistic studies of redox processes catalyzed by bifunctional iridium complexes, and synthesis of iridium-functionalized MOFs2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The purpose of this doctoral thesis is to investigate and develop catalytic processes mediated by iridium(III) complexes. By understanding the mechanisms, the weaknesses of the designed catalysts can be identified and be overcome in the following generation.

    The thesis is composed of two general sections dedicated to the synthesis and applications of homogeneous catalysts and to the preparation of heterogeneous catalysts based on metal-organic frameworks (MOFs). After a general introduction (Chapter 1), the first part of the thesis (Chapters 2-4, and Appendix 1) covers the use of several homogeneous bifunctional [Cp*Ir(III)] catalysts in a variety of chemical transformations, as well as mechanistic studies.

    Chapter 2 summarizes the studies on the N-alkylation of anilines with benzyl alcohols catalyzed by bifunctional Ir(III) complexes. Mechanistic investigations when the reactions were catalyzed by Ir(III) complexes with a hydroxy-functionalized N-heterocyclic carbene (NHC) ligand are discussed, followed by the design of a new generation of catalysts. The chapter finishes presenting the improved catalytic performance of these new complexes.   

    A family of these NHC-iridium complexes was evaluated in the acceptorless dehydrogenation of alcohols, as shown in Chapter 3. The beneficial effect of a co-solvent was investigated too. Under these base-free conditions, a wide scope of alcohols was efficiently dehydrogenated in excellent yields. The unexpected higher activity of the hydroxy-containing bifunctional NHC-Ir(III) catalysts, in comparison to that of the amino-functionalized one, was investigated experimentally.

    In the fourth chapter, the catalytic process presented in Chapter 3 was further explored on 1,4- and 1,5-diols, which were transformed into their corresponding tetrahydrofurans and dihydropyrans, respectively. Mechanistic investigations are also discussed.

    In the second part of the thesis (Chapter 5), a Cp*Ir(III) complex was immobilized into a MOF. The heterogenization of the metal complex was achieved efficiently, reaching high ratios of functionalization. However, a change in the topology of the MOF was observed. In this chapter, the use of advanced characterization techniques such as X-ray absorption spectroscopy (XAS) and pair distribution function (PDF) analyses enabled to study a phase transformation in these materials.

  • 17.
    Hamark, Christoffer
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The sweet side of molecular structure: NMR spectroscopic studies of glycans and their interactions with proteins2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, within the topic of bioorganic chemistry, the molecular structure of carbohydrates has been studied. Carbohydrates, or glycans, are ubiquitous biomolecules exhibiting a wide range of biological roles. The specific functions of these molecules are largely determined by their interactions with proteins and molecular structure ultimately governs such specialized recognition events.

    Glycan-binding proteins, such as lectins or enzymes, often interact with their sweet ligands in a transient fashion and nuclear magnetic resonance spectroscopy (NMR) is a viable technique to probe these complexes. In particular, ligand-based NMR techniques have been employed, typically in combination with other biophysical as well as biochemical and computational methods. The aim of this work has been to gain new insights about specific biological systems, to develop methods and to devise protocols for their studies.

    The first two papers cover NMR-interaction studies of native ligands as well as inhibitor glycans with the enzyme hen egg-white lysozyme and the lectin botulinum neurotoxin type A. Screening experiments were performed to investigate ligand affinities and selectivities. Solution models in combination with X-ray crystal structures were compared in order to evaluate their agreement and the details of interactions.

    A method for application in carbohydrate ligand NMR-screening was developed in paper three. The heteronucleus selenium was exploited as a reporter of selenoglycosides binding to lectins. 77Se NMR spectroscopy proved sensitive to binding events and the presented approach should be useful in large screenings of glycomimetic inhibitors.  In order to obtain sufficient amounts of glycans for bioorganic studies their production often relies on chemical synthesis. In the last paper, the structure of some conformationally highly activated glycosyl donors was thoroughly investigated and related to their reactivity in synthetic glycosylation reactions.  

  • 18.
    Hermansson, Kerstin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The structures of three bacterial polysaccharides and model studies on oligosaccharides and polyisoprenoids using NMR and FAB-MS1993Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Some vicinally branched milk and blood group oligosaccharides were analyzed using nuclear magnetic resonance (NMR) spectroscopy in order to investigate NMR chemical shift changes that originate from the branching. These 13C-NMR chemical shift changes were used to calculate NMR spectra of oligo- and polysaccharides using the computer program CASPER.

    The structures of three bacterial polysaccharides from Aerococcus viridans var. homari, Fusobacterium necrophorum and Vibrio cholerae 0:5 were investigated using NMR spectroscopy, fast atom bombardment mass spectrometry (FAB-MS) and chemical degradation as the principal methods. All of these polysaccharides contained unusual sugars and non-sugar components, some of which had not been found in nature previously.

    FAB-MS was used for determination of structural features of polyisoprenoids. Different matrices and additives for positive ion FAB-MS of model polyprenol and dolichol compounds were investigated. Negative ion FAB-MS spectra showed peaks for the molecular ions of dolichyl phosphates from rat liver extracts.

  • 19.
    Horváth, Attila
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium(II)-Catalyzed Reactions of Allenes with Lithium Bromide and Cyclization of α-Amino Allenes to Pyrrolines2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is based on three novel palladium(II)-catalyzed reactions of allenes with lithium bromide and a bromonium ion induced cyclization of allenyl amides to pyrrolines. In Paper I a 1,2-functionalization of allenes is presented where bromide adds as a first nucleophile followed by intramolecular attack by an oxygen or nitrogen nucleophile. Chapter 2 deals with the extension of this reaction to different nitrogen nucleophiles such as urea, carbamate, and N-tosyl carbamate providing access to substituted pyrrolidines and oxazolidines in good yields under mild reaction conditions.

    Paper II deals with a stereoconvergent, palladium(II)-catalyzed SN2’ reaction of α-acetoxy allenes with bromide as nucleophile. In this reaction substituted (Z,E)-2-bromo-1,3-dienes are produced in good yields with excellent diastereo-selectivity.

    Paper III describes a mild racemization reaction of chiral allenes. The effect of the functional group present in the molecule on the reaction rate is examined. All these reactions published in Papers I-III proceed through a common intermediate: a 2-bromo-(π-allyl)palladium complex.

    The fourth paper describes a simple, efficient, and enantiocontrolled cyclization of N-protected α-allenyl amines with N-bromosuccinimide (NBS) to afford 3-bromo-pyrrolines. The synthesis of optically active 2,5-dehydroprolinol derivative is also described. The mechanism, scope, and limitations of all four reactions are discussed in this thesis.

  • 20.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of organocatalytic asymmetric transformations2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The ability of amino acids and amino acid derivatives to mediate various organocatalytic asymmetric transformations has been investigated and applied in the development of various reactions. This work describes the development of a direct catalytic asymmetric α-aminomethylation of ketones and aldehydes, a catalytic asymmetric aziridination, hydrophosphination and amination of α,β-unsaturated aldehydes.

  • 21.
    Ioannidis, Panagiotis
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of 5'-C-phosphonomethyl, 2'-C- and 3'-C-branched nucleoside analogues as potential candidates for therapeutic intervention towards HIV1993Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Syntheses of some 5'-C-phosphonomethyl-, 2'-C- and 3'-C-branched nucleoside analogues as potential anti-HIV agents are described. Synthesis of the various nucleoside analogues is based either on the construction of a suitably protected sugar moiety that can be glycosylated with different nucleoside bases by the Vorbrüggen procedure, or on the use of a novel alcohol transposition in the carbohydrate moiety of different 2'-C- or 3'-C-methylene nucleoside analogues, using the reagent system chlorodiphenylphosphine-iodine-imidazole. All target compounds were tested for anti-HIV activity. Of these, only 2',3'-dideoxy-2'-Chydroxymethylcytidine and l-(3,5-dideoxy-ß-D-cryrAro-hexofuranosyl)thymine demonstrated moderate and weak anti-HIV activities, respectively.

  • 22.
    Johansson, Mikael
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of Biomimetic Catalytic Systems for Selective Oxidations with H2O2 and O22008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Four different catalytic systems were studied for biomimetic coupled oxidations using H2O2 or O2. In the first example, osmium tetroxide works as a substrate-selective catalyst for dihydroxylation of olefins. Electron transfer to H2O2 is facilitated by electron transfer mediators (ETMs). In one case VO(acac)2 or MeReO3 was used as ETM; in the other case a combination of flavin and tertiary amine was used as ETMs. These three systems were immobilized in the ionic liquid [bmim]PF6 for the purpose of recycling of the catalyst.

    In the second example, an organocatalyst (a flavin) was used for the oxidation of sulfides to sulfoxides and this catalytic system was recycled and reused in an ionic liquid.

    In the third example, primary aromatic amines were oxidized by H2O2 to nitroso compounds in a selenium-catalyzed oxidation. The nitrosoarenes were used in a one-pot hetero Diels-Alder reaction with dienes forming 1,2-oxazines.

    In the fourth example, a cobalt salophen complex was immobilized in different zeolites. The catalyst was used in aerobic oxidation of p-hydroquinone and the zeolite catalyst could be reused. The oxidative carbocyclization of ene-allenes was tested successfully using the triple catalytic system consisting of palladium(II), p-benzoquinone, and the immobilized catalyst for O2 activation.

    All these systems gave mild and selective oxidations with environmentally friendly and inexpensive terminal oxidants.

  • 23.
    Jonasson, Catrin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium (II)-catalyzed oxidations of allenes and conjugated dienes2000Doctoral thesis, comprehensive summary (Other academic)
  • 24.
    Kask, Kalev
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Galanin receptor: studies with site-directed mutagenesis, agonists and antagonists1995Doctoral thesis, comprehensive summary (Other academic)
  • 25.
    Kjellberg, Alexandra
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Studies of oligosaccharides and carbon-13 enriched bacterial polysaccharides using NMR spectroscopy and computer simulations1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The conformation and dynamics of the trisaccharide methyl β-D-Glcp-(1--> 2)[β-D-Glcp-(1 --> 3)] α-D-Manp and its constituent disaccharides methyl β-D-Glcp-(1 --> 2) α-D-Manp and methyl β-D-Glcp-(1 --> 3) α-D-Manp have been studied using computer simulations and NMR spectroscopy. The computer simulations applied were Metropolis Monte Carlo simulations employing the HSEA force field and Langevin dynamics simulations using the PARM22 and CHEAT95 force fileds. The NMR methods used were measurement of long-range heteronuclear coupling constants across the glycosidic linkages, measurement of carbon-13 nuclear relaxation rates for the determination of dynamical parameters according the Lipari-Szabo "model free" approach and measurements of homonuclear NOE and TROE cross relaxation rates for the determination of proton-proton distances. Experimental data were then compared to the corresponding parameters extracted from the various computer simulations.

    Studies of the carbon-13 labelled O-polysaccharides from Escherichia coli O25 and O91 have also been performed. 13C-13C TOCSY experiments, with the spin-lock on the carbon-13 nuclei, were applied to sugar residues of different geometries. This circumvented the problem of hampered magnetisation transfer encountered in residues with 3JHH < 2Hz when the spin-lock is applied on the protons.The carbon-13 labelling was also used to demonstrate the biosynthesis of one of the substituents in the Escherichia coli O91 O-polysaccharide.

  • 26.
    Krumlinde, Patrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal- and lipase-catalyzed reactions: Dynamic resolutions, hydrogen transfer and enzyme engineering2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis mainly focuses on chemoenzymatic processes and can be divided into three parts: The first part of the thesis, chapters 2-4, is devoted to the development of combined ruthenium- and enzyme-catalyzed dynamic processes. In these processes the metal catalyst racemizes (epimerizes) the alcohol substrate via hydrogen transfer and the enzyme transforms the substrate into enantiomerically enriched product. Chapter 2 focuses on bicyclic diols, where a process was developed to provide the enantiomerically pure product diacetates in high yield. The diacetates were then hydrolyzed using various protocols to yield the corresponding enantio- and diastereoenriched diols. Two of the substrates were mono-oxidized to yield the enantioenriched hydroxyketones in high yield. One of the hydroxyketones was subsequently employed in the formal synthesis of Sertraline in a highly enantioselective manner. Chapter 3 deals with the application of dynamic kinetic resolution in the synthesis of a pesticide derivative, which is obtained in high yield and high enantiomeric excess. Chapter 4 describes the use of dynamic kinetic resolution to set the configuration of a non-activated stereocenter in primary alcohols by taking advantage of the intermediate aldehydes intrinsic enolization behavior. A wide range of primary alcohols with a stereogenic center in β-position were dynamically resolved using this approach.

    The second part, chapters 5-6, deals with different types of enzyme engineering. In chapter 5, a lipase from Pseudomonas aeruginosa was mutated using directed evolution to increase the enantioselectivity of the lipase towards an allenic substrate. In chapter 6, a racemization catalyst was anchored to the active site of both cutinase and Candida Antarctica lipase.

    In the last part, chapter 7, an immobilized transition metal catalyst was used in transfer hydrogenation, a process which is closely related to the racemization of alcohols. The catalyst was used to reduce carbonyl compounds to the corresponding alcohols and was applicable to a wide range of substrates.

  • 27.
    Kärkäs, Markus
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development and Mechanistic Studies of Molecularly Defined Water Oxidation Catalysts: Catalysts for a Green and Sustainable Future2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis deals with the development of complexes that are active catalysts for H2O oxidation. Promoting proton-coupled electron transfer has been a highly important feature in the development of these catalysts.

    The first part deals with the modification of ligand frameworks for the development of a ruthenium complex capable of withstanding the highly oxidizing conditions required for H2O oxidation. 

    The second part of the thesis describes the development of two single-site ruthenium(III) complexes, housing two meridionally coordinating tridentate benzimidazole ligands. Studies on these complexes revealed that they can mediate H2O oxidation, both by the use of a chemical oxidant and photochemically, and that the ligand frameworks were important in promoting proton-coupled electron transfer events.

    In the third part, systematic modifications are introduced into one of the catalysts developed in the second part of the thesis. All of the complexes were shown to be active water oxidation catalysts (WOCs), and kinetic studies confirmed that all catalysts displayed a first-order dependence on catalyst concentration, thereby validating that H2O oxidation occurs on a single metal site. By using linear free-energy relationships it was possible to elucidate the unusual behavior exerted by the ligand framework during the catalytic cycle.

    The fourth part concerns the development of a ruthenium(III) WOC, containing a tetradentate bioinspired ligand architecture, and its deactivation pathway during H2O oxidation catalysis. This revealed an unexplored, and perhaps general, deactivation pathway for ruthenium-based WOCs. Evidence was also found that the ruthenium WOC reaches a high-valent ruthenium(VI) state which is the active species in H2O oxidation.

    Finally, the fifth and last part deals with the development of a dinuclear manganese complex. Utilizing a bioinspired, highly functionalized ligand, enabled the formation of the first homogeneous manganese-based WOC capable of promoting catalytic H2O oxidation with one-electron oxidants.

  • 28.
    Landström, Jens
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Structure, dynamics and interactions of biomolecules: Investigations by NMR spectroscopy and computational methods2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, the structure, dynamics and interactions of proteins and carbohydrates are investigated using mainly NMR spectroscopy and computer simulations.

    Oligosaccharides representing a Salmonella O-antigen have been synthesized and their dynamic behavior and interaction with the bacteriophage P22 tail-spike protein have been studied by NMR spectroscopy, MD and docking simulations. A binding mechanism between the protein and the O-antigen has been proposed.

    Transient hydrogen bonds have been defined and examined in an E. coli polysaccharide and in a pentasaccharide representing the repeating unit, using MD simulation and NMR spectroscopy.

    Conformational dynamics of a trisaccharide representing the repeating unit of an A. salmonicida O-antigen have been investigated by MD simulations. The simulation together with relaxation matrix calculations reveals a conformational exchange on a ns timescale and explains an unusual NOE.

    A fragment-based screening for inhibitors of the glycosyltransferase GTB acceptor site has been performed using NMR spectroscopy and SPR. IC50 values of the binding fragments are reported. Complex structures of the fragments and GTB have been proposed using docking simulations.

    A fragment-based screening for inhibitors of the WaaG glycosyltransferase donor site has been performed using NMR spectroscopy and three compounds were selected. Structures of the WaaG-fragment complexes have been suggested from docking simulations. Binding of natural substrates and activity has also been investigated by NMR spectroscopy. MD simulations have been carried out on WaaG with and without bound donor substrate. The simulation revealed a conformational change upon substrate binding.

    Interactions between HEWL and carbohydrate ligands have been investigated, using a combination of weak affinity chromatography, NMR spectroscopy and computer simulations. KDs of the ligands have been presented as well as the solution structures of two HEWL-disaccharide complexes.

  • 29.
    Lavén, Gaston
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Expanding the H-phosphonate and H-phosphonothioate chemistry towards biologically important phosphate analogs2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on chemical transformations of H-phosphonate and H-phosphonothioate and can be divided in two parts. The first part, is devoted to the development of the palladium-catalyzed P-C bond formation. Both mechanistic and synthetic studies of the transformations have been performed. The stereochemical aspects of palladium catalyzed arylation and benzylation of DNA analogs containing H-phosphonate and H-phosphonothioate have been studied.

    In chapter 5 the condensation using Mitsunobu reaction of H-phosphonate function and nucleoside has been studied. Efficient protocols for the synthesis of nucleoside H-phosphonate monoester were developed.

    The last chapter deals with development of silylation-mediated transesterfication of phenyl H-phosphonothioate as a thiophosphonylating agent. The methodology was used to prepare nucleoside H-phosphonothioate monomeric building blocks in good yields.

  • 30.
    Lee, Bao-Lin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of metal complexes for water oxidation2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In an artificial version of photosynthesis, sunlight and water are used to produce fuels. Our research focuses on the bottleneck in this process, the photooxidation of water. In the course of developing a water oxidation catalyst, a number of 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 Ru complex with a ligand containing imidazole and phenol motifs. Additionally, a dinuclear Mn complex with a ligand that contains benzimidazoles and carboxylates coordinating to the metal atoms was also developed. This Mn complex was then covalently linked to [Ru(bpy)3]2+-type photosensitisers, resulting in three different bimetallic dyads. Finally, a dinuclear Fe complex containing the same ligand as the dinuclear Mn complex was synthesised.

    The potential of the three H3bbpmp complexes as catalysts for oxidation of organic compounds was investigated and it was found that the Ru complex catalyses the oxidation of alcohols to the corresponding ketone or aldehyde using (diacetoxyiodo)benzene as oxidant. The Co 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 Ru complex and the dinuclear Mn and Fe complexes proved to catalyse water oxidation when employing stoichiometric amounts of the oxidant [Ru(bpy)3](PF6)3. Furthermore, using [Ru(bpy)2(deeb)](PF6)2 as photosensitiser together with Na2S2O8 as sacrificial electron acceptor in aqueous phosphate buffer at pH = 7.2, photochemical water oxidation was demonstrated. The bimetallic dyads however, did not show catalytic activity for the oxidation of water.

  • 31.
    Leijondahl, Karin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis and asymmetric transformations of diols by enzyme- and ruthenium catalysis2008Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The major part of this thesis describes the synthesis of aliphatic secondary diols and the development of lipase- and ruthenium-catalyzed asymmetric transformations of these diols.

    Several acyclic 1,4-diols and 1,5-diols were synthesized, and by combining a lipase-catalyzed asymmetric transformation with a ruthenium-catalyzed epimerization, enantiomerically- and diastereomerically enriched diacetates were obtained. The scope and limitations of the system were also investigated, and some problems were encountered with electron-deficient diols. The diacetate products were further transformed into natural product heterocycles and chiral ligands.

    A thorough study of the enzyme-catalyzed asymmetric transformation of 1,3-cyclohexanediol was also performed. It was found that there was a difference in the enzyme selectivity for the cis- and trans- diols, respectively, and while poor selectivity was observed for the trans-diol, cis-1,3-cyclohexanediol could be efficiently desymmetrized. By adding different epimerization catalysts, both cis- and trans-1,3-cyclohexanediol could be obtained in high enantio- and diastereoselectivities.

    The use of hydrogen transfer for the reduction of cyclic 1,3-diketones was also demonstrated, and the reactions could in many cases be carried out in a microwave oven.

  • 32.
    Lindquist, Charlotta
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Design & Synthesis of Protein Interacting Affinity Ligands and Protease Inhibitors2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is a growing need of both protein drugs and synthetic drugs in the fight against many life-threatening diseases. The first part of this thesis deals with the design and synthesis of high affinity binding ligands for the purification of protein drugs. The second part describes design and synthesis of protease inhibitors targeting the cysteine protease cathepsin S and the serine protease hepatitis C NS3/4A.

    In work with parallel synthesis of new affinity chromatography ligands, indole was used as the scaffold for both solid phase and solution phase syntheses. A library of 1,3-disubstituted indoles was prepared via an iterative Mannich reaction sequence. The first Mannich reaction provided 3-aminomethylindoles, while the second Mannich reaction introduced an additional aminomethyl group at the N1 position of the indole ring. A library of 25 substituted indoles was prepared in moderate to good yields and purity.

    Inhibition of the cysteine protease cathepsin S is an attractive target for drug development of inhibitors having potential for regulation of autoimmune diseases and allergic disorders. Syntheses targeting the cysteine protease cathepsin S were performed by a solid phase approach. The structure-activity-relationships (SAR) of variations in the P3 sulfonamide part of 4-amidofuran-3-one inhibitors are presented. Several highly potent inhibitors were found, in both enzyme and cellular assays.

    The hepatitis C virus (HCV), causes a chronic liver condition which can lead to cirrhosis and liver cancer. The  serine protease hepatitis C NS3/4A is a promising target for development of HCV drugs. In the syntheses of novel HCV NS3/4A inhibitors, four new P2 substituents were first incorporated on a proline-based linear scaffold. The most potent P2 substituent, quinazoline, was evaluated in a larger study yielding more rigidified cyclopentane-based macrocyclic inhibitors. The SAR exercise resulted in several inhibitors with excellent potency in the low nanomolar range.

  • 33.
    Lindström, Ulf
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis and [3,3]-Sigmatropic Rearrangement of Vinylaziridines2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [sv]

    A general synthetic route from vinylepoxides to vinylaziridines via 1,2-amino alcohols was developed. The 1,2-amino alcohols were obtained from a stereospecific and regioselective aminolysis of vinylepoxides. The synthetic scope of the aminolysis could be expanded by the use of a microwave-assisted protocol. Some of the 1,2-amino alcohols were dehydrated with PPh3/DEAD to afford N-H vinylaziridines. All of the so obtained N-H vinylaziridines were acylated to give the corresponding N-acyl vinylaziridines. When variously substituted N-acyl vinylaziridines were subjected to LiHMDS in THF, the resulting amide enolates underwent a stereoselective aza-[3,3]-Claisen rearrangement to give mono-, di- and trisubstituted seven-membered lactams. The scope and limitations of the rearrangement were investigated. Finally, the aminolysis of vinylepoxides was applied in an asymmetric synthesis of (+)-1-deoxynojirimycin.

  • 34.
    Mannerstedt, Karin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Oligosaccharides from the Inner Core Structure of Haemophilus Influenzae and Neisseria meningitidis Lipopolysaccharides2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the synthesis of oligosaccharides corresponding to different parts of the lipopolysaccharide (LPS) inner core structure from Haemophilus influenzae and Neisseria meningitidis. Chapter 2 describes the synthesis of a protected trisaccharide common to H. influenzae and N. meningitidis LPS, which can be used as a versatile precursor in further syntheses of larger LPS structures. In Chapter 3 syntheses towards phosphoethanolamine substituted trisaccharides corresponding to H. influenzae and N. meningitidis structures are presented. In Chapter 4 the synthesis of a H. influenzae tetrasaccharide structure, with and without a phosphoethanolamine substituent in the 6-position of the second heptose unit, is described. Conjugation to biotin of these two tetrasaccharides is also performed. Chapter 5 describes the synthesis of a spacer-equipped Kdo acceptor that is subsequently attached to the tetrasaccharide described in Chapter 4 forming a pentasaccharide from the inner core structure of H. influenzae. Similar to the synthesis of the tetrasaccharide, a phosphoethanolamine is attached to the 6 position of the second heptose. Chapter 5 also describes the synthesis of various Kdo thioglycoside donors and their evaluation in glycosylation reactions using different promoters and reaction conditions.

  • 35.
    Nyhlén, Jonas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanistic Studies on Transition Metal and Biocatalytic Systems by Computer Modeling2008Doctoral thesis, comprehensive summary (Other academic)
  • 36.
    Nyhlén, Jonas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Theoretical modeling of metal- and enzyme catalyzed transformations2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is focused on describing and predicting catalytic reactions. The major part of the work is based on density functional theory (DFT). In some cases where the size of the investigated system precluded the use of more accurate methods molecular dynamics was employed. In several cases the proposed mechanism was later tested in the laboratory. A few examples where the predictions were confirmed are:

    • The formation of an acyl intermediate in the activation of a ruthenium catalyst used for racemizing alcohols. This intermediate was observed by both NMR and in situ FT-IR.
    • The improvement of the substrate specificity and catalytic activity of Candida antarctica lipase A by modifying amino acids close to the active site.
    • The improved specificity of Candida antarctica lipase B toward δ-substituted secondary alcohols by an enzyme variant where the alanine in position 281 was exchanged for a serine.

    In other cases experimental results were complemented with a theoretical investigation, for example:

    • The observed second order rate constant for a ruthenium based catalyst used for water oxidation was explained and a novel intramolecular mechanism based on a high valent ruthenium dimer was suggested.
    • The effects of electron withdrawing/donating axial ligands on the performance of ruthenium catalyzed water oxidation were addressed.
    • Mechanisms of H2 activation by Lewis acid/Lewis base adducts were rationalized. One example of the predictive power of computational chemistry is the mechanism of hydrogen uptake by phosphanylboranes; the potential energy barrier for the transition state could be predicted within a few kcal/mol based on the orbital energies of the starting material.
  • 37.
    Olsson, Johan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Bacterial Oligosaccharides from N. meningitidis and Mechanistic Details of Stereoselective Glycosylations Using a Novel Bicyclic Donor2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis includes two parts. The first part, comprising Chapters 3, 4 and 5, describes the synthesis of bacterial oligosaccharides. In Chapters 3 and 4, the synthesis of branched and phosphorylated oligosaccharide structures corresponding to inner core epitopes of the lipopolysaccharide (LPS) of the Gram-negative bacteria N. meningitidis are discussed. A series of different spacer-equipped, phosphorylated and non-phosphorylated, glycosides has been synthesized as a part of a program involving development of a glycoconjugate-based vaccine against meningitis. Chapter 5 describes the synthesis of a tetrasaccharide corresponding to the repeating unit of the extracellular capsular polysaccharide (CPS) found in S. enteritidis. A short and efficient synthetic route to a trisaccharide acceptor corresponding to the common Gal-Man-Rha backbone found in several Salmonella O-antigen is presented. Further more, the synthesis of a novel tyveloside thioglycoside and the final glycosylation to assemble the complete target tetrasaccharide is reported.

    The second part, Chapters 6 and 7, describes the development of a novel type of glycosyl donor, a 2N,3O-oxazolidinone protected bicyclic thioglycoside. This donor can be used in stereoselective glycosylations where, by tuning the reaction conditions, either complete α- or β-selectivity can be obtained from the same donor/acceptor system. A mechanistic explanation for this behaviour, involving initial formation of the β-anomer followed by a AgOTf-catalyzed in situ endocyclic anomerization to yield the more stable corresponding α-anomer, has been established. The suggested mechanism was supported by a series of NMR-experiments. Finally, in Chapter 7, the synthesis and use of a galacto-configured 2N,3O-oxazolidinone donor for the synthesis of a serine 2-acetamido 2-deoxy galactoside, a versatile building block for the synthesis of mucin O-glycan core structures, is discussed.

  • 38.
    Pascanu, Vlad
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic Processes Mediated by Metal−Organic Frameworks: Reactivity and Mechanistic Studies2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present thesis describes the development of heterogeneous catalytic methodologies using metal−organic frameworks (MOFs) as porous matrices for supporting transition metal catalysts. A wide spectrum of chemical reactions is covered. Following the introductory section (Chapter 1), the results are divided between one descriptive part (Chapter 2) and four experimental parts (Chapters 3–6).

    Chapter 2 provides a detailed account of MOFs and their role in heterogeneous catalysis. Specific synthesis methods and characterization techniques that may be unfamiliar to organic chemists are illustrated based on examples from this work.

    Pd-catalyzed heterogeneous C−C coupling and C−H functionalization reactions are studied in Chapter 3, with focus on their practical utility. A vast functional group tolerance is reported, allowing access to substrates of relevance for the pharmaceutical industry. Issues concerning the recyclability of MOF-supported catalysts, leaching and operation under continuous flow are discussed in detail.

    The following chapter explores puzzling questions regarding the nature of the catalytically active species and the pathways of deactivation for Pd@MOF catalysts. These questions are addressed through detailed mechanistic investigations which include in situ XRD and XAS data acquisition. For this purpose a custom reaction cell is also described in Chapter 4.

    The scope of Pd@MOF-catalyzed reactions is expanded in Chapter 5. A strategy for boosting the thermal and chemical robustness of MOF crystals is presented. Pd@MOF catalysts are coated with a protecting SiO2 layer, which improves their mechanical properties without impeding diffusion. The resulting nanocomposite is better suited to withstand the harsh conditions of aerobic oxidation reactions. In this chapter, the influence of the nanoparticles’ geometry over the catalyst’s selectivity is also investigated.

    While Chapters 3–5 dealt with Pd-catalyzed processes, Chapter 6 introduces hybrid materials based on first-row transition metals. Their reactivity is explored towards light-driven water splitting. The heterogenization process leads to stabilized active sites, facilitating the spectroscopic probing of intermediates in the catalytic cycle.

  • 39.
    Pathi Pati, Stalin Reddy
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of new Catalytic Methods for the Selective Synthesis of Heterocycles2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the field of organic chemistry, the development of new catalytic methods for the synthesis of complex molecules from simple precursors is a top priority. The main focus of this thesis concerns the diastereoselective synthesis of heterocyclic compounds using main group elements as Lewis acid catalysts.

    The first part of this thesis deals with an annulation reaction of nitrones with oxiranes, aziridines, and thiiranes using Al(III) or In(III) catalysts. From this protocol, 1,4,2-dioxazinanes, 1,2,4-oxadiazinanes, and 1,4,2-oxathiazinanes were obtained in moderate to high yields with excellent diastereoselectivity. The transformation was found to be stereospecific and proceed via an SN2-mechanism.

    The second and third parts concern the development of In(III)-catalyzed annulation of carbonyl compounds, amines, and alkynyl enones. InBr3 was found to be an efficient catalyst for the activation of alkynyl enones in a multicomponent reaction with aldehydes and amines. The method affords cyclopenta[c]furans in high yields and in good to excellent diastereomeric ratios. Bicyclo[3.n.1]alkenone derivatives were formed via a double Michael addition reaction of cyclic ketones, amines, and alkynyl enones, in the presence of InCl3. The utility of these protocols was also demonstrated by sequential transformations.

    In the fourth part, AgOTf and CuI were found to be efficient catalysts for the activation of pyridine-substituted enynes towards enamines, providing indolizine derivatives in high yield and good diastereomeric ratios.

    In the last part of the thesis, 1,2-aminoarylation of γ,δ-unsaturated oxime esters with arylboronic acids using Ni catalysis is discussed. The protocol demonstrates the potential of Ni-catalysts for the generation of iminyl radicals to furnish functionalized pyrroline derivatives. The utility of this protocol was exemplified by transforming the pyrroline products to the corresponding pyrrole and pyrrolidine derivatives. 

  • 40.
    Ruda, Katinka
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of inositol phosphoglycans and analogues thereof1998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the synthesis of inositol phosphoglycans (IPG) corresponding to glycosyl-phosphatidylinositol (GPI) anchors found on the cell surface of the parasite Leishmania. Synthesis of an IPG which is a putative second messenger for insulin, and of analogues thereof is also discussed.

    The IPG structures synthesized contain mono-, tri-, and hexasaccharides linked to an inositol phosphate. Analogues of the putative second messenger contain glucosamine, instead of myo-inositol phosphate, coupled to either phosphorylated D-mannose or phosphorylated L-fucose. The synthetic work involved the development of procedures for obtaining optically pure myo-inositol-glucosamine derivatives, the formation of phosphomono- and diesters (both cyclic and acyclic) and oligosaccharide synthesis.

  • 41.
    Rydner, Lina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of strategies for construction of thioglycoside building blocks corresponding to repeating triads of Cryptococcus neoformans GXM capsular polysaccharide2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focuses on the development of methods for synthesis of thioglycoside building blocks corresponding to the repeating units of the capsular polysaccharide (CPS) of Cryptococcus neoformans, an opportunistic fungal pathogen. The building blocks are suitable for construction of large synthetic oligosaccharides related to the native CPS-structures which are to be used in biological studies in order to identify protective epitopes with the aim to develop a glycoconjugate vaccine against C. neoformans infections.

    Chapter 3 describes the improved synthesis of di- and trisaccharide glucuronic acid-containing thioglycoside blocks by introduction of the carboxylic acid motif at the di- and trisaccharide level through oxidation of a glucose residue. The new approach requires a number of extra steps, but has proven to be more reliable and more easily reproducible since problems encountered in glycosylations with glucuronic acid donors and benzylation of glucuronic acid-containing derivatives are circumvented.

    In Chapter 4 the development of a synthetic route to xylose-substituted tri- and tetrasaccharide building blocks where the protecting group strategy allows for orthogonal glycosylations with thioglycoside acceptors is discussed.

    Chapter 5 describes the synthetic pathway to the glucuronic acid-containing derivatives according to the methodology developed in Chapter 4 and the assembly of a hexasaccharide building block corresponding to the repeating triad of serotype A.

    In Appendix І an alternative strategy for synthesis of glucuronic acid-substituted derivatives by direct introduction of a perbenzylated glucuronic acid trichloroacetimidate donor where stereoselectivity is achieved through the use of an 1,6-anhydro acceptor.

  • 42.
    Segerstedt, Eva
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Approaches to the synthesis of candidate glycoconjugate vaccines against non-typeable Haemophilus influenzae2003Doctoral thesis, comprehensive summary (Other academic)
  • 43.
    Skantz, Linnéa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of biologically active oligosaccharides of the Lewis b family and investigations towards the synthesis of glycoclusters2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The gastric pathogen Helicobacter pylori is a Gram negative bacterium which may cause diseases such as peptic ulceration and gastric adenocarcinoma. It colonises a host by attaching to the gastric epithelial cells, an attachment mediated by outer membrane proteins on the bacterial surface, e.g, the blood group antigen binding adhesin, BabA. This adhesin recognises and binds to specific carbohydrates, Lewis blood group antigens, on the epithelial cell walls.

    This thesis presents the synthesis of three oligosaccharides of the Lewis family. A new and improved block synthesis of a Leb hexasaccharide and synthesis of HSA-conjugates thereof are described. Also presented are the syntheses of a Leb pentasaccharide and a B-Leb heptasaccharide via linear routes. The latter strategy is designed to enable the synthesis of other Lewis blood group antigens by only minor changes in protection patterns.

    Investigations have been made towards finding a route for the synthesis of glycoclusters using of unprotected carbohydrates. The biologically active dendrimers will be used in examinations of binding to galectin-3, an important animal lectin abundant in nature.

    The thesis also includes an efficient synthesis of an oxazolidinone protected thioethyl LacNAc disaccharide, and its ability as a donor has been examined.

  • 44.
    Solin, Niclas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of Palladium-Catalyzed Transformations Involving η1-Allypalladium Species2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is focused on investigation of the structure, reactivity and isomerization reactions of η1-allylpalladium complexes, which are key intermediates in catalytic transformations. The first part of this thesis concerns the structure and reactivity of bis-allylpalladium complexes. We have studied the regioselective palladium-catalyzed coupling reaction of various dialkylsubstituted allyl chlorides with allylstannanes and benzylidenemalonitrile, affording functionalized 1,7-octadienes. We have also found that benzylidenemalonitrile can be replaced by isocyanates providing bis-allylated amides. The second part is a computational study on the η3-η1-η3 isomerization of allylpalladium complexes. The mechanism of the isomerization was studied by DFT. It was found that the isomerization involves tetra-coordinated η1-allylpalladium intermediates. Alkyl substitution of the metalated carbon leads to destabilization of the η1-allylpalladium intermediate, which increases the activation energy of the isomerization process. The last part describes our efforts to extend the synthetic scope of mono-allylpalladium chemistry to include catalytic allylation of imine and aldehyde substrates. We have found that this reactivity can be achieved by the use of strongly coordinating tridentate ligands on palladium. The η1-allylpalladium intermediate has been observed by NMR-spectroscopy, and DFT calculations have been performed to show the feasibility of an electrophilic attack occuring on the allyl moiety.

  • 45.
    Stenutz, Roland
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The structure and conformation of saccharides determined by experiment and simulation1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A computer program, CASPER, for sequence determination of oligosaccharides and regular polysaccharides using NMR-data, has been extended to support multiply branched structures. The program has been modified to allow the use of incomplete experimental data since spectral overlap can be a problem even at high fields. The resulting program was tested and used in the structure determination of the capsular polysaccharide from Klebsiella type K52.

    Four carboxyethyl-substituted sugars, methyl 4-O-[(R)- and (S)-1-carboxyethyl]-a-L-rhamnopyranoside and methyl 6-O-[(R)- and (S)-1-carboxyethyl]-a-D-galactopyranoside have been synthesized. The conformational properties of the latter two have been investigated by both NMR spectroscopy and molecular modelling studies. For the NMR-studies stereospecifically deuterated compounds were prepared.

  • 46.
    Sundén, Henrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Organocatalytic Domino Reactions2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Organocatalyzed reactions involving activation strategies of ketones and aldehydes are important processes in organic chemistry. These activation strategies serve as a versatile platform for the construction of several domino reactions. This thesis describes the development of six new asymmetric or-ganocatalyzed domino reactions for the enantioselective formation of carbo-cycles or heterocycles. The domino reactions are based on two major activation pathways the domino “iminium-enamine” and the domino “enamine-iminium”. Making use of the domino “iminium-enamine” reaction, 2H-1-benzopyrans, 2H-1-benzothiopyrans and 1,2-dihydroquinolines and cyclopropanes can be obtained in high yields and excellent ee´s. Via the amine-catalyzed domino “enamine-iminium” reaction the synthesis of aza-Diels-Alder and Diels-Alder products can be achieved with high ee´s and yields. Moreover, a mechanistic model is proposed for each reaction that enables the stereochemical outcome of the reaction to be predicted.

  • 47.
    Svansson, Lars
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of a heptasaccharide and some 3'-C-branched nucleoside analogues1992Doctoral thesis, comprehensive summary (Other academic)
  • 48.
    Thalén, Lisa K.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition Metal- and Enzyme-Catalyzed Reactions of Primary Amines and Allylic Alcohols: Powerful Tools in the Preparation of Pharmaceutically Important Compounds2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Dynamic kinetic resolution (DKR) has been applied to primary amines utilizing a ruthenium catalyst and an (R)-selective lipase to provide the corresponding amides in up to 95% isolated yield and up to >99% ee. Further investigations of the chemoenzymatic DKR of amines show that it is general and can be applied to a wide range of amines. The protocol was found to be applicable with both isopropyl acetate and dibenzyl carbonate as acyl donors. In the latter case, release of the free amine from the carbamate products was carried out under very mild conditions. A new route to prepare norsertraline, an antidepressant, utilizing DKR as one of the key steps has also been developed.

    Further investigations of the DKR of 1-phenylethylamine led to the development of a protocol that could be used on gram scale. Several parameters were studied including catalyst loading, acyl donor used, and concentration of the reaction. The Ru-catalyst loading was decreased from 4 mol% to 1.25 mol% and the enzyme catalyst loading was decreased from 40 mg/mmol substrate to 10 mg/mmol substrate.

    The racemization of pipecoloxylidide, an intermediate in the synthesis of commonly used anesthetics, was carried out. This racemization method was developed for its potential use in an integrated process that combines enantiomer separation techniques and racemization of the undesired enantiomer. The integration of racemization of the undesired enantiomer would increase the overall yield of the desired enantiomer and thus make the procedure highly efficient.

    DKR has also been applied to allylic alcohols utilizing a ruthenium catalyst and either an (R)-selective lipase or an (S)-selective protease to provide the corresponding allylic esters in high yield and high ee. A copper-catalyzed allylic substitution was then applied to provide the corresponding alkenes with inversion of stereochemistry. Subsequent C-C double bond cleavage afforded pharmaceutically important a-methyl substituted carboxylic acids in high ee.

  • 49.
    Tinnis, Fredrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic Formation of Amides2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The amide functionality is a highly important chemical bond, found in a great number of synthetic products such as pharmaceuticals, polymers and agrochemicals. The focus of this thesis has been directed towards efficient, mild and environmentally friendly methods for amide formations. The first part is devoted to the investigation of a Lewis acid catalyzed protocol for direct condensation of non-activated carboxylic acids and amines. ZrCl4 was found to be a highly active catalyst and a low catalytic loading enabled for high yields of secondary and tertiary amides under relatively mild conditions. The second part of the thesis describes our investigations towards a catalytic method for primary amides. We demonstrated that the transformation was feasible by performing minor alterations to the previous Lewis acid based procedure. A variety of primary amides could be obtained in high yields by the use of carbamates, as a non-gaseous source of ammonia in combination with carboxylic acids and catalytic amounts of TiCl4 or ZrCl4. Furthermore, the protocol was extended to include catalytic formation of N,N-dimethylamides from non-activated carboxylic acids.

    The use of immobilized metal nanoparticles as heterogeneous catalysts has emerged as a highly investigated research area. The final chapter of this thesis deals with the successful application of an immobilized Pd nanocatalyst for amide formation via the aminocarbonylation reaction of aryl iodides. The Pd0-AmP-MCF catalyst was found to operate through a “release and catch” mechanism, in which PdII species were released into the solution and then re-deposited onto the support after completion of the reaction. It was discovered that the combination of aryl halide and amine was the cause of the leaching, and furthermore that the homogeneous Pd species catalyzed the aminocarbonylation reaction. A selection of aryl iodides were evaluated using 2 mol% of Pd0-AmP-MCF under atmospheric pressure of CO, and the corresponding amides were obtained in good to high yields.

  • 50.
    van der Werf, Angela
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transformations of Nitrosoarenes and Alkynyl Enones: Selective Synthesis of Nitrogen-Containing Compounds2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The nitrogen atom plays a unique role in organic chemistry. It is abundantly found in organic materials and is responsible for the activity of many biologically relevant compounds. In this thesis, nitrosoarenes and keto- and pyridyl-substituted enynes are used as convenient starting materials for the selective synthesis of nitrogen-containing compounds.

    Nitrosoarenes are versatile compounds that can undergo a broad range of reactions. The nature of the nitroso group is significantly different from that of related nitrogen-based functional groups and this can be used as an advantage in the development of new methodology. In the first part of this thesis, the para-selective halogenation of nitrosoarenes with copper(II) halides as halogenating reagents is explored. The one-pot transformation of the products to the corresponding nitroarenes and anilines is demonstrated. The use of nitrosoarenes for radical N-perfluoroalkylation is presented in the next chapters. N-Perfluoroalkylation is a relatively new field and only a limited number of reagents and substrates have been employed so far. In this thesis, the stable and convenient Langlois reagent was used to achieve selective N-trifluoromethylation of nitrosoarenes to obtain the corresponding hydroxylamines. Longer perfluoroalkyl chains were investigated as well, but the less stable products were defluorinated to form hydroxamic acid derivatives. These products could be reduced to yield perfluoroalkyl amides.

    Keto- and pyridyl-substituted enynes are starting materials designed to undergo cyclization reactions in the presence of a metal catalyst and a nucleophile. This offers the possibility to obtain a variety of more complex molecular structures in a single step. In the second half of the thesis, the reaction between these starting materials and enamines is explored. A range of cyclopenta[c]furans were synthesized in good yields and with high diastereoselectivities from alkynyl enones and enamines with InBr3 as the catalyst. The enamines were formed in situ in a multicomponent reaction. Pyridyl-substituted enynes are the pyridine analogues of alkynyl enones and were found to form polycyclic indolizines in the reaction with cyclic enamines with AgOTf as a catalyst. Good yields and high to excellent diastereoselectivities were obtained. When the reaction was performed with in situ-generated enamines, different indolizine derivatives were obtained.

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