Digitala Vetenskapliga Arkivet

Change search
Refine search result
45678910 301 - 350 of 4163
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 301.
    Barrozo, Alexandre
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Liao, Qinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Esguerra, Mauricio
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Marloie, Gael
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Florian, Jan
    Loyola Univ Chicago, Dept Chem & Biochem, Chicago, IL 60660 USA..
    Williams, Nicholas H.
    Univ Sheffield, Dept Chem, Sheffield S3 7HF, S Yorkshire, England..
    Kamerlin, Shina C. Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Computer simulations of the catalytic mechanism of wild-type and mutant beta-phosphoglucomutase2018In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 16, no 12, p. 2060-2073Article in journal (Refereed)
    Abstract [en]

    beta-Phosphoglucomutase (beta-PGM) has served as an important model system for understanding biological phosphoryl transfer. This enzyme catalyzes the isomerization of beta-glucose-1-phosphate to -glucose-6-phosphate in a two-step process proceeding via a bisphosphate intermediate. The conventionally accepted mechanism is that both steps are concerted processes involving acid-base catalysis from a nearby aspartate (D10) side chain. This argument is supported by the observation that mutation of D10 leaves the enzyme with no detectable activity. However, computational studies have suggested that a substrate-assisted mechanism is viable for many phosphotransferases. Therefore, we carried out empirical valence bond (EVB) simulations to address the plausibility of this mechanistic alternative, including its role in the abolished catalytic activity of the D10S, D10C and D10N point mutants of beta-PGM. In addition, we considered both of these mechanisms when performing EVB calculations of the catalysis of the wild type (WT), H20A, H20Q, T16P, K76A, D170A and E169A/D170A protein variants. Our calculated activation free energies confirm that D10 is likely to serve as the general base/acid for the reaction catalyzed by the WT enzyme and all its variants, in which D10 is not chemically altered. Our calculations also suggest that D10 plays a dual role in structural organization and maintaining electrostatic balance in the active site. The correct positioning of this residue in a catalytically competent conformation is provided by a functionally important conformational change in this enzyme and by the extensive network of H-bonding interactions that appear to be exquisitely preorganized for the transition state stabilization.

    Download full text (pdf)
    fulltext
  • 302.
    Bartholomeyzik, Teresa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Investigation of Selectivity in Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes.Manuscript (preprint) (Other academic)
  • 303.
    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.

  • 304.
    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.

  • 305.
    Bartholomeyzik, Teresa
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mazuela, Javier
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pendrill, Robert
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Deng, Youqian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes: Control of Selectivity and Role of H2O2014In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, no 33, p. 8696-8699Article in journal (Refereed)
    Abstract [en]

    Highly selective protocols for the carbocyclization/arylation of allenynes using arylboronic acids are reported. Arylated vinylallenes are obtained with the use of BF3 center dot Et2O as an additive, whereas addition of water leads to arylated trienes. These conditions provide the respective products with excellent selectivities (generally > 97:3) for a range of boronic acids and different allenynes. It has been revealed that water plays a crucial role for the product distribution.

    Download full text (pdf)
    fulltext
  • 306.
    Bartholomeyzik, Teresa
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pendrill, Robert
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jiang, Tuo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Complex Kinetics in a Palladium(II)-Catalyzed Oxidative Carbocyclization: Untangling of Competing Pathways, Pre-Catalyst Activation, and Product MixturesManuscript (preprint) (Other academic)
  • 307.
    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)
  • 308.
    Bartoszewicz, Agnieszka
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transition metal-catalysed hydrogen transfer processes for C-C and C-N bond formation: Synthetic studies and mechanistic investigations2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis focusses on synthetic studies and mechanistic investigations into reactions involving hydrogen-transfer processes.

    In the first part, the development of an efficient method for the synthesis of β-hydroxy ketones (aldols) and β-amino ketones (Mannich products) from allylic alcohols and aldehydes is described. These reactions use  Ru(η5-C5Ph5)(CO)2Cl as the catalyst. The reaction parameters were optimised in order to suppress the formation of undesired by-products. Neutral and mild reaction conditions enabled the synthesis of a variety of aldol products in up to 99% yield, with a good syn/anti ratio. The influence of the stereoelectronic properties of the catalyst on the reaction outcome was also studied. Based on the results obtained, a plausible reaction mechanism has been proposed, involving as the key steps the 1,4-addition of hydride to α,β-unsaturated ketones and the formation of ruthenium (Z)-enolates.

    In the second part of this thesis, a ruthenium-catalysed tandem isomerisation/C-H activation reaction is presented. A number of ruthenium complexes, phosphine ligands, and additives were evaluated in order to establish the optimal reaction conditions. It was found that the use of a stable ruthenium catalyst, Ru(PPh3)3Cl2, together with PtBu3 and HCO2Na resulted in an efficient tandem transformation. Using this procedure, a variety of ortho-alkylated ketones were obtained in excellent yields. Moreover, homoallylic alcohols could also be used as starting materials for the reaction, which further expands the substrate scope. Mechanistic investigations into the isomerisation part of the process were carried out.

    The last project described in the thesis deals with the design and preparation of novel bifunctional iridium complexes containing an N-(2-hydroxy-isobutyl)-N-Heterocyclic carbene ligand. These complexes were used as catalysts to alkylate amines using alcohols as latent electrophiles. The catalytic system developed here was found to be one of the most active systems reported to date, allowing the reaction to be performed at temperatures as low as 50 °C for the first time. A broad substrate scope was examined. Combined experimental and theoretical studies into the reaction mechanism are consistent with a metal-ligand bifunctional activity of the new catalyst.

    Download full text (pdf)
    fulltext
  • 309.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    González Miera, Greco
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Marcos, Rocio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Norrby, Per-Ola
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanistic Studies on the Alkylation of Amines with Alcohols Catalyzed by a Bifunctional Iridium Complex2015In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 5, no 6, p. 3704-3716Article in journal (Refereed)
    Abstract [en]

    The mechanism of the N-alkylation of amines with alcohols catalyzed by an iridium complex containing an N-heterocyclic carbene (NHC) ligand with a tethered alcohol/alkoxide functionality was investigated by a combination of experimental and computational methods. The catalyst resting state is an iridium hydride species containing the amine substrate as a ligand, and decoordination of the amine, followed by coordination of the imine intermediate to the iridium center, constitute the rate-determining step (rds) of the catalytic process. The alcohol/alkoxide that is tethered to the NHC participates in every step of the catalytic cycle by accepting or releasing protons and forming hydrogen bonds with the reacting species. Thus, the iridium complex with the alcohol/alkoxide tethered to the N-heterocyclic carbene ligand acts as a bifunctional catalyst.

    Download full text (pdf)
    fulltext
  • 310.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jezowska, Martina M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Laymand, Kevin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mobus, Juri
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of β-Hydroxy and β-Amino Ketones from Allylic Alcohols Catalyzed by Ru(η5-C5Ph5)(CO)2Cl2012In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 9, p. 1517-1530Article in journal (Refereed)
    Abstract [en]

    An efficient method for the synthesis of beta-hydroxy and beta-amino ketones from allylic alcohols catalyzed by Ru(5-C5Ph5)(CO)2Cl is described. The influence of the stereoelectronic properties of the catalyst on the reaction outcome has been studied. Optimization of the reaction conditions supressed the formation of undesired side products such as saturated ketones, benzyl alcohols, and a,beta-unsaturated ketones. Several aromatic and aliphatic allylic alcohols have been reacted with a large variety of aldehydes or imines to produce beta-hydroxy ketones or beta-amino ketones, respectively, in yields up to 99%. Based on experimental data, a mechanism via ruthenium alkoxides and ruthenium aldoxides is proposed. In addition, a C-bound ruthenium enolate has been characterized.

    Download full text (pdf)
    fulltext
  • 311.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Livendahl, Madeleine
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of b-Hydroxy Ketones from Allylic Alcohols via Catalytic Formation of Ruthenium Enolates2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 34, p. 10547-10550Article in journal (Refereed)
    Abstract [en]

    The most efficient Ru-catalyzed isomerization–aldol reaction from allylic alcohols has been achieved by using [η5-(Ph5Cp)Ru(CO)2Cl] as the catalyst. The bulky pentaphenylcyclopentadienyl ligand on the ruthenium atom prevents protonation at the oxygen of the Ru–enolate intermediate and completely suppresses the formation of unwanted ketone byproducts (see scheme). The domino transformation is as good as it can be: aldols are obtained in quantitative yields at ambient temperature.

  • 312.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Marcos, Rocio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sahoo, Suman
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Inge, A. Ken
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A Highly Active Bifunctional Iridium Complex with an Alcohol/Alkoxide-Tethered N-Heterocyclic Carbene for Alkylation of Amines with Alcohols2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 45, p. 14510-14519Article, review/survey (Refereed)
    Abstract [en]

    A series of new iridium(III) complexes containing bidentate N-heterocyclic carbenes (NHC) functionalized with an alcohol or ether group (NHC?OR, R=H, Me) were prepared. The complexes catalyzed the alkylation of anilines with alcohols as latent electrophiles. In particular, biscationic IrIII complexes of the type [Cp*(NHC-OH)Ir(MeCN)]2+2[BF4-] afforded higher-order amine products with very high efficiency; up to >99?% yield using a 1:1 ratio of reactants and 12.5 mol?% of Ir, in short reaction times (216 h) and under base-free conditions. Quantitative yields were also obtained at 50?degrees C, although longer reaction times (4860 h) were needed. A large variety of aromatic amines have been alkylated with primary and secondary alcohols. The reactivity of structurally related iridium(III) complexes was also compared to obtain insights into the mechanism and into the structure of possible catalytic intermediates. The IrIII complexes were stable towards oxygen and moisture, and were characterized by NMR, HRMS, single-crystal X-ray diffraction, and elemental analyses.

    Download full text (pdf)
    fulltext
  • 313.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Building molecular complexity via tandem Ru-catalyzed isomerization/C-H activation2009In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 11, no 8, p. 1749-1752Article in journal (Refereed)
    Abstract [en]

    A tandem isomerization/C-H activation of allylic alcohols was performed using a catalytic amount of RUCl(2)(PPh(3))(3). A variety of ortho alkylated ketones have been obtained in excellent yields. This tandem process relies on an in situ generation of a carbonyl functional group that directs the ortho C-H bond activation.

    Download full text (pdf)
    fulltext
  • 314. Barzegar, Hamid Reza
    et al.
    Nitze, Florian
    Malolepszy, Artur
    Stobinski, Leszek
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Wagberg, Thomas
    Water Assisted Growth of C-60 Rods and Tubes by Liquid-Liquid Interfacial Precipitation Method2012In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 17, no 6, p. 6840-6853Article in journal (Refereed)
    Abstract [en]

    C-60 nanorods with hexagonal cross sections are grown using a static liquid-liquid interfacial precipitation method in a system of C-60/m-dichlorobenzene solution and ethanol. Adding water to the ethanol phase leads instead to C-60 tubes where both length and diameter of the C-60 tubes can be controlled by the water content in the ethanol. Based on our observations we find that the diameter of the rods/tubes strongly depends on the nucleation step. We propose a liquid-liquid interface growth model of C-60 rods and tubes based on the diffusion rate of the good C-60 containing solvent into the poor solvent as well as on the size of the crystal seeds formed at the interface between the two solvents. The grown rods and tubes exhibit a hexagonal solvate crystal structure with m-dichlorobenzene solvent molecules incorporated into the crystal structure, independent of the water content. An annealing step at 200 degrees C at a pressure <1 kPa transforms the grown structures into a solvent-free face centered cubic structure. Both the hexagonal and the face centered cubic structures are very stable and neither morphology nor structure shows any signs of degradation after three months of storage.

  • 315.
    Barzegar, Hamid Reza
    et al.
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Nitze, Florian
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Malolepszy, Artur
    Stobinski, Leszek
    Tai, Cheuk-Wai
    Wågberg, Thomas
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Water assisted growth of C60 rods and tubes by liquid-liquid interfacial precipitation method2012In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 17, no 6, p. 6840-6853Article in journal (Refereed)
    Abstract [en]

    C60 nanorods with hexagonal cross sections are grown using a static liquid-liquid interfacial precipitation method in a system of C60/m-dichlorobenzene solution and ethanol. Adding water to the ethanol phase leads instead to C60 tubes where both length and diameter of the C60 tubes can be controlled by the water content in the ethanol. Based on our observations we find that the diameter of the rods/tubes strongly depends on the nucleation step. We propose a liquid-liquid interface growth model of C60 rods and tubes based on the diffusion rate of the good C60 containing solvent into the poor solvent as well as on the size of the crystal seeds formed at the interface between the two solvents. The grown rods and tubes exhibit a hexagonal solvate crystal structure with m-dichlorobenzene solvent molecules incorporated into the crystal structure, independent of the water content. An annealing step at 200 °C at a pressure <1 kPa transforms the grown structures into a solvent-free face centered cubic structure. Both the hexagonal and the face centered cubic structures are very stable and neither morphology nor structure shows any signs of degradation after three months of storage.

    Download full text (pdf)
    fulltext
  • 316.
    Bashir, Tariq
    et al.
    University of Borås, School of Engineering.
    Bakare, Fatimat
    University of Borås, School of Engineering.
    Baghaei, Behnaz
    University of Borås, School of Engineering.
    Mehrjerdi, Adib Kalantar
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Influence of different organic solvents and oxidants on insulating and film-forming properties of PEDOT polymer2013In: Iranian polymer journal, ISSN 1026-1265, E-ISSN 1735-5265, Vol. 22, no 8, p. 599-611Article in journal (Refereed)
    Abstract [en]

    Processing of conjugate polymers has always been a challenge because of their poor solubility and infusibility in organic and inorganic solvents. The processibility and applications of intrinsically conductive polymers (ICPs) can be enhanced by producing their solutions or dispersions in different suitable solvents. It can also be achieved by preparing un-doped or electrically neutral polymers, which can further be transformed in semiconductor after oxidation/reduction reaction. The present study focuses on the preparation of active dispersions of poly (3,4-ethylenedioxythiophene) (PEDOT) conductive polymer in various organic solvents. For this purpose, the polymerization of 3,4-ethylenedioxythiophene (EDOT) monomer was carried out in three different organic solvents, ethanol, 1-butanol and acetonitrile with two commonly used oxidants, ferric (III) chloride (FeCl3) and ferric (III) p-toluenesulfonate (FepTS). In this regard, the oxidant and monomer solutions with variable molar concentrations (0.25, 0.5, 1.0 M) were prepared in particular solvents and then these solutions were mixed with different monomer/oxidant volume ratios. The obtained dispersions of PEDOT can readily be polymerized on the surface of different materials after solvent evaporation and a uniform film can be achieved. The effect of molar as well as volume concentrations of EDOT monomer and oxidant on insulating (undoped/neutral) and film forming properties of PEDOT was investigated. These dispersions were applied on a transparent PET film and cellulosic fibers (viscose), dried at room temperature and analyzed using scanning electron microscope (SEM), optical microscope and ATR-FTIR spectroscopic analysis. The electrical characterization of undoped PEDOT-coated fibers was performed on Keithly picoammeter. This study contributes to obtain a simpler and instantaneous polymerization method of PEDOT preparation and to enhance its application area.

  • 317.
    Bashir, Tariq
    et al.
    University of Borås, School of Engineering.
    Fast, Lars
    Skrifvars, Mikael
    University of Borås, School of Engineering.
    Persson, Nils-Krister
    University of Borås, Swedish School of Textiles.
    Electrical Resistance Measurement Methods and Electrical Characterization of Poly(3,4-ethylenedioxythiophene)- Coated Conductive Fibers2012In: Journal of Applied Polymer Science, ISSN 0021-8995, E-ISSN 1097-4628, Vol. 124, no 4, p. 2954-2961Article in journal (Refereed)
    Abstract [en]

    Textile fibers and yarns of high conductivity, and their integration into wearable textiles for different electronic applications, have become an important research field for many research groups throughout the world. We have produced novel electrically conductive textile yarns by vapor-phase polymerization (VPP) of a conjugated polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), on the surface of commercially available textile yarns (viscose). In this article, we have presented a novel setup for electrical resistance measurements, which can be used not only for fibrous structures but also for woven structures of specific dimensions. We have reported a two-point resistance- measuring method using an already manufactured setup and also a comparison with the conventionally used method (so-called crocodile clip method). We found that the electrical properties of PEDOT-coated viscose fibers strongly depend on the concentration of oxidant (FeCl3)and the doping (oxidation) process of PEDOT. To evaluate the results, we used mass specific resistance values of PEDOT-coated viscose yarns instead of normal surface resistance values. The voltage–current (V–I) characteristics support the ohmic behavior of coated fibers to some extent. Monitoring of the charging effect of the flow of current through conductive fibers for prolonged periods of time showed that conductivity remains constant. The change in electrical resistance values with increase in the length of coated fibers was also reported. The resistance measuring setup employed could also be used for continuous measurement of resistance in the production of conductive fibers, as well as for four-point resistance measurement.

  • 318. Bassanini, Ivan
    et al.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Industrial Biotechnology. CNR, Italy.
    Riva, Sergio
    Dicarboxylic esters: Useful tools for the biocatalyzed synthesis of hybrid compounds and polymers2015In: Beilstein Journal of Organic Chemistry, ISSN 2195-951X, E-ISSN 1860-5397, Vol. 11, p. 1583-1595Article, review/survey (Refereed)
    Abstract [en]

    Dicarboxylic acids and their derivatives (esters and anhydrides) have been used as acylating agents in lipase-catalyzed reactions in organic solvents. The synthetic outcomes have been dimeric or hybrid derivatives of bioactive natural compounds as well as functionalized polyesters.

  • 319. Bastos, Erick L.
    et al.
    Farahani, Pooria
    Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil.
    Bechara, Etelvino J. H.
    Baader, Wilhelm J.
    Four‐membered cyclic peroxides: Carriers of chemical energy2017In: Journal of Physical Organic Chemistry, ISSN 0894-3230, E-ISSN 1099-1395, Vol. 30, no 9, article id e3725Article, review/survey (Refereed)
    Abstract [en]

    Four‐membered cyclic peroxides are high‐energy compounds often associated tocold light emission, but whose chemical and biological roles are still matters ofdebate. The often‐dangerous synthesis of 1,2‐dioxetanes, achieved around 50 yearsago, has been mastered over the years to a point where some derivatives are commerciallyavailable. This fact does not imply that 1,2‐dioxetanes can be convenientlyprepared in the gram scale or that the synthesis of analogous 1,2‐dioxetanones andthe elusive 1,2‐dioxetanedione are simple. Important questions on the mechanism ofchemiluminescence and bioluminescence reactions are under experimental and theoreticalscrutiny. The available data have contributed to relate structural and mediumeffects to the quantum efficiency of these compounds to produce excited states.Consequently, such peroxides have been suggested to produce biologically relevantelectronically excited species in vivo in the absence of light. The connection of thishypothesis with melanin‐mediated photodamage in the dark has renewed the interestin such cyclic peroxides. This reviewgives some insight on the synthesis, chemiluminescencemechanism, and biological relevance of 1,2‐dioxetanes, 1,2‐dioxetanones,and 1,2‐dioxetanedione and provides practical protocols for those interested inengaging this field.

  • 320. Basu, Basudeb
    et al.
    Paul, Susmita
    Kundu, Samir
    Byström, Emil
    Irgum, Knut
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Almqvist, Fredrik
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Organic Polymeric Resins Embedded with Pd NPs: Newly Designed, Efficient and Chemoselective Catalyst for Reduction of Nitrobenzenes2017In: Current Organocatalysis, ISSN 2213-3372, Vol. 4, no 1, p. 48-61Article in journal (Refereed)
    Abstract [en]

    Background: Organic polymer supported palladium nanoparticles (NPs) are important for use as heterogeneous catalyst in various organic reactions. This works describes Pd Nps immobilized on to polystyrene-based ion-exchange resin surface for use as catalyst in the reduction of nitrobenzenes. The heterogeneous catalyst was found useful for hydrogenation of nitro group under both catalytic transfer hydrogenation (CTH) as well as by using molecular hydrogen (H2).

    Methods: The catalyst was prepared from Amberlite IRA 900 Cl after rinsing with formic acid (10%) and subsequent treatment with Na2PdCl4 in DMF. The resulting Pd Nps immobilized resins was designated as VersaCat Pd and used for CTH of nitrobenzenes in the presence of H-donors (sodium formate, formic acid, hydrazine hydrate) and also for hydrogenation with H2 gas. The catalyst was characterized by FT-IR, MAS-NMR, SEM, TEM and XPS and surface morphologies were studied before and after the reaction.

    Results: Hydrogenations of nitrobenzenes under CTH using different H-source and direct use of H2 gas were achieved successfully with good to excellent yields. Reactions were performed under mild conditions and high degree of chemoselectivity was also observed. The catalyst was recyclable, used for six consecutive runs with appreciable conversions and showed higher activity (> 3 times) in terms of metalcontent than commercially available Pd/C (10%) in the hydrogenation of nitrobenzenes using H2 gas. The TEM images showed that Pd Nps are evenly distributed with size 50-200 mm on polymeric matrices and there was no significant changes observed after the first catalytic run. However, considerable rupture of the polymeric surface occurred after six runs, as seen from SEM studies.

    Conclusion: The present study establishes high catalytic efficiency and chemoselectivity of the newly developed organic polystyrene-based resin-soaked Pd NPs (VersaCat Pd) in the reduction of nitrobenzenes. Both CTH and hydrogenation using H2 gas were successfully done. Interestingly, hydrazine hydrate offered excellent control over chemoselectivity under CTH conditions and allowed clean conversion from nitro to amine, while keeping a chloro substitutent unaffected. Hydrogenation using molecular H2 gave maximum TOF. Easy preparation, high efficacy, TOF, chemoselectivity, and versatile applications are notable features for this heterogeneous palladium catalyst (VersaCat Pd). These features are often required in chemical industries.

  • 321. Battistel, Marcos D.
    et al.
    Pendrill, Robert
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Freedberg, Daron I.
    Direct Evidence for Hydrogen Bonding in Glycans: A Combined NMR and Molecular Dynamics Study2013In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 117, no 17, p. 4860-4869Article in journal (Refereed)
    Abstract [en]

    We introduce the abundant hydroxyl groups of glycans as NMR handle's and structural probes to expand the repertoire of tools for structure function studies on glycans in solution. To this end, we present the facile detection and assignment of hydroxyl groups in a Wide range of sample concentrations (0.5-1700 mM) and temperatures, ranging from -5 to 25 degrees C.,We then exploit this information to directly detect hydrogen bonds, well-known for their importance in molecular structural determination through NMR. Via HSQC-TOCSY, we were able to determine the directionality; of these hydrogen bonds in sucrose Furthermore, by means Of molecular dynamics simulations in conjunction with NMR, we establish that one Out of the three detected hydrogen bonds arises from intermolecular interactions. This finding may shed light on glycan glycan interactions and glycan recognition by proteins.

    Download full text (pdf)
    fulltext
  • 322.
    Baumann, Herbert
    Stockholm University, Faculty of Science.
    Synthesis of and NMR and conformational studies on some 3-O-, 4-O- and 3,4-di-O-glycopyranosyl-substituted methyl d-glycopyranosides1988Doctoral thesis, comprehensive summary (Other academic)
  • 323. Beckmann, Katrin
    et al.
    Uchtenhagen, Hannes
    Berggren, Gustav
    Anderlund, Magnus F
    Thapper, Anders
    Messinger, Johannes
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Styring, Stenbjörn
    Kurz, Philipp
    Formation of stoichiometrically 18O-labelled oxygen from the oxidation of 18O-enriched water mediated by a dinuclear manganese complex-a mass spectrometry and EPR study2008In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 1, p. 668-76Article in journal (Refereed)
    Abstract [en]

    Oxygen formation was detected for the oxidations of various multinuclear manganese complexes by oxone (HSO5-) in aqueous solution. To determine to what extent water was the source of the evolved O2, H218O isotope-labelling experiments coupled with membrane inlet mass spectrometry (MIMS) were carried out. We discovered that during the reaction of oxone with [Mn2(OAc)2(bpmp)]+ (1), stoichiometrically labelled oxygen (18O2) was formed. This is the first example of a homogeneous reaction mediated by a synthetic manganese complex where the addition of a strong chemical oxidant yields 18O2 with labelling percentages matching the theoretically expected values for the case of both O-atoms originating from water. Experiments using lead acetate as an alternative oxidant supported this finding. A detailed investigation of the reaction by EPR spectroscopy, MIMS and Clark-type oxygen detection enabled us to propose potential reaction pathways.

  • 324.
    Bedecs, Katarina
    Stockholm University, Faculty of Science, Department of Neurochemistry and Neurotoxicology.
    Galanin in the rat dorsal spinal cord: an inhibitor peptide in sensory processing1995Doctoral thesis, comprehensive summary (Other academic)
  • 325. Bedekar, Ashutosh V.
    et al.
    Andersson, Pher
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    A New Class of Bis-Oxazoline Ligands for the Cu-Catalysed Asymmetric Cyclopropanation of Olefins1996In: Tetrahedron Letters, Vol. 37, no 23, p. 4073-4076Article in journal (Refereed)
  • 326. Bedekar, Ashutosh V.
    et al.
    Koroleva, Elise B.
    Andersson, Pher
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Investigation of the Effects of the Structure and Chelate Size of Bis-oxazoline Ligands in the Asymmetric Copper-Catalyzed Cyclopropanation of Olefins: Design of a New Class of Ligands1997In: J. Org. Chem., no 62, p. 2518-2526Article in journal (Refereed)
  • 327. Bedin, Michele
    et al.
    Karim, Alavi
    Reitti, Marcus
    Carlsson, Anna-Carin C
    Topić, Filip
    Cetina, Mario
    Pan, Fangfang
    Havel, Vaclav
    Al-Ameri, Fatima
    Sindelar, Vladimir
    Rissanen, Kari
    Gräfenstein, Jürgen
    Erdelyi, Mate
    Counterion influence on the N-I-N halogen bond.2015In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 6, no 7, p. 3746-3756Article in journal (Refereed)
    Abstract [en]

    A detailed investigation of the influence of counterions on the [N-I-N]+ halogen bond in solution, in the solid state and in silico is presented. Translational diffusion coefficients indicate close attachment of counterions to the cationic, three-center halogen bond in dichloromethane solution. Isotopic perturbation of equilibrium NMR studies performed on isotopologue mixtures of regioselectively deuterated and nondeuterated analogues of the model system showed that the counterion is incapable of altering the symmetry of the [N-I-N]+ halogen bond. This symmetry remains even in the presence of an unfavorable geometric restraint. A high preference for the symmetric geometry was found also in the solid state by single crystal X-ray crystallography. Molecular systems encompassing weakly coordinating counterions behave similarly to the corresponding silver(i) centered coordination complexes. In contrast, systems possessing moderately or strongly coordinating anions show a distinctly different behavior. Such silver(i) complexes are converted into multi-coordinate geometries with strong Ag-O bonds, whereas the iodine centered systems remain linear and lack direct charge transfer interaction with the counterion, as verified by 15N NMR and DFT computation. This suggests that the [N-I-N]+ halogen bond may not be satisfactorily described in terms of a pure coordination bond typical of transition metal complexes, but as a secondary bond with a substantial charge-transfer character.

  • 328. Bednarska, Joanna
    et al.
    Zalesny, Robert
    Tian, Guangjun
    Natarajan Arul, Murugan
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Bartkowiak, Wojciech
    Nonempirical Simulations of Inhomogeneous Broadening of Electronic Transitions in Solution: Predicting Band Shapes in One- and Two-Photon Absorption Spectra of Chalcones2017In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 22, no 10, article id 1643Article in journal (Refereed)
    Abstract [en]

    We have examined several approaches relying on the Polarizable Embedding (PE) scheme to predict optical band shapes for two chalcone molecules in methanol solution. The PE-TDDFT and PERI-CC2 methods were combined with molecular dynamics simulations, where the solute geometry was kept either as rigid, flexible or partly-flexible (restrained) body. The first approach, termed RBMD-PE-TDDFT, was employed to estimate the inhomogeneous broadening for subsequent convolution with the vibrationally-resolved spectra of the molecule in solution determined quantum-mechanically (QM). As demonstrated, the RBMD-PE-TDDFT/QM-PCM approach delivers accurate band widths, also reproducing their correct asymmetric shapes. Further refinement can be obtained by the estimation of the inhomogeneous broadening using the RBMD-PERI-CC2 method. On the other hand, the remaining two approaches (FBMD-PE-TDDFT and ResBMD-PE-TDDFT), which lack quantum-mechanical treatment of molecular vibrations, lead to underestimated band widths. In this study, we also proposed a simple strategy regarding the rapid selection of the exchange-correlation functional for the simulations of vibrationally-resolved one-and two-photon absorption spectra based on two easy-to-compute metrics.

  • 329.
    Beeren, Sophie R.
    et al.
    Tech Univ Denmark, Dept Chem, Kemitorvet Bldg 207, DK-2800 Lyngby, Denmark..
    McTernan, Charlie T.
    Francis Crick Inst, Artificial Mol Machinery Lab, 1 Midland Rd, London NW1 1AT, England.;Kings Coll London, Dept Chem, Britannia House,7 Trinity St, London SE1 1DB, England..
    Schaufelberger, Fredrik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    The mechanical bond in biological systems2023In: Chem, ISSN 2451-9308, E-ISSN 2451-9294, Vol. 9, no 6, p. 1378-1412Article, review/survey (Refereed)
    Abstract [en]

    The field of mechanically interlocked molecules (MIMs) has advanced rapidly in recent years, with much work focused on their use in materials, sensing, and catalysis. However, the use of MIMs in biology and biomedicine has been limited, despite the identifica-tion of naturally occurring MIMs in DNA and proteins and the poten-tial advantages of the mechanical bond in fields such as nanomedi-cine and tissue engineering. Difficulties in the synthesis of MIMs, along with their limited solubility and stability in biological media, have until recently impeded their wider application in biology. Contemporary advances have, however, enabled a broader integra-tion of the mechanical bond in biology; the mechanical interlocking endows these systems with unique functional advantages. Herein, we summarize recent advances in the application of small-molecule, biologically derived, and polymeric MIMs in biology, highlighting synergies ripe for future exploration.

  • 330.
    Begnini, Fabio
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry. Uppsala University.
    Development of Novel Macrocyclic Inhibitors of Protein-Protein Interactions: Applied to the Keap1-Nrf2 Complex2019Licentiate thesis, comprehensive summary (Other academic)
    Download (pdf)
    Fabio Begnini - Licentiate Thesis Abstract - 2019
  • 331.
    Begnini, Fabio
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Poongavanam, Vasanthanathan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Atilaw, Yoseph
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Erdélyi, Máté
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Schiesser, Stefan
    Kihlberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Cell Permeability of Isomeric Macrocycles: Predictions and NMR Studies2021In: ACS Medicinal Chemistry Letters, ISSN 1948-5875, E-ISSN 1948-5875, Vol. 12, no 6, p. 983-990Article in journal (Refereed)
    Abstract [en]

    Conformation-dependent 3D descriptors have been shown to provide better predictions of the physicochemical properties of macrocycles than 2D descriptors. However, the computational identification of relevant conformations for macrocycles is nontrivial. Herein, we report that the Caco- 2 cell permeability difference between a pair of diastereomeric macrocycles correlated with their solvent accessible 3D polar surface area and radius of gyration. The descriptors were calculated from the macrocycles’ solution- phase conformational ensembles and independently from ensembles obtained by conformational sampling. Calculation of the two descriptors for three other stereo- and regioisomeric macrocycles also allowed the correct ranking of their cell permeability. Methods for conformational sampling may thus allow ranking of passive permeability for moderatelyflexible macrocycles, thereby contributing to the prioritization of macro- cycles for synthesis in lead optimization.

    Download full text (pdf)
    fulltext
  • 332. Begum, Sartaz
    et al.
    Munissi, Joan J.E.
    Buriyo, Amelia S.
    Makangara, John J.
    Lucantoni, Leonardo
    Avery, Vicky M.
    Erdélyi, Máté
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry.
    Nyandoro, Stephen S.
    Antiplasmodial, Antimicrobial and Cytotoxic Activities of Extracts from Selected Medicinal Plants Growing in Tanzania2020In: Journal of Biologically Active Products from Nature, ISSN 2231-1866, Vol. 10, no 2, p. 165-176Article in journal (Refereed)
    Abstract [en]

    This paper reports on the evaluation of antiplasmodial, antimicrobial and cytotoxic activities of extracts from eleven plant species traditionally used by some Tanzanian coastal communities for treatment of malaria, microbial infections and related ailments. Crude extracts from selected plant species namely Acacia zanzibarica,  Danais  xanthorrhoea, Diospyros  loureiriana  ssp.  rufescens, Erythrina  sacleuxii, Newtonia paucijuga, Pentas lanceolata, Scorodophloeus fischeri, Stuhlmannia moavi, Tarenna pavettoides, Tessmannia burttii  and  Toussaintia  orientalis  growing  in  Tanzania  were  investigated  using  an  imaging-based  assay (antiplasmodial), well diffusion and microplate dilution methods (antimicrobial) and human embryonic kidney cells (HEK 293) and brine shrimp larvae assays (toxicity). The extracts exhibited activities of varying potencies and cytotoxicity with IC 50 values ranging from 0.45±0.09 to 75.70±24.19 μg/mL against Plasmodium falciparum (3D7 strain), MIC ranging from 0.25 to 2.0 mg/mL (against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Cryptococcus neoformans), LC 50 ranging from 0.75 to 1000 μg/mL against brine shrimp larvae (Artemia salina) and IC 50 ranging from 4.02±1.05 to more than 289 μg/mL against HEK 293 cells. The observed bioactivities of some of the investigated plant extracts validate their ethnomedicinal use and are indicative of the presence of bioactive ingredients for further phytochemical investigations.

  • 333. Begum, Sartaz
    et al.
    Nyandoro, Stephen
    Buriyo, Amelia
    Makangara, John
    Munissi, Joan
    Duffy, Sandra
    Avery, Vicky
    Erdelyi, Mate
    University of Gothenburg.
    Bioactivities of extracts, debromolaurintrerol and fucosterol from Macroalgae species2018In: Tanzania Journal of Science, ISSN 2507-7961, Vol. 44, no 2, p. 104-116Article in journal (Refereed)
    Abstract [en]

    Parasitic diseases including malaria, and other numerous microbial infections and physiological diseases are threatening the global population. Tanzanian coast shores are endowed with a variety of macroalgae (seaweeds), hitherto unsystematically explored to establish their biomedical potentials. Thus, antiplasmodial activity using malarial imaging assay, antimicrobial activity using microplate dilution technique, antioxidant activity using DPPH radical scavenging method and cytotoxicity using brine shrimp test were carried out on crude extracts from the selected species of algae (Acanthophora spicifera, Cystoseira myrica, Cystoseira trinodis, Laurencia filiformis, Padina boryana, Sargassum oligocystum, Turbinaria crateriformis, Ulva fasciata and Ulva reticulata) occurring along the coast of Tanzania. The extracts showed antimicrobial activities with MIC ranging from 0.3- 5.0 µg/mL against Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Cryptococcus neoformans; DPPH radical scavenging activity at EC50 1.0- 100 µg/mL and cytotoxicity on brine shrimp larvae with LC50 value ranging from20 - 1000 µg/mL. The extracts from C. myrica and P. boryana inhibited growth of Plasmodium falciparum (3D7 strain) by 80 and 71%, respectively at 40 µg/mL while a sesquiterpene debromolaurinterol (1) which was chromatographically isolated from C. myrica exhibited antiplasmodial activity with IC50 20 µM whereas a sterol fucosterol (2) from P. boryana showed weak activity at 40 µM. Bioactivities portrayed by the investigated extracts indicate their ingredients as potential sources of bioactive agents that warrant further explorations.

  • 334.
    Behren, Sandra
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Development and Evaluation of Tools to Explore Posttranslational HexNAc-Tyrosine and Mucin-Type O-Glycosylation2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Glycosylation is the most abundant form of post-translational modification (PTM). Recently, O-glycosylation attracted much attention in the glycoproteomic field due to its association with various diseases, such as pathogenic infections and cancer. However, glycoproteomic analysis of O-linked glycosylation is highly challenging due its structural diversity and complexity. New and efficient methods need to be developed to obtain a better understanding of the biological functions of O-glycans. In the presented thesis, glycopeptide microarrays were used as tools to explore the role of mucin type O-glycosylation in cancer, bacterial adhesion processes and galectin recognition on a molecular level, and to get insights into a new group of tyrosine O-glycosylation. A better understanding of these carbohydrate-protein interactions on a molecular level could facilitate the development of glycomimetic inhibitors to fight bacterial infections or block glycan binding proteins involved in cancer progression, or improve the design of novel carbohydrate-based cancer vaccines.

    In the first part of this work, tools were developed to elucidate the role of a novel group of PTMs, where N-acetylhexosamine (HexNAc = α-GalNAc, α- or β-GlcNAc) was found to modify the hydroxyl group of tyrosine. Synthetic glycopeptides carrying this new modification, as well as glycopeptide microarray libraries were prepared to evaluate the abilities of plant lectins (carbohydrate-binding proteins) to detect HexNAc-O-Tyr modifications. These lectins are commonly used in glycoproteomic work flows to detect and enrich glycopeptides and -proteins. Additionally, HexNAc-O-Tyr-specific rabbit antibodies were raised and immunologically analyzed by enzyme-linked immunosorbent assays, western blot and microarray binding studies.

    In the second part of the presented thesis, synthetic mucin glycopeptide microarray libraries were prepared and employed to explore carbohydrate-protein interactions of galectins, bacterial lectins and tumor specific antibodies. Mucin glycoproteins are part of the mucus barrier that protects the host against invading pathogens. However, bacteria and viruses have co-evolved with the human host and have developed strategies to promote virulence, for example by adhering to glycans on the host cell-surface. To combat bacterial infections, their virulence and pathogenicity must be understood on a molecular level. In this work, mucin glycopeptides were enzymatically modified with different fucose motifs and used to determine the fine binding specificities of fucose-recognizing lectins LecB from Pseudomonas aeruginosa and the Clostridium difficile toxin A. Furthermore, a synthesis strategy was developed to generate simplified mucin core glycopeptides that could be used as scaffolds to enzymatically generate LacdiNAc modified glycopeptides. They could be used in microarray binding studies to evaluate the glycan binding preferences of various proteins, including the Helicobacter pylori lectin LabA and human galectins, which play roles in cancer development and progression. Aberrant glycosylation of mucin glycoproteins has been associated with various types of cancer. Tumor specific carbohydrate antigens on mucins represent attractive antigenic targets for the development of effective anti-cancer vaccines. In this work, antibodies induced by tumor-associated MUC1 glycopeptide-bacteriophage Qβ vaccine conjugates were immunologically analyzed using MUC1 glycopeptide microarray libraries.

    Download full text (pdf)
    fulltext
    Download (pdf)
    spikblad
    Download (jpg)
    presentationsbild
  • 335.
    Behren, Sandra
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Delgado, Sandra
    Arda, Ana
    Jiménez-Barbero, Jesús
    Westerlind, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Binding Specificities of Human Galectins toward Mucin Glycopeptide LibrariesManuscript (preprint) (Other academic)
  • 336.
    Behren, Sandra
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Funder, Tobias
    Westerlind, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis of Simplified Mucin Cores 1-4 MUC1 and MUC5AC Glylcopeptides for Enzymatic Modification with LacdiNAc MotifsManuscript (preprint) (Other academic)
  • 337.
    Behren, Sandra
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Leibniz-Institut für Analytische Wissenschaften, Dortmund, Germany.
    Schorlemer, Manuel
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Leibniz-Institut für Analytische Wissenschaften, Dortmund, Germany.
    Schmidt, Gudula
    Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Freiburg, Freiburg, Germany.
    Westerlind, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Leibniz-Institut für Analytische Wissenschaften, Dortmund, Germany.
    Aktories, Klaus
    Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Universität Freiburg, Freiburg, Germany.
    Antibodies directed against GalNAc- and GlcNAc-O-Tyrosine posttranslational modifications – a new tool for glycoproteomic detection2023In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 29, no 29, article id e202300392Article in journal (Refereed)
    Abstract [en]

    In the last decade, it was discovered that protein mucin-type O-glycosylation and O-GlcNAcylation modify Tyr residues besides the well explored Thr and Ser amino acids. Several glycoproteomic studies have identified α-GalNAc-O-Tyr modifications, and studies propose that β-GlcNAc-O-Tyr also exists as a new group of posttranslational modifications (PTMs). Specific bacterial toxins have further been identified to modify host GTPases with α-GlcNAc-O-Tyr to promote bacterial virulence. Despite being identified on numerous proteins, the biological roles, biosynthesis and expression of GalNAc- and GlcNAc-O-Tyr modifications are poorly understood. A major obstacle is the lack of tools to specifically detect and identify proteins containing these modifications. With this in mind, we prepared vaccine constructs and raised antibodies to enable selective detection of proteins carrying these new PTMs. The obtained polyclonal antibody sera were evaluated using ELISA and glycopeptide microarrays and were found to be highly selective for GlcNAc- and GalNAc-O-Tyr glycopeptides over the corresponding Ser- and Thr-modifications. For microarray analysis, synthetic GlcNAc- and GalNAc-O-Tyr Fmoc-amino acids were prepared and applied in Fmoc-SPPS to obtain an extensive O-glycopeptide library. After affinity purification, the antibodies were applied in western blot analysis and showed specific detection of α-GlcNAc-O-Tyr modified RhoA GTPase.

    Download full text (pdf)
    fulltext
  • 338.
    Behren, Sandra
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schorlemer, Manuel
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Xiao, Yao
    Woods, Robert J.
    Marcelo, Filipa
    Westerlind, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Deciphering the Molecular Recognition of GalNAc- and GlcNAc-O-Tyrosine Glycopeptides by Plant LectinsManuscript (preprint) (Other academic)
  • 339.
    Behren, Sandra
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Westerlind, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Novel approaches to design glycan-based antibacterial inhibitors2023In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 26, no 1, article id e202200795Article, review/survey (Refereed)
    Abstract [en]

    The interactions between bacterial lectins and carbohydrates on the host cell surface can mediate bacterial adhesion, invasion, and immune evasion. Multivalency plays a key role in these binding events. However, additional molecular mechanisms greatly impact multivalent binding recognition. To develop specific and effective bacterial inhibitors, a deeper understanding of the complex underlying mechanisms of bacterial adhesion processes is necessary. By interfering with bacterial adhesion, synthetic multivalent glycoconjugates do not only have the potential to improve or replace antibiotic treatments, but also represent useful tools to study carbohydrate-pathogen interactions. In this review, we highlight a few recent advances in the synthesis and application of synthetic glycan-based scaffolds to uncover the nature of glycan-bacteria interactions and to design efficient bacterial inhibitors.

    Download full text (pdf)
    fulltext
  • 340.
    Behren, Sandra
    et al.
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Yu, Jin
    Imperial College, London.
    Pett, Christian
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Schorlemer, Manuel
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Heine, Viktoria
    RWTH Aachen University.
    Fischöder,, Thomas
    RWTH Aachen University.
    Elling, Lothar
    RWTH Aachen University.
    Westerlind, Ulrika
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Bacteria Lectin Recognition Towards Fucose Binding Motifs Highlights the Impact of Presenting Mucin Core GlycopeptidesManuscript (preprint) (Other academic)
    Abstract [en]

    Mucin glycoproteins are essential components of the mucosal protective barrier, which constantly senses and clears the host from pathogens. Throughout evolution, bacteria and virus have developed strategies to modulate and penetrate the mucosal barrier and cause virulence by interacting with the glycans of membrane-bound mucins at the epithelial cell-surface. These interactions may promote bacteria cell-adhesion, biofilm formation, protein toxin delivery, or cause an inflammatory environment. O-fucosylated glycan epitopes are commonly found on mucin glycoproteins, and are key ligands of many bacterial and viral lectins (glycan binding proteins). Herein we describe a chemoenzymatic synthesis strategy to efficiently prepare an extensive library of fucosylated mucin core tandem repeats glycopeptides to elucidate the fine fucose-binding specificities of the Pseudomonas aeruginosa lectin LecB and the Clostridium difficile toxin A. Therefore, glycan core structures were decorated with terminal Lewis and H-antigens, which play critical roles in infection biology. The fucosylated mucin glycopeptides were applied in microarray binding studies to explore the importance of the glycan and peptide backbone presentation of these terminal antigens in binding interactions with the two bacterial lectins. 

  • 341.
    Beigoli, Sima
    et al.
    Mashhad Univ Med Sci, Endoscop & Minimally Invas Surg Res Ctr, Mashhad, Razavi Khorasan, Iran..
    Behrouz, Sepideh
    Mashhad Univ Med Sci, Appl Biomed Res Ctr, Mashhad, Razavi Khorasan, Iran.;Mashhad Univ Med Sci, Fac Med, Dept Physiol, Mashhad, Razavi Khorasan, Iran..
    Memarzia, Arghavan
    Mashhad Univ Med Sci, Appl Biomed Res Ctr, Mashhad, Razavi Khorasan, Iran.;Mashhad Univ Med Sci, Fac Med, Dept Physiol, Mashhad, Razavi Khorasan, Iran..
    Ghasemi, Seyyedeh Zahra
    Mashhad Univ Med Sci, Appl Biomed Res Ctr, Mashhad, Razavi Khorasan, Iran.;Mashhad Univ Med Sci, Fac Med, Dept Physiol, Mashhad, Razavi Khorasan, Iran..
    Boskabady, Marzie
    Mashhad Univ Med Sci, Sch Dent, Dent Mat Res Ctr, Mashhad, Razavi Khorasan, Iran.;Mashhad Univ Med Sci, Sch Dent, Dept Pediat Dent, Mashhad, Razavi Khorasan, Iran..
    Marefati, Narges
    Mashhad Univ Med Sci, Appl Biomed Res Ctr, Mashhad, Razavi Khorasan, Iran.;Mashhad Univ Med Sci, Fac Med, Dept Physiol, Mashhad, Razavi Khorasan, Iran..
    Kianian, Farzaneh
    Univ Tehran Med Sci, Sch Med, Dept Physiol, Tehran, Iran..
    Khazdair, Mohammad Reza
    Birjand Univ Med Sci, Cardiovasc Dis Res Ctr, Birjand, Iran..
    El-Seedi, Hesham
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Farmakognosi. Jiangsu Univ, Int Res Ctr Food Nutr & Safety, Zhenjiang 212013, Jiangsu, Peoples R China; Al Rayan Coll, Al Rayan Res & Innovat Ctr, Medina 42541, Saudi Arabia.
    Boskabady, Mohammad Hosein
    Mashhad Univ Med Sci, Appl Biomed Res Ctr, Mashhad, Razavi Khorasan, Iran.;Mashhad Univ Med Sci, Fac Med, Dept Physiol, Mashhad, Razavi Khorasan, Iran..
    Effects of Allium cepa and Its Constituents on Respiratory and Allergic Disorders: A Comprehensive Review of Experimental and Clinical Evidence2021In: Evidence-based Complementary and Alternative Medicine, ISSN 1741-427X, E-ISSN 1741-4288, Vol. 2021, article id 5554259Article, review/survey (Refereed)
    Abstract [en]

    The health benefits of Allium cepa (A. cepa) have been proclaimed for centuries. Various pharmacological and therapeutic effects on respiratory, allergic, and immunologic disorders are shown by A. cepa and its constituents. Flavonoids such as quercetin and kaempferol, alk(en)yl cysteine sulfoxides including S-methyl cysteine sulfoxide and S-propyl cysteine sulfoxide, cycloalliin, thiosulfinates, and sulfides are the main compounds of the plant. A. cepa displays broad-spectrum pharmacological activities including antioxidant, anti-inflammatory, antihypertensive, and antidiabetic effects. Our objective in this review is to present the effects of A. cepa and its constituents on respiratory, allergic, and immunologic disorders. Different online databases were searched to find articles related to the effect of A. cepa extracts and its constituents on respiratory, allergic, and immunologic disorders until the end of December 2020 using keywords such as onion, A. cepa, constituents of A. cepa, therapeutic effects and pharmacological effects, and respiratory, allergic, and immunologic disorders. Extracts and constituents of A. cepa showed tracheal smooth muscle relaxant effects, indicating possible bronchodilator activities or relieving effects on obstructive respiratory diseases. In experimental animal models of different respiratory diseases, the preventive effect of various extracts and constituents of A. cepa was induced by their antioxidant, immunomodulatory, and anti-inflammatory effects. The preventive effects of the plant and its components on lung disorders induced by exposure to noxious agents as well as lung cancer, lung infection, and allergic and immunologic disorders were also indicated in the experimental and clinical studies. Therefore, this review may be considered a scientific basis for development of therapies using this plant, to improve respiratory, allergic, and immunologic disorders.

    Download full text (pdf)
    FULLTEXT01
  • 342.
    Beiroth, Femke
    et al.
    Christiana Albertina Univ Kiel, Otto Diels Inst Organ Chem, Otto Hahn Pl 3-4, D-24118 Kiel, Germany.
    Koudelka, Tomas
    Christiana Albertina Univ Kiel, Inst Expt Med, Systemat Prote & Bioanalyt, Niemannsweg 11, D-24105 Kiel, Germany.
    Overath, Thorsten
    Christiana Albertina Univ Kiel, Inst Expt Med, Systemat Prote & Bioanalyt, Niemannsweg 11, D-24105 Kiel, Germany.
    Knight, Stefan D.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structural Biology.
    Tholey, Andreas
    Christiana Albertina Univ Kiel, Inst Expt Med, Systemat Prote & Bioanalyt, Niemannsweg 11, D-24105 Kiel, Germany.
    Lindhorst, Thisbe K.
    Christiana Albertina Univ Kiel, Otto Diels Inst Organ Chem, Otto Hahn Pl 3-4, D-24118 Kiel, Germany.
    Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH2018In: Beilstein Journal of Organic Chemistry, ISSN 2195-951X, E-ISSN 1860-5397, Vol. 14, p. 1890-1900Article in journal (Refereed)
    Abstract [en]

    Photoaffinity labeling is frequently employed for the investigation of ligand-receptor interactions in solution. We have employed an interdisciplinary methodology to achieve facile photolabeling of the lectin FimH, which is a bacterial protein, crucial for adhesion, colonization and infection. Following our earlier work, we have here designed and synthesized diazirine-functionalized mannosides as high-affinity FimH ligands and performed an extensive study on photo-crosslinking of the best ligand (mannoside 3) with a series of model peptides and FimH. Notably, we have employed high-performance mass spectrometry to be able to detect radiation results with the highest possible accuracy. We are concluding from this study that photolabeling of FimH with sugar diazirines has only very limited success and cannot be regarded a facile approach for covalent modification of FimH.

    Download full text (pdf)
    fulltext
  • 343. Belda, O
    et al.
    Kaiser, N F
    Bremberg, U
    Larhed, M
    Hallberg, A
    Moberg, C
    Highly stereo- and regioselective allylations catalyzed by Mo-pyridylamide complexes: Electronic and steric effects of the ligand2000In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 65, no 18, p. 5868-5870Article in journal (Refereed)
  • 344. Beletskaya, I.P
    et al.
    Bregadze, V.I.
    Ivushkin, V.A.
    Petrovskii, P.V.
    Sivaev, I.B.
    Sjöberg, Stefan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry II. Organisk kemi.
    Zhigareva, G.B.
    New B-substituted derivatives of m-carborane, p-carborane, and cobalt bis(1,2-decarbollide) anion2004In: J. Organomet. Chem., no 689, p. 2920-Article in journal (Refereed)
  • 345.
    Belfrage, Anna Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Design and Synthesis of Hepatitis C Virus NS3 Protease Inhibitors: Targeting Different Genotypes and Drug-Resistant Variants2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Since the first approved hepatitis C virus (HCV) NS3 protease inhibitors in 2011, numerous direct acting antivirals (DAAs) have reached late stages of clinical trials. Today, several combination therapies, based on different DAAs, with or without the need of pegylated interferon-α injection, are available for chronic HCV infections. The chemical foundation of the approved and late-stage HCV NS3 protease inhibitors is markedly similar. This could partly explain the cross-resistance that have emerged under the pressure of NS3 protease inhibitors. The first-generation NS3 protease inhibitors were developed to efficiently inhibit genotype 1 of the virus and were less potent against other genotypes.

    The main focus in this thesis was to design and synthesize a new class of 2(1H)-pyrazinone based HCV NS3 protease inhibitors, structurally dissimilar to the inhibitors evaluated in clinical trials or approved, potentially with a unique resistance profile and with a broad genotypic coverage. Successive modifications were performed around the pyrazinone core structure to clarify the structure-activity relationship; a P3 urea capping group was found valuable for inhibitory potency, as were elongated R6 residues possibly directed towards the S2 pocket. Dissimilar to previously developed inhibitors, the P1’ aryl acyl sulfonamide was not essential for inhibition as shown by equally good inhibitory potency for P1’ truncated inhibitors. In vitro pharmacokinetic (PK) evaluations disclosed a marked influence from the R6 moiety on the overall drug-properties and biochemical evaluation of the inhibitors against drug resistant enzyme variants showed retained inhibitory potency as compared to the wild-type enzyme. Initial evaluation against genotype 3a displayed micro-molar potencies. Lead optimization, with respect to improved PK properties, were also performed on an advanced class of HCV NS3 protease inhibitors, containing a P2 quinazoline substituent in combination with a macro-cyclic proline urea scaffold with nano-molar cell based activities.

    Moreover, an efficient Pd-catalyzed C-N urea arylation protocol, enabling high yielding introductions of advanced urea substituents to the C3 position of the pyrazinone, and a Pd-catalyzed carbonylation procedure, to obtain acyl sulfinamides, were developed. These methods can be generally applicable in the synthesis of bioactive compounds containing peptidomimetic scaffolds and carboxylic acid bioisosteres.

    Download full text (pdf)
    fulltext
    Download (jpg)
    presentationsbild
  • 346.
    Belfrage, Anna Karin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Abdurakhmanov, Eldar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Åkerblom, Eva
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Brandt, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Oshalim, Anna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Gising, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Skogh, Anna
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Neyts, Johan
    Danielson, U. Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Sandström, Anja
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Discovery of pyrazinone based compounds that potently inhibit the drug resistant enzyme variant R155K of the hepatitis C virus NS3 protease2016In: Bioorganic & Medicinal Chemistry, ISSN 0968-0896, E-ISSN 1464-3391, Vol. 24, no 12, p. 2603-2620Article in journal (Refereed)
    Abstract [en]

    Herein, we present the design and synthesis of 2(1H)-pyrazinone based HCV NS3 protease inhibitors with variations in the C-terminus. Biochemical evaluation was performed using genotype 1a, both the wildtype and the drug resistant enzyme variant, R155K. Surprisingly, compounds without an acidic sulfonamide retained good inhibition, challenging our previous molecular docking model. Moreover, selected compounds in this series showed nanomolar potency against R155K NS3 protease; which generally confer resistance to all HCV NS3 protease inhibitors approved or in clinical trials. These results further strengthen the potential of this novel substance class, being very different to the approved drugs and clinical candidates, in the development of inhibitors less sensitive to drug resistance.

  • 347.
    Belfrage, Anna Karin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Gising, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Svensson, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Åkerblom, Eva
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Sköld, Christian
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Sandström, Anja
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Efficient and Selective Palladium-Catalysed C-3 Urea Couplings to 3,5-Dichloro-2(1H)-pyrazinones2015In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 5, p. 978-986Article in journal (Refereed)
    Abstract [en]

    The development of a robust palladium-catalysed urea N-arylation protocol to install various ureas at the 3-position of the 2(1H)-pyrazinone scaffold is described. The method involves Pd(OAc)2 in combination with bidentate ligands, xantphos [4,5-bis(diphenylphosphino)-9,9-dimethylxanthene] in particular, and resulted in good to excellent coupling yields of aliphatic, aromatic, and sterically hindered ureas. Furthermore, the C-3 chlorine was shown to be selectively displaced in the presence of aryl halide ureas, and this finding was supported by density functional theory (DFT) calculations. This allows further diversification of the scaffold for the production of compound libraries. Overall, the protocol facilitates further exploitation of pyrazinones as beta-sheet-inducing scaffolds in the development of sophisticated peptidomimetics/protease inhibitors. This is exemplified here by the synthesis of a new pyrazinone-based hepatitis C virus (HCV) NS3 protease inhibitor.

  • 348. Belfrage, Anna Karin
    et al.
    Wakchaure, Prasad
    Larhed, Mats
    Sandström, Anja
    Palladium-catalyzed carbonylation of aryl iodides with sulfinamidesManuscript (preprint) (Other academic)
  • 349.
    Belfrage, Anna Karin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Wakchaure, Prasad
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Larhed, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Sandström, Anja
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Palladium-Catalyzed Carbonylation of Aryl Iodides with Sulfinamides2015In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 32, p. 7069-7074Article in journal (Refereed)
    Abstract [en]

    A facile palladium(0)-catalyzed carbonylative protocol for the generation of new acyl-sulfinamides in moderate to good yields is described. Aliphatic and aromatic sulfinamides were exploited as hitherto unexplored nucleophiles in carbonylation chemistry, with use of CO gas generated ex situ from Mo(CO)6 in a sealed two-chamber system. Both electron-poor and electron-rich (hetero)aryl iodides were employed as electrophiles. The two-chamber system and the use of an inorganic base were essential for efficacious synthesis of acyl-sulfinamide products. Finally, it was demonstrated that a one-pot (or single-vial) synthesis of acyl-sulfinamides was feasible under CO at balloon pressure in the presence of Cs2CO3 as base.

  • 350.
    Belhaj, Mohamed Hedi
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Copper and nickel catalyzed synthesis of 1,3-diynes and exploration of cobalt catalyzed C-H activation in unconventional solvents2022Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
45678910 301 - 350 of 4163
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf