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  • 51. Odille, Fabrice G. J.
    et al.
    Jonsson, Stefan
    Stjernqvist, Susann
    Rydén, Tobias
    Lund University.
    Wärnmark, Kenneth
    On the Characterization of Dynamic Supramolecular Systems: A General Mathematical Association Model for Linear Supramolecular Copolymers and Application on a Complex Two-Component Hydrogen-Bonding System2007In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, no 34, p. 9617-9636Article in journal (Refereed)
    Abstract [en]

    A general mathematical model for the characterization of the dynamic (kinetically labile) association of supramolecular assemblies in solution is presented. It is an extension of the equal K (EK) model by the stringent use of linear algebra to allow for the simultaneous presence of an unlimited number of different units in the resulting assemblies. It allows for the analysis of highly complex dynamic equilibrium systems in solution, including both supramolecular homo- and copolymers without the recourse to extensive approximations, in a field in which other analytical methods are difficult. The derived mathematical methodology makes it possible to analyze dynamic systems such as supramolecular copolymers regarding for instance the degree of polymerization, the distribution of a given monomer in different copolymers as well as its position in an aggregate. It is to date the only general means to characterize weak supramolecular systems. The model was fitted to NMR dilution titration data by using the program Matlab((R)), and a detailed algorithm for the optimization of the different parameters has been developed. The methodology is applied to a case study, a hydrogen-bonded supramolecular system, salen 4+porphyrin 5. The system is formally a two-component system but in reality a three-component system. This results in a complex dynamic system in which all monomers are associated to each other by hydrogen bonding with different association constants, resulting in homo- and copolymers 4,,5,, as well as cyclic structures 6 and 7, in addition to free 4 and 5. The system was analyzed by extensive NMR dilution titrations at variable temperatures. All chemical shifts observed at different temperatures were used in the fitting to obtain the Delta H degrees and Delta S degrees values producing the best global fit. From the derived general mathematical expressions, system 4+5 could be characterized with respect to above-mentioned parameters.

  • 52. Ohlin, C. André
    et al.
    Beni, Zoltan
    Laurenczy, Gábor
    Ruiz, Nuria
    Masdeu-Bulto, Anna M.
    Heterogeneous dehalogenation of arylhalides in the presence of ionic liquids2007In: Applied organometallic chemistry, ISSN 0268-2605, E-ISSN 1099-0739, Vol. 21, no 3, p. 156-160Article in journal (Refereed)
    Abstract [en]

    Dehydrohalogenation of haloaromatics in ionic liquids derived from ethylmethylimidazolium or similar salts has been performed using Pd-C, Pd(OAc)(2) and other catalysts using formate salts as a hydrogen source. In the ionic liquid [emim][BF4], chlorobenzene was dehalogenated by up to 40%, bromobenzene up to 25% and iodobenzene up to 41% in 2 h. Reactions in the absence of the ionic liquid were also performed.

  • 53.
    Pei, Zhichao
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dong, Hai
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Caraballo, Rémi
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of Positional Thiol Analogs of β-D-Galactopyranose2007In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 29, p. 4927-4934Article in journal (Refereed)
    Abstract [en]

    Approaches toward the synthesis of thio- beta -D -galactose derivatives are described. These compounds were prepared from the parent carbohydrates: D-galactose, methyl P-D-galactoside and methyl P-D-glucoside, respectively. It was found that not only the strategies of protecting group introduction and selective deprotection, but also the choices of solvent and nucleophilic reagent concentration were crucial to allow the efficient introduction of sulfur at different positions of the galactose ring. The effects from the solvent, the nucleophilic reagent concentration, and the protecting group patterns have been investigated. The results clearly show that ester protecting groups play highly important roles for the synthesis of thio-containing carbohydrates, requiring nonpolar solvents to suppress the neighboring group participation. For the Lattrell-Dax (nitrite -mediated) inversion reaction, employed in the synthetic route to the 2-thio-beta-D-galactoside, intramolecular nucleophilic attack, as well as stronger stereospecific ester activation, are necessary to overcome hindrance from 4,6-O-benzylidene protection.

  • 54.
    Pemberton, Nils
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Synthesis and functionalization of ring-fused 2-pyridones: Targeting pili formation in E. coli2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bicyclic dihydrothiazolo fused 2-pyridones have been studied as a new class of antibacterial agents, termed pilicides, that target the formation of adhesive bacterial surface organelles (pili) in pathogenic bacteria. Synthetic methods to further functionalize the bicyclic 2-pyridone scaffold have been developed in order to increase water-solubility and thereby facilitate biological evalua-tions. This was accomplished by introducing aminomethylenes at the open position C-6. Tertiary amines were introduced via a microwave–assisted Mannich reaction and a synthetic route based on a formyl intermediate gave access to primary, secondary and tertiary amines, but also to other interesting functionalities. Biological evaluation confirmed that several of the function-alized compounds inhibited pili formation in uropathogenic E. coli., as dem-onstrated by assays of hemagglutination, biofilm formation and adherence to bladder cells. Co-crystallizing one of the pilicides with the target protein gave information about the binding site and based on this a mechanism of action was proposed, which was supported experimentally by surface plas-mon resonance and single point mutations in the protein.

    Furthermore, the previously developed acylketene imine reaction used to prepare bicyclic thiazolo fused 2-pyridone pilicides has been developed to allow preparation of other ring-fused 2-pyridone systems. Benzo[a]quinolizine-4-ones and indolo[2,3-a]quinolizine-4-ones could be prepared in a fast and simple manner starting from dihydroisoquinolines and a β-carboline. Finally, this method could also be applied for the preparation of heteroatom analogs of the previously studied sulfur containing pilicides. Biological evaluations established that the sulfur atom can be replaced by oxygen and still maintain the ability to prevent pili assembly.

  • 55.
    Piens, Kathleen
    et al.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Henriksson, Maria
    KTH, School of Biotechnology (BIO).
    Gullfot, Fredrika
    Lopez, Marie
    Fauré, Régis
    Ibatullin, Farid M.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Teeri, Tuula T.
    KTH, School of Biotechnology (BIO), Glycoscience.
    Driguez, Hugues
    Brumer, Harry
    KTH, School of Biotechnology (BIO), Glycoscience.
    Glycosynthase activity of hybrid aspen xyloglucan endo-transglycosylase PttXET16-34 nucleophile mutants2007In: Organic and Biomolecular Chemistry, ISSN 1477-0520, Vol. 5, no 24Article in journal (Refereed)
    Abstract [en]

    Glycosynthases are active-site mutants of glycoside hydrolases that catalyse glycosyl transfer using suitable activated donor substrates without competing product hydrolysis ( S. M. Hancock, M. D. Vaughan and S. G. Withers, Curr. Opin. Chem. Biol., 2006, 10, 509-519). Site-directed mutagenesis of the catalytic nucleophile, Glu-85, of a Populus tremula x tremuloides xyloglucan endo-transglycosylase (PttXET16-34, EC 2.4.1.207) into alanine, glycine, and serine yielded enzymes with glycosynthase activity. Product analysis indicated that PttXET16-34 E85A in particular was able to catalyse regio- and stereospecific homo- and hetero- condensations of alpha-xylogluco-oligosaccharyl fluoride donors XXXG alpha F andXLLG alpha F to produce xyloglucans with regular sidechain substitution patterns. This substrate promiscuity contrasts that of the Humicola insolens Ce17B E197A glycosynthase, which was not able to polymerise the di-galactosylated substrate XLLG alpha F. The production of the PttXET16-34 E85A xyloglucosynthase thus expands the repertoire of glycosynthases to include those capable of synthesising structurally homogenenous xyloglucans

  • 56.
    Piera, Julio
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Persson, Andreas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Caldentey, Xisco
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Water as nucleophile in palladium-catalyzed oxidative carbohydroxylation of allene-substituted conjugated dienes2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 46, p. 14120-14121Article in journal (Refereed)
    Abstract [en]

    An efficient palladium(II)-catalyzed oxidative carbohydroxylation of allene-substituted conjugated dienes in aqueous media has been developed. The reaction is conducted employing p-benzoquinone as the stoichiometric reoxidant for the palladium or under aerobic conditions with essentially the same outcome. It is worth mentioning that this is the first example of a palladium(II)-catalyzed oxidation where a carbon−carbon bond is formed in water and also one of the few cases of nucleophilic attack by water on a (π-allyl)palladium complex.

  • 57. Pozo-Gonzalo, Cristina
    et al.
    Pomposo, Jose A.
    Rodriguez, Javier
    Schmidt, Elena Yu.
    Vasil'tsov, Alexander M.
    Zorina, Nadezhda V.
    Ivanov, Andrey V.
    Trofimov, Boris A.
    Mikhaleva, Al'bina I.
    Zaitsev, Alexey B.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis and electrochemical study of narrow band gap conducting polymers based on 2,2 '-dipyrroles linked with conjugated aza-spacers2007In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 157, no 1, p. 60-65Article in journal (Refereed)
    Abstract [en]

    A series of 2,2'-dipyrrole monomers separated by aza-spacers (N,N'-bis-(1H-pyrrol-2-ylmethylene)-benzene-1,4-diamine; N-4,N-4'-bis(1H-pyrrol-2-ylmethylene)-biphenyl-4,4'-diamine; N,N'-bis-[1-(1H-pyrrol-2-yl)-ethylidene]-hydrazine; and 4,4'-bis[(1H-pyrrol-2-yl)-diazenyl] biphenyl) have been synthesised using modified Schiff and azo-coupling reactions. The new 2,2'-dipyrroles linked with conjugated aza-spacers have been evaluated as precursors of narrow band gap conducting polymers. Electrochemically synthesized poly(N,N'-bis-[1-(1H-pyrrol-2-yl)ethylidene]-hydrazine) displays a narrow band gap of just 0.7 eV, making it a suitable candidate for optoelectronic applications.

  • 58.
    Rios, Ramón
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sundén, Henrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Vesely, Jan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dziedzic, Pawel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A simple organocatalytic enantioselective cyclopropanation of alpha-beta-unsaturated aldehydes2007In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 349, p. 1028-1032Article in journal (Refereed)
  • 59.
    Rosengren, Johan
    et al.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Bathgate, Ross
    Craik, David
    Daly, Norelle
    Haugaard-Kedström (published under the name Haugaard-Jönsson), Linda M.
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Hossain, Akther
    Lin, Feng
    Wade, John
    Structural insights into the action of relaxin peptide hormones2007In: Proceedings of the 4th International Peptide Symposium / [ed] Wilce, Jackie, Cairns, Australia, 2007Conference paper (Refereed)
  • 60.
    Slättegård, Rikard
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Structures Related to the Capsular Polysaccharide of Neisseria meningitidis Serogroup A and to Mycothiol2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the synthesis of structures related to the capsular polysaccharide of Neisseria meningitidis serogroup A and the synthesis of analogues of mycothiol, a compound produced by Mycobacterium tuberculosis. The first part of the thesis describes the synthesis of structural elements present in the native capsular polysaccharide of Neisseria meningitidis serogroup A. In this part, an improved synthesis of 2-azido-2-deoxy-D-mannopyranose is included. The second part of the thesis describes the formation of stable C-phosphonate analogues related to the capsular polysaccharide. The last part outlines the formation of analogues of mycothiol, where the syntheses of a bicyclic analogue and a thioglycosidic analogue are described.

  • 61.
    Stamatov, Stephan D.
    et al.
    -.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry. -.
    Regioselective and stereospecific opening of an oxirane system mediated by trifluoroacetic acid and halide anions. A new direct approach to C3-vicinal halohydrins.: -2007In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, ISSN -, Vol. 48, no -, p. 1887-1889Article in journal (Refereed)
    Abstract [en]

    -

  • 62.
    Steen, Robert
    Mälardalen University, Department of Biology and Chemical Engineering.
    The Synthesis of Molecular Switches Based Upon Ru(II) Polypyridyl Architecture for Electronic Applications2007Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    According to the famous axiom known as Moore’s Law the number of transistors that can be etched on a given piece of silicon, and therefore the computing power, will double every 18 to 24 months. For the last 40 years Moore’s prediction has held true as computers have grown more and more powerful. However, around 2020 hardware manufac-turers will have reached the physical limits of silicon. A proposed solution to this dilemma is molecular electronics. Within this field researchers are attempting to develop individual organic molecules and metal complexes that can act as molecular equivalents of electronic components such as diodes, transistors and capacitors. By utilizing molecular electronics to construct the next generation of computers processors with 100,000 times as many components on the same surface area could potentially be created.

    We have synthesized a range of new pyridyl thienopyridine ligands and compared the electrochemical and photophysical properties of their corresponding Ru(II) complexes with that with the Ru(II) complexes of a variety of ligands based on 6-thiophen-2-yl-2,2´-bipyridine and 4-thiophen-2-yl-2,2´-bipyridine. While the electrochemistry of the Ru(II) complexes were similar to that of unsubstituted [Ru(bpy)3]2+, substantial differences in luminescence lifetimes were found. Our findings show that, due to steric interactions with the auxiliary bipy-ridyl ligands, luminescence is quenched in Ru(II) complexes that in-corporate the 6-thiophen-2-yl-2,2´-bipyridine motif, while it is on par with the luminescence of [Ru(bpy)3]2+ in the Ru(II) complexes of the pyridyl thienopyridine ligands. The luminescence of the Ru(II) com-plexes based on the 4-thiophen-2-yl-2,2´-bipyridine motif was en-hanced compared to [Ru(bpy)3]2+ which indicates that complexes of this category are the most favourable for energy/electron-transfer sys-tems.

    At the core of molecular electronics are the search for molecular ON/OFF switches. We have synthesized a reversible double cyclome-tallated switch based on the Ru(tpy) complex of 3,8-bis-(6-thiophen-2-yl-pyridin-2-yl)-[4,7]phenanthroline. Upon treatment with acid/base the complex can be switched between the cyclometallated and the S-bonded form. This prototype has potentially three different states which opens the path to systems based on ternary computer logic.

  • 63.
    Strübing, Dirk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krumlinde, Patrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Piera, Julio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dynamic kinetic resolution of primary alcohols with an unfunctionalized stereogenic center in the beta-position2007In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 349, p. 1577-1581Article in journal (Refereed)
  • 64.
    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.

  • 65.
    Sundén, Henrik
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A highly enantioselective catalytic domino aza-Michael/aldol reaction: one-pot organocatalytic asymmetric synthesis of 1,2-dihydroquinolidines2007In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 349, p. 827-832Article in journal (Refereed)
  • 66.
    Tilliet, Mélanie
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Levacher, Vincent
    Laboratoire de Chimie Organique Fine et Hétérocyclique, UMR 6014, Université et INSA de Rouen.
    Polymer-Bound Pyridine-Bis(oxazoline). Preparation through Click Chemistry and Evaluation in Asymmetric Catalysis2007In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 349, no 13, p. 2079-2084Article in journal (Refereed)
    Abstract [en]

    A pyridine-bis(oxazoline) ligand was efficiently immobilized by copper(I)-catalyzed azide-alkyne cycloaddition onto a polystyrene resin. The so obtained click-pybox resin 1a was associated with various metal salts (YbCl3, LuCl3, CuOTf) and the resulting resin-bound catalysts were explored in ring-opening of cyclohexene oxide, silylcyanation of benzaldehyde and alkynylation of imines. These new polymer-supported catalysts exhibit good to excellent performances in terms of catalytic activity, enantioselectivity and recyclability.

  • 67.
    Torssell, Staffan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Stereoselective Synthesis of Amino Alcohols: Applications to Natural Product Synthesis2007Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis is divided into four separate parts with amino alcohols as the common feature.

    The first part of the thesis describes the development of an efficient three-component approach to the synthesis of α-hydroxy-β-amino esters. Utilizing a highly diastereoselective Rh(II)-catalyzed 1,3-dipolar cycloaddition of carbonyl ylides to various aldimines, syn-α-hydroxy-β-amino esters are formed in high yields and excellent diastereoselectivities. An asymmetric version was also developed by employing chiral α-methylbenzyl imines as dipolarophiles yielding enantiomerically pure syn-α-hydroxy-β-amino esters. This methodology was also applied on a short asymmetric synthesis of the paclitaxel side-chain as well as in an asymmetric synthetic approach towards the proteasome inhibitor omuralide. Furthermore, the use of chiral Rh(II) carboxylates furnishes the syn-α-hydroxy-β-amino esters in moderate enantioselectivity (er up to 82:18), which indicates that the reaction proceeds via a metal-associated carbonyl ylide.

    The second part describes the development of a 1,3-dipolar cycloaddition reaction of azomethine ylides to aldehydes for the synthesis of α-amino-β-hydroxy esters. Different methods for the generation of the ylides, including Vedejs’ oxazole methology and an Ag(I)/phosphine-catalyzed approach have been evaluated. The best results were obtained with the Ag(I)/phosphine approach, which yielded the desired α-amino-β-hydroxy ester in 68% yield and 3.4:1 syn:anti-selectivity.

    The last two parts deals with the total synthesis of the amino alcohol-containing natural products D-erythro-sphingosine and (−)-stemoamide. The key transformation in the sphingosine synthesis is a cross-metathesis reaction for the assembly of the polar head group and the aliphatic chain. In the stemoamide synthesis, the key feature is an iodoboration/Negishi/RCM-sequence for the construction of the β,γ-unsaturated azepine core of stemoamide followed by a stereoselective bromolactonization/1,4-reduction strategy for the installation of the requisite C8-C9 trans-stereochemistry.

  • 68.
    Torssell, Staffan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wanngren, Emil
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Total Synthesis of (-)-Stemoamide2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 11, p. 4246-4249Article in journal (Refereed)
    Abstract [en]

    A stereocontrolled total synthesis of (-)-stemoamide (1) is presented. The synthesis starts from commercially available (S)-pyroglutaminol (4). A chemoselective iodoboration of 5 was used to access key intermediate 3. The beta,gamma-unsaturated azepine derivative 2 was obtained via a Pd(0)-catalyzed sp(2)-sp(3) Negishi cross-coupling using a Reformatsky nucleophile followed by a ring-closing metathesis reaction. The required C8-C9 trans-stereochemistry of 1 was accessed through a stereoselective bromolactonization/1,4-reduction sequence.

  • 69.
    Tuzina, Pavel
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Somfai, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lewis acid mediated 1,2 -rearrangement of ammonium ylides2007In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 48, no 28, p. 4947-4949Article in journal (Refereed)
    Abstract [en]

    The first example of Lewis acid mediated [1,2]-rearrangement of various glycine derivatives has been developed. A brief study of steric and electronic properties of the migrating group is presented. The corresponding amides were obtained in good yields and in the case of substrate 4d, moderate diastereoselectivity was observed.

  • 70. Vesely, Jan
    et al.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Guiling
    Rios, Ramon
    Cordova, Armando
    Organocatalytic Enantioselective Aziridination of α,β-Unsaturated Aldehydes2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, p. 778-Article in journal (Refereed)
  • 71.
    Vesely, Jan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Organocatalytic enantioselective aziridination of alpha,beta-unsaturated aldehydes2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, p. 778-781Article in journal (Refereed)
  • 72.
    Wahlström, Niklas
    et al.
    Unit for Organic Chemistry, Department of Biosciences and Nutrition, Karolinska Institute, Novum Research Park.
    Slätt, Johnny
    Unit for Organic Chemistry, Department of Biosciences and Nutrition, Karolinska Institute, Novum Research Park.
    Stensland, Birgitta
    Early Development, AstraZeneca R&D, Södertälje, Sweden.
    Ertan, Anne
    Early Development, AstraZeneca R&D, Södertälje, Sweden.
    Bergman, Jan
    Unit for Organic Chemistry, Department of Biosciences and Nutrition, Karolinska Institute, Novum Research Park.
    Janosik, Tomasz
    Unit for Organic Chemistry, Department of Biosciences and Nutrition, Karolinska Institute, Novum Research Park.
    Synthetic Applications of Cyanoacetylated Bisindoles: Synthesis of Novel Cycloheptadiindoles, Indolocarbazoles, and Related Aza Analogues.2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 15, p. 5886-5889Article in journal (Refereed)
    Abstract [en]

    (Chemical Equation Presented) Cyclization reactions involving cyanoacetylated bisindoles have been studied, providing access to various novel cyclohepta[2,1-b:3,4-b′]diindole derivatives as well as some related fused pentacyclic systems. Treatment of 3-cyanoacetyl-2,3′-diindolylmethane with methanesulfonic acid gave 6-(cyanomethyl)indolo[3,2-b]carbazole in a good yield.

  • 73. Wang, Xuefeng
    et al.
    Ohlin, C. André
    Lu, Qinghua
    Fei, Zhaofu
    Hu, Jun
    Dyson, Paul J.
    Cytotoxicity of ionic liquids and precursor compounds towards human cell line HeLa2007In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 9, no 11, p. 1191-1197Article in journal (Refereed)
    Abstract [en]

    The toxicity of ethyl-, butyl-, octyl-, benzyl-, and allyl-substituted 1-alkyl-3-methylimidazolium, alkylpyridinium, N-alkyl-N, N-dimethyl-N-(2-hydroxyethyl) ammonium (choline derivatives) and alkyl-triethylammonium salts towards HeLa cells has been studied. The relative toxicities have been determined in the presence and absence of foetal bovine serum using an MTT assay after 24 and 48 h, and attempts to determine possible sources of the observed toxicity investigated using microscopy and by measuring the intracellular calcium concentration, presence of reactive oxygen species and mitochondrial membrane potential in cells exposed to 1-ethyl-3-methylimidazolium tetrafluoroborate.

  • 74. Wang, Zhen
    et al.
    Liu, Jian-Hui
    He, Cheng-Jiang
    Jiang, Shi
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Li-Cheng
    Azadithiolates cofactor of the iron-only hydrogenase and its PR3-monosubstituted derivatives: Synthesis, structure, electrochemistry and protonation2007In: Journal of Organometallic Chemistry, ISSN 0022-328X, E-ISSN 1872-8561, Vol. 692, no 24, p. 5501-5507Article in journal (Refereed)
    Abstract [en]

    The core structure (mu-SCH2)(2)NH[Fe-2(CO)(6)](5) of Fe-only hydrogenases active site model has been synthesized by the condensation of iron carbonyl sulfides, formaldehyde and silyl protected amine. Its monosubstituted complexes (mu-SCH2)(2)NH[Fe-2(CO)(5)PR3] (R = Ph (6), Me (7)) were accordingly prepared. The coordination configurations of 5 and 6 were characterized by X-ray crystallography. Protonation of complex 7 to form the N-protonated product occurs in an acetonitrile solution upon addition of triflic acid. The redox properties of these model complexes were studied by cyclic voltammetry.

  • 75. Wang, Zhen
    et al.
    Liu, Jianhui
    He, Chengjiang
    Jiang, Shi
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Diiron azadithiolates with hydrophilic phosphatriazaadamantane ligand as iron-only hydrogenase active site models: Synthesis, structure, and electrochemical study2007In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 360, no 7, p. 2411-2419Article in journal (Refereed)
    Abstract [en]

    Three novel complexes (mu-adt)[Fe-2(CO)(5)PTA] (2-PTA), (mu-adt)[Fe-2(CO)(4)PTA(2)](2-PTA(2)) and (mu-adt)[Fe-2(CO)(5)DAPTA] (2-DAPTA), where adt is SCH2N(CH2CH2CH3)CH2S, PTA stands for 1,3,5-triaza-7-phosphaadamantane and DAPTA is 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane, were prepared as the models of the iron hydrogenase active site through controlled CO displacement of (mu-adt)[Fe-2(CO)(6)] with PTA and DAPTA. The coordination configurations of 2-PTA and 2-PTA(2) were characterized by X-ray crystallography. The disubstituted diiron complex 2-PTA(2) features a basal/apical coordination mode, instead of the typical transoid basal/basal configuration. Protonation of three complexes only occurred at the bridging-N atom, rather than at the tertiary nitrogen atom on the PTA or DAPTA ligands. Electrochemical properties of the complexes were studied in acetonitrile or a mixture of acetonitrile and water in the presence of acetic acid, by cyclic voltammetry. The current sensitivity of the reduced species to acid concentration in the presence of H2O is greater than in the pure CH3CN solution.

  • 76.
    Wiklund, Susanne
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Spectroscopic data and multivariate analysis: tools to study genetic perturbations in poplar trees2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In our society in the 21st century one of the greatest challenges is to provide raw materials to the industry in a sustainable way. This requires increased use of renewable raw materials such as wood. Wood is widely used in pulp, paper and textile industries and ongoing research efforts aim to extend the use of wood in e.g. liquid biofuels and green chemicals. At Umeå Plant Science Center (UPSC) poplar trees are used as model systems to study wood formation. The objective is to understand the function of the genes underlying the wood forming process. This knowledge could result in improved chemical and physical wood properties suitable for different industrial processes. This will in turn meet the demands for a sustainable development.

    This thesis presents tools and strategies to unravel information regarding genetic perturbations in poplar trees by the use of nuclear magnetic resonance (NMR) spectroscopy and multivariate analysis (MVA). Furthermore, gas chromatography/mass spectrometry (GC/MS) is briefly discussed in this context. Multivariate methods to find patterns and trends in NMR data have been used for more than 30 years. In the beginning MVA was applied in pattern recognition studies in order to characterize chemical structures with different ligands and in different solvents. Today, the multivariate methods have developed and the research have changed focus towards the study of biofluids from plant extracts, urine, blood plasma, saliva etc. NMR spectra of biofluids can contain thousands of resonances, originating from hundreds of different compounds. This type of complex data can be hard to summarize and interpret without appropriate tools and require sophisticated strategies for data evaluation. Related fields of research are rapidly growing and are here referred to as metabolomics.

    Five different research projects are presented which includes analysis of poplar samples where macromolecules such as pectin and also small molecules such as metabolites were analysed by high resolution magic angle spinning (HR/MAS) NMR spectroscopy, 1H-13C HSQC NMR and GC/MS. The discussion topics include modelling of metabolomic time dependencies in combination with genetic variation, validation of orthogonal projections to latent structures (OPLS) models, selection of putative biomarkers related to genetic modification from OPLS-discriminant analysis (DA) models, measuring one of the main components found in the primary cell-walls of poplar i.e. pectin, the use of Fourier transformed two-dimensional (2D) NMR data in OPLS modelling and model complexity in a PLS model.

  • 77.
    Wingstrand, Erica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Li, Fei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    O-Acylated Cyanohydrins: Versatile Intermediates and Products2007In: Chimica Oggi, ISSN 0392-839X, Vol. 25, no 5, p. 14-15Article in journal (Refereed)
    Abstract [en]

    Addition of ketonitriles to prochiral aromatic or aliphatic aldehydes in the presence of a catalytic system consisting of a chiral Lewis acid and an achiral Lewis base gives access to chiral enantioenriched O-acylated cyanohydrins. The products are useful for diverse potential applications.

  • 78.
    Wingstrand, Erica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hamberg, Anders
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    655-ORGN - Synthesis of highly enantioenriched cyanohydrins by dual Lewis acid - Lewis base activation2007In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 234, p. 655-ORGN-Article in journal (Other academic)
    Abstract [en]

    Enantioenriched acylated cyanohydrins serve as versatile synthons and are themselves important synthetic targets.  By using our efficient catalytic dual Lewis acid - Lewis base activation system, a range of α-ketonitriles were added to both arom. and aliph. aldehydes affording highly enantioenriched O-acylated cyanohydrins in excellent yields.  The reactions proceeded smoothly in only one step with perfect atom economy.  Our recent results as well as the scope and limitations of the system will be presented together with mechanistic aspects.

  • 79. Yoo, Eun Jeong
    et al.
    Ahlquist, Mårten
    Department of Chemistry, Building 201, Kemitorvet Technical University of Denmark.
    Kim, Seok Hwan
    Bae, Imhyuck
    Fokin, Valery V.
    Sharpless, K. Barry
    Chang, Sukbok
    Copper-catalyzed synthesis of N-sulfonyl-1,2,3-triazoles: Controlling selectivity2007In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 46, no 10, p. 1730-1733Article in journal (Refereed)
    Abstract [en]

    (Chemical Equation Presented) 4-Substituted 1-(N-sulfonyl)-1,2,3-triazoles are selectively obtained by using the Cu-catalyzed azide-alkyne cycloaddition reaction with sulfonyl azides. Performing the reaction at 0°C in chloroform in the presence of 2,6-lutidine and Cul as the catalyst effectively prevents the ketenimine pathway and provides convenient access to N-sulfonyltriazoles in good to excellent yields.

  • 80.
    Zalubovskis, Raivis
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Fjellander, Ester
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Szabó, Zoltán
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Stereochemical Control of Chirally Flexible Phosphepines2007In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2007, no 1, p. 108-115Article in journal (Refereed)
    Abstract [en]

    The barriers to interconversion of the two enantiomeric atropisomers of 6-methoxy-6,7-dihydro-5H-dibenzo[c,e]phosphepine and that of the diastereomeric forms of 6-(-)menthoxy-6,7-dihydro-3H-dibenzo[c,e]phosphepine were determined by NMR spectroscopical methods to be 19.3 and 18.5 kcalmol(-1), respectively, at 298 K. The ratio of the atropisomers was shown to depend on the group bound to phosphorus. Only complexes with two homochiral ligands bound to the each metal center were obtained upon reaction with [Rh(COD)(2)](+) BF4-. The Rh complexes catalyzed the hydrogenation of alpha-acetamidocinnamate. The major isomer of 6-(-)-menthoxy-6,7-dihydro-5H-dibenzo[c,e]phosphepine was found to exhibit higher activity but to afford a product with lower ee than its diastereomer.

  • 81.
    Zou, Dapeng
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Andersson, Samir
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Rong
    KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sun, Shiguo
    Åkermark, Björn
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Selective binding of cucurbit 7 uril and beta-cyclodextrin with a redox-active molecular triad Ru(bpy)(3)-MV2+-naphthol2007In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 45, p. 4734-4736Article in journal (Refereed)
    Abstract [en]

    A 1:1:1 inclusion complex is formed by the binding interactions among beta-CD, CB[ 7] hosts, and Ru(bpy)(3)-terminated viologen naphthalene guest in aqueous solution, in which the positions of both CB[7] and beta-CD are closer to the Ru stopper than in the respective 1:1 inclusion complexes, forming a tightened nut on bolt'' structural mode.

12 51 - 81 of 81
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