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  • 1.
    Ali, Tara
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Weintraub, Andrej
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural determination of the O-antigenic polysaccharide from the Shiga toxin-producing Escherichia coli O1712006Inngår i: Carbohydrate Research, ISSN 0008-6215, Vol. 341, s. 1878-1883Artikkel i tidsskrift (Fagfellevurdert)
  • 2.
    Anderlund, Magnus F.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zheng, J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ghiladi, M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kritikos, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Rivière, Erik
    Sun, Licheng
    Girerd, Jean-Jaques
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A New, Dinuclear High Spin Manganese(III) Complex with Bridging Phenoxy and Methoxy Groups. Structure and Magnetic Properties2006Inngår i: Inorganic Chemistry Communications, ISSN 1387-7003, E-ISSN 1879-0259, Vol. 9, nr 12, s. 1195-1198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new μ-phenoxy-μ-metoxy di-manganese(III) complex with the trisphenolic ligand, 2,6-bis[((2-hydroxybenzyl)(2-pyridylmethyl)amino)methyl]-4-methylphenol, was isolated as a perchlorate salt. The X-ray structure shows that the two manganese(III) ions are in a distorted octrahedral enviroment with approximately perpendicular Jahn–Teller axes. Investigation of the molar magnetic susceptibility reveals a ferromagnetic coupling between the two high-spin manganese(III) ions. Fitting of the data led to g = 2 and J = 12.5 cm−1

  • 3.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Strategies for fine-tuning the catalytic activity of pincer-complexes2006Inngår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 47, nr 50, s. 8999-9001Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Various methoxy substituted pincer-complexes were prepared in order to study the substituent effects on the catalytic activity in palladium catalyzed opening of vinyl epoxides and boronation of cinnamyl alcohol. The results clearly show that methoxy substitution at the para-position of the pincer-complex leads to up to fourfold acceleration of the catalytic reactions, while substitution of the side-arms does not change the activity of the complex or leads to a slight deceleration of the catalytic processes.

  • 4.
    Bogár, Krisztián
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Fransson, Ann-Britt L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric synthesis of 3,5-disubstituted piperidines by enzyme-metal combo catalysis2006Inngår i: Enzymatic Synthesis, Stockholm, Sweden, 2006Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 5.
    Borén, Linnéa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Xu, Yongmei
    Córdova, Armando
    Bäckvall, Jan-Erling
    (S)-Selective Kinetic Resolution and Chemoenzymatic Dynamic Kinetic Resolution of Secondary Alcohols2006Inngår i: Chemistry: a European Journal, ISSN 0947-6539, Vol. 12, nr 1, s. 225-232Artikkel i tidsskrift (Fagfellevurdert)
  • 6. Cotton, Hanna K.
    et al.
    Norinder, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Screening of Ligands in the Asymmetric Metallocenethiolatocopper(I)-Catalyzed Allylic Substitution with Grignard Reagents2006Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 62, nr 24, s. 5632-5640Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Screening of metallocenethiolate ligands for copper(I)-catalyzed substitution of allylic acetates with Grignard reagents has been carried out. The previously used ligand, lithium (R,Sp)-2-(1-dimethylaminoethyl)ferrocenylthiolate (4a), possessing both central and planar chirality, was the starting point for the screening. It was found that the diastereomeric ligand lithium (R,Rp)-2-(1-dimethylaminoethyl)ferrocenylthiolate (4b) exhibiting reversed planar chirality gave increased enantioselectivity in the allylic substitution, at least when cinnamyl acetate was used as a substrate. The ruthenocene-based ligand lithium (R,Sp)-2-(1-dimethylaminoethyl)ruthenocenylthiolate (4c) gave an enhanced reaction rate, but lower chiral induction. The use of disulfide bis[(R,Sp)-2-(1-dimethylaminoethyl)ferrocenyl]disulfide (7a) as a ligand precursor worked well but resulted in lower enantioselectivity.

  • 7.
    Cumpstey, Ian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    New oligosaccharide analogues: non-glycosidically linked thioether-bridged pseudodisaccharides2006Inngår i: Synlett, ISSN 0936-5214, nr 11, s. 1711-1714Artikkel i tidsskrift (Fagfellevurdert)
  • 8.
    Dziedzic, Pawel
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Weibiao, Zou
    Hafrén, Jonas
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The small peptide-catalyzed direct asymmetric aldol reaction in water2006Inngår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 4, s. 38-40Artikkel i tidsskrift (Fagfellevurdert)
  • 9.
    Ekström, Jesper
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Abrahamsson, Maria
    Olson, Carol
    Bergquist, Jonas
    Kanyak, Feliz B.
    Eriksson, Lars
    Sun, Licheng
    Åkermark, Björn
    Becker, Hans-Christian
    Hammarström, Leif
    Ott, Sascha
    Bio Inspired Side-on Attachment of a Ruthenium Photo-sensitizer to an Iron Hydrogenase Active Site Model2006Inngår i: Dalton Transactions, ISSN 1477-9226, nr 38, s. 4599-4606Artikkel i tidsskrift (Fagfellevurdert)
  • 10.
    Fransson, Ann-Britt L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Deracemization of Functionalized Alcohols via Combined Ruthenium and Enzyme Catalysis2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The major part of this thesis describes the synthesis of enantiopure alcohols and diols by combining ruthenium-catalyzed racemization or epimerization and lipase-catalyzed asymmetric transformations. A minor part of this thesis is focused on ruthenium-catalyzed redox reactions for transfer hydrogenation of 1,3-cycloalkanediketones.

    Kinetic resolution of racemic γ-hydroxy acid derivatives was performed via Pseudomonas cepacia lipase (PS-C)-catalyzed transesterification. γ-Hydroxy esters and γ-hydroxy amides were studied showing in higher selec-tivity and yields for the γ-hydroxy amides. The enzyme PS-C tolerates both variation in the chain length and different functionalities giving good to high enantioselectivity. Combining enzymatic kinetic resolution with a ruthenium-catalyzed racemization led to a dynamic kinetic resolution (DKR). The use of 2,4-dimethyl-3-pentanol as a hydrogen source to suppress ketone formation in the dynamic kinetic resolution increased the yields of the acetate product. The synthetic utility of this procedure was illustrated by the practical synthesis of the γ-lactone (R)-5-methyltetrahydrofuran-2-one.

    A distereoselective transformation of cis/trans-1,3-cyclohexandiol using Candida antarctica lipase B (CALB)-catalyzed transesterification was of interest. Desymmetrization of cis-1,3-cyclohexanediol to the (R-monoacetate was successfully accomplished. Enantiopure (R,R)-diacetate was obtained from the (R)-monoacetate in a DYKAT process at room tem-perature. Metal- and enzyme-catalyzed transformation of cis/trans-1,3-cyclohexanediol using PS-C, gives a high diastereoselectivity for cis-diacetate. The (S)-mono-acetate was obtained from cis-diacetate by CALB-catalyzed hydrolysis. In addition, it was shown, by the use of deuterium-labeling that intramolecular acyl migration does not occur in the transformation of cis-monoacetate to the cis-diacetate.

    Ruthenium-catalyzed transfer hydrogenation of 1,3-cyclohexanedione under microwave heating was developed as an efficient and fast method for the preparation of 1,3-cycloalkandiols.

  • 11.
    Fransson, Ann-Britt L.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Xu, Yongmei
    Leijondahl, Karin
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enzymatic Resolution, Desymmetrization and Dynamic Kinetic Asym-metric Transformation of 1,3-Cycloalkanediols2006Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, nr 17, s. 6309-6316Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient desymmetrization of cis-1,3-cyclohexanediol to (1S,3R)-3-(acetoxy)-1-cyclohexanol ((R,S)-2a) was performed via Candida antarctica lipase B (CALB)-catalyzed transesterification, in high yield (up to 93%) and excellent enantioselectivity (ee's up to >99.5%). (R,R)-Diacetate ((R,R)-3a) was obtained in a DYKAT process at room temperature from (1S,3R)-3-acetoxy-1-cyclohexanol ((R,S)-2a), in a high trans/cis ratio (91:9) and in excellent enantioselectivity of >99%. Metal- and enzyme-catalyzed dynamic transformation of cis/trans-1,3-cyclohexanediol using PS-C gave a high diastereoselectivity for cis-diacetate (cis/trans = 97:3). The (1R,3S)-3-acetoxy-1-cyclohexanol (ent-(R,S)-2a) was obtained from cis-diacetate by CALB-catalyzed hydrolysis in an excellent yield (97%) and selectivity (>99% ee). By deuterium labeling it was shown that intramolecular acyl migration does not occur in the transformation of cis-monoacetate to the cis-diacetate.

  • 12. Fransson, Ann-Britt
    et al.
    Xu, Yongmei
    Leijondahl, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Enzymatic resolution, desymmetrization and dynamic kinetic asymmetric transformation of 1,3-cycloalkanediols2006Inngår i: Journal of organic chemistry, ISSN 0022-3263, Vol. 71, nr 17, s. 6309-6316Artikkel i tidsskrift (Fagfellevurdert)
  • 13.
    Fryxelius, Jacob
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Design and Synthesis of Ligands for High-Valent Metal Oxidation Catalysts2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

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

  • 14. Gao, Weiming
    et al.
    Liu, Jianhui
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Bidentate phosphine ligand based Fe2S2-containing macromolecules: synthesis, characterization, and catalytic electrochemical hydrogen production2006Inngår i: Inorganic Chemistry, ISSN 0020-1669, Vol. 45, nr 23, s. 9169-9171Artikkel i tidsskrift (Fagfellevurdert)
  • 15.
    Ibrahem, Ismail
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic asymmetric alpha-aminomethylation of cyclohexanones2006Inngår i: Synthesis, ISSN 0039-7881, nr 23, s. 4060-4064Artikkel i tidsskrift (Fagfellevurdert)
  • 16.
    Ibrahem, Ismail
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Weibiao
    Casas, Jesus
    Sunden, Henrik
    Cordova, Armando
    Direct Organocatalytic Enantioselective α-Aminomethylation of Ketones2006Inngår i: Tetrahedron, Vol. 62, s. 357-Artikkel i tidsskrift (Fagfellevurdert)
  • 17.
    Jansson, Jennie L. M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Maliniak, Arnold
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Conformational Dynamics of Oligosaccharides: NMR Techniques and Computer Simulations2006Inngår i: NMR Spectroscopy and Computer Modeling of Carbohydrates: Recent Advances / [ed] Johannes F. G Vliegenthar & Robert J. Woods, American Chemical Society (ACS), 2006, s. 20-39Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    NMR spectroscopy techniques in conjunction with molecular dynamics simulations facilitate description of conformation and dynamics of oligosaccharides in solution. Herein we describe approaches based on hetero-nuclear carbon-proton spin-spin coupling constants useful for assessing conformational preferences at the glycosidic linkage, exemplified for á-cyclodextrin. Furthermore, we utilize hetero-nuclear carbon-proton residual dipolar couplings together with molecular dynamics simulations in the analysis of the conformational dynamics of the milk oligosaccharide Lacto-N-neotetraose.

  • 18. Ji, Sanhao
    et al.
    Ju, Yong
    Fu, Hua
    Zhao, Yufen
    Johansson, Tommy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The influences of a nitrogen atom position in dinucleoside 2-,3-,4-pyridylphosphonates on fragmentation patterns in electrospray ionization multistage tandem mass spectra2006Inngår i: Nucleosides, Nucleotides, and Nucleic Acids, ISSN 1525-7770, Vol. 25, s. 771-784Artikkel i tidsskrift (Fagfellevurdert)
  • 19. Johansson, Per-Ola
    et al.
    Bäck, Marcus
    Kvarnström, Ingemar
    Jansson, Katarina
    Vrang, Lotta
    Hamelink, Elizabeth
    Hallberg, Anders
    Rosenquist, Åsa
    Samuelsson, Bertil
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Potent inhibitors of the hepatitis C virus NS3 protease: use of a novel P2 cyclopentane-derived template2006Inngår i: Bioorganic & Medicinal Chemistry, ISSN 0968-0896, Vol. 14, s. 5136-5151Artikkel i tidsskrift (Fagfellevurdert)
  • 20.
    Jonsson, K. Hanna M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Methyl 4-O-benzoyl-2,3-O-isopropylidene-a-L-rhamnopyranoside2006Inngår i: Acta Crystallographica Section C: Crystal Structure Communications, ISSN 0108-2701, E-ISSN 1600-5759, Vol. 62, nr 8, s. o447-o449Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The title compound, C17H22O6, having an ester group at O4 of the hexopyranosyl sugar residue shows for the exo-cyclic C=O bond a conformation that is eclipsed to the C4-H4 bond. The two related torsion angles are denoted by syn and cis conformations. The q1 torsion angle (H4-C4-O4-C10) is indicated to have a similar conformation in solution as analyzed by NMR spectroscopy and a Karplus-type relationship.

  • 21.
    Jonsson, K. Hanna M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Weintraub, Andrej
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural studies of the O-antigenic polysaccharide from Shigella dysenteriae type 3 and Escherichia coli O124, a reinvestigation2006Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 341, s. 2986-2989Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Landersjö, Clas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stevensson, Baltzar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Eklund, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Östervall, Jennie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Maliniak, Arnold
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Söderman, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Molecular conformations of a disaccharide investigated using NMR spectroscopy2006Inngår i: Journal of Biomolecular NMR, ISSN 0925-2738, E-ISSN 1573-5001, Vol. 35, s. 89-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The molecular structure of -l-Rhap-(1→ 2)--l-Rhap-OMe has been investigated using conformation sensitive NMR parameters: cross-relaxation rates, scalar 3 J CH couplings and residual dipolar couplings obtained in a dilute liquid crystalline phase. The order matrices of the two sugar residues are different, which indicates that the molecule cannot exist in a single conformation. The conformational distribution function, , related to the two glycosidic linkage torsion angles and was constructed using the APME method, valid in the low orientational order limit. The APME approach is based on the additive potential (AP) and maximum entropy (ME) models. The analyses of the trajectories generated in molecular dynamics and Langevin dynamics (LD) computer simulations gave support to the distribution functions constructed from the experimental NMR parameters. It is shown that at least two conformational regions are populated on the Ramachandran map and that these regions exhibit very different molecular order. Electronic Supplementary Material  Supplementary material is available for this article at http://www.dx.doi.org/10.1007/s10858-006-9006-0 and is accessible for authorized users.

  • 23.
    Leijondahl, Karin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Fransson, Ann-Britt
    Bäckvall, Jan-Erling
    Ruthenium-catalyzed transfer hydrogenation/hydrogenation of 1,3-cycloalkanediones to 1,3-cycloalkanediols using microwave heating2006Inngår i: Journal of organic chemistry, ISSN 0022-3263, Vol. 71, nr 22, s. 8622-8625Artikkel i tidsskrift (Fagfellevurdert)
  • 24. Li, Chun-Yan
    et al.
    Zhang, Xiao-Bing
    Han, Zhi-Xiang
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Shen, Guo-Li
    Yu, Ru-Qin
    A wide pH range optical sensing system based on a sol-gel encapsulated amino-functionalised corrole2006Inngår i: The Analyst, ISSN 0003-2654, Vol. 131, s. 388-393Artikkel i tidsskrift (Fagfellevurdert)
  • 25. Lindén, Auri A.
    et al.
    Johansson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hermanns, Nina
    Bäckvall, Jan-E.
    Efficient and Selective Sulfoxidation by Hydrogen Peroxide, Using a Recyclable Flavin-[bmim]PF6 Catalytic System2006Inngår i: Journal of organic chemistry, ISSN 0022-3263, Vol. 71, nr 10, s. 3849 -3853Artikkel i tidsskrift (Fagfellevurdert)
  • 26.
    Mannerstedt, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of Oligosaccharides from the Inner Core Structure of Haemophilus Influenzae and Neisseria meningitidis Lipopolysaccharides2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

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

  • 27.
    Norinder, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric Synthesis and Mechanistic Studies on Copper(I)-Catalyzed Substitution of Allylic Substrates2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis deals with the copper-catalyzed substitution of allylic substrates.

    In the first part of this thesis, the synthesis of a series of metallocenethiolates is described. The thiolates were examined as ligands in the enantioselective copper(I)-catalyzed γ-substitution of allylic acetates.

    The second part describes a study on copper-catalyzed α-substitution of enantiomerically pure secondary allylic esters. It was observed that the degree of chirality transfer is strongly dependent on the reaction temperature. The loss of chiral information is consistent with an equilibration of the allylCu(III) intermediates prior to product formation, which is essential in order to realize a copper-catalyzed dynamic kinetic asymmetric transformation process.

    The third part describes a study on copper-catalyzed stereoselective α-substitution of enantiopure acyclic allylic esters. This method, when combined, with ruthenium and enzyme catalyzed dynamic kinetic resolution of allylic alcohols, provides a straightforward route to pharmaceutically important α-methyl carboxylic acids.

    The fourth part is a mechanistic study on the reaction of perfluoroallyl iodide with organocuprates. Experimental studies as well as theoretical calculations were used to explain the contrasting reactivity of perfluoroallyl iodide vs. allyl iodide in cuprate allylation reactions.

    In the fifth part, the development of a practical and useful method for the preparation of pentasubstituted acylferrocenes is presented.

  • 28.
    Norinder, Jakob
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yoshikai, Naohiko
    Bäckvall, Jan-Erling
    Nakamura, Eiichi
    Unusual Homocoupling in the Reaction of Diorganocuprates with an Allylic Halide2006Inngår i: Organometallics, Vol. 25, nr 9, s. 2129 -2132Artikkel i tidsskrift (Fagfellevurdert)
  • 29.
    Närhi, Katja
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Studies on Palladium-Catalyzed Carbocyclizations of Allene-Substituted Olefins and 1,3-Dienes2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the development and mechanistic studies of carbocyclization reactions of allene-substituted olefins and 1,3-dienes, catalyzed by palladium(0) and palladium(II). These reactions results in the formation of [n,3,0] bicyclic systems (n = 3-5) with high stereoselectivity and in good to excellent yields.

    The first carbocyclization presented is a novel palladium(0)-catalyzed cyclo- isomerization of allene-substituted olefins.

    Secondly an efficient aerobic biomimetic system has been developed for a Pd(II)-catalyzed allylic oxidative carbocyclization of allene-substituted olefins.

    Additionally, during the studies of palladium-catalyzed carbocyclizations of allene-substituted olefins, it was found that in the absence of palladium a mild thermal ene-reaction occurs. In this manner stereodefined, functionalized bicyclic compounds are obtained with good regioselectivity and in high yields.

    The third and fourth carbocyclization developed are a palladium(II)-catalyzed oxidation and a palladium(0)-catalyzed intramolecular telomerization of allene-substituted 1,3-dienes.

    A mechanistic study of the palladium(II)-catalyzed oxidation of allene-substituted 1,3-dienes was made, and reaction intermediates could be isolated. The stereochemistry of the reaction intermediates was assigned, and this made it possible to suggest a mechanism for the reaction. The presented mechanism is a trans carbopalladation of the 1,3-diene, where the allene act as the carbon nucleophile. Due to different stereochemical outcomes of the stoichiometric and catalytic reactions, this mechanism could only explain the stoichiometric reaction. Another mechanism for the catalytic reaction was suggested, which rationalizes both the regio- and stereochemistry of the products.

  • 30.
    Närhi, Katja
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Franzén, Johan
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    An unexpectedly mild thermal alder-ene-type cyclization of enallenes2006Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, ISSN 0022-3263, Vol. 71, nr 7, s. 2914-2917Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mild, thermal Alder-ene reaction of enallenes has been developed. The allenic double bond acts as the "ene" and generates a carbon-carbon bond to an unactivated olefinic "enophile" in DMF at 120 degrees C to give [n.3.0] bicyclic systems (n = 3-5) in good yields. Except for a minor [2 + 2] cycloaddition byproduct, the reaction proceeded with complete atom economy, as there is no requirement of a catalyst or additional reactants, and no waste products are formed in the process.

  • 31. Olofsson, B.
    et al.
    Bogár, Krisztián
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Fransson, A.-B.L.
    Bäckvall, Jan-E.
    Divergent Asymmetric Synthesis of 3,5-Disubstituted Piperidines2006Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, nr 21, s. 8256-8260Artikkel i tidsskrift (Fagfellevurdert)
  • 32.
    Olofsson, Berit
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Aggarwal, Varinder K.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantioselective alfa-Arylation of Ketones: Application to the Synthesis of (–)-Epibatidine2006Inngår i: Sterochemistry, Bürgenstock, Switzerland, 2006Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 33.
    Olofsson, Berit
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Aggarwal, Varinder K.
    Bristol University, UK.
    Enantioselective alfa-Arylation of Ketones: Application to the Synthesis of (–)-Epibatidine2006Inngår i: Organikerdagarna, Kalmar, Sweden, 2006, s. Le21, P47-Konferansepaper (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    The enantioselective introduction of electrophiles alfa to carbonyl compounds occupies a central position in asymmetric synthesis. Although asymmetric alkylations have been well developed, high enantioselectivity in α-arylation of ketones has only been achieved in a limited number of cases.

    We have developed a direct arylation reaction of cyclohexanones, employing diaryl iodonium(III) salts as electrophiles. The reaction was made enantioselective by the use of a chiral base, resulting in 2,4-substituted cyclohexanones in high yields and with high enantiomeric excesses and diastereoselectivities.

    This methodology was applied in a short, enantioselective synthesis of (–)-Epibatidine, an alkaloid recently isolated from the Ecuadorian poison frog Epipedobates tricolor. The synthesis was accomplished in 6 steps and 31% overall yield, thus providing the shortest and most efficient asymmetric route to this important compound to date.

  • 34.
    Olofsson, Berit
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Aggarwal, Varinder K.
    Bristol University, UK.
    Synthesis of Novel Heteroaryl Iodonium Salts and Enantioselective a-Arylation of Cyclohexanones2006Inngår i: 2nd Int. Conference on Hypervalent Iodine, 2006Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    We have developed a direct arylation reaction of cyclohexanones employing diaryl iodonium(Ill) salts as electrophiles. The

    reaction was made enantiosilective by the use of a chiral base, resultinginZ,4-disubstituted cyclohexanones in high yields and with high enantiomeric excesses and diastereoselectivities. Novel heteroaryl iodonium salts were subsequently synthesized and employed in the coupling to variously substituted cyclohexanones.

  • 35.
    Olofsson, Berit
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bogár, Krisztián
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Fransson, Ann-Britt L
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Divergent asymmetric synthesis of 3,5-disubstituted piperidines.2006Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, nr 21, s. 8256-60Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A divergent synthesis of various 3,5-dioxygenated piperidines with interesting pharmacological properties is described. A mixture of the achiral cis- and racemic trans-3,5-piperidine diol could be efficiently obtained from N-benzylglycinate in five steps by the use of chemoenzymatic methods. In the subsequent enzyme- and Ru-catalyzed reaction, the rac/meso diol mixture was efficiently transformed to the cis-(3R,5S)-diacetate with excellent diastereoselectivity and in high yield. Further transformations of the cis-diacetate selectively delivered the cis-piperidine diol and the cis-(3R,5S)-hydroxy acetate. Alternatively, the DYKAT could be stopped at the monoacetate stage to give the trans-(3R,5R)-hydroxy acetate.

  • 36.
    Olofsson, Berit
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Somfai, Peter
    Organisk kemi, KTH.
    Vinylepoxides in Organic Synthesis2006Inngår i: Aziridines and Epoxides in Organic Synthesis, Wiley-VCH: Weinheim , 2006, s. 315-347Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Vinylepoxides have become important intermediates in organic synthesis. The main reason for this is the development of selective methods for their subsequent transformations. As vinylepoxides are a special type of allylic electrophiles, it is necessary to control both the regioselectivity and the diastereoselectivity in their reactions with nucleophiles. The practical usefulness of vinylepoxides in synthesis will, however, always be dictated by their availability. Several methods for the asymmetric preparation of vinyloxiranes have been developed and it can be expected that the use of these compounds in organic synthesis will increase. This chapter starts with a discussion of the available techniques for preparing vinylepoxides, with emphasis on asymmetric methods. In the second part various transformations of vinylepoxides are summarized.

  • 37.
    Olsson, Vilhelm
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sebelius, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Direct Boronation of Allyl Alcohols with Diboronic Acid Using Palladium Pincer-Complex Catalysis. A Remarkably Facile Allylic Displacement of the Hydroxy Group under Mild Reaction Conditions2006Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, nr 14, s. 4588-4589Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Allyl alcohols were converted to allyl boronic acids and subsequently to trifluoro(allyl)borates with tetrahydroxy diboron using palladium pincer-complex catalysis. These reactions are regio- and stereoselective proceeding with high isolated yields. Competitive boronation experiments indicate that under the applied reaction conditions the allylic displacement of a hydroxy group is faster than the displacement of an acetate leaving group. It is assumed that the hydroxy group of the allyl alcohol is converted to a diboronic acid ester functionality, which can easily be substituted.

  • 38.
    Rios, Ramón
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sundén, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhao, Gui-Ling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A one-pot organocatalytic asymmetric entry to tetrahydrothioxanthenones2006Inngår i: Tetrahedron Letters, Vol. 47, nr 49, s. 8679-8682Artikkel i tidsskrift (Fagfellevurdert)
  • 39.
    Samec, Joseph S. M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Éll, Alida H.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åberg, Jenny B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Privalov, Timofei
    Kungliga Tekniska Högskolan.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för strukturkemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic Study of Hydrogen Transfer to Imines from a Hydroxycyclopentadienyl Ruthenium Hydride. Experimental Support for a Mechanism Involving Coordination of Imine to Ruthenium Prior to Hydrogen Transfer2006Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, nr 44, s. 14293-14305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reaction of [2,3,4,5-Ph4(η5-C4COH)Ru(CO)2H] (2) with different imines afforded ruthenium amine complexes at low temperatures. At higher temperatures in the presence of 2, the complexes decomposed to give [Ru2(CO)4(μ-H)(C4Ph4COHOCC4Ph4)] (1) and free amine. Electron-rich imines gave ruthenium amine complexes with 2 at a lower temperature than did electron-deficient imines. The negligible deuterium isotope effect (kRuHOH/kRuDOD = 1.05) observed in the reaction of 2 with N-phenyl[1-(4-methoxyphenyl)ethylidene]amine (12) shows that neither hydride (RuH) nor proton (OH) is transferred to the imine in the rate-determining step. In the dehydrogenation of N-phenyl-1-phenylethylamine (4) to the corresponding imine 8 by [2,3,4,5-Ph4(η4-C4CO)Ru(CO)2] (A), the kinetic isotope effects observed support a stepwise hydrogen transfer where the isotope effect for C−H cleavage (kCHNH/kCDNH = 3.24) is equal to the combined (C−H, N−H) isotope effect (kCHNH/kCDND = 3.26). Hydrogenation of N-methyl(1-phenylethylidene)amine (14) by 2 in the presence of the external amine trap N-methyl-1-(4-methoxyphenyl)ethylamine (16) afforded 90−100% of complex [2,3,4,5-Ph4(η4-C4CO)]Ru(CO)2NH(CH3)(CHPhCH3) (15), which is the complex between ruthenium and the amine newly generated from the imine. At −80 °C the reaction of hydride 2 with 4-BnNH-C6H9=NPh (18), with an internal amine trap, only afforded [2,3,4,5-Ph44-C4CO)](CO)2RuNH(Ph)(C6H10-4-NHBn) (19), where the ruthenium binds to the amine originating from the imine, showing that neither complex A nor the diamine is formed. Above −8 °C complex 19 rearranged to the thermodynamically more stable [Ph4(η4-C4CO)](CO)2RuNH(Bn)(C6H10-4-NHPh) (20). These results are consistent with an inner sphere mechanism in which the substrate coordinates to ruthenium prior to hydrogen transfer and are difficult to explain with the outer sphere pathway previously proposed.

  • 40. Schwartz, Lennart
    et al.
    Ekström, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lomoth, Reiner
    Ott, Sascha
    Dynamic Ligation at the First Amine-coordinated Iron Hydrogenase Active Site Mimic2006Inngår i: Chemical Communications, ISSN 1359-7345, nr 40, s. 4206-4208Artikkel i tidsskrift (Fagfellevurdert)
  • 41.
    Sebelius, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Synthesis and Transformation of Organoboranes2006Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis presents the development of new palladium-catalyzed transformations involving synthesis and application of allylborane reagents. In these reactions various palladium sources, including pincer complexes and commonly used catalysts were applied.

    A new transformation for allylation of aldehyde and imine substrates was devised using allyl acetates, diboronate reagents and catalytic amounts of Pd2(dba)3. By employment of commercially available chiral diboronates enantioenriched homoallyl alcohols could be obtained.

    We have also developed a palladium-catalyzed method for synthesis of functionalized allylboronic acids from vinyl cyclopropane, vinyl aziridine, allyl acetate and allyl alcohol substrates using diboronic acid as reagent. In this process a highly selective selenium based pincer-complex was used as catalyst. The resulting allylboronic acid products were converted to potassium trifluoro(allyl)borates or allylboronates.

    The functionalized allylboronic acids generated in the above procedure were employed as reagents in two synthetic transformations. One of these transformations involves a palladium(0)-catalyzed coupling reaction between allylboronic acids and aryl iodides. The reaction was regioselective for the branched allylic product, typically difficult to prepare in the absence of directing groups. We also developed another transformation for allylation of aldehydes with allyl alcohols via allylboronic acid intermediate. This procedure can be performed as a simple one-pot sequence affording homoallyl alcohols with excellent stereo- and regioselectivity.

  • 42.
    Sebelius, Sara
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olsson, Vilhelm J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wallner, Olov A.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Coupling of Allylboronic Acids with Iodobenzenes. Selective Formation of the Branched Allylic Product in the Absence of Directing Groups2006Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, nr 25, s. 8150-8151Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Palladium-catalyzed coupling reactions of functionalized allylboronic acids with iodobenzenes were achieved under standard Suzuki−Miyaura coupling conditions. The coupling reactions afforded selectively the branched allylic products in high to excellent yields. In contrast to palladium-catalyzed nucleophilic substitution reactions proceeding via (η3-allyl)palladium intermediates, this process does not require directing groups in the allyl moiety to achieve substitution at the congested allylic terminus. The regioselectivity of the process was largely unaffected by the substituent effects of the iodobenzenes and the allylic substrates.

  • 43.
    Selander, Nicklas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sebelius, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Estay, Cesar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Highly Selective and Robust Palladium-Catalysed Carbon-Carbon Coupling between Allyl Alcohols and Aldehydes via Transient Allylboronic Acids2006Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 18, s. 4085-4087Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The highly regio- and stereoselective coupling of allyl alcohols with aldehydes could be achieved with 5 mol-% of SeCSe pincer complex catalyst and p-toluenesulfonic acid in the presence of diboronic acid. The transformations have a broad synthetic scope, and the high yields were obtained without the use of an inert atmosphere and carefully dried solvents.

  • 44. Sjödin, Martin
    et al.
    Irebo, Tania
    Utas, Josefin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lind, Johan
    Merényi, Gabor
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hammarström, Leif
    Kinetic Effects of Hydrogen-bonds on Proton-Coupled Electron Transfer from Phenols2006Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, nr 40, s. 13076-13083Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The kinetics and mechanism of proton-coupled electron transfer (PCET) from a series of phenols to a laser flash generated [Ru(bpy)3]3+ oxidant in aqueous solution was investigated. The reaction followed a concerted electron−proton transfer mechanism (CEP), both for the substituted phenols with an intramolecular hydrogen bond to a carboxylate group and for those where the proton was directly transferred to water. Without internal hydrogen bonds the concerted mechanism gave a characteristic pH-dependent rate for the phenol form that followed a Marcus free energy dependence, first reported for an intramolecular PCET in Sjödin, M. et al. J. Am. Chem. Soc. 2000, 122, 3932−3962 and now demonstrated also for a bimolecular oxidation of unsubstituted phenol. With internal hydrogen bonds instead, the rate was no longer pH-dependent, because the proton was transferred to the carboxylate base. The results suggest that while a concerted reaction has a relatively high reorganization energy (λ), this may be significantly reduced by the hydrogen bonds, allowing for a lower barrier reaction path. It is further suggested that this is a general mechanism by which proton-coupled electron transfer in radical enzymes and model complexes may be promoted by hydrogen bonding. This is different from, and possibly in addition to, the generally suggested effect of hydrogen bonds on PCET in enhancing the proton vibrational wave function overlap between the reactant and donor states. In addition we demonstrate how the mechanism for phenol oxidation changes from a stepwise electron transfer−proton transfer with a stronger oxidant to a CEP with a weaker oxidant, for the same series of phenols. The hydrogen bonded CEP reaction may thus allow for a low energy barrier path that can operate efficiently at low driving forces, which is ideal for PCET reactions in biological systems.

  • 45. Teodorovic, Peter
    et al.
    Slättegård, Rikard
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Oscarson, Stefan
    Synthesis of stable C-phosphonate analogues of Neisseria meningitidis group A capsular polysaccharide structures using modified Mitsunobu reaction2006Inngår i: Organic and biomolecular chemistry, Vol. 4, nr 4, s. 4485-4490Artikkel i tidsskrift (Fagfellevurdert)
  • 46.
    Teodorovic, Peter
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Slättegård, Rikard
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Oscarson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of stable C-phosphonate analogues of Neisseria meningitidis group A capsular polysaccharide structures using modified Mitsunobu reaction2006Inngår i: Organic & Biomolecular Chemistry, ISSN 1477-0520, Vol. 4, s. 4485-4490Artikkel i tidsskrift (Fagfellevurdert)
  • 47.
    Utas, Josefin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hydrogen Bonded Phenols as Models for Redox-Active Tyrosines in Enzymes2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis deals with the impact of hydrogen bonding on the properties of phenols. The possibility for tyrosine to form hydrogen bonds to other amino acids has been found to be important for its function as an electron transfer mediator in a number of important redox enzymes. This study has focused on modeling the function of tyrosine in Photosystem II, a crucial enzyme in the photosynthetic pathway of green plants.

    Hydrogen bonds between phenol and amines in both inter- and intramolecular systems have been studied with quantum chemical calculations and also in some solid-state structures involving phenol and imidazole.

    Different phenols linked to amines have been synthesized and their possibilities of forming intra- and intermolecular hydrogen bonds have been studied as well as the thermodynamics and kinetics of the generation of phenoxyl radicals via oxidation reactions.

    Since carboxylates may in principle act as hydrogen bond acceptors in a manner similar to imidazole, proton coupled electron transfer has also been studied for a few phenols intramolecularly hydrogen bonded to carboxylates with the aim to elucidate the mechanism for oxidation. Electron transfer in a new linked phenol—ruthenium(II)trisbipyridine complex was studied as well.

    The knowledge is important for the ultimate goal of the project, which is to transform solar energy into a fuel by an artificial mimic of the natural photosynthetic apparatus

  • 48.
    Utas, Josefin E.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kritikos, Mikael
    Sandström, Dick
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Water as a hydrogen bonding bridge between a phenol and imidazole. A simple model for water binding in enzymes.2006Inngår i: Biochimica et Biophysica Acta, ISSN 0006-3002, Vol. 1757, s. 1592-1596Artikkel i tidsskrift (Fagfellevurdert)
  • 49.
    Utas, Josefin E.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Efficient Synthesis of 2-Substituted Imidazoles by Palladium-Catalyzed Cross-Coupling with Benzylzinc Reagents2006Inngår i: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, nr 12, s. 1965-1967Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Substituted benzylzinc reagents have been used in novel cross-coupling reactions with 2-iodo imidazoles to form compounds containing both a phenol and an imidazole moiety. The ­intramolecular hydrogen-bonding properties of these compounds were subsequently studied.

  • 50.
    Utas, Josefin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kritikos, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Sandström, Dick
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Water as a Hydrogen Bonding Bridge between a Phenol and Imida-zole. A Simple Model for Water Binding in Enzymes2006Inngår i: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1757, nr 12, s. 1592-1596Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The X-ray crystal structure of the mono-hydrate of 2,2-bis(imidazol-1-ylmethyl)-4-methylphenol has been determined. Three hydrogen bonds hold water very tightly in the crystal, as determined by deuterium solid-state NMR. The hydrogen bond between the phenolic hydroxyl and water appears to have about the same strength as the direct hydrogen bond to imidazole, suggesting that the structure can be a good model for hydrogen bonds that are mediated by a water molecule in enzymes.

12 1 - 50 of 59
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