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  • 1.
    Ayesa, Susana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Argyopoulus, Dimitris
    Maltseva, Tatiana
    Sund, Christian
    Samuelsson, Bertil
    An Expeditious Library Synthesis of N-Monoalkylated Aminopiperidines and –pyrrolidines2004Ingår i: European Journal of Organic Chemistry, ISSN 1434-193x, nr 12, s. 2723-2737Artikel i tidskrift (Refereegranskat)
  • 2.
    Balan, Daniela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The three-component aza-Baylis-Hillman reaction: development and application2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

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

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

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

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

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

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

  • 3.
    Balan, Daniela
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Adolfsson, Hans
    Efficient microwave-assisted formation of functionalized 2,5-dihydropyrroles using ruthenium-catalyzed ring-closing metathesis2004Ingår i: Tetrahedron Letters, Vol. 45, nr 15, s. 3089-3092Artikel i tidskrift (Refereegranskat)
  • 4. Closson, Adam
    et al.
    Johansson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Ionic liquid-immobilized catalytic system for biomimetic dihydroxylation of olefins2004Ingår i: Chemical Communication, ISSN 0366-5607, nr 13, s. 1494-1495Artikel i tidskrift (Refereegranskat)
  • 5.
    Cotton, Hanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chiral metallocene ligands for transition metal-catalysed reactions2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 6.
    Csjernyik, Gábor
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Studies of Biomimtic Oxidations and Racemizations2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

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

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

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

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

  • 7.
    Csjernyik, Gábor
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bogár, Krisztián
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    New Efficient Ruthenium Catalysts for Racemization of Alcohols at Room Temperature2004Ingår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 45, nr 36, s. 6799-6802Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    5-Pentaphenylcyclopentadienyl)RuCl(CO)2 was found to catalyze efficiently the racemization of chiral alcohols such as (S)-1-phenylethanol, (S)-1-phenylpropan-2-ol, (S)-4-phenylbutan-2-ol and (S)-4-methoxy-1-phenylethanol at room temperature in the presence of a base. The catalytic activity of three other Ru(II) complexes was also investigated. The effects of halide and solvent were studied as well.

  • 8. Córdova, A
    et al.
    Sundén, H
    Engqvist, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The Direct Amino Acid-Catalyzed Asymmetric Incorporation of Molecular Oxygen to Organic Compounds2004Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, Vol. 126, nr 29, s. 8914-8915Artikel i tidskrift (Refereegranskat)
  • 9.
    Edin, Michaela
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Córdova, Armando
    Tandem enantioselective organo- and biocatalysis: a direct entry for the synthesis of enantiomerically pure aldols2004Ingår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 45, s. 7697-7701Artikel i tidskrift (Refereegranskat)
  • 10.
    Edin, Michaela
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Steinreiber, Johannes
    Bäckvall, Jan-E.
    One-pot synthesis of enantiopure syn-1,3-diacetates from racemic diastereomeric mixtures of 1,3-diols by dynamic kinetic asymmetric transformation2004Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 101, s. 5761-5766Artikel i tidskrift (Refereegranskat)
  • 11.
    Eklund, Robert
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Roscic, Maja
    Nordmark, Eva-Lisa
    Widmalm, Göran
    Horvat, Stefica
    Stereochemical assignment of diastereomeric imidazolidinone ring containing bicyclic sugar-peptide addects: NMR Spectroscopy and molecular calculations2004Ingår i: European Journal of Organic Chemistry, ISSN 1434-193X, nr 22, s. 4641-4647Artikel i tidskrift (Refereegranskat)
  • 12.
    Engqvist, Magnus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Casas, J
    Sundén, H
    Ibrahem, I
    Córdova, A
    Direct Organoctalytic Asymmetric α-Oxidation of Ketones with Iodosobenzene and N-sulfonyloxaziridine2004Ingår i: Tetrahedron letters, ISSN 0040-4039, Vol. 46, nr 12, s. 2053-2057Artikel i tidskrift (Refereegranskat)
  • 13.
    Franzén, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Carbocyclizations of Allenes with Unsaturated Hydrocarbons2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

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

  • 14.
    Horváth, Attila
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-Catalyzed Reactions of Allenes with Lithium Bromide and Cyclization of α-Amino Allenes to Pyrrolines2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

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

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

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

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

  • 15.
    Horváth, Attila
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mild and Efficient Palladium(II)-Catalyzed Racemization of Allenes2004Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 8, s. 964-965Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Allenes undergo racemization in the presence of catalytic amounts of Pd(OAc)2/LiBr under mild conditions; the reaction proceeds via a bromopalladation–debromopalladation sequence and tolerates various functional groups.

     

  • 16.
    Horváth, Attila
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Benner, Jessica
    Simple, Enantiocontrolled Synthesis of 3-Pyrrolines from α-Amino Allenes2004Ingår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2004, nr 15, s. 3240-3243Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cyclization of -amino allenes in the presence of N-bromosuccinimide afforded pyrrolines in good yields. The products were obtained with high enantiomeric excesses when optically active allenes were used as substrates. The synthesis of a 2,5-dehydroprolinol derivative is also presented.

  • 17. Huang, Ping
    et al.
    Högblom, Joakim
    Anderlund, Magnus F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Magnuson, Ann
    Styring, Stenbjörn
    Light-indused multistep oxidation of dinuclear manganese complexes for artificial photosyntesis2004Ingår i: Journal of Inorganic Biochemistry, ISSN 0162-0134, Vol. 98, nr 5, s. 733-745Artikel i tidskrift (Refereegranskat)
  • 18.
    Ibrahem, Ismail
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Casas, Jesus
    Cordova, Armando
    Direct Catalytic Enantioselective a-aminomethylation of ketones2004Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 43, s. 6528-Artikel i tidskrift (Refereegranskat)
  • 19.
    Johansson, Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ruthenium(II) Polypyridyl Complexes: Applications in Artificial Photosynthesis2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Molecular mimics of PS II, which consist of a photosensitizer linked to electron acceptors/donors, are attractive candidates for the conversion of solar energy into chemical energy. Several different classes of sensitizers have been studied and among these, ruthenium(II) polypyridyl complexes continue to attract major attention.

    The first part of this thesis presents the photophysical properties, stereochemistry, and general synthesis of ruthenium(II) polypyridyl complexes based on 2,2´-bipyridyl and 2,2´:6´,2´´-terpyridyl ligands. The second part deals with ruthenium(II) polypyridyl complexes linked to electron acceptors (benzoquinone, naphthalene diimide) and electron donors (phenothiazine, tyrosine, manganese complexes). Functionalized 2,2´-bipyridines and 2,2´:6´,2´´-terpyridines were synthesized and used in the stepwise assembly of the chromophore-quencher complexes. These were fully characterized and the redox properties were studied by cyclic and differential pulse voltammetry. The intramolecular charge-separated states formed after light excitation of the ruthenium(II) unit were observed by time-resolved absorption and EPR spectroscopy.

    In the third part of this thesis, the synthesis and photophysical properties of a novel class of bistridentate ruthenium(II) polypyridyl complexes based on bipyridyl-pyridyl methane ligamds are discussed. The solution structures of the homoleptic and heteroleptic complexes were studied by 2D NMR techniques. The X-ray structure of one of the homoleptic complexes has been solved. The effect on the excited state lifetime for these ruthenium(II) complexes compared to the parent [Ru(tpy)2]2+ is discussed. Finally, in one of the heteroleptic complexes an interesting reversible linkage iomerization was observed that could be induced either electrochemically or chemically.

  • 20. Johansson, Olof
    et al.
    Wolpher, Henriette
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Borgström, Magnus
    Hammarström, Leif
    Bergquist, Jonas
    Sun, Licheng
    Åkermark, Björn
    Intramolecular charge separation in a hydrogen bonded tyrosine-ruthenium(II)-naphtalene diimide triad2004Ingår i: Chemical Communications, ISSN 1359-7345, nr 2, s. 194-195Artikel i tidskrift (Refereegranskat)
  • 21.
    Johansson, Olof
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wolpher, Henriette
    Borgström, Magnus
    Hammarström, Leif
    Bergquist, Jonas
    Sun, Licheng
    Åkermark, Björn
    Intramolecular charge separation in a hydrogen bonded tyrosune-ruthenium(II) baphthalene diimide triad2004Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, s. 194-195Artikel i tidskrift (Refereegranskat)
  • 22.
    Johansson, Tommy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Studies on Transformations of H-Phosphonates into DNA Analogues Containing P-S or P-C Bonds2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis, mechanistic and synthetic studies on transformations of H-phosphonates into DNA analogues containing P-S or P-C bonds are described.

    Configurational stability of dinucleoside H-phosphonates and the stereochemical course of their sulfurisation in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were investigated. In light of these studies, the reported stereoselective sulfurisation of dinucleoside H-phosphonates and benzoylphosphonates in the presence of DBU was proved to be incorrect.

    Efficient protocols for the synthesis of new nucleotide analogues with non-ionic C-phosphonate internucleotide linkages were developed. The synthesis of dinucleoside 2-pyridylphosphonates was successfully performed by a DBU-promoted reaction of H-phosphonate diesters with N-methoxypyridinium salts. The thio analogues, 2-pyridyl- and 4-pyridyl phosphonothioate diesters, could be obtained by modifying the reactions developed for their oxo counterparts. Dinucleoside 3-pyridylphosphonates were prepared via a palladium(0)-catalysed cross coupling strategy that could be extended also to the synthesis of nucleotide analogues with metal-complexing properties, i.e. terpyridyl- and bipyridylphosphonate derivatives.

    Oligonucleotides modified with pyridylphosphonate internucleotide linkages have been prepared and preliminary studies on their hybridisation properties and resistance towards enzymatic degradation were performed.

    Finally, nucleotidic units for the incorporation of pyridylphosphonate groups at the 5’-terminus of oligonucleotides were designed. Condensations of such units with a suitably protected nucleoside afforded after oxidation the expected dinucleoside (3’-5’)-phosphates with pyridylphosphonate monoester functions at the 5’-ends.

  • 23.
    Johansson, Tommy
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Nucleoside H-phosphonates.: Part 19. Efficient entry to novel nucleotide analogues with 2-pyridyl and 4-pyridylphosphonothioate internucleotide linkages2004Ingår i: Tetrahedron, ISSN 0040-4020, Vol. 60, nr 2, s. 389-395Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Synthetic and 31P NMR spectroscopy studies resulted in the development of efficient protocols for the stereospecific synthesis of a novel type of nucleotide analogues, 2-pyridyl- and 4-pyridylphosphonothioates. The underlying chemistry involves formation of the P–C bond via a base-promoted reaction of suitably protected dithymidine H-phosphonothioates with N-methoxypyridinium tosylate in acetonitrile, or with trityl chloride in pyridine, to produce high yields of nucleotide analogues with a 2-pyridyl- or 4-pyridyl moiety directly bound to the phosphorus centre.

  • 24.
    Kjellgren, Johan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sundén, Henrik
    Szabó, Kálmán J.
    Palladium Pincer-Complex Catalyzed Trimethyltin Substitution of Functionalized Propargylic Substrates: An Efficient Route to Propargyl- and Allenyl-Stannanes2004Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, nr 2, s. 474-476Artikel i tidskrift (Refereegranskat)
  • 25.
    Lahmann, Martina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bülow, Linnea
    Teodorović, Peter
    Gybäck, Helena
    Oscarson, Stefan
    Synthesis of the Lewis b hexasaccharide and HSA-conjugates thereof2004Ingår i: Glycoconjugate Journal, ISSN 0282-0080, E-ISSN 1573-4986, Vol. 21, nr 5, s. 251-256Artikel i tidskrift (Refereegranskat)
  • 26.
    Larsson, Andreas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis, structure and conformation of oligo- and polysaccharides2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Carbohydrates are a complex group of biomolecules with a high structural diversity. Their almost omnipresent occurrence has generated a broad field of research in both biology and chemistry. This thesis focuses on three different aspects of carbohydrate chemistry, synthesis, structure elucidation and the conformational analysis of carbohydrates.

    The first paper describes the synthesis of a penta- and a tetrasaccharide related to the highly branched capsular polysaccharide from Streptococcus pneumoniae type 37. In the second paper, the structure of the O-antigenic repeating unit from the lipopolysaccharide of E. coli 396/C1 was determined along with indications of the structure of the biological repeating unit. In addition, its structural and immunological relationship with E. coli O126 is discussed. In the third paper, partially protected galactopyranosides were examined to clarify the origin of an intriguing 4JHO,H coupling, where a W-mediated coupling pathway was found to operate. In the fourth paper, the conformation of methyl a-cellobioside is studied with a combination of molecular dynamics simulations and NMR spectroscopy. In addition to the expected syn-conformation, detection and quantification of anti-ø and anti-ψ conformers was also possible.

  • 27.
    Larsson, Andreas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Urbina, Felipe
    bKarolinska Institute, Department of Microbiology, Pathology and Immunology, Division of Clinical Bacteriology.
    Yang, Zhennai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Weintraub, Andrej
    Karolinska Institute, Department of Microbiology, Pathology and Immunology, Division of Clinical Bacteriology.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural and immunochemical relationship between the O-antegenic polysaccharides from the enteroaggregative Escherichia coli strain 396/C1 and Escherichia coli O1262004Ingår i: Carbohydrate Research, ISSN 0008-6215, Vol. 339, nr 8, s. 1491-1496Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure of the O-antigen polysaccharide (PS) from the enteroaggregative Escherichia coli strain 396/C-1 has been determined. Sugar and methylation analyses together with 1H and 13C NMR spectroscopy were the main methods used. Inter-residue correlations were determined by 1H,1H-NOESY, 1H,13C-heteronuclear multiple-bond correlation and dipole–dipole cross-correlated relaxation experiments. The PS is composed of pentasaccharide repeating units with the following structure:

    Full-size image (2K)

    Analysis of NMR data reveals that on average the PS consists of 13 repeating units and indicates that the biological repeating unit contains an N-acetylglucosamine residue at its reducing end. This structure is different to that reported for the O-antigen polysaccharide from E. coli O126. Monospecific anti-E. coli O126 rabbit serum from The International Escherichia and Klebsiella Centre did not distinguish between the E. coli strain 396/C-1 and the E. coli O126 reference strain, neither in slide agglutination nor in an indirect enzyme immunoassay. Subsequent successful serotyping of the E. coli strain 396/C-1 showed it to be E. coli O126:K+:H27.

  • 28.
    Lavén, Gaston
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Nilsson, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Silylation-Mediated Transesterification of Phenyl H-Phosphonothioate: A New Entry to Nucleoside H-Phosphonothioate Monoesters2004Ingår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 24, s. 5111-5114Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    O-Phenyl H-phosphonothioate undergoes a facile transesterification with suitably protected nucleosides upon in situ silylation with tert-butyldiphenylsilyl chloride in pyridine/toluene to produce the corresponding 3'-H-phosphonothioates in good yields. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).

  • 29. Martín-Matute, B.
    et al.
    Edin, M.
    Bogár, Krisztián
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Highly compatible metal and enzyme catalysts for efficient dynamic kinetic resolution of alcohols at ambient temperature2004Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, Vol. 43, nr 47, s. 6535-6539Artikel i tidskrift (Refereegranskat)
  • 30. Martín-Matute, Belén
    et al.
    Edin, Michaela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bogár, Krisztián
    Bäckvall, Jan-E.
    Highly compatible metal and enzyme catalysts for efficient dynamic kinetic resolution of alcohols at ambient temperature2004Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 43, s. 6535-6539Artikel i tidskrift (Refereegranskat)
  • 31.
    Naidoo, Kevin J.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chen, Jeff Yu-Jen
    Jansson, Jennie L. M.
    Widmalm, Göran
    Maliniak, Arnold
    Molecular properties related to the anomalous solubility of β-cyclodextrin2004Ingår i: Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 108, nr 14, s. 4236-4238Artikel i tidskrift (Refereegranskat)
  • 32.
    Nilsson, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Studies on Oxidative Couplings in H-Phosphonate Chemistry2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis oxidative coupling of H-phosphonate and H phosphonothioate diesters with different alcohols and amines are presented. Since the reactions with alcohols previously have been particularly unfavourable due to competing side reactions, a modified protocol leading to high coupling yields of structurally diverse hydroxylic components was developed. The phosphorylation reaction was studied using 31P NMR spectroscopy and for the first time the previously only postulated reactive intermediate involved in these reactions was observed.

    The use of iodine in combination with a bulky chlorosilane in pyridine was found to have a profound effect on both the suppression of side reactions and the rate of the oxidative couplings, and led to a clean formation of phosphorylated products in high yields. This synthetic protocol was then extended to include coupling reactions with bis-functional reagents containing hexamethylene linkers to provide handles for derivatisations of oligonucleotides.

    A synthetic protocol consisting of the stereospecific oxidative coupling of amines with H-phosphonate diesters to produce phosphoroamidates was designed in such a way that it permitted control of the stereochemical outcome of the reactions.

    Based on a silylation-mediated reaction utilising phenyl H phosphonothioate monoester as a thiophosphonyl transferring agent, a method was developed and used for the preparation of H-phosphonothioate building blocks for the synthesis of DNA analogues.

  • 33.
    Nilsson, Johan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Controlling Stereochemistry During Oxidative Coupling: Preparation of Rp or Sp Phosphoramidates from One P-Chiral Precursor2004Ingår i: Chemical Communications, ISSN 1359-7345, Vol. 22, s. 2566-2567Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Stereochemical outcome of oxidative coupling of H-phosphonate diesters with amines, promoted by iodine, can be controlled to obtain the corresponding phosphoramidate diesters with inversion or with retention of configuration at the phosphorus centre

  • 34.
    Nordmark, Eva-Lisa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural and Interaction Studies of Bacterial Polysaccharides by NMR Spectroscopy2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    An introduction to bacterial polysaccharides and the methods for structural determination are described in the first two parts of the thesis.

    In a structural elucidation of bacterial polysaccharides NMR experiments are important as is component analysis. A short description of immunochemical methods such as enzyme immunoassays is included. Two NMR techniques used for interaction studies, trNOE and STD NMR, are also discussed.

    The third part of the thesis discusses and summarizes the results from the included papers. The structures of the exopolysaccharides produced by two lactic acid bacteria are determined by one- and two dimensional NMR experiments. One is a heteropolysaccharide produced by Streptococcus thermophilus and the other a homopolysaccharide produced by Propionibacterium freudenreichii. The structure of an acidic polysaccharide from a marine bacterium with two serine residues in the repeating unit is also investigated. The structural and immunological relationship between two O-antigenic polysaccharides from Escherichia coli strain 180/C3 and O5 is discussed and investigated. Finally, interaction studies of an octasaccharide derived from the Salmonella enteritidis O-antigen and a bacteriophage are described which were performed with NMR experiments.

  • 35. Pan, Jingxi
    et al.
    Xu, Yunhua
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Benkö, Gabor
    Feyziyev, Yashar
    Styring, Stenbjörn
    Sun, Licheng
    Åkermark, Björn
    Polivka, Tomas
    Sundström, Villy
    Stepwise Charge Separation from a Ruthenium-Tyrosine Complex to a Nanocrystalline TiO2 Film2004Ingår i: The Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 108, nr 34, s. 12904-12910Artikel i tidskrift (Refereegranskat)
  • 36. Pan, Jingxi
    et al.
    Xu, Yunhua
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Sundström, Villy
    Polivka, Tomas
    Carotenoid and Pheophytin on Semiconductor Surface: Self-Assembly and Photoinduced Electron Transfer2004Ingår i: Journal of the American Chemical Society, Vol. 126, nr 10, s. 3066-3067Artikel i tidskrift (Refereegranskat)
  • 37.
    Samec, Joseph S M
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Éll, Alida H
    Bäckvall, Jan-E
    Mechanism of hydrogen transfer to imines from a hydroxycyclopentadienyl ruthenium hydride: Support for a stepwise mechanism2004Ingår i: Chemical Communications, ISSN 1359-7345, nr 23, s. 2748-2749Artikel i tidskrift (Refereegranskat)
  • 38. Segerstedt, Eva
    et al.
    Mannerstedt, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johansson, Mikael
    Oscarson, Stefan
    Synthesis of the Branched Trisaccharide L-Glycero-α-D-manno-heptopyranosyl-(1→3)-[β-D-glucopyranosyl-(1→4)]-L-glycero-α-D-manno-heptopyranose, Protected to Allow Flexible Access to Neisseria and Haemophilus LPS Inner Core Structures2004Ingår i: Journal of carbohydrate chemistry, ISSN 0732-8303, Vol. 23, nr 8&9, s. 443-452Artikel i tidskrift (Refereegranskat)
  • 39.
    Solin, Niclas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development of Palladium-Catalyzed Transformations Involving η1-Allypalladium Species2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

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

  • 40.
    Solin, Niclas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kjellgren, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pincer complex catalyzed allylation of aldehyde and imine substrates via nucleophilic η1-allyl palladium intermediates: A new concept for palladium catalyzed allylic substitution reactions2004Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, nr 22, s. 7026-7033Artikel i tidskrift (Refereegranskat)
  • 41.
    Staaf, Mikael
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Söderman, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Höög, Christer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Determination of conformational flexibility of methyl α-cellobioside in solution by NMR spectroscopy and molecular simulations*2004Ingår i: Journal of Physical Chemistry A, ISSN 1089-5639, Vol. 108, nr 18, s. 3932-3937Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The conformational flexibility of methyl α-cellobioside in water and dimethyl sulfoxide solutions was investigated by 1D 1H,1H T-ROESY experiments. In combination with molecular dynamics simulations, effective proton−proton distances could be derived using experimentally determined cross-relaxation rates. An anti-ψ-conformational state was present in both solvents confirming a previous flexibility hypothesis at this torsion angle. In water solution, an anti-φ-conformational state was also detected and quantified. These results show that already at the disaccharide level a large flexibility is present at the glycosidic linkage. In addition to the syn-conformation which is present to 93% for the title compound in water solution, the minor anti-φ- and anti-ψ-conformational states are populated to 2% and 5%, respectively.

  • 42. Sundén, H
    et al.
    Engqvist, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Casas, J
    Córdova, A
    Direct Amino Acid-Catalyzed Asymmetric α-Oxidation of Ketones with Molecular Oxygen2004Ingår i: Angewandte Chemie, ISSN 0044-8249, Vol. 116, nr 47, s. 6694-6697Artikel i tidskrift (Refereegranskat)
  • 43.
    Verboom, Renzo C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-catalyzed intramolecular 1,4-oxyacyloxylation of conjugated dienes2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 44.
    Wallner, Olov
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J
    Palladium Pincer Complex-Catalyzed Allylic Stannylation with Hexaalkylditin Reagents2004Ingår i: Organic Letters, ISSN 1523-7060, Vol. 6, nr 11, s. 1829-1831Artikel i tidskrift (Refereegranskat)
  • 45. Wolpher, Henriette
    et al.
    Johansson, Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Abrahamsson, Maria
    Kritikos, Mikael
    Sun, Licheng
    Åkermark, Björn
    A tridentate ligand for preparation of bisterpyridine-like ruthenium(II) complexes with an increased excited state lifetime2004Ingår i: Inorganic Chemistry Communications, ISSN 1387-7003, Vol. 7, nr 3, s. 337-340Artikel i tidskrift (Refereegranskat)
  • 46.
    Wolpher, Henriette
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johansson, Olof
    Abrahamsson, Maria
    Kritikos, Mikael
    Sun, Licheng
    Åkermark, Björn
    A tridentate ligand for preparation of bisterpyridine-like ruthenium(II) complexes with an increased excited state lifetime2004Ingår i: Inorganic Chemistry Communications, ISSN 1387-7003, Vol. 7, nr 3, s. 337-340Artikel i tidskrift (Refereegranskat)
1 - 46 av 46
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