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  • 51.
    Alam, Rauful
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pilarski, Lukasz T.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pershagen, Elias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stereoselective intermolecular allylic C-H trifluoroacetoxylation of functionalized alkenes2012Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, nr 21, s. 8778-8781Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pd-catalyzed allylic C-H trifluoroacetoxylation of substituted alkenes was performed using PhI(OCOCF3)(2) as the oxidant and acyloxy source. Trifluoroacetoxylation of monosubstituted cyclopentenes and cyclohexenes proceeds with excellent regio- and diastereoselectivity. Studies with one of the possible (eta(3)-allyl)Pd(II) intermediates suggest that the reaction proceeds via stereoselective formation of Pd(IV) intermediates and subsequent stereo- and regioselective reductive elimination of the product.

  • 52.
    Alam, Rauful
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Raducan, Mihai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Diastereoselective allylboration of wide variety of carbonyl compounds using allylboronic acids: Construction of adjacent tertiary and quaternary centers2013Inngår i: Abstracts of papers of The American Chemical Society, American Chemical Society (ACS), 2013, Vol. 246, s. 364-ORGN-Konferansepaper (Fagfellevurdert)
  • 53.
    Alam, Rauful
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vollgraff, Tobias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of Adjacent Quaternary Stereocenters by Catalytic Asymmetric Allylboration2015Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, nr 35, s. 11262-11265Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Allylboration of ketones with gamma-disubstituted allylboronic acids is performed in the presence of chiral BINOL derivatives. The reaction is suitable for single-step creation of adjacent quaternary stereocenters with high selectivity. We show that, with an appropriate choice of the chiral catalyst and the stereoisomeric prenyl substrate, full control of the stereo- and enantioselectivity is possible in the reaction.

  • 54.
    Alamsetti, Santosh Kumar
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Persson, Andreas K. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Intramolecular Hydroamination of Propargylic Carbamates and Carbamothioates2014Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, nr 5, s. 1434-1437Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient and simple methodology was developed for the synthesis of oxazolidinones, oxazolidinthiones, imidazolidinthiones, and imidazolidinones from the corresponding propargylic starting materials using Pd(OAc)(2) and n-Bu4NOAc as catalysts in DCE at room temperature.

  • 55.
    Alamsetti, Santosh Kumar
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Persson, Andreas K. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Scalable Synthesis of Oxazolones from Propargylic Alcohols through Multistep Palladium(II) Catalysis: beta-Selective Oxidative Heck Coupling of Cyclic Sulfonyl Enamides and Aryl Boroxines2013Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, nr 51, s. 13745-13750Artikkel i tidsskrift (Fagfellevurdert)
  • 56. Alexakis, A.
    et al.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krause, N.
    Pàmies, O.
    Diéguez, M.
    Enantioselective copper-catalyzed conjugate addition and allylic substitution reactions2008Inngår i: Chemical Reviews, ISSN 0009-2665, Vol. 108, nr 8, s. 2796-2823Artikkel i tidsskrift (Fagfellevurdert)
  • 57.
    Algarra, Andres G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Computational Insights into the Isomerism of Hexacoordinate Metal-Sarcophagine Complexes: The Relationship between Structure and Stability2015Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 3, s. 503-511Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The hexacoordinate complexes that the macrobicyclic ligands {(NH3)(2)sar)(2+) and {NMe3)(2)sar}(2+) (sar = 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane) form with transition metals such as Co-III, Co-II and Cu-II can adopt several isomeric structures. In this article, we have firstly employed DFT methods lo compute the relative stability of their Delta-ob(3), Delta-ob(2)lel, Delta-lel(2)ob and Delta-lel(3) isomers, as well as the activation barriers for their interconversion. In agreement with the experimental data, the results show that, in general, the different isomers of the Co-III and Co-II complexes present similar free energies, whereas the Cu-II complexes show a strong tendency towards the lel(3) form. In addition, the interplay between the structure and stability of these species has been studied by combining shape maps with a distortion/interaction energy analysis. In contrast to the geometries close to the ideal octahedron that all the studied Co complexes present, the le)3 structures of [Cu{(NH3)(2)sar}](4+) and [Cu{(NMe3)(2)sar](4+) are better described. as trigonal prisms. In such structures the ligand adopts a conformation significantly more stable than in the other isomers, and this drives the formation of lel(3)-[Cu{(NH3)(2)sar}](4+) and lel(3)-[Cu{(NNe3)(2)sar}](4+). Overall, the results show a clear relationship between the stability of a given isomer and its degree of distortion with respect to the ideal octahedron (or trigonal prism), with the latter being ultimately dependent on the transition metal and its radius.

  • 58.
    Algarra, Andres G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Aullon, Gabriel
    Bemhardt, Paul V.
    Martinez, Manuel
    Computational Insights on the Geometrical Arrangements of Cu(II) with a Mixed-Donor N3S3 Macrobicyclic Ligand2014Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 53, nr 1, s. 512-521Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The macrobicyclic mixed-donor N3S3 cage ligand AMME-N(3)S(3)sar (1-methyl-8-amino-3,13,16-trithia-6,10,19-triazabicyclo[6.6.6]eicosane) can form complexes with Cu(II) in which it acts as hexadentate (N3S3) or tetradentate (N2S2) donor. These two complexes are in equilibrium that is strongly influenced by the presence of halide ions (Br- and Cl-) and the nature of the solvent (DMSO, MeCN, and H2O). In the absence of halides the hexadentate coordination mode of the ligand is preferred and the encapsulated complex (Cu-in(2+)) is formed. Addition of halide ions in organic solvents (DMSO or MeCN) leads to the tetradentate complex (Cu-out(+)) in a polyphasic kinetic process, but no Cu-out(+) complex is formed when the reaction is performed in water. Here we applied density functional theory calculations to study the mechanism of this interconversion as well as to understand the changes in the reactivity associated with the presence of water. Calculations were performed at the B3LYP/(SDD,6-31G**) level, in combination with continuum (MeCN) or discrete-continuum (H2O) solvent models. Our results show that formation of Cu-out(+) in organic media is exergonic and involves sequential halide-catalyzed inversion of the configuration of a N-donor of the macrocycle, rapid halide coordination, and inversion of the configuration of a S-donor. In aqueous solution the solvent is found to have an effect on both the thermodynamics and the kinetics of the reaction. Thermodynamically, the process becomes endergonic mainly due to the preferential solvation of halide ions by water, while the kinetics is influenced by formation of a network of H-bonded water molecules that surrounds the complex.

  • 59.
    Ali, Tara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural Studies of O-Polysaccharides from Diarrhoeal Escherichia coli2007Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    This thesis describes the structural analysis of O-polysaccharides from the Gram-negative bacterium Escherichia coli that is a diarrhoeal pathogen. The Escherichia coli serotypes investigated were O178, O171, O166 and O128. The methods used in these studies were nuclear magnetic resonance spectroscopy and component analysis.

    All analysed serotypes had pentasaccharide repeating units. E. coli strain O128 and O166 was shown to have the topology of four carbohydrate residues in the backbone while the 5-residue backbone is found in E. coli O178 and O171.

    The biological repeating units have been determined for the analysed polysaccharides and it was shown that all of the serotypes studied had a 3-substituted N-acetylgalactosamine residue at the reducing end. From this it was deduced that the terminal end of E. coli O171 and O128 have sialic acid and blood type antigens, respectively. This should make E. coli O171 and O128 less recognizable to the immune system as a foreign invader. This can result in that E. coli O171 and O128 may evade the immune system more easily.

  • 60.
    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 Escherichia coli O1662007Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 342, nr 2, s. 274-278Artikkel i tidsskrift (Fagfellevurdert)
  • 61.
    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)
  • 62.
    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 studies of the O-antigenic polysaccharides from the enteroaggregative Escherichia coli strain 87/D2 and international type strains from E. coli O1282008Inngår i: Carbohydrate Research, ISSN 0008-6215, Vol. 343, nr 4, s. 695-702Artikkel i tidsskrift (Fagfellevurdert)
  • 63.
    Alpe, Marianne
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of oligosaccharides related to the capsular polysaccharides of Streptococcus pneumoniae serotype 9 and of Cryptococcus neoformans2003Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

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

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

  • 64.
    Anderlund, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dinuclear Manganese Complexes for Artificial Photosynthesis: Synthesis and Properties2005Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis deals with the synthesis and characterisation of a series of dinuclear manganese complexes. Their ability to donate electrons to photo-generated ruthenium(III) has been investigated in flash photolysis experiments followed by EPR-spectroscopy. These experiment shows several consecutive one-electron transfer steps from the manganese moiety to ruthenium(III), that mimics the electron transfer from the oxygen evolving centre in photosystem II.

    The redox properties of these complexes have been investigated with electro chemical methods and the structure of the complexes has been investigated with different X-ray techniques. Structural aspects and the effect of water on the redox properties have been shown.

    One of the manganese complexes has been covalently linked in a triad donor-photosensitizer-acceptor (D–P–A) system. The kinetics of this triad has been investigated in detail after photo excitation with both optical and EPR spectroscopy. The formed charge separated state (D–P–A+) showed an unusual long lifetime for triad based on ruthenium photosensitizers.

    The thesis also includes a study of manganese-salen epoxidation reactions that we believe can give an insight in the oxygen transfer mechanism in the water oxidising complex in photosystem II.

  • 65.
    Anderlund, Magnus F.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Högblom, Joakim
    Shi, Wei
    Huang, Ping
    Eriksson, Lars
    Weihe, Högni
    Styring, Stenbjörn
    Åkermark, Björn
    Magnuson, Ann
    Synthesis, Structure and Redox Chemistry of a Dinuclear Manganese Complex with a Novel Unsymmetric N5O2 LigandManuskript (Annet vitenskapelig)
  • 66.
    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

  • 67. Anderson, Mattias
    et al.
    Afewerki, Samson
    Berglund, Per
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Mid Sweden University, Sweden.
    Total Synthesis of Capsaicin Analogues from Lignin-Derived Compounds by Combined Heterogeneous Metal, Organocatalytic and Enzymatic Cascades in One Pot2014Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 356, nr 9, s. 2113-2118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The total synthesis of capsaicin analogues was performed in one pot, starting from compounds that can be derived from lignin. Heterogeneous palladium nanoparticles were used to oxidise alcohols to aldehydes, which were further converted to amines by an enzyme cascade system, including an amine transaminase. It was shown that the palladium catalyst and the enzyme cascade system could be successfully combined in the same pot for conversion of alcohols to amines without any purification of intermediates. The intermediate vanillyl-amine, prepared with the enzyme cascade system, could be further converted to capsaicin analogues without any purification using either fatty acids and a lipase, or Schotten-Baumann conditions, in the same pot. An aldol compound (a simple lignin model) could also be used as starting material for the synthesis of capsaicin analogues. Using l-alanine as organocatalyst, vanillin could be obtained by a retro-aldol reaction. This could be combined with the enzyme cascade system to convert the aldol compound to vanillylamine in a one-step one-pot reaction.

  • 68.
    Andersson, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Determination of the structures of three bacterial polysaccharides and synthesis and use of new spacers for glycoconjugate formation1993Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

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

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

  • 69. Andersson, Samir
    et al.
    Zou, Dapeng
    Zhang, Rong
    Sun, Shiguo
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Selective positioning of CB[8] on two linked viologens and electrochemically driven movement of the host molecule2009Inngår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 8, s. 1163-1172Artikkel i tidsskrift (Fagfellevurdert)
  • 70.
    Angles d'Ortoli, Thibault
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Assembling and Unraveling Carbohydrates Structures: Conformational analysis of synthesized branched oligosaccharides2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Advances in the elaboration of vaccines and enzyme inhibitors rely on acquiring more knowledge about protein-carbohydrate binding events. Furthermore, the relationships between biological function and the three-dimensional properties of large glycans can be studied by focusing on the structural components they contained, namely, by scaling down the system under analysis. Chemical methods are useful assets as they allow the isolation and determination of epitopes; these small and recognizable fragments that lead to very specific interactions. In this thesis, biologically relevant saccharides were obtained using recently developed concepts in carbohydrate synthesis and NMR spectroscopy was used to unravel their conformational preferences.

    In paper I, the convergent synthesis of the tetrasaccharide found in the natural product solaradixine is described. Reactivity enhanced disaccharide glycosyl donors were coupled to a disaccharide acceptor in a 2 + 2 fashion. The computer program CASPER was subsequently used to verify the synthesized structure.

    The conformation arming concept employed in paper I was further investigated in paper II. An NMR-based methodology enabled the determination of the ring conformations of a set of donors. Subsequently, glycosylation reactions were performed and yields were correlated to donors ring shapes. Perturbations in the rings shape caused by bulky silyl ether protective groups were sufficient to boost the potency of several donors. As a matter of fact, complex branched oligosaccharides could be obtained in good to excellent yields.

    In paper III, NMR spectroscopy observables were measured to elucidate the ring shape, the mutual orientation of the rings across the glycosidic bond and the positions of the side chains of 5 trisaccharides found in larger structures. With the aid of molecular dynamics simulations, their overall conformational propensities were revealed.

    Finally, the software CASPER prediction skills were improved by adding, inter alia, NMR information of synthesized mono- and disaccharides to its database. Unassigned chemical shifts from polysaccharides served as input to challenge its ability to solve large carbohydrate structures.

  • 71.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hamark, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structure-Reactivity Relationships of Conformationally Armed Disaccharide Donors and Their Use in the Synthesis of a Hexasaccharide Related to the Capsular Polysaccharide from Streptococcus pneumoniae Type 372017Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, nr 15, s. 8123-8140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To advance the field of glycobiology, efficient synthesis methods of oligosaccharides and glycoconjugates are a requisite. In glycosylation reactions using superarmed donors, both selectivity and reactivity issues must be considered, and we herein investigate these aspects for differently protected beta-linked 2-O-glycosylated glucosyl donors carrying bulky tert-butyldimethylsilyl groups to different extents. The acceptors in reactions being secondary alcohols presents a challenging situation with respect to steric crowding. Conformational pyranose ring equilibria of the superarmed disaccharide donors with axial-rich substituents contained skew and boat conformations, and three-state models were generally assumed. With NIS/TfOH as the promotor, 2,6-di-tert-butyl-4-methylpyridine as the base, and a dichloromethane/toluene solvent mixture, ethyl 1-thio-beta-d-glucosyl disaccharide donors having 6-O-benzyl group(s) besides tert-butyldimethylsilyl groups were efficiently coupled at -40 degrees C to the hydroxyl group at position 3 of glucopyranosyl acceptors to form beta-(1 -> 2),beta-(1 -> 3)-linked trisaccharides, isolated in excellent 95% yield. The more axial-rich donors in skew and boat conformations are thus preorganized closer to the assumed transition state in these glycosylation reactions. The developed methodology was subsequently applied in the synthesis of a multibranched hexasaccharide related to the capsular polysaccharide from Streptococcus pneumoniae type 37, which consists of a beta-(1 -> 3)-linked backbone and a beta-(1 -> 2)-linked side chain of D-glucosyl residues in disaccharide repeating units.

  • 72.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mobarak, Hani
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ståhle, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hamark, Christoffer
    Fontana, Carolina
    Engström, Olof
    Apostolica, Patricia
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Complete 1H and 13C NMR chemical shift assignments of mono- to tetrasaccharides as basis for NMR chemical shift predictions of oligo- and polysaccharides using the computer program CASPERManuskript (preprint) (Annet vitenskapelig)
  • 73.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sjöberg, Nils A.
    Vasiljeva, Polina
    Lindman, Jonas
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bergenstråhle-Wohlert, Malin
    Wohlert, Jakob
    Temperature Dependence of Hydroxymethyl Group Rotamer Populations in Cellooligomers2015Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 119, nr 30, s. 9559-9570Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Empirical force fields for computer simulations of carbohydrates are often implicitly assumed to be valid also at temperatures different from room temperature for which they were optimited: Herein, the temperature dependence of the hydroxymethyl group rotamer populations in short oligogaccharides is invegtigated using Molecular dynamics simulations and NMR spectroscopy. Two oligosaccharides, methyl beta-cellobioside and beta-cellotetraose were simulated using three different carbohydrate force fields (CHARMM C35, GLYCAM06, and GROMOS 56A(carbo)) in combination with different water models (SPC, SPC/E, and TIP3P) using replica exchange molecular dynamics simulations. For comparison, hydroxymethyl group rotamer populations were investigated for methyl beta-cellobioside and cellopentaose based- on measured NMR (3)J(H5,H6) coupling constants, in the latter case by using a chemical shift selective NMR-filter. Molecular dynamics simulations in combination with NMR spectroscopy show that the temperature dependence of the hydroxymethyl rotamer population in these short cellooligomers, in the range 263-344 K, generally becomes exaggerated in simulations when compared to experimental data, but also that it is dependent on simulation conditions, and most notably properties of the water model.

  • 74.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of the tetrasaccharide glycoside moiety of Solaradixine and rapid NMR-based structure verification using the program CASPER2016Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 72, nr 7, s. 912-927Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The major glycoalkaloid in the roots of Solanum laciniatum is Solaradixine having the branched tetrasaccharide beta-D-Glcp-(1 -> 2)-beta-D-Glcp-(1 -> 3)[alpha-L-Rhap-(1 -> 2)]-beta-D-Galp linked to O3 of the steroidal alkaloid Solasodine. We herein describe the synthesis of the methyl glycoside of the tetrasaccharide using a super-armed disaccharide as a donor molecule. A 2-(naphthyl)methyl protecting group was used in the synthesis of the donor since it was tolerant to a wide range of reaction conditions. The 6-O-benzylated-hexa-O-tert-butyldimethylsilyi-protected beta-D-Glcp-(1 -> 2)-beta-D-Glcp-SEt donor, which avoided 1,6-anydro formation, was successfully glycosylated at O3 of a galactoside acceptor molecule. However, subsequent glycosylation at O2 by a rhamnosyl donor was unsuccessful and instead a suitably protected alpha-L-Rhap(1 -> 2)-beta-D-Galp-OMe disaccharide was used as the acceptor molecule together with a super-armed beta-D-Glcp-(1 -> 2)-beta-D-Glcp-SEt donor in the glycosylation reaction, to give a tetrasaccharide in a yield of 55%, which after deprotection resulted in the target molecule, the structure of which was verified by the NMR chemical shift prediction program CASPER.

  • 75.
    Ankner, Tobias
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Cosner, Casey C.
    Helquist, Paul
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium- and Nickel-Catalyzed Alkenylation of Enolates2013Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, nr 6, s. 1858-1871Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Transition-metal-catalyzed alkenylation of enolates provides a direct method to synthesize broadly useful ,-unsaturated carbonyl compounds from the corresponding carbonyl compound and alkenyl halides. Despite being reported in the early seventies, this reaction class saw little development for many years. In the past decade, however, efforts to develop this reaction further have increased considerably, and many research groups have reported efficient coupling protocols, including enantioselective versions. These reactions most commonly employ palladium catalysts, but there are also some important reports using nickel. There are many examples of this powerful transformation being used in the synthesis of complex natural products.

  • 76.
    Arafa, Wael A. A.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kärkäs, Markus D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lee, Bao-Lin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liao, Rong-Zhen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Berends, Hans-Martin
    Messinger, Johannes
    Siegbahn, Per E. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dinuclear manganese complexes for water oxidation: evaluation of electronic effects and catalytic activity2014Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, nr 24, s. 11950-11964Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During recent years significant progress has been made towards the realization of a sustainable and carbon-neutral energy economy. One promising approach is photochemical splitting of H2O into O-2 and solar fuels, such as H-2. However, the bottleneck in such artificial photosynthetic schemes is the H2O oxidation half reaction where more efficient catalysts are required that lower the kinetic barrier for this process. In particular catalysts based on earth-abundant metals are highly attractive compared to catalysts comprised of noble metals. We have now synthesized a library of dinuclear Mn-2 (II,III) catalysts for H2O oxidation and studied how the incorporation of different substituents affected the electronics and catalytic efficiency. It was found that the incorporation of a distal carboxyl group into the ligand scaffold resulted in a catalyst with increased catalytic activity, most likely because of the fact that the distal group is able to promote proton-coupled electron transfer (PCET) from the high-valent Mn species, thus facilitating O-O bond formation.

  • 77. Arafa, Wael A. A.
    et al.
    Mohamed, Ashraf M.
    Abdel-Magied, Ahmed F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    ULTRASOUND-MEDIATED THREE-COMPONENT REACTION ON-WATER PROTOCOL FOR THE SYNTHESIS OF NOVEL MONO- AND BIS-1,3-THIAZIN-4-ONE DERIVATIVES2017Inngår i: Heterocycles, ISSN 0385-5414, E-ISSN 1881-0942, Vol. 94, nr 8, s. 1439-1455Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Green synthetic and catalyst-free strategy towards the synthesis of novel mono- and bis-1,3-thiazin-4-one scaffolds through a one pot, reaction of carbon disulfide, monoacetylenic esters and amines under ultrasonication has been reported. The merits of this protocol comprise no need for tedious workup steps and afforded the desired products in excellent yields make this synthetic protocol more efficient and worthy of further attentiveness. Moreover, the method exhibited excellent score in a number of green metrics.

  • 78. Arafa, Wael Abdelgayed Ahmed
    et al.
    Abdel-Magied, Ahmed Fawzy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Nuclear Material Authority, Egypt.
    Utilization of ultrasonic irradiation as green and effective one-pot protocol to prepare a novel series of bis-2-amino-1,3,4-oxa(thia) diazoles and bis-tetrazoles2017Inngår i: ARKIVOC, ISSN 1551-7004, E-ISSN 1551-7012, s. 327-340Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In an effective and straightforward conversion, bis-semicarbazones and bis-thiosemicarbazones are transformed into a diversity of novel substituted bis-2-amino-1,3,4-oxadiazoles and bis-2-amino-1,3,4-thiadiazoles, respectively under ultrasonic irradiation. Bis-tetrazoles are obtained from the dialdehydes by sequential reaction with hydroxylamine hydrochloride, phosphorus pentoxide and sodium azide without isolation of the intermediates oximes and nitriles. All the reactions proceed cleanly and smoothly under mild conditions, with short reaction times and broad functional groups possibility. No side reactions were observed. [GRAPHICS]

  • 79. Arewång, Carl Johan
    et al.
    Lahmann, Martina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Oscarson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Tidén, Anna-Karin
    Synthesis of urine drug metabolites: glucuronic acid glycosides of phenol intermediates2007Inngår i: Carbohydrate Research, ISSN 0008-6215, Vol. 342, nr 7, s. 970-974Artikkel i tidsskrift (Fagfellevurdert)
  • 80. Ashour, Radwa M.
    et al.
    Abdel-Magied, Ahmed F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Nuclear Materials Authority, Egypt.
    Abdel-Khalek, Ahmed A.
    Helaly, O. S.
    Ali, M. M.
    Preparation and characterization of magnetic iron oxide nanoparticles functionalized by L-cysteine: Adsorption and desorption behavior for rare earth metal ions2016Inngår i: Journal of Environmental Chemical Engineering, ISSN 2160-6544, E-ISSN 2213-3437, Vol. 4, nr 3, s. 3114-3121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, magnetic iron oxide nanoparticles functionalized with L-cysteine (Cys-Fe3O4 NPs) was synthesized and fully characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier transform infra-red (FTIR), thermogravimetric analysis (TGA) and zeta potential measurements. The synthesized Cys-Fe(3)O(4)NPs has been evaluated as a highly adsorbent for the adsorption of a mixture of four rare earths RE3+ ions (La3+, Nd3+, Gd3+ and Y3+) from digested monazite solutions. The influence of various factors on the adsorption efficiency such as, the contact time, sample pH, temperature, and concentration of the stripping solution were investigated. The results indicate that Cys-Fe3O4 NPs achieve high removal efficiency 96.7, 99.3, 96.5 and 87% for La3+, Nd3+, Gd3+ and Y3+ ions, respectively, at pH = 6 within 15 min, and the adsorbent affinity for metal ions was found to be in order of Nd3+ > La3+ > Gd3+ > Y3+ ions. Using the Langmuir model, a maximum adsorption capacity of La3+, Nd3+, Gd3+ and Y3+ at room temperature was found to be 71.5, 145.5, 64.5 and 13.6 mg g (1), respectively. The Langmuir isotherm and pseudo-second order model fitted much better than the other isotherms and kinetic models. The obtained results for the thermodynamic parameters confirmed the spontaneous and endothermic nature of the process. Moreover, the desorption was carried out with 0.1 M nitric acid solutions. In addition, Cys-Fe3O4 NPs can be used as a highly efficient adsorbent for the adsorption of La3+, Nd3+, Gd3+ and Y3+ ions from digested monazite solutions.

  • 81.
    Aydin, Juhanes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Fine-tuning of the catalytic activity and selectivity of palladium pincer complexes2007Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is focused on optimization of the catalytic properties of so-called pincer complexes. This work involved synthesis of a large variety of palladium pincer complexes, which were applied in various organic transformations. Optimization of the catalytic properties (also called fine-tuning) was directed to increase the catalytic activity as well as the chemo- and stereo-selectivity of the complexes. This could be achieved by varying the heteroatoms in the terdentate pincer ligand, by changing the electronic properties of the coordinated aryl moiety and by implementing chiral functionalities in the pincer complexes.

    In the cross-coupling reaction of vinyl epoxides and aziridines with organoboronic acids the chemoselectivity of the reaction could be increased by employment of pincer complexes instead of commonly used palladium(0) catalysts. Furthermore, application of a methoxy substituent in the aromatic subunit of the complex considerably increased the activity of the pincer complex catalyst.

    Fine-tuning of the stereoselectivity in electrophilic allylation reactions was achieved using a wide variety of BINOL and biphenanthrol based pincer complexes. The synthesis of these highly stable chiral palladium complexes was accomplished by using an efficient modular approach. The highest enantioselectivity (85% ee) was obtained by applying biphenanthrol based pincer complexes.

    We have presented the first palladium pincer complex catalyzed condensation of sulfonimines with isocyanoacetate. Variation of the heteroatoms in the terdentate ligand of the complex strongly influenced the stereoselectivity of the catalytic transformation. The highest stereoselectivity was obtained by using phosphine based pincer complexes. We have also succeeded to isolate and fully characterize the key intermediate of this reaction.

  • 82.
    Aydin, Juhanes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Novel Pincer Complex-Catalyzed Transformations: Including Asymmetric Catalysis2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis is focused on the development of new pincer complex-catalyzed transformations. Optimization of the catalytic properties (fine-tuning) was directed to increase the catalytic activity as well as the chemo-, stereo- and enantioselectivity of the complexes. This was achieved by varying the heteroatoms in the terdentate pincer ligand, by changing the electronic properties of the coordinated aryl moiety and by implementing chiral functionalities in the pincer complexes.

    In the cross-coupling reaction of vinyl epoxides and aziridines with organoboronic acids the chemoselectivity of the reaction could be increased by employment of pincer complexes instead of commonly used Pd(0) catalysts. Furthermore, the introduction of a methoxy substituent in the aromatic subunit of the complex considerably increased the activity of the pincer complex catalyst.

    Fine-tuning of the enantioselectivity in electrophilic allylation reactions was achieved by using a wide variety of new BINOL- and biphenanthrol-based pincer complexes. The highest enantioselectivity (85% ee) was obtained by applying biphenanthrol-based pincer complexes.

    Stereoselective pincer complex-catalyzed condensation of sulfonylimines with isocyanoacetate could be achieved under mild reaction conditions. By application of chiral PCP catalysts, 2-imidazolines could be obtained with up to 86% ee.

    A new pincer complex-catalyzed C-H bond functionalization based reaction between organonitriles and sulfonylimines affords homoallylic amines and beta-aminonitriles in high yields. The asymmetric version of this process affords beta-aminonitriles with up to 71% ee.

    In the last chapter, a pincer complex-catalyzed redox coupling reaction is described. In this highly regio- and stereoselective process the integrity of the pincer catalysts is fully retained. This catalytic reaction proceeds with a high level of functional group tolerance, as allylic acetate and aryl halide functionalities are retained.

  • 83.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Conrad, Cathrin S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stereoselective pincer-complex catalyzed C-H functionalization of benzyl nitriles under mild conditions. An efficient route to β-aminonitriles2008Inngår i: Organic Letters, ISSN 1523-7060, Vol. 10, nr 22, s. 5175-5178Artikkel i tidsskrift (Fagfellevurdert)
  • 84.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kumar, K. Senthil
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium pincer complex-catalyzed condensation of sulfonimines and isocyanoacetate to imidazoline derivatives. Dependence of the stereoselectivity on the ligand effects2007Inngår i: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 349, nr 17-18, s. 2585-2594Artikkel i tidsskrift (Fagfellevurdert)
  • 85.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kumar, K. Senthil
    Sayah, Mahmoud J.
    Wallner, Olov A.
    Szabó, Kálmán J.
    Synthesis and Catalytic Application of Chiral 1,1‘-Bi-2-naphthol- and Biphenanthrol-Based Pincer Complexes: Selective Allylation of Sulfonimines with Allyl Stannane and Allyl Trifluoroborate2007Inngår i: The Journal of Organic Chemistry, ISSN 0022-3263, Vol. 72, nr 13, s. 4689-4697Artikkel i tidsskrift (Fagfellevurdert)
  • 86.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Larsson, Johanna M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pincer complex-catalyzed redox coupling of alkenes with iodonium salts via presumed palladium(IV) intermediates2009Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 11, nr 13, s. 2852-2854Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Palladium pincer complexes directly catalyze the redox coupling reactions of functionalized alkenes and iodonium salts. The catalytic process, which is suitable for mild catalytic functionalization of allylic acetates and electron-rich alkenes, probably occurs through Pd(IV) intermediates. Due to the strong metal−ligand interactions, the oxidation of phosphine and amine ligands of the pincer complexes can be avoided in the presented reactions.

  • 87.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Larsson, Johanna M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pincer Complex-Catalyzed Coupling Reactions via Palladium (IV) Intermediates2009Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 11, nr 13, s. 2852-2854Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Palladium pincer complexes directly catalyze the redox coupling reactions of functionalized alkenes and iodonium salts. The catalytic process, which is suitable for mild catalytic functionalization of allylic acetates and electron-rich alkenes, probably occurs through Pd(IV) intermediates. Due to the strong metal−ligand interactions, the oxidation of phosphine and amine ligands of the pincer complexes can be avoided in the presented reactions.

  • 88.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rydén, Andreas
    Szabó, Kálmán J.
    Chiral palladium-pincer complex catalyzed asymmetric condensation of sulfonimines and isocyanoacetate2008Inngår i: Tetrahedron: Asymmetry, ISSN 0957-4166, Vol. 19, nr 15, s. 1867-1870Artikkel i tidsskrift (Fagfellevurdert)
  • 89.
    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.

  • 90.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Senthil, Kumar K
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sayah, Mahmoud J
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wallner, Olov A
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J
    Synthesis and catalytic application of chiral 1,1'-Bi-2-naphthol- and biphenanthrol-based pincer complexes: selective allylation of sulfonimines with allyl stannane and allyl trifluoroborate.2007Inngår i: Journal of Organic Chemistry, Vol. 72, nr 13, s. 4689-4697Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    New easily accessible 1,1'-bi-2-naphthol- (BINOL-) and biphenanthrol-based chiral pincer complex catalysts were prepared for selective (up to 85% enantiomeric excess) allylation of sulfonimines. The chiral pincer complexes were prepared by a flexible modular approach allowing an efficient tuning of the selectivity of the catalysts. By employment of the different enantiomeric forms of the catalysts, both enantiomers of the homoallylic amines could be selectively obtained. Both allyl stannanes and allyl trifluoroborates can be employed as allyl sources in the reactions. The biphenanthrol-based complexes gave higher selectivity than the substituted BINOL-based analogues, probably because of the well-shaped chiral pocket generated by employment of the biphenanthrol complexes. The enantioselective allylation of sulfonimines presented in this study has important implications for the mechanism given for the pincer complex-catalyzed allylation reactions, confirming that this process takes place without involvement of palladium(0) species.

  • 91.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Senthil Kumar, Kuppusamy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic studies of the palladium pincer complex-catalyzed condensation of sulfonimines and isocyanoacetate to imidazoline derivatives2008Inngår i: Abstracts of Papers, 235th ACS National Meeting, New Orleans, LA, United States, April 6-10, 2008, 2008Konferansepaper (Annet vitenskapelig)
  • 92.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantioselective palladium pincer complex catalyzed carbon carbon coupling reactions between tosylimines and various nucleophiles2008Inngår i: Abstracts of Papers, 236th ACS National Meeting, Philadelphia, PA, United States, August 17-21, 2008, Washington, DC: American Chemical Society , 2008Konferansepaper (Annet vitenskapelig)
  • 93.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-pincer complex catalyzed C-C coupling of allyl nitriles with tosyl imines via regioselective allylic C-H bond functionalization2008Inngår i: Organic Letters, ISSN 1523-7060, Vol. 10, nr 13, s. 2881-2884Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mechanistically new palladium-pincer complex catalyzed allylation of sulfonimines is presented. This reaction involves C-H bond functionalization of allyl nitriles under mild conditions. The reaction proceeds with a high regioselectivity, without allyl rearrangement of the product. Modeling studies indicate that the carbon-carbon bond formation process proceeds via (η1-allyl)palladium pincer complex intermediates.

  • 94.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic considerations for the enantioselective palladium pincer complex catalyzed carbon-carbon coupling reactions2008Inngår i: Abstracts of Papers, 236th ACS National Meeting, Philadelphia, PA, United States, August 17-21, 2008, Washington, DC: American Chemical Society , 2008Konferansepaper (Annet vitenskapelig)
  • 95.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wallner, Olov A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olsson, Vilhelm J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Application of BINOL based pincer-complexes for palladium-catalyzed transformations2007Inngår i: Abstracts of Papers, 233rd ACS National Meeting, Chicago, IL, United States, March 25-29, 2007, 2007Konferansepaper (Annet vitenskapelig)
  • 96.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wallner, Olov A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olsson, Vilhelm J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium pincer complex catalyzed asymmetric transformations of sulfonimines2007Inngår i: Abstracts of Papers, 233rd ACS National Meeting, Chicago, IL, United States, March 25-29, 2007, 2007Konferansepaper (Annet vitenskapelig)
  • 97.
    Ayesa Alvarez, Susana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Design and Synthesis of Amine Building Blocks and Protease Inhibitors2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The first part of this thesis addresses the design and synthesis of amine building blocks accomplished by applying two different synthetic procedures, both of which were developed using solid-phase chemistry. Chapter 1 presents the first of these methods, entailing a practical solid-phase parallel synthesis route to N-monoalkylated aminopiperidines and aminopyrrolidines achieved by selective reductive alkylation of primary and/or secondary amines. Solid-phase NMR spectroscopy was used to monitor the reactions for which a new pulse sequence was developed. The second method, reported in Chapter 2, involves a novel approach to the synthesis of secondary amines starting from reactive alkyl halides and azides. The convenient solid-phase protocol that was devised made use of the Staudinger reaction in order to accomplish highly efficient alkylations of N-alkyl phosphimines or N-aryl phosphimines with reactive alkyl halides.

    The second part of the thesis describes the design and synthesis of three classes of protease inhibitors targeting the cysteine proteases cathepsins S and K, and the serine protease hepatitis C virus (HCV) NS3 protease. Chapter 4 covers the design, solid-phase synthesis, and structure-activity relationships of 4-amidofurane-3-one P1-containing inhibitors of cathepsin S and the effects of P3 sulfonamide groups on the potency and selectivity towards related cathepsin proteases. This work resulted in the discovery of highly potent and selective inhibitors of cathepsin S. Two parallel solid-phase approaches to the synthesis of a series of aminoethylamide inhibitors of cathepsin K are presented in Chapter 5. Finally, Chapter 6 reports peptide-based HCV NS3 protease inhibitors containing a non-electrophilic allylic alcohol moiety as P1 group and also outlines efforts to incorporate this new template into low-molecular-weight drug-like molecules.

  • 98.
    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 –pyrrolidines2004Inngår i: European Journal of Organic Chemistry, ISSN 1434-193x, nr 12, s. 2723-2737Artikkel i tidsskrift (Fagfellevurdert)
  • 99.
    Ayesa, Susana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Chen, Jing-May
    Classon, Björn
    Gallego, Jose
    Grabowska, Urszula
    Henderson, Ian
    Heyer, Narinder
    Johnson, Tony
    Kangasmetsä, Jussi
    Liley, Mark
    Nilsson, Magnus
    Parkes, Kevin
    Rakos, Laszlo
    Tozer, Matthew J.
    Wilson, Michelle
    Preparation and Characterization of Aminoethylamide Inhibitors of the Cysteine Proteinase Cathepsin KInngår i: European Journal of Medicinal Chemistry, ISSN 0223-5234Artikkel i tidsskrift (Fagfellevurdert)
  • 100.
    Ayesa, Susana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lindquist, Charlotta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Agback, Tatiana
    Benkestock, Kurt
    Classon, Björn
    Henderson, Ian
    Hewitt, Ellen
    Jansson, Katarina
    Kallin, Anders
    Sheppard, Dave
    Samuelsson, Bertil
    Solid-phase parallel synthesis and SAR of 4-amidofuran-3-one inhibitors of cathepsin S: Effect of sulfonamides P3 substituents on potency and selectivity.2009Inngår i: Bioorganic & Medicinal Chemistry, ISSN 0968-0896, E-ISSN 1464-3391, Vol. 17, nr 3, s. 1307-1324Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Highly potent and selective 4-amidofuran-3-one inhibitors of cathepsin S are described. The synthesis and structure–activity relationship of a series of inhibitors with a sulfonamide moiety in the P3 position is presented. Several members of the series show sub-nanomolar inhibition of the target enzyme as well as an excellent selectivity profile and good cellular potency. Molecular modeling of the most interesting inhibitors describes interactions in the extended S3 pocket and explains the observed selectivity towards cathepsin K.

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