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  • 1. Abrahamsson, Maria
    et al.
    Lundqvist, Maria J.
    Wolpher, Henriette
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johansson, Olof
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Bergquist, Jonas
    Rasmussen, Torben
    Becker, Hans-Christian
    Hammarström, Leif
    Norrby, Per-Ola
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Persson, Petter
    Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands2008In: Inorganic Chemistry, ISSN 0020-1669, Vol. 47, no 9, p. 3540-3548Article in journal (Refereed)
  • 2.
    Ahlford, Katrin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lind, Jesper
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Mäler, Lena
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rhodium-catalyzed asymmetric transfer hydrogenation of alkyl and aryl ketones in aqueous media2008In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 10, no 8, p. 832-835Article in journal (Refereed)
    Abstract [en]

    A novel lipophilic rhodium catalyst was evaluated in the enantioselective transfer hydrogenation of ketones in water using sodium formate as the hydride donor, and in the presence of sodium docecylsulfonate. Alkyl alkyl ketones were reduced in good yields and in moderate to good enantioselectivities, and the reduction of aryl alkyl ketones proceeded with excellent enantioselectivity (up to 97% ee).

  • 3.
    Akhtar, Tashfeen
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Cumpstey, Ian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Unusual synthesis of carbohydrate sec-sec ether-linked pseudodisaccharides2008In: Carbohydrate Research, ISSN 0008-6215, Vol. 343, no 12, p. 2094-2100Article in journal (Refereed)
  • 4. Alexakis, A.
    et al.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krause, N.
    Pàmies, O.
    Diéguez, M.
    Enantioselective copper-catalyzed conjugate addition and allylic substitution reactions2008In: Chemical Reviews, ISSN 0009-2665, Vol. 108, no 8, p. 2796-2823Article in journal (Refereed)
  • 5.
    Ali, Tara
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Weintraub, Andrej
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Structural studies of the O-antigenic polysaccharides from the enteroaggregative Escherichia coli strain 87/D2 and international type strains from E. coli O1282008In: Carbohydrate Research, ISSN 0008-6215, Vol. 343, no 4, p. 695-702Article in journal (Refereed)
  • 6.
    Aydin, Juhanes
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Conrad, Cathrin S.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stereoselective pincer-complex catalyzed C-H functionalization of benzyl nitriles under mild conditions. An efficient route to β-aminonitriles2008In: Organic Letters, ISSN 1523-7060, Vol. 10, no 22, p. 5175-5178Article in journal (Refereed)
  • 7.
    Aydin, Juhanes
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rydén, Andreas
    Szabó, Kálmán J.
    Chiral palladium-pincer complex catalyzed asymmetric condensation of sulfonimines and isocyanoacetate2008In: Tetrahedron: Asymmetry, ISSN 0957-4166, Vol. 19, no 15, p. 1867-1870Article in journal (Refereed)
  • 8.
    Aydin, Juhanes
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-pincer complex catalyzed C-C coupling of allyl nitriles with tosyl imines via regioselective allylic C-H bond functionalization2008In: Organic Letters, ISSN 1523-7060, Vol. 10, no 13, p. 2881-2884Article in journal (Refereed)
    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.

  • 9.
    Ayesa, Susana
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samuelsson, Bertil
    Classon, Björn
    A One-Pot, Solid-Phase Synthesis of Secondary Amines from Reactive Alkyl Halides and an Alkyl Azide2008In: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, no 1, p. 77-79Article in journal (Refereed)
  • 10. Back, Marcus
    et al.
    Nyhlen, Jonas
    Kvarnstrom, Ingemar
    Appelgren, Sara
    Borkakoti, Neera
    Jansson, Katarina
    Lindberg, Jimmy
    Nystrom, Susanne
    Hallberg, Anders
    Rosenquist, Asa
    Samuelsson, Bertil
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Design, synthesis and SAR of potent statine-based BACE-1 inhibitors: Exploration of P1 phenoxy and benzyloxy residues2008In: Bioorganic & Medicinal Chemistry, ISSN 0968-0896, E-ISSN 1464-3391, Vol. 16, no 21, p. 9471-9486Article in journal (Refereed)
    Abstract [en]

    Several BACE-1 inhibitors with low nanomolar level activities, encompassing a statine-based core structure with phenyloxymethyl- and benzyloxymethyl residues in the P1 position, are presented. The novel P1 modi. cation introduced to allow the facile exploration of the S1 binding pocket of BACE-1, delivered highly promising inhibitors.

  • 11.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kalek, Marcin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iodine-promoted silylation of alcohols with silyl chlorides. Synthetic and mechanistic studies2008In: Tetrahedron, ISSN 0040-4020, Vol. 64, no 37, p. 8843-8850Article in journal (Refereed)
  • 12.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kalek, Marcin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The case for the intermediacy of monomeric metaphosphate analogues during oxidation of H-phosphonothioate, H-phosphonodithioate, and H-phosphonoselenoate monoesters: mechanistic and synthetic studies2008In: The Journal of Organic Chemistry, ISSN 0022-3263, Vol. 73, no 13, p. 5029-5038Article in journal (Refereed)
  • 13.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Livendahl, Madeleine
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient synthesis of beta-hydroxy ketones from allylic alcohols by catalytic formation of ruthenium enolates2008In: Chemistry: a European Journal, ISSN 0947-6539, Vol. 14, no 34, p. 10547-10550Article in journal (Refereed)
  • 14.
    Bartoszewicz, Agnieszka
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Livendahl, Madeleine
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of b-Hydroxy Ketones from Allylic Alcohols via Catalytic Formation of Ruthenium Enolates2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 34, p. 10547-10550Article in journal (Refereed)
    Abstract [en]

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

  • 15.
    Bielawski, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aili, David
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Regiospecific One-Pot Synthesis of Diaryliodonium Tetrafluoroborates from Arylboronic Acids and Aryl Iodides2008In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 73, no 12, p. 4602-4607Article in journal (Refereed)
    Abstract [en]

    Diaryliodonium salts have recently received considerable attention as mild arylation reagents in organic synthesis. This paper describes a regiospecific, sequential one-pot synthesis of symmetrical and unsymmetrical diaryliodonium tetrafluoroborates, which are the most popular salts in metal-catalyzed arylations. The protocol is fast and high-yielding and has a large substrate scope. Furthermore, the corresponding diaryliodonium triflates can conveniently be obtained via an in situ anion exchange.

  • 16.
    Covarrubias, Adrian Suarez
    et al.
    Department of Cell and Molecular Biology, Uppsala University, Sweden.
    Högbom, Martin
    Department of Cell and Molecular Biology, Uppsala University, Sweden.
    Bergfors, Terese
    Department of Cell and Molecular Biology, Uppsala University, Sweden.
    Carroll, Paul
    Institute for Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, London.
    Mannerstedt, Karin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oscarson, Stefan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Parish, Tanya
    Institute for Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, London.
    Jones, T Alwyn
    Department of Cell and Molecular Biology, Uppsala University, Sweden.
    Mowbray, Sherry L
    Department of Molecular Biology, Swedish University of Agricultural Sciences, Biomedical Center, Uppsala, Sweden.
    Structural, biochemical, and in vivo investigations of the threonine synthase from Mycobacterium tuberculosis.2008In: Journal of Molecular Biology, ISSN 0022-2836, E-ISSN 1089-8638, Vol. 381, no 3, p. 622-33Article in journal (Refereed)
    Abstract [en]

    Threonine biosynthesis is a general feature of prokaryotes, eukaryotic microorganisms, and higher plants. Since mammals lack the appropriate synthetic machinery, instead obtaining the amino acid through their diet, the pathway is a potential focus for the development of novel antibiotics, antifungal agents, and herbicides. Threonine synthase (TS), a pyridoxal-5-phosphate-dependent enzyme, catalyzes the final step in the pathway, in which L-homoserine phosphate and water are converted into threonine and inorganic phosphate. In the present publication, we report structural and functional studies of Mycobacterium tuberculosis TS, the product of the rv1295 (thrC) gene. The structure gives new insights into the catalytic mechanism of TSs in general, specifically by suggesting the direct involvement of the phosphate moiety of the cofactor, rather than the inorganic phosphate product, in transferring a proton from C4' to C(gamma) in the formation of the alphabeta-unsaturated aldimine. It further provides a basis for understanding why this enzyme has a higher pH optimum than has been reported elsewhere for TSs and gives rise to the prediction that the equivalent enzyme from Thermus thermophilus will exhibit similar behavior. A deletion of the relevant gene generated a strain of M. tuberculosis that requires threonine for growth; such auxotrophic strains are frequently attenuated in vivo, indicating that TS is a potential drug target in this organism.

  • 17.
    Cribiù, Riccardo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cumpstey, Ian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stereospecific debenzylative cycloetherification of carbohydrate-derived allylic alcohols, ethers and esters to form vinyl C-furanosides2008In: Chemical Communications, ISSN 1359-7345, no 10, p. 1246-1248Article in journal (Refereed)
  • 18.
    Cumpstey, Ian
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gehrke, Sebastian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Erfan, Sayeh
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cribiù, Riccardo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Studies on the synthesis of valienamine and 1-epi-valienamine starting from D-glucose or L-sorbose2008In: Carbohydrate Research, ISSN 0008-6215, Vol. 343, no 10-11, p. 1675-1692Article in journal (Refereed)
  • 19. Dutheuil, Guillaume
    et al.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aggarwal, Varinder K.
    Direct synthesis of functionalized allylic boronic esters from allylic alcohols and inexpensive reagents and catalysts2008In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, no 14, p. 2293-2297Article in journal (Refereed)
    Abstract [en]

    A remarkably simple and effective system for the direct conversion of allylic alcohols into high value allylic boronic esters using commercially available reagents and catalysts is described.

  • 20.
    Dziedzic, Pawel
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ibrahem, Ismail
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Direct catalytic asymmetric three-component Mannich reactions with dihydroxyacetone: enantioselective synthesis of amino sugar derivatives2008In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 49, no 5, p. 803-807Article in journal (Refereed)
    Abstract [en]

    Highly enantioselective, amino acid-catalyzed, one-pot three-component asymmetric Mannich reactions between dihydroxyacetone, p-anisidine, and aldehydes are presented. The reactions proceeded with high chemo- and stereoselectivity and furnished the corresponding α,α′-dihydroxy-β-aminoketones in high yields with 82–95% ee.

  • 21.
    Dziedzic, Pawel
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Vesely, Jan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic asymmetric synthesis of the docetaxel (Taxotere) side chain: organocatalytic highly enantioselective synthesis of esterification-ready alpha-hydroxy-beta-amino acids2008In: Tetrahedron Letters, ISSN 0040-4039, Vol. 49, no 47, p. 6631-6634Article in journal (Refereed)
    Abstract [en]

    A highly enantioselective catalytic route to protected β-amino-α-hydroxy acids, such as the side chain of Taxotere, is presented. The organocatalytic asymmetric reactions between unmodified protected α-oxyaldehydes and N-Boc-protected aryl imines give the corresponding compound with up to >19:1 dr and 99–99% ee.

  • 22.
    Ericsson, Daniel J.
    et al.
    1Department of Cell and Molecular Biology, Uppsala University, Biomedical Center.
    Kasrayan, Alex
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johansson, Patrik
    1Department of Cell and Molecular Biology, Uppsala University, Biomedical Center.
    Bergfors, Terese
    1Department of Cell and Molecular Biology, Uppsala University, Biomedical Center.
    Sandström, Anders G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mowbray, Sherry L.
    Department of Molecular Biology, Swedish University of Agricultural Sciences, Biomedical Center.
    X-Ray structure of Candida antarctica lipase A shows a novel lid structure and a likely mode of interfacial activation2008In: Journal of Molecular Biology, ISSN 0022-2836, Vol. 376, no 1, p. 109-119Article in journal (Refereed)
    Abstract [en]

    In nature, lipases (EC 3.1.1.3) catalyze the hydrolysis of triglycerides to form glycerol and fatty acids. Under the appropriate conditions, the reaction is reversible, and so biotechnological applications commonly make use of their capacity for esterification as well as for hydrolysis of a wide variety of compounds. In the present paper, we report the X-ray structure of lipase A from Candida antarctica, solved by single isomorphous replacement with anomalous scattering, and refined to 2.2-Å resolution. The structure is the first from a novel family of lipases. Contrary to previous predictions, the fold includes a well-defined lid as well as a classic α/β hydrolase domain. The catalytic triad is identified as Ser184, Asp334 and His366, which follow the sequential order considered to be characteristic of lipases; the serine lies within a typical nucleophilic elbow. Computer docking studies, as well as comparisons to related structures, place the carboxylate group of a fatty acid product near the serine nucleophile, with the long lipid tail closely following the path through the lid that is marked by a fortuitously bound molecule of polyethylene glycol. For an ester substrate to bind in an equivalent fashion, loop movements near Phe431 will be required, suggesting the primary focus of the conformational changes required for interfacial activation. Such movements will provide virtually unlimited access to solvent for the alcohol moiety of an ester substrate. The structure thus provides a basis for understanding the enzyme's preference for acyl moieties with long, straight tails, and for its highly promiscuous acceptance of widely different alcohol and amine moieties. An unconventional oxyanion hole is observed in the present structure, although the situation may change during interfacial activation

  • 23.
    Eriksson, Lars
    et al.
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Widmalm, Göran
    Department of Organic Chemistry.
    Methyl 3-O-alpha-D-mannopyranosyl beta-D-glucopyranoside tetrahydrate2008In: Acta Crystallographica Section E, ISSN 1600-5368, Vol. E64, no 8, p. o1639-o1640Article in journal (Refereed)
  • 24.
    Färnbäck, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Methyl 2-O-beta-L-fucopyranosyl alpha-D-glucopyranoside monohydrate: a synchrotron study2008In: Acta Crystallographica Section C, ISSN 0108-2701, Vol. 64, no 2, p. o31-o32Article in journal (Refereed)
  • 25. Gagliardo, Marcella
    et al.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mehendale, Nilesh C.
    van Koten, Gerard
    Klein Gebbink, Robertus J. M.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic performance of symmetrical and unsymmetrical sulfur-containing pincer complexes: synthesis and tandem catalytic activity of the first PCS-pincer palladium complex2008In: Chemistry: a European journal, ISSN 0947-6539, Vol. 14, no 16, p. 4800-4809Article in journal (Refereed)
  • 26. Gao, Weiming
    et al.
    Liu, Jianhui
    Jiang, Weina
    Wang, Mei
    Weng, Linhong
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    An azadithiolate bridged Fe2S2 complex as active site model of FeFe-hydrogenase covalently linked to a Re(CO)3(bpy)(py) photosensitizer aiming for light-driven hydrogen production2008In: Comptes Rendus Chimie, ISSN 1631-0748, Vol. 11, no 8, p. 915-921Article in journal (Refereed)
  • 27. González, David
    et al.
    Grilló, María-Jesús
    De Miguel, María-Jesús
    Ali, Tara
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Arce-Gorvel, Vilma
    Delrue, Rose-May
    Conde-Álvarez, Raquel
    Munoz, Pilar
    López-Goni, Ignacio
    Iriarte, Maite
    Marín, Clara-M.
    Weintraub, Andrej
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zygmunt, Michel
    Letesson, Jean-Jacques
    Gorvel, Jean-Pierre
    Blasco, José-María
    Moriyón, Ignacio
    Brucellosis vaccines: assessment of Brucella melitensis lipopolysaccharide rough mutants defective in core and O-polysaccharide synthesis and export2008In: PLoS ONE, ISSN 1932-6203, Vol. 3, no 7, p. e2760 (1-15)Article in journal (Refereed)
  • 28. Gupta, Garima
    et al.
    Gemma, Emiliano
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oscarson, Stefan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Surolia, Avadhesha
    Defining substrate interactions with calreticulin: an isothermal titration calorimetric study2008In: Glycoconjugate Journal, ISSN 0282-0080, Vol. 25, no 8, p. 797-802Article in journal (Refereed)
  • 29. Hammar, Peter
    et al.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Himo, Fahmi
    Density functional theory study of the stereoselectivity in small peptide-catalyzed intermolecular aldol reactions2008In: Tetrahedron: Asymmetry, ISSN 0957-4166, Vol. 19, no 13, p. 1617-1621Article in journal (Refereed)
  • 30.
    Hoben, Christine E.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kanupp, Lisa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Practical chemoenzymatic dynamic kinetic resolution of primary amines via transfer of a readily removable benzyloxycarbonyl group2008In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 49, no 6, p. 977-979Article in journal (Refereed)
  • 31.
    Ibrahem, Ismail
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hammar, Peter
    Vesely, Jan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Organocatalytic asymmetric hydrophosphination of alpha,beta-unsaturated aldehydes: Development, mechanism and DFT calculations2008In: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 350, no 11-12, p. 1875-1884Article in journal (Refereed)
  • 32.
    Ibrahem, Ismail
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramon
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Vesely, Jan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cordova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic enantioselective 5-hydroxyisoxazolidine synthesis: An asymmetric entry to beta-amino acids2008In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, no 7, p. 1153-1157Article in journal (Refereed)
    Abstract [en]

    The highly chemo- and enantioselective organocatalytic tandem reaction between N-carbamate-protected hydroxylamines and a,p-unsaturated aldehydes is presented. The reaction represents a unique entry for the asymmetric synthesis of 5-hydroxyisoxazolidines, oxazolidin-5-ones or gamma-hydroxyamino alcohols in high yields and 90-99% ee. A procedure for the conversion of the oxazolidin-5-ones into the corresponding beta-amino acids is also described.

  • 33.
    Ibrahem, Ismail
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Gui-Ling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rios, Ramón
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Vesely, Jan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sundén, Henrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dziedzic, Pawel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    One-pot organocatalytic domino Michael/alpha-alkylation reactions: direct catalytic enantioselective cyclopropanation and cyclopentanation reactions2008In: Chemistry: a European journal, ISSN 0947-6539, Vol. 14, no 26, p. 7867-7879Article in journal (Refereed)
  • 34.
    Johansson, Mikael
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Purse, Byron W.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Terasak, Osamu
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aerobic Oxidations Catalyzed by Zeolite-Encapsulated Cobalt Salophen2008In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 350, no 11-12, p. 1807-1815Article in journal (Refereed)
    Abstract [en]

    Cobalt salophen was encapsulated in a series of zeolites with a wide variation of the silicon-to-aluminium atomic ratio and with different cations. The zeolite-cobalt salophen catalysts were prepared using the “ship-in-a-bottle technique” where the complex was synthesized in the super cage of the zeolite and therefore locked into the pocket. The encapsulated catalysts were then tested in the aerobic oxidation of hydroquinone to p-benzoquinone; the best encapsulated catalyst was shown to be an efficient electron-transfer mediator in a palladium-catalyzed aerobic oxidative carbocyclization.

  • 35.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bartoszewicz, Agnieszka
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of nucleoside phosphorothio-, phosphorodithio- and phosphoroselenoate diesters via oxidative esterification of the corresponding H-phosphonate analogues2008In: Nucleic Acids Symposium Series, ISSN 0261-3166, Vol. 52, p. 285-286Article in journal (Refereed)
  • 36.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-catalyzed C-P bond formation: Mechanistic studies on the ligand substitution and the reductive elimination. An intramolecular catalysis by the acetate group in PdII complexes2008In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 27, no 22, p. 5876-5888Article in journal (Refereed)
    Abstract [en]

    Ligand substitution and reductive elimination of the palladium-catalyzed C−P bond forming cross-coupling were investigated in depth. It was found that for PhPdII(PPh3)2X (X = I, Br, Cl) complexes, a step commonly referred to as ligand substitution commenced with coordination of an H-phosphonate diester, followed by its deprotonation to form an equilibrium mixture of penta- and tetracoordinate palladiumphosphonate intermediates, from which reductive elimination of the product (diethyl phenylphosphonate) occurred. For the acetate counterpart, PhPdII(PPh3)2(OAc), the incorporation of a phosphonate moiety to the complex was preceded by a rate-determining removal of the supporting phosphine ligand, facilitated by an intramolecular catalysis by the acetate group. Both the reaction steps, i.e., formation of palladiumphosphonate intermediates and reductive elimination, were significantly faster for the acetate versus halides containing PdII complexes investigated. Similar observations were found to be true also for bidentate ligand complexes [(dppp)PdII(Ph)X]; however, in this instance, a single palladiumphosphonate intermediate, (dppp)PdII(Ph)(PO(OEt)2), could be observed by 31P NMR spectroscopy. The synthetic and kinetic studies on the cross-coupling reaction of diethyl H-phosphonate with phenyl halides permitted us to elucidate a crucial catalytic role of an acetate group in PdII complexes and to propose two distinctive catalytic cycles, which complemented traditional Pd0/PdII schemes, for the palladium-mediated C−P bond formation.

  • 37.
    Kalek, Marcin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ziadi, Asraa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Microwave-assisted palladium-catalyzed cross-coupling of aryl and vinyl halides with H-phosphonate diesters2008In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 10, no 20, p. 4637-4640Article in journal (Refereed)
    Abstract [en]

    A general and efficient method for the microwave-assisted formation of the C−P bond was developed. Using a prevalent palladium catalyst, Pd(PPh3)4, a quantitative cross-coupling of various H-phosphonate diesters with aryl and vinyl halides was achieved in less than 10 min. The reactions occurred with retention of configuration at the phosphorus center and in the vinyl moiety. Using this protocol, several C-phosphonates, including those bearing nucleoside and cholesteryl moieties, were prepared in high yields.

  • 38.
    Karlsson, Erik A.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanism of the palladium-catalyzed carbohydroxylation of allene-substituted conjugated dienes: rationalization of the recently observed nucleophilic attack by water on a (pi-allyl)palladium intermediate2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 30, p. 9175-9180Article in journal (Refereed)
    Abstract [en]

    The mechanism of the palladium-catalyzed oxidative carbohydroxylation of allene-substituted 1,3-cyclohexadiene was studied by DFT calculations. All intermediates and transition states of the reaction were identified and their structures were calculated. The calculations confirm the mechanism previously proposed and show that the CC bond-forming step occurs via insertion of one of the double bonds of 1,3-cyclohexadiene into a Pdvinyl bond of a vinylpalladium intermediate. This reaction leads to a (π-allyl)palladium intermediate, and coordination of benzoquinone and a double bond in the molecule to Pd creates a highly reactive cationic π-allyl complex, which is readily attacked by water according to the calculations.

  • 39. Koshino, Masanori
    et al.
    Solin, Niclas
    Tanaka, Takatsugu
    Isobe, Hiroyuki
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nakamura, Eiichi
    Imaging the passage of a single hydrocarbon chain through a nanopore2008In: Nature Nanotechnology, ISSN 1748-3387, E-ISSN 1748-3395, Vol. 3, no 10, p. 595-597Article in journal (Refereed)
    Abstract [en]

    Molecular transport through nanoscale pores in films, membranes and wall structures is of fundamental importance in a number of physical, chemical and biological processes(1-6). However, there is a lack of experimental methods that can obtain information on the structure and orientation of the molecules as they pass through the pore, and their interactions with the pore during passage. Imaging with a transmission electron microscope is a powerful method for studying structural changes in single molecules as they move(7,8) and for imaging molecules confined inside carbon nanotubes(9). Here, we report that such imaging can be used to observe the structure and orientation of a hydrocarbon chain as it passes through nanoscale defects in the walls of a single-walled carbon nanotube to the vacuum outside, and also to study the interactions between the chain and the nanopore. Based on experiments at 293 K and 4 K we conclude that the major energy source for the molecular motions observed at 4 K is the electron beam used for the imaging.

  • 40.
    Landström, Jens
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nordmark, Eva-Lisa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eklund, Robert
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Weintraub, Andrej
    Seckler, Robert
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Interaction of a Salmonella enteritidis O-antigen octasaccharide with the phage P22 tailspike protein by NMR spectroscopy and docking studies2008In: Glycoconjugate Journal, ISSN 0282-0080, E-ISSN 1573-4986, Vol. 25, no 2, p. 137-143Article in journal (Refereed)
  • 41.
    Leijondahl, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Borén, Linnéa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Braun, Roland
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantiopure 1,5-diols from dynamic kinetic asymmetric transformation: Useful synthetic intermediates for the preparation of heterocycles2008In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 10, no 10, p. 2027-2030Article in journal (Refereed)
    Abstract [en]

    Dynamic kinetic asymmetric transformation (DYKAT) of a series of 1,5-diols has been performed in the presence of Candida antarctica lipase B (CALB), Pseudomonas cepacia lipase H (PS-C II), and ruthenium catalyst 4. The resulting optically pure 1,5-diacetates are useful synthetic intermediates, which was demonstrated by the syntheses of both an enantiopure 2,6-disubstituted piperidine and an enantiopure 3,5-disubstituted morpholine.

  • 42. Li, Xueqiang
    et al.
    Wang, Mei
    Zhang, Suping
    Pan, Jingxi
    Na, Yong
    Liu, Jianhui
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Noncovalent assembly of a metalloporphyrin and an iron hydrogenase active-site model: photo-induced electron transfer and hydrogen generation2008In: The Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 112, no 27, p. 8198-8202Article in journal (Refereed)
  • 43.
    Liao, Rong-Zhen
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yu, Jian-Guo
    Raushel, Frank M.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Theoretical Investigation of the Reaction Mechanism of the Dinuclear Zinc Enzyme Dihydroorotase2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 14, p. 4287-4292Article in journal (Refereed)
    Abstract [en]

    The reaction mechanism of the dinuclear zinc enzyme dihydroorotase was investigated by using hybrid density functional theory. This enzyme catalyzes the reversible inter-conversion of dihydroorotate and carbamoyl aspartate. Two reaction mechanisms in which the important active site residue Asp250 was either protonated or unprotonated were considered. The calculations establish that Asp250 must be unprotonated for the reaction to take place. The bridging hydroxide is shown to be capable of performing nucleophilic attack on the substrate from its bridging position and the role of Zn-beta is argued to be the stabilization of the tetrahedral intermediate and the transition state leading to it, thereby lowering the barrier for the nucleophilic attack. It is furthermore concluded that the rate-limiting step is the protonation of the amide nitrogen by Asp250 coupled with C-N bond cleavage, which is consistent with previous experimental findings from isotope labeling studies.

  • 44.
    Mannerstedt, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Segerstedt, Eva
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olsson, Johan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oscarson, Stefan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of a common tetrasaccharide motif of Haemophilus influenzae LPS inner core structures2008In: Organic & Biomolecular Chemistry, ISSN 1477-0520, Vol. 6, no 6, p. 1087-1091Article in journal (Refereed)
  • 45. Na, Yong
    et al.
    Wang, Mei
    Pan, Jingxi
    Zhang, Pan
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Visible light-driven electron transfer and hydrogen generation catalyzed by bioinspired [2Fe2S] complexes2008In: Inorganic Chemistry, ISSN 0020-1669, Vol. 47, no 7, p. 2805-2810Article in journal (Refereed)
  • 46. Naidoo, Kevin J.
    et al.
    Gamieldien, M. Riedaa
    Yu-Jen Chen, Jeff
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Maliniak, Arnold
    Glucose orientation and dynamics in α-, β-, and γ-cyclodextrins2008In: The Journal of Physical Chemistry B, ISSN 1089-5647, Vol. 112, no 47, p. 15151–15157-Article in journal (Refereed)
    Abstract [en]

    We investigate, using molecular dynamics (MD) computer simulations, the conformational behavior of α-, β-, and γ-cyclodextrins (CDs). Our analysis of a 30 ns trajectory of CD solution dynamics reveals the underlying conformational behaviours of the CDs that explain their relative flexibility. The distributions of the torsion angles related to the glycosidic linkages, P(ϕ,ψ) were calculated for the three CDs. Most noticeable is the limited range in ϕ torsion rotations compared with ψ rotations for all the CDs. This difference between the three CDs is amplified in the motion and dynamics of their glucose monomers when we monitor their orientational and librational positions relative to the macrocyclic mean plane. The relaxation times of the monomers to their equilibrium orientations follow the pattern γ-CD > α-CD > β-CD. The root-mean-square deviations of the motion of the monomer centers of mass from the mean macrocyclic planes exhibit the same trend.

  • 47.
    Nozière, Barbara
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A Kinetic and Mechanistic Study of the Amino Acid Catalyzed Aldol Condensation of Acetaldehyde in Aqueous and Salt Solutions2008In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 112, no 13, p. 2827-2837Article in journal (Refereed)
    Abstract [en]

    The amino acid-catalyzed aldol condensation is of great interest in organic synthesis and natural environments such as atmospheric particles. But kinetic and mechanistic information on these reactions is limited. In this work, the kinetics of the aldol condensation of acetaldehyde in water and aqueous salt solutions (NaCl, CaCl2, Na2SO4, MgSO4), catalyzed by five amino acids (glycine, alanine, serine, arginine, and proline) at room temperature (295 ± 2K) has been studied. Monitoring the formation of three products, crotonaldehyde, 2,4-hexadienal, and 2,4,6-octatrienal by UV-Visible absorption over 200 – 1100 nm revealed two distinct kinetic regimes: at low amino acid concentrations (in all cases, below 0.1 M) the overall reaction was first order with respect to acetaldehyde and kinetically limited by the formation of the enamine intermediate. At larger amino acid concentrations (at least 0.3 M) the kinetics was second order and controlled by the C-C bond-forming step. The first-order rate constants increased linearly with amino acid concentration, consistent with the enamine formation. Inorganic salts further accelerated the enamine formation according to their pKb plausibly by facilitating the iminium and/or enamine formation. The rate constant of the C-C bond-forming step varied with the square of amino acid concentration, suggesting the involvement of two amino acid molecules. Thus, the reaction proceeded via a Mannich pathway. However, the contribution of an aldol pathway, first-order in amino acid, could not be excluded. Our results show that the rate constant for the self-condensation of acetaldehyde in aqueous atmospheric aerosols (up to 10 of mM of amino acids) is identical as in sulfuric acid 10 - 15 M (kI ~ 10-7 - 10-6 s-1), clearly illustrating the potential importance of amino acid catalysis in natural environments. This work also demonstrates that under usual laboratory conditions and in natural environments aldol condensation is likely to be kinetically controlled by the enamine formation. Notably, kinetic investigations of the C-C bond-forming addition step would only be possible with high concentrations of amino acids.

  • 48.
    Nyhlén, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis and optical resolution of an allenoic acid by diastereomeric salt formation induced by chiral alkaloids2008In: Chirality, ISSN 0899-0042, Vol. 20, no 1, p. 47-50Article in journal (Refereed)
  • 49.
    Nyhlén, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sandström, Anders G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bocola, Marco
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Influence of delta-functional groups on the enantiorecognition of secondary alcohols by Candida antarctica lipase B2008In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 9, no 12, p. 1968-1974Article in journal (Refereed)
    Abstract [en]

    The selectivity of acetylation of delta-functionalized secondary alcohols catalyzed by Candida antarctica lipase B has been examined by molecular dynamics. The results from the simulation show that a delta-alcohol functionality forms a hydrogen bond with the carbonyl group of Thr 40. This interaction stabilizes the tetrahedral intermediate and thus leads to selective acetylation of the R enantiomer. A stabilizing interaction of the delta-(R)-acetoxy group with the peptide NH of alanine 282 was also observed. No stabilizing interaction could be found for the delta-keto functionality, and it is proposed that this is the reason for the experimentally observed decrease in enantioselectivity. From these results, it was hypothesized that the enantioselectivity could be restored by mutating the alanine in position 281 for serine. The mutation was made experimentally, and the results show that the E value increased from 9 to 120.

  • 50.
    Olsson, Johan D. M.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Lahmann, Martina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oscarson, Stefan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Investigations of glycosylation reactions with 2-N-acetyl-2N,3O-oxazolidinone-protected glucosamine donors2008In: The Journal of Organic Chemistry, ISSN 0022-3263, Vol. 73, no 18, p. 7181-7188Article in journal (Refereed)
12 1 - 50 of 80
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