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  • 1501.
    Xu, Yunhua
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis and Photoinduced Electron Transfer of Donor-Sensitizer-Acceptor Systems2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Artificial systems involving water oxidation and solar cells are promising ways for the conversion of solar energy into fuels and electricity. These systems usually consist of a photosensitizer, an electron donor and / or an electron acceptor. This thesis deals with the synthesis and photoinduced electron transfer of several donor-sensitizer-acceptor supramolecular systems.

    The first part of this thesis describes the synthesis and properties of two novel dinuclear ruthenium complexes as electron donors to mimic the donor side reaction of Photosystem II. These two Ru2 complexes were then covalently linked to ruthenium trisbipyridine and the properties of the resulting trinuclear complexes were studied by cyclic voltammetry and transient absorption spectroscopy.

    The second part presents the synthesis and photoinduced electron transfer of covalently linked donor-sensitizer supramolecular systems in the presence of TiO2 as electron acceptors. Electron donors are tyrosine, phenol and their derivatives, and dinuclear ruthenium complexes. Intramolecular electron transfer from the donor to the oxidized sensitizer was observed by transient absorption spectroscopy after light excitation of the Ru(bpy)32+ moiety. The potential applications of Ru2-based electron donors in artificial systems for water oxidation and solar cells are discussed.

    In the final part, the photoinduced interfacial electron transfer in the systems based on carotenoids and TiO2 is studied. Carotenoids are shown to act as both sensitizers and electron donors, which could be used in artificial systems to mimic the electron transfer chain in natural photosynthesis.

  • 1502. Xu, Yunhua
    et al.
    Duan, Lele
    Tong, Lianpeng
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Visible light-driven water oxidation catalyzed by a highly efficient dinuclear ruthenium complex2010Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 46, nr 35, s. 6506-6508Artikel i tidskrift (Refereegranskat)
  • 1503.
    Xu, Yunhua
    et al.
    Royal Institute of Technology (KTH).
    Duan, Lele
    Royal Institute of Technology (KTH).
    Åkermark, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Tong, Lianpeng
    Royal Institute of Technology (KTH).
    Lee, Bao-Lin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhang, Rong
    Dalian University of Technology (DUT), (P.R. China).
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Royal Institute of Technology (KTH), Department of Organic Chemistry.
    Synthesis and catalytic water oxidation activities of ruthenium complexes containing neutral ligands2011Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, nr 34, s. 9520-9528Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two dinuclear and one mononuclear ruthenium complexes containing neutral polypyridyl ligands have been synthesised as pre-water oxidation catalysts and characterised by 1H and 13C NMR spectroscopy and ESI-MS. Their catalytic water oxidation properties in the presence of [Ce-(NH4)2(NO3)6] (CeIV) as oxidant at pH 1.0 have been investigated. At low concentrations of CeIV (5 mM), high turnover numbers of up to 4500 have been achieved. An 18O-labelling experiment established that both O atoms in the evolved O2 originate from water. Combined electrochemical study and electrospray ionisation mass spectrometric analysis suggest that ligand exchange between coordinated 4-picoline and free water produces Ru aquo species as the real water oxidation catalysts.

  • 1504.
    Xu, Yunhua
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eilers, Gerriet
    Borgström, Magnus
    Pan, Jingxi
    Abrahamsson, Maria
    Magnuson, Ann
    Lomoth, Reiner
    Bergquist, Jonas
    Polivka, Tomas
    Sun, Licheng
    Sundström, Villy
    Styring, Stenbjörn
    Hammarström, Leif
    Åkermark, Björn
    Synthesis and Characterization of Novel Dinuclear Ruthenium Complexes Covalently Linked to Ru(II) Trisbipyridine: an Approach to Mimics of the Donor Side of PS IIManuskript (Övrigt vetenskapligt)
  • 1505. Xu, Yunhua
    et al.
    Fischer, Andreas
    Duan, Lele
    Tong, Lianpeng
    Gabrielsson, Erik
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Chemical and light-driven oxidation of water catalyzed by an efficient dinuclear ruthenium complex2010Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, nr 47, s. 8934-8937Artikel i tidskrift (Refereegranskat)
  • 1506.
    Xu, Yunhua
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pan, Jie
    Huang, Ping
    Feyziyev, Yashar
    Lomoth, Reiner
    Hammarström, Leif
    Styring, Stenbjörn
    Polivka, Tomas
    Sundström, Villy
    Åkermark, Björn
    Sun, Licheng
    Synthesis and Photoinduced Electron Transfer Study of a Substituted Phenol Covalently Linked to Ruthenium Trisbipyridine with or without Four Ester GroupsManuskript (Övrigt vetenskapligt)
  • 1507.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Stereoselective Formation of C–O, C–C and C–B Bonds: A Voyage from Asymmetric Reactions Enabled by Lipases to Stereoselective Palladium-Catalyzed Oxidative Transformations of Enallenes2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis has been focused on enzymatic kinetic resolutions and stereoselective oxidative transformations of enallenes catalyzed by PdII.

    In the first part of the thesis, a detailed discussion on Candida antarctica lipase B (CALB)-catalyzed kinetic resolution (KR) of δ-functionalized alkan-2-acetates is shown. We gained a deeper insight into the mechanism of enzyme-substrate recognition. Changing from an anhydrous solvent to water or a water-containing organic solvent enhanced the enantioselectivity. The effect of –OH was also confirmed by a lipase mutant suggesting that the water molecule mentioned above can be partly mimicked.

    In the second part of the thesis, we developed an efficient KR for allenic alcohols. On this basis, a novel synthesis of optically pure 2-substituted 2,3-dihydrofurans from allenic alcohols via a Ru-catalyzed cycloisomerization was reported. The developed protocol enabled us to assemble an optically pure precursor for total synthesis with three chiral centers from readily available allenol in 2 days.

    In the third part, we reported a class of reactions involving C–H cleavage under mild conditions: PdII-catalyzed oxidative transformations of enallenes. These reactions are particularly attractive since a number of meticulous structures have been achieved from readily accessible starting materials. The directing effect of an unsaturated hydrocarbon was found to be key for these transformations.

    In the final part, we developed the carbonylative insertion reaction discussed in the third part of the thesis into an asymmetric version. By using this methodology, a number of cyclopentenone compounds were obtained in good to excellent enantioselectivity.

  • 1508.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development and Application ofEnzymatic Asymmetric Synthesis ofFunctionalized Alcohols2015Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The main focus of this thesis lies on enzymatic asymmetric organic reactions. In the first part ofthis work, we looked into the lipase-catalyzed transesterification and hydrolysis at the molecularlevel. It was shown that the low enantioselectivity of CALB-catalyzed transesterification of a δ-functionalized alkan-2-ol to its acetate does not correlate at all with the high enantioselectivity ofthe CALB-catalyzed hydrolysis of the corresponding acetate in water. This lack of correlation isunusual and for unfunctionalized alkan-2-ol derivatives there is a very good correlation betweenthe enantioselectivity of transesterification of the alcohol and hydrolysis of the correspondingacetate with a high enantioseletivity in both cases. The results confirm previous predictions frommolecular modeling. The water effect was mimicked by CALB variant Ala281Ser, whichshowed an enhanced enantioselectivity in transesterification of δ-functionalized alkan-2-olscompared to wild type CALB.

    In the second part of the thesis, enzymatic kinetic resolution to resolve 1-substituted buta-2,3-dien-1-ol was studied. The initial goal was to use Shvo catalyst as racemization catalyst for anenvisioned dynamic kinetic resolution of this substrate. To our surprise, 2,3-dihydrofurans wasformed when α-allenic alcohols was treated with Shvo catalyst and the chiral center that endedup in the product was unchanged. Based on the KR and cycloisomerization, we furthermoredeveloped a one-pot procedure combining kinetic resolution and cyclization to optically pureoxygen-containing heterocycles. The mechanism of the Ru-catalyzed cycloisomerization wasstudied and a Ru-carbenoid was suggested as a crucial intermediate for forming the 2,3-dihydrofurans.

  • 1509.
    Yang, Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lihammar, Richard
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Investigation of the Impact of Water on the Enantioselectivity Displayed by CALB in the Kinetic Resolution of δ-Functionalized Alkan-2-ol Derivatives2014Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, nr 42, s. 13517-13521Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is shown that the low enantioselectivity of Candida antarctica lipase B (CALB)-catalyzed transesterification of a δ-functionalized alkan-2-ol to its acetate does not correlate at all with the high enantioselectivity of the CALB-catalyzed hydrolysis of the corresponding acetate in water. This lack of correlation is unusual and for unfunctionalized alkan-2-ol derivatives there is a very good correlation between the enantioselectivity of transesterification of the alcohol and hydrolysis of the corresponding acetate (E>200 in both cases). The results confirm previous predictions from molecular modeling. The water effect was mimicked by CALB variant Ala281Ser, which showed an enhanced enantioselectivity in transesterification of δ-functionalized alkan-2-ols compared to wild-type CALB.

  • 1510.
    Yang, Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wulff, William D.
    Yin, Xiaopeng
    Zhu, Can
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantioselective Palladium-Catalyzed Carbonylative Carbocyclization of Enallenes via Cross-Dehydrogenative Coupling with Terminal Alkyne: Efficient Construction of a-Chirality of Ketones2017Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, nr 16, s. 4535-4539Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An enantioselective PdII/Brønsted acid-catalyzed carbonylative carbocyclization of enallenes ending with a cross-dehydrogenative coupling (CDC) with a terminal alkyne was developed. VAPOL phosphoric acid was found as the best co-catalyst among the examined 28 chiral acids, for inducing the enantioselectivity of α-chiral ketones. As a result, a number of chiral cyclopentenones were easily synthesized in good to excellent enantiomeric ratio with good yields.

  • 1511.
    Yang, Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhu, Can
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enzyme- and Ruthenium-Catalyzed Enantioselective Transformation of alpha-Allenic Alcohols into 2,3-Dihydrofurans2016Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 18, s. 5568-5572Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An efficient one-pot method for the enzyme- and ruthenium-catalyzed enantioselective transformation of alpha-allenic alcohols into 2,3-dihydrofurans has been developed. The method involves an enzymatic kinetic resolution and a subsequent ruthenium-catalyzed cycloisomerization, which provides 2,3-dihydrofurans with excellent enantioselectivity (up to >99%ee). A ruthenium carbene species was proposed as a key intermediate in the cycloisomerization.

  • 1512.
    Yang, Hai-Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pathipati, Stalin R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Nickel-Catalyzed 1,2-Aminoarylation of Oxime Ester-Tethered Alkenes with Boronic Acids2017Ingår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 12, s. 8441-8445Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A nickel-catalyzed 1,2-aminoarylation of oximeester-tethered alkenes with boronic acids was developed. A variety of pyrroline derivatives were synthesized in good yields via the successive formation of C(sp(3))-N and C(sp(3))-C(sp(2)) bonds. For cyclobutanone-derived oxime esters, the reaction provided aliphatic nitriles incorporating an aromatic group in the gamma-position. A mechanism involving iminyl radical and carbon-centered radical intermediates was proposed.

  • 1513.
    Yang, Hai-Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A redox-economical synthesis of trifluoromethylated enamides with the Langlois reagent2017Ingår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 15, nr 8, s. 1771-1775Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A redox-economical strategy for the synthesis of trifluoromethylated enamides using copper catalysis is reported. The reaction employs the inexpensive Langlois reagent (CF3SO2Na) and takes place without the need of an external oxidant. The trifluoromethylated enamide products can easily be converted into the corresponding ketone, saturated amide or oxazole.

  • 1514.
    Yang, Hai-Bin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Divergent Iron-Catalyzed Coupling of O-Acyloximes with Silyl Enol Ethers2017Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, nr 8, s. 1779-1783Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An iron-catalyzed coupling reaction of O-acyloximes and O-benzoyl amidoximes with silyl enol ethers is reported. The protocol provides access to functionalized pyrroles, 1,6-ketonitriles, pyrrolines and imidazolines via carbon-centered radicals generated from an initially formed iminyl radical. The intramolecular cyclization and ring-opening processes of the iminyl radical take place preferentially over reactions that proceed through a 1,3-hydrogen transfer, providing insights into iron-catalyzed reactions with oxime derivatives. The cheap and environmentally friendly iron catalyst, the broad substrate scope and the functional group compatibility make this protocol useful for synthesis of valuable nitrogen-containing products.

  • 1515. Yang, Mingjun
    et al.
    Angles d'Ortoli, Thibault
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Säwén, Elin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jana, Madhurima
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    MacKerell, Jr., Alexander D.
    Delineating the conformational flexibility of trisaccharides from NMR spectroscopy experiments and computer simulations2016Ingår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 18, nr 28, s. 18776-18794Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The conformation of saccharides in solution is challenging to characterize in the context of a single well-defined three-dimensional structure. Instead, they are better represented by an ensemble of conformations associated with their structural diversity and flexibility. In this study, we delineate the conformational heterogeneity of five trisaccharides via a combination of experimental and computational techniques. Experimental NMR measurements target conformationally sensitive parameters, including J couplings and effective distances around the glycosidic linkages, while the computational simulations apply the well-calibrated additive CHARMM carbohydrate force field in combination with efficient enhanced sampling molecular dynamics simulation methods. Analysis of conformational heterogeneity is performed based on sampling of discreet states as defined by dihedral angles, on root-mean-square differences of Cartesian coordinates and on the extent of volume sampled. Conformational clustering, based on the glycosidic linkage dihedral angles, shows that accounting for the full range of sampled conformations is required to reproduce the experimental data, emphasizing the utility of the molecular simulations in obtaining an atomic detailed description of the conformational properties of the saccharides. Results show the presence of differential conformational preferences as a function of primary sequence and glycosidic linkage types. Significant differences in conformational ensembles associated with the anomeric configuration of a single glycosidic linkage reinforce the impact of such changes on the conformational properties of carbohydrates. The present structural insights of the studied trisaccharides represent a foundation for understanding the range of conformations adopted in larger oligosaccharides and how these molecules encode their conformational heterogeneity into the monosaccharide sequence.

  • 1516. Yang, Tao
    et al.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ju, Jing
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Liu, Zheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wang, Yingxia
    Li, Guobao
    Liao, Fuhui
    Martin-Matute, Belen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Jianhua
    Microporous Aluminoborates with Large Channels: Structural and Catalytic Properties2011Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, nr 52, s. 12555-12558Artikel i tidskrift (Refereegranskat)
  • 1517.
    Yang, Yuzhu
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of Allenes by Catalytic Coupling of Propargyl Carbonates with Aryl Iodides in the Presence of Diboron Species2016Ingår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, nr 1, s. 250-255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bimetallic copper-/palladium-catalyzed multicomponent reaction of propargyl carbonates, aryl iodides, and diboron species was studied. This procedure can be used for synthesis of di-, tri-, and tetra-substituted allenes. Using diboronic acid, the reaction is supposed to proceed via allenylboronic acid intermediate.

  • 1518.
    Yao, Qingxia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bermejo Gómez, Antonio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Su, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Pascanu, Vlad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yun, Yifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zheng, Haoquan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Chen, Hong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Liu, Leifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Abdelhamid, Hani Nasser
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Martin-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Series of Highly Stable Isoreticular Lanthanide Metal-Organic Frameworks with Expanding Pore Size and Tunable Luminescent Properties2015Ingår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, nr 15, s. 5332-5339Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of highly porous isoreticular lanthanide-based metal organic frameworks (LnMOFs) denoted as SUMOE-7I to SUMOE-7IV (SU = Stockholm University; Ln = La, Ce, Pr, Nd, Sm, Eu, and Gd) have been synthesized using tritopic carboxylates as the organic linkers. The SUMOF-7 materials display one-dimensional pseudohexagonal channels with the pore diameter gradually enlarged from 8.4 to 23.9 angstrom, as a result of increasing sizes of the organic linkers. The structures have been solved by single crystal X-ray diffraction or rotation electron diffraction (RED) combined with powder X-ray diffraction (PXRD). The SUMOF-7 materials exhibit robust architectures with permanent porosity. More importantly, they exhibit exceptionally high thermal and chemical stability. We show that, by inclusion of organic dye molecules, the luminescence properties of the MOFs can be elaborated and modulated, leading to promising applications in sensing and optics.

  • 1519.
    Yao, Qingxia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Bermejo Gómez, Antonio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Su, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Pascanu, Vlad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yun, Yifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zheng, Haoquan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Chen, Hong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Liu, Leifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Highly porous isoreticular lanthanide metal-organic frameworksManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    As an emerging type of porous materials, metal–organic frameworks (MOFs) have the advantages over conventional inorganic porous materials in that their structures and functions are systematically and predictably designable. Isoreticular expansion is an efficient way for systematic design and control of pore size and shape for MOFs. By using our proposed strategy, a series of highly porous isoreticular lanthanide-based metal-organic frameworks with systematic pore apertures has been obtained, which afford an isoreticular series of MIL-103 structures (termed SUMOF-7I to IV) with pore apertures ranging from 7.2 Å to 23 Å. These materials demonstrated exhibit robust architectures with permanent porosity, and exceptional thermal stability and chemical stability in various solvents. The combination of luminescence property and significant porosity of these MOFs enable them as a potential platform for multifunctional purpose.

  • 1520. Yotapan, Nattawut
    et al.
    Paptchikhine, Alexander
    Bera, Milan
    Avula, Satya Kumar
    Vilaivan, Tirayut
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. University of Kwazulu Natal, South Africa.
    Simple Proline-Derived Phosphine-Thiazole Iridium Complexes for Asymmetric Hydrogenation of Trisubstituted Olefins2013Ingår i: Asian Journal of Organic Chemistry, ISSN 2193-5807, Vol. 2, nr 8, s. 674-680Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Proline-based phosphine-thiazole/imidazole ligands have been synthesized and successfully applied in the homogeneous, iridium-catalyzed, asymmetric hydrogenation of trisubstituted functionalized and unfunctionalized olefins. Five different sets of ligands were prepared then evaluated for their catalytic activity and enantioselectivity in asymmetric hydrogenation.

  • 1521.
    Yu, Zheng-Bao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Han, Yu
    Zhao, Lan
    Huang, Shiliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zheng, Qi-Yu
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Intergrown New Zeolite Beta Polymorphs with Interconnected 12-Ring Channels Solved by Combining Electron Crystallography and Single-Crystal X-ray Diffraction2012Ingår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 24, nr 19, s. 3701-3706Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Two new polymorphs of zeolite beta, denoted as SU-78A and SU-78B, were synthesized by employing dicyclohexylammonium hydroxides as organic structuredirecting agents. The structure was solved by combining transmission electron microscopy and single-crystal X-ray diffraction. SU-78 is an intergrowth of SU-78A and SU-78B and contains interconnected 12-ring channels in three directions. The two polymorphs are built from the same building layer, similar to that for the zeolite beta family. The layer stacking in SU-78, however, is different from those in zeolite beta polymorph A, B, and C, showing new zeolite framework topologies. SU-78 is thermally stable up to 600°C.

  • 1522.
    Yuan, Ning
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Swedish University of Agricultural Sciences, Sweden.
    Pascanu, Vlad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Huang, Zhehao
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Heidenreich, Niclas
    Leubner, Sebastian
    Inge, A. Ken
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Gaar, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stock, Norbert
    Persson, Ingmar
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Probing the active catalytic species generated from Pd(II)@MIL-101-NH2 in Heck coupling reactions: An operando X-ray absorption spectroscopy studyArtikel i tidskrift (Refereegranskat)
  • 1523.
    Yuan, Weiming
    et al.
    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.
    Rhodium-Catalyzed Geminal Oxyfluorination and Oxytrifluoro-Methylation of Diazocarbonyl Compounds2016Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 29, s. 8410-8415Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new reaction for the rhodium-catalyzed geminal-difunctionalization-based fluorination is presented. The substrates are aromatic and aliphatic diazocarbonyl compounds. As the fluorine source a stable and easily accessible benziodoxole reagent was used. A variety of alcohol, phenol, and carboxylic acid reagents were employed to introduce the second functionality. The reaction was extended to trifluoromethylation using a benziodoxolon reagent. The fluorination and trifluoromethylation reactions probably proceed by a rhodium-containing onium ylide type intermediate, which is trapped by either the F or CF3 electrophiles.

  • 1524.
    Yuan, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic Intramolecular Aminofluorination, Oxyfluorination, and Carbofluorination with a Stable and Versatile Hypervalent Fluoroiodine Reagent2015Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, nr 29, s. 8533-8537Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Application of a fluoroiodine analogue of the Togni reagent was studied in fluorocyclization reactions. In the presence of a transition-metal catalyst the applied fluoroiodine reagent can be used for aminofluorination, oxyfluorination, and carbofluorination reactions. The described procedure has a very broad synthetic scope for preparation of functionalized hetero- and isocyclic compounds having a tertiary fluorine substituent.

  • 1525.
    Yuan, Weiming
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rhodium-Catalyzed Oxy-Aminofluorination of Diazoketones with Tetrahydrofurans and N-Fluorobenzenesulfonimide2016Ingår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, nr 10, s. 6687-6691Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have developed a rhodium-catalyzed oxy-aminofluorination method for transformation of diazoketones. The reaction is based on addition of tetrahydrofuran derivatives and N-fluorobenzenesulfonimide (NFSI) to the diazoketone substrate. The reaction can be performed under mild conditions with high regioselectivity. The synthetic scope involves a wide variety of diazoketones and tetrahydrofuran derivatives. The reaction is supposed to proceed via a tetrahydrofuran based onium ylide intermediate, which is formed from rhodium-carbenoid.

  • 1526.
    Zaccheus, Mona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural and Conformational Studies of Oligo- and Polysaccharides2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The focus of this thesis is to examine the structural properties of polysaccharides produced by bacteria, as well as the dynamic and conformational behavior of a synthetically derived oligosaccharide.

    The primary structures of the O-polysaccharide repeating units of four different Escherichia coli (E. coli) strains, namely O175, O177, O103 and TD2158, as well as the first report of a capsular polysaccharide produced by lactic acid bacteria Leuconostoc mesenteroides ssp. cremoris PIA2 are reported in paper I–V. Structural analyses have been performed using a combination of nuclear magnetic resonance spectroscopy and chemical component analysis.

    The elucidated structures in paper I–III, as well as paper V, are composed of linear repeating units of varying composition and length. In paper IV, the structure of the O-polysaccharide repeating unit of E. coli TD2158 is determined to be a branched hexasaccharide structure with a heterogeneous substitution pattern, with either a β-GlcpNAc or β-Glcp residue branching to the backbone chain. Incubation with bacteriophage HK620 tailspike protein shows that the polysaccharide is selectively cleaved at the α-GlcpNAc-(1→2)-α-Rhap-linkage of the backbone chain, yielding a 9:1 ratio of β-GlcpNAc/β-Glcp containing hexasaccharides after digestion.

    In paper VI the conformational properties of a trisaccharide, which constitutes an internal epitope of the LeaLex hexasaccharide over-expressed on the surface of squamous lung cancer cells, have been analyzed using NMR spectroscopy and molecular dynamics simulations. The β-(1→3)-linkage of the trisaccharide was shown to be highly flexible.

  • 1527.
    Zaccheus, Mona
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jackson, Trudy A.
    Wang, An
    Auzanneau, France-Isabelle
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Conformational Dynamics of a Central Trisaccharide Fragment of the LeaLex Tumor Associated Antigen Studied by NMR Spectroscopy and Molecular Dynamics Simulations2012Ingår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 25, s. 4705-4715Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Certain carbohydrate structures are recognized as cancer antigens, and identification of these and relevant epitopes are essential in fighting the disease. The trisaccharide beta-D-GlcpNAc-(1?3)-beta-D-Galp-(1?4)-beta-D-GlcpNAc-OMe represents a model for the central region of the LeaLex hexasaccharide and it has herein been investigated by 1D 1H,1H-NOESY experiments to obtain effective interresidue protonproton distances as well as by 2D J-HMBC experiments to determine transglycosidic 3JCH coupling constants. Molecular dynamics (MD) simulations using explicit water as solvent and three different carbohydrate force fields, namely, GLYCAM06, PARM22/SU01, and CHARMM2011, were employed for the interpretation of experimental data. Overall, the force field based MD simulations are able to reproduce the experimental data and the ? torsion angle at the beta-(1?3)-linkage is concluded to be flexible. In addition, different minor states were present for the three force fields with either anti-? or non-exo-anomeric conformations. Transitions between the exo-anomeric and the non-exo-anomeric conformations for the f torsion angle at the beta-(1?4)-linkage in one of the MD simulations were analyzed in detail. It was found that hydrogen-bonding water molecules, interresidue hydrogen bonds and the transitions between antiperiplanar and synperiplanar conformations for the tH torsion angle of an N-acetyl group were all essential in the description of the glycosidic transition process. In particular, the transition of tH may be a general way of regulating other transitions into less populated but biologically important conformational regions.

  • 1528.
    Zaccheus, Mona V.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ali, Tara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Cloeckaert, Axel
    Zygmunt, Michel S.
    Weintraub, Andrej
    Iriarte, Maite
    Moriyon, Ignacio
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The Epitopic and Structural Characterization of Brucella suis Biovar 2 O-Polysaccharide Demonstrates the Existence of a New M-Negative C-Negative Smooth Brucella Serovar2013Ingår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 1, s. e53941-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The brucellae are Gram-negative bacteria that cause an important zoonosis. Studies with the main Brucella species have shown that the O-antigens of the Brucella smooth lipopolysaccharide are alpha-(1 -> 2) and alpha-(1 -> 3)-linked N-formyl-perosamine polysaccharides that carry M, A and C (A = M, A>M and A<M) epitopes relevant in serodiagnosis and typing. We report that, in contrast to the B. suis biovar 1 O-antigen used as a reference or to all described Brucella O-antigens, B. suis biovar 2 O-antigen failed to bind monoclonal antibodies of C (A = M), C (M>A) and M specificities. However, the biovar 2 O-antigen bound monoclonal antibodies to the Brucella A epitope, and to the C/Y epitope shared by brucellae and Yersinia enterocolitica O:9, a bacterium that carries an N-formyl-perosamine O-antigen in exclusively alpha-(1 -> 2)-linkages. By C-13 NMR spectroscopy, B. suis biovar 1 but not B. suis biovar 2 or Y.enterocolitica O:9 polysaccharide showed the signal characteristic of alpha-(1 -> 3)-linked N-formyl-perosamine, indicating that biovar 2 may altogether lack this linkage. Taken together, the NMR spectroscopy and monoclonal antibody analyses strongly suggest a role for alpha-(1 -> 3)-linked N-formyl-perosamine in the C (A = M) and C (M>A) epitopes. Moreover, they indicate that B. suis biovar 2 O-antigen lacks some lipopolysaccharide epitopes previously thought to be present in all smooth brucellae, thus representing a new brucella serovar that is M-negative, C-negative. Serologically and structurally this new serovar is more similar to Y. enterocolitica O:9 than to other brucellae.

  • 1529.
    Zaccheus, Mona V.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Broeker, Nina K.
    Lundborg, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Uetrecht, Charlotte
    Barbirz, Stefanie
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural studies of the O‐antigen polysaccharide from Escherichia coli TD2158 having O18 serogroup specificity and aspects of its interaction with the tailspike endoglycosidase of the infecting bacteriophage HK6202012Ingår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 357, s. 118-125Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have analyzed the O-antigen polysaccharide of the previously uncharacterized Escherichia coli strain TD2158 which is a host of bacteriophage HK620. This bacteriophage recognizes and cleaves the polysaccharide with its tailspike protein (TSP). The polysaccharide preparation as well as oligosaccharides obtained from HK620TSP endoglycosidase digests were analyzed with NMR spectroscopy. Additionally, sugar analysis was performed on the O-antigen polysaccharide and MALDI-TOF MS was used in oligosaccharide analysis. The present study revealed a heterogeneous polysaccharide with a hexasaccharide repeating unit of the following structure: α-D-Glcp-(1→6|) →2)-α-L-Rhap-91→6)-α-D-Glcp-(1→4)-α-D-Ga|lp-(1→3)-α-D-GlcpNAc-(1→ β-D-Glcp/β-D-GlcpNAc-(1→3) A repeating unit with a D-GlcNAc substitution of D-Gal has been described earlier as characteristic for serogroup O18A1. Accordingly, we termed repeating units with D-Glc substitution at D-Gal as O18A2. NMR analyses of the polysaccharide confirmed that O18A1- and O18A2-type repeats were present in a 1:1 ratio. However, HK620TSP preferentially bound the D-GlcNAc-substituted O18A1-type repeating units in its high affinity binding pocket with a dissociation constant of 140 μM and disfavored the O18A2-type having a β-D-Glcp-(1→3)-linked group. As a result, in hexasaccharide preparations, O18A1 and O18A2 repeats were present in a 9:1 ratio stressing the clear preference of O18A1-type repeats to be cleaved by HK620TSP.

  • 1530.
    Zani, Lorenzo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of novel amino-acid-derived sulfinamides and their evaluation as ligands for the enantioselective transfer hydrogenation of ketones2008Ingår i: European Journal of Organic Chemistry, ISSN 1434-193X, nr 27, s. 4655-4664Artikel i tidskrift (Refereegranskat)
  • 1531. Zerbetto, Mirco
    et al.
    d'Ortoli, Thibault Angles
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Polimeno, Antonino
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Differential Dynamics at Glycosidic Linkages of an Oligosaccharide as Revealed by C-13 NMR Spin Relaxation and Stochastic Modeling2018Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 122, nr 8, s. 2287-2294Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Among biomolecules, carbohydrates are unique in that not only can linkages be formed through different positions, but the structures may also be branched. The trisaccharide beta-D-Glcp-(1 -> 3)[beta-D-Glcp-(1 -> 2)]-alpha-D-Manp-OMe represents a model of a branched vicinally disubstituted structure. A C-13 site -specific isotopologue, with labeling in each of the two terminal glucosyl residues, enabled the acquisition of high-quality C-13 NMR relaxation parameters, T-1 and T-2, and heteronuclear NOE, with standard deviations of <= 0.5%. For interpretation of the experimental NMR data, a diffusive chain model was used, in which the dynamics of the glycosidic linkages is coupled to the global reorientation motion of the trisaccharide. Brownian dynamics simulations relying on the potential of mean force at the glycosidic linkages were employed to evaluate spectral densities of the spin probes. Calculated NMR relaxation parameters showed a very good agreement with experimental data, deviating <3%. The resulting dynamics are described by correlation times of 196 and 174 ps for the beta-(1 -> 2)- and beta-(1 -> 3)-linked glucosyl residues, respectively, i.e., different and linkage dependent. Notably, the devised computational protocol was performed without any fitting of parameters.

  • 1532. Zerbetto, Mirco
    et al.
    Kotsyubynskyy, Dmytro
    Kowalewski, Jozef
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Widmalm, Goran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Polimeno, Antonino
    Stochastic Modeling of Flexible Biomolecules Applied to NMR Relaxation: I. Internal Dynamics of Cyclodextrins; y-Cyclodextrin as a Case Study2012Ingår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 116, nr 44, s. 13159-13171Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we address the description of the dynamics of cyclodextrins in relation with nuclear magnetic resonance (NMR) relaxation data collected for hydroxymethyl groups. We define an integrated computational approach based on the definition and parametrization of a stochastic equation able to describe the relevant degrees of freedom affecting the NMR observables. The computational protocol merges molecular dynamics simulations and hydrodynamics approaches for the evaluation of most of the molecular parameters entering the stochastic description of the system. We apply the method to the interpretation of the C-13 NMR relaxation of the -CH2OH group of cyclodextrins. We use gamma-cyclodextrin as a case study. Results are in agreement with quantitative and qualitative analyses performed in the past with simpler models and molecular dynamics simulations. The element of novelty in our approach is in the treatment of the coupling of the relevant internal (glucopyranose ring twisting/tilting and hydroxymethyl group jumps) and global (molecular tumbling) degrees of freedom.

  • 1533. Zerbetto, Mirco
    et al.
    Polimeno, Antonino
    Kotsyubynskyy, Dmytro
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Ghalebani, Leila
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Kowalewski, Jozef
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för fysikalisk kemi.
    Meirovitch, Eva
    Olsson, Ulrika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    An integrated approach to NMR spin relaxation in flexible biomolecules: Application to β-D-glucopyranosyl-(1→6)-α-D-mannopyranosyl-OMe2009Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, nr 23, s. p234501-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The description of the reorientational dynamics of flexible molecules is a challenging task, in particular when the rates of internal and global motions are comparable. The commonly used simple mode-decoupling models are based on the assumption of statistical independence between these motions. This assumption is not valid when the time scale separation between their rates is small, a situation that was found to arise in oligosaccharides in the context of certain internal motions. To make possible the interpretation of NMR spin relaxation data from such molecules, we developed a comprehensive approach generally applicable to flexible rotators with one internal degree of freedom. This approach integrates a stochastic description of coupled global tumbling and internal torsional motion, quantum chemical calculations of the local potential and the local geometry at the site of the restricted torsion, and hydrodynamics-based calculations of the diffusive properties. The method is applied to the disaccharide -D-Glcp-(16)--D-[6-13C]-Manp-OMe dissolved in a DMSO-d6/D2O cryosolvent. The experimental NMR relaxation parameters, associated with the 13CH2 probe residing at the glycosidic linkage, include 13C T1 and T2 and 13C-{1H} nuclear Overhauser enhancement (NOE) as well as longitudinal and transverse dipole-dipole cross-correlated relaxation rates, acquired in the temperature range of 253–293 K. These data are predicted successfully by the new theory with only the H–C–H angle allowed to vary. Previous attempts to fit these data using mode-decoupling models failed.

  • 1534. Zhang, Di
    et al.
    Liu, Jianguo
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Mid Sweden University, Sweden.
    Liao, Wei-Wei
    Recent Developments in Palladium-Catalyzed Oxidative Cascade Carbocyclization2017Ingår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 10, s. 7051-7063Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this Perspective, we describe recent advances on Pd-catalyzed oxidative cascade carbocyclizations. These cascade processes enable efficient construction of the molecular complexity and structural diversity of carbocyclic compounds via introducing diverse functionalities concomitant with multiple C-C bond-formations in one-pot operations. In many cases, these processes are facilitated by Pd-catalysts alone, while cocatalysis by combination of Pd catalyst and other catalysts are also discussed, since they represent a new entry to address the preparation of functionalized cyclic compounds with high efficiency and selectivity.

  • 1535.
    Zhang, Jiji
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Metathesis Mechanism of Zinc-Catalyzed Fluorination of Alkenes with Hypervalent Fluoroiodine2017Ingår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, nr 2, s. 1093-1100Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Density functional theory calculations are used to unravel the mechanism of the Zn-catalyzed fluorocyclization reaction of alkenes using fluoro-benziodoxole reagent. In the initial step Zn coordinates to the fluorine atom of the fluoro-benziodoxole reagent. An important activation step for the fluorination involves Zn-mediated isomerization of the benziodoxole reagent. The activation is followed by a metathesis step to form the C-F bond and a nucleophilic substitution, closing the ring to yield the final aminofluorination product. This mechanism has feasible energy barriers and accounts for the observed selectivity outcome. An alternative mechanism involving an iodocyclopropylium cation intermediate is shown to be associated with high energies.

  • 1536. Zhao, Dongbo
    et al.
    Johansson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    In Situ Generation of Nitroso Compounds from Catalytic Hydrogen Peroxide Oxidation of Primary Aromatic Amines and Their One-Pot Use in Hetero-Diels–Alder Reactions2007Ingår i: European journal of organic chemistry, ISSN 1434-193X, nr 26, s. 4431–4436-Artikel i tidskrift (Refereegranskat)
  • 1537.
    Zhao, Dongbo
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johansson, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    In situ generation of nitroso compounds from catalytic hydrogen peroxide oxidation of primary aromatic amines and their one-pot use in hetero-Diels-Alder reactions2007Ingår i: European Journal of Organic Chemistry, ISSN 1434-193X, Vol. -, nr 26, s. 4431-4436Artikel i tidskrift (Refereegranskat)
  • 1538.
    Zhao, Gui-Ling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Catalytic asymmetric Baylis–Hillman reactions and surroundings2010Ingår i: Catalytic Asymmetric Conjugate Reactions / [ed] Armando Córdova, Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA , 2010, 1, s. 393-438Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 1539.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A one-pot combination of amine and heterocyclic carbene catalysis: direct asymmetric synthesis of beta-hydroxy and beta-malonate esters from alpha,beta-unsaturated aldehydes2007Ingår i: Tetrahedron Letters, Vol. 48, s. 5976-5980Artikel i tidskrift (Refereegranskat)
  • 1540.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    ECAs of organolithium reagents, Grignard reagents, and examples of Cu-catalyzed ECAs2010Ingår i: Catalytic Asymmetric Conjugate Reactions / [ed] Armando Córdova, Weinheim: Wiley-VCH Verlag GmbH & Co. KGaA , 2010, 1, s. 145-167Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 1541.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic asymmetric synthesis of 1,2,3-prim,sec,sec-triols2006Ingår i: Synlett, ISSN 0936-5214, nr 20, s. 3521-3524Artikel i tidskrift (Refereegranskat)
  • 1542.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ullah, Farman
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för strukturkemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic enantioselective domino synthesis of highly functionalized cyclohexanes with an all-carbon quaternary stereocenter2009Ingår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 50, nr 26, s. 3458-3462Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A highly enantioselective organocatalytic domino Michael/aldol reaction is presented. The reaction is catalyzed by chiral amines and gives access to highly functionalized cyclohexanes with one all-carbon quaternary stereocenter and multiple chiral stereocenters in high yields and 83–98% ee.

  • 1543.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hafrén, Jonas
    Deiana, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Heterogeneous "organoclick" derivatization of polysaccharides: Photochemical thiol-ene click modification of solid cellulose2010Ingår i: Macromolecular rapid communications, ISSN 1022-1336, E-ISSN 1521-3927, Vol. 31, nr 8, s. 740-744Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A simple and direct method for derivatization of solid polysaccharides is presented. The novel methodology is based on the combination of organic acid-catalyzed esterification or etherification and photochemical thiol-ene click derivatization of a heterogeneous polysaccharide. The solid cellulose was “organoclick” modified with aryl, alkyl and polyester groups, respectively. The modification allows for a highly modular and metal free surface modification of solid polysaccharides.

  • 1544.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Bonneau, Charlotte
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    One-pot catalytic enantioselective domino nitro-Michael/Michael synthesis of cyclopentanes with four stereocenters2008Ingår i: Chemistry: a European journal, ISSN 0947-6539, Vol. 14, nr 32, s. 10007-10011Artikel i tidskrift (Refereegranskat)
  • 1545.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sundén, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Amine-catalyzed asymmetric epoxidation of alpha,beta-unsaturated aldehydes2007Ingår i: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 349, nr 7, s. 1210-1224Artikel i tidskrift (Refereegranskat)
  • 1546.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Korotvicka, Ales
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Deiana, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kullberg, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric synthesis of Maraviroc (UK-427,857)2010Ingår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 352, nr 13, s. 2291-2298Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The asymmetric synthesis of Maraviroc (UK-427,857), a chemochine receptor 5 (CCR-5) receptor antagonist, based on an expeditious organocatalytic enantioselective assembly of the chiral β-amino aldehyde key fragment is presented. The reactions were performed on a gram-scale and allow for the rapid construction of new Maraviroc analogues.

  • 1547.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rios, Ramón
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vesely, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Eriksson, Lars
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic enantioselective aminosylfenylation of alpha,beta-unsaturated aldehydes2008Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, Vol. 47, nr 44, s. 8468-8472Artikel i tidskrift (Refereegranskat)
  • 1548.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ullah, Farman
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Luca, Deiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhang, Qiong
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för strukturkemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dynamic kinetic asymmetric transformation (DYKAT) by combined amine- and transition-metal-catalyzed enantioselective cycloisomerization2010Ingår i: Chemistry: a European Journal, ISSN 0947-6539, Vol. 16, nr 5, s. 1585-1591Artikel i tidskrift (Refereegranskat)
  • 1549.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vesely, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Rios, Ramón
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ibrahem, Ismail
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sundén, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly diastereo- and enantioselective catalytic domino thia-Michael/aldol reactions: Synthesis of benzothiopyrans with three contiguous stereocenters2008Ingår i: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 350, nr 2, s. 237-242Artikel i tidskrift (Refereegranskat)
  • 1550.
    Zhao, Gui-Ling
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vesely, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Christensen, Kirsten E.
    Bonneau, Charlotte
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic highly enantioselective conjugate addition of aldehydes to alkylidine malonates2008Ingår i: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 350, nr 5, s. 657-661Artikel i tidskrift (Refereegranskat)
2829303132 1501 - 1550 av 1585
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