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  • 1.
    Afewerki, Samson
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Breistein, Palle
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Pirttilä, Kristian
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Deiana, Luca
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden.
    Dziedzic, Pawel
    Univ Stockholm, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Catalytic Enantioselective beta-Alkylation of alpha,beta-Unsaturated Aldehydes by Combination of Transition-Metal- and Aminocatalysis: Total Synthesis of Bisabolane Sesquiterpenes2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, no 32, p. 8784-8788Article in journal (Refereed)
    Abstract [en]

    Branching out! The first co-catalytic enantioselective (up to 98:2 e.r.) β-alkylation of α,β-unsaturated aldehydes by combination of simple chiral amine and copper catalysts provides β-branched aldehydes in a one-pot protocol (see scheme). The methodology was applied to the short total syntheses of bisabolane sesquiterpenes (S)-(+)-curcumene, (E)-(S)-(+)-3- dehydrocurcumene and (S)-(+)-tumerone. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 2.
    Afewerki, Samson
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Guangning, Ma
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Highly enantioselective organo/metal cooperative catalysis for construction of spirocyclopentaneoxindoles2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248, article id 173-ORGNArticle in journal (Other academic)
  • 3.
    Afewerki, Samson
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Rydfjord, Jonas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Breistein, Palle
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Direct Regiospecific and Highly Enantioselective Intermolecular α-Allylic Alkylation of Aldehydes By Combination of Transition Metal and amine Catalysts2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 10, p. 2972-2977Article in journal (Refereed)
    Abstract [en]

    The first direct intermolecular regiospecific and highly enantioselective α-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd 0 complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecificα-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed. Go organic! Directintermolecular regiospecific and highly enantioselective α-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd 0complexes and simple chiral amines as co-catalysts is disclosed (see scheme). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 4.
    Afewerki, Samson
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Stockholm Univ, Berzelii Ctr EXSELENT, SE-10691 Stockholm, Sweden.
    Ma, Guangning
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Liu, Leifeng
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden .
    Sun, Junliang
    Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden .
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences. Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden .
    Highly Enantioselective Control of Dynamic Cascade Transformations by Dual Catalysis: Asymmetric Synthesis of Polysubstituted Spirocyclic Oxindoles2015In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 5, no 2, p. 1266-1272Article in journal (Refereed)
    Abstract [en]

    The highly enantioselective (up to >99.5:0.5 er) synthesis of polysubstituted spirocyclic oxindoles with four new contiguous stereocenters, including the spiro all-carbon quaternary center, is disclosed. It is accomplished by the highly stereoselective control of a dynamic conjugate/intramolecular allylic alkylation relay sequence based on the synergistic cooperation of metal and chiral amine catalysts in which the careful selection of organic Nand, metal complex, and chiral amine is essential. The intermolecular C-C bond-forming step occurred only when both the metal and chiral amine catalysts were present.

  • 5.
    Breistein, Palle
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Johansson, Jonas
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Lin, S.
    Deiana, Luca
    Sun, J.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    One-step catalytic enantioselective 5-hydroxy-α-quaternary proline synthesis: An asymmetric entry to highly functionalized α-quaternary proline derivativesManuscript (preprint) (Other academic)
  • 6.
    Cordova, Armando
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Alimohammadzadeh, Rana
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Sanhueza, Italo
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Tai, Cheuk-Wai
    Stockholm University, Stockholm.
    Osong, Sinke H.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Engstrand, Per
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    A sustainable strategy for production and functionalization of nanocelluloses2019In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 91, no 5, p. 865-874Article in journal (Refereed)
    Abstract [en]

    A sustainable strategy for the neat production and surface functionalization of nanocellulose from wood pulp is disclosed. It is based on the combination of organocatalysis and click chemistry ("organoclick" chemistry) and starts with nanocellulose production by organic acid catalyzed hydrolysis and esterification of the pulp under neat conditions followed by homogenization. This nanocellulose fabrication route is scalable, reduces energy consumption and the organic acid can be efficiently recycled. Next, the surface is catalytically engineered by "organoclick" chemistry, which allows for selective and versatile attachment of different organic molecules (e.g. fluorescent probes, catalyst and pharmaceuticals). It also enables binding of metal ions and nanoparticles. This was exemplified by the fabrication of a heterogeneous nanocellulose-palladium nanoparticle catalyst, which is used for Suzuki cross-coupling transformations in water. The disclosed surface functionalization methodology is broad in scope and applicable to different nanocelluloses and cellulose based materials as well.

  • 7.
    Córdova, Armando
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Breistein, Palle
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Deiana, Luca
    Zhao, Gui-Ling
    Dziedzic, Pawel
    Pirttilä, Kristian
    Lin, Shuangzheng
    TOC-Trends in Organic Chemistry: Selective Catalysis2010Conference paper (Other academic)
  • 8.
    Deiana, Luca
    et al.
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Dziedzic, Pawel
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Zhao, Gui-Ling
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Vesely, Jan
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Ibrahem, Ismail
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Rios, Ramon
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden .
    Sun, Junliang
    Stockholm Univ, Arrhenius Lab, Dept Struct Chem, S-10691 Stockholm, Sweden.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics. Stockholm Univ, Arrhenius Lab, Dept Organ Chem, S-10691 Stockholm, Sweden.
    Catalytic Asymmetric Aziridination of alpha,beta-Unsaturated Aldehydes2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, no 28, p. 7904-7917Article in journal (Refereed)
    Abstract [en]

    The development, scope, and application of the highly enantioselective organocatalytic aziridination of α,β-unsaturated aldehydes is presented. The aminocatalytic azirdination of α,β-unsaturated aldehydes enables the asymmetric formation of β-formyl aziridines with up to >19:1 d.r. and 99 % ee. The aminocatalytic aziridination of α-monosubstituted enals gives access to terminal α-substituted-α-formyl aziridines in high yields and up to 99 % ee. In the case of the organocatalytic aziridination of disubstituted α,β-unsaturated aldehydes, the transformations were highly diastereo- and enantioselective and give nearly enantiomerically pure β-formyl-functionalized aziridine products (99 % ee). A highly enantioselective one-pot cascade sequence based on the combination of asymmetric amine and N-heterocyclic carbene catalysis (AHCC) is also disclosed. This one-pot three-component co-catalytic transformation between α,β-unsaturated aldehydes, hydroxylamine derivatives, and alcohols gives the corresponding N-tert-butoxycarbonyl and N-carbobenzyloxy-protected β-amino acid esters with ee values ranging from 92-99 %. The mechanisms and stereochemistry of all these catalytic transformations are also discussed.

  • 9.
    Duan, Ran
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Acid-Catalyzed Synthesis of Foamed Materials from Renewable Sources2014In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 53, no 45, p. 17597-17603Article in journal (Refereed)
    Abstract [en]

    In this study, lightweight biobased foamed materials were successfully synthesized by the modification of renewable polysaccharides, such as starch and microcrystalline cellulose. Low-cost and nontoxic organic acids were utilized as catalysts in the first-step esterification reaction of the synthesis. The effects of different reaction conditions on the water absorbency and weight loss of freeze-casted polysaccharide–citrate–chitosan foams are discussed. Physical properties, such as pore-size distributions and compressive stress–strain curves, of the foams were determined. The characterization results show that the amide bonds formed between the carboxylic acid groups of polysaccharide–citrate and the amino groups of chitosan are crucial to the foamed material’s performance.

  • 10.
    Duan, Ran
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Hedenström, Erik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    New approaches toward producing foamed materials from renewable sources.2013Conference paper (Refereed)
  • 11.
    Eivazihollagh, Alireza
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Bäckström, Joakim
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Dahlström, Christina
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Carlsson, Fredrik
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Lindman, Björn
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    One-pot synthesis of cellulose-templated copper nanoparticles with antibacterial properties2017In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 187, p. 170-172Article in journal (Refereed)
    Abstract [en]

    We report a facile in situ synthesis of spherical copper nanoparticles (NPs) templated by a gelled cellulose II matrix under alkaline aqueous reaction conditions. In under 20 min, the hybrid material could be obtained in a one-pot reaction. Field-emission scanning electron microscopy (FE-SEM) revealed that the polycrystalline NPs of 200–500 nm were well distributed in the regenerated cellulose matrix. The average Cu crystallite size was of the order of 20 nm, as estimated from both X-ray diffraction (XRD) and FE-SEM. XRD data also indicated that the composite contained up to approximately 20% Cu2O. In suspensions containing the hybrid material, growth of Escerichia coli and Staphylococcus aureus strains was inhibited by 80% and 95%, respectively, after 72 h. The synthesis procedure offers a general approach to designing various low-cost hybrid materials of almost any shape, and the concept could be extended to utilization areas such as catalysis, functional textiles, and food packaging as well as to electronic applications.

  • 12.
    Ibrahem, Ismail
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Breistein, Palle
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    One-pot three-component catalytic asymmetric synthesis of homoallylboronates2012In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY. Vol 243, American Chemical Society (ACS), 2012, p. 889-INOR-Conference paper (Refereed)
    Abstract [en]

    1. A novel one-pot three-component catalytic enantioselective reaction between bis(pinacolato)diboron, enals and 2-(triphenylphosphoranylidene)acetate esters employing inexpensive bench stable Cu salts and simple chiral amine as co-catalysts is presented. The reaction proceeds via a tandem catalytic asymmetric conjugate borane addition/Wittig sequence where the b-boration step is 1,4-selective and gives the corresponding homoallylboronate products with high enantiomeric ratios (up to 97.5:2.5 er).

    2. The direct intermolecular regiospecific and highly enantioselective a-allylic alkylation of linear aldehydes by combination of achiral bench stable Pd(0) complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific a-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 er). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals and 2-alkyl-butane-1,4-diols.

  • 13.
    Ibrahem, Ismail
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Breistein, Palle
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    One-Pot Three-Component Catalytic Enantioselective Synthesis of Homoallylboronates2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 50, p. 12036-12041Article in journal (Refereed)
    Abstract [en]

    No longer a simple bor(ation): The title reaction between bis(pinacolato)diboron, enals, and 2-(triphenylphosphoranylidene)acetates employing bench-stable copper salts and a simple chiral amine co-catalyst is presented. The reaction proceeds through a catalytic asymmetric conjugate borane addition/Wittig sequence wherein the β-boration step is 1,4-selective and gives the corresponding homoallylboronate products with high enantiomeric ratios.

  • 14.
    Ibrahem, Ismail
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Breistein, Palle
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    One-pot three-component highly selective synthesis of homoallylboronates by using metal-free catalysis2012In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, no 17, p. 5175-5179Article in journal (Refereed)
    Abstract [en]

    Metal-free selectivity: The first metal-free one-pot three-component highly chemo- and regioselective catalytic synthesis of homoallylboranes using simple N-heterocyclic carbenes (NHC) and amines is presented. The catalytic reaction between B 2(pin) 2, α,β-unsaturated aldehydes and 2-(triphenylphosphoranylidene)acetate esters proceeds through a catalytic metal-free β-boration/Wittig cascade sequence (see scheme). © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 15.
    Ibrahem, Ismail
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Iqbal, Muhammad Naeem
    Stockholm University.
    Verho, Oscar
    Stockholm University.
    Eivazihollagh, Alireza
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Olsén, Peter
    Stockholm University.
    Edlund, Håkan
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Tai, Cheuk-Wai
    Stockholm University.
    Norgren, Magnus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Johnston, Eric V.
    Sigrid Therapeutics, Universitetsvägen 8 (Villa Bellona), Stockholm.
    Copper Nanoparticles on Controlled Pore Glass and TEMPO for the Aerobic Oxidation of Alcohols2018In: ChemNanoMat, ISSN 2199-692X, Vol. 4, no 1, p. 71-75Article in journal (Refereed)
    Abstract [en]

    Herein, we report on the facile synthesis of a heterogeneous copper nanocatalyst and its combination with 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) for the aerobic oxidation of alcohols to their corresponding carbonyl compounds. This low cost copper nanocatalyst was found to exhibit excellent recyclability, making it a highly attractive catalytic system from an economical and environmental point of view. Extensive characterization of the catalyst by a number of techniques revealed that it was comprised of well-dispersed Cu(I/II) nanoparticles with an average size of around 6nm.

  • 16.
    Ibrahem, Ismail
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Ma, Guangning
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Palladium/Chiral Amine Co-catalyzed Enantioselective beta-Arylation of alpha,beta-Unsaturated Aldehydes2013In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 3, p. 878-882Article in journal (Refereed)
    Abstract [en]

    Palladium and a simple chiral amine are used as co-catalysts for the enantioselective conjugate addition of aryl boronic acids to α,β-unsaturated aldehydes (see scheme). The synthetic utility of this co-catalyzed reaction was demonstrated in the short total syntheses of (R)-(-)-curcumene and 4-aryl-2-ones. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 17.
    Ibrahem, Ismail
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Santoro, Stefano
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden.
    Himo, Fahmi
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Enantioselective Conjugate Silyl Additions to alpha,beta-Unsaturated Aldehydes Catalyzed by Combination of Transition Metal and Chiral Amine Catalysts2011In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, no 2-3, p. 245-252Article in journal (Refereed)
    Abstract [en]

    We report that transition metal-catalyzed nucleophilic activation can be combined with chiral amine-catalyzed iminium activation as exemplified by the unprecedented enantioselective conjugate addition of a dimethylsilanyl group to alpha,beta-unsaturated aldehydes. These reactions proceed with excellent 1,4-selectivity to afford the corresponding beta-silyl aldehyde products 3 in high yields and up to 97:3 er using inexpensive bench stable copper salts and simple chiral amine catalysts. The reaction can also generate a quaternary stereocenter with good enantioselectivity. Density functional calculations are performed to elucidate the reaction mechanism and the origin of enantioselectivity.

  • 18.
    M, Yu
    et al.
    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, United States.
    Ibrahem, Ismail
    Boston Coll, Merkert Chem Ctr, Dept Chem, Chestnut Hill, MA 02467 USA.
    Hasegawa, M
    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, United States.
    Schrock, R.
    Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
    Hoveyda, H
    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, United States.
    Enol Ethers as Substrates for Efficient Z- and Enantioselective Ring-Opening/Cross-Metathesis Reactions Promoted by Stereogenic-at-Mo Complexes; Utility in Chemical Synthesis and Mechanistic Attributes2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 5, p. 2788-2799Article in journal (Refereed)
    Abstract [en]

    The first examples of catalytic enantioselective ring-opening/cross- metathesis (EROCM) reactions that involve enol ethers are reported. Specifically, we demonstrate that catalytic EROCM of several oxa-and azabicycles, cyclobutenes and a cyclopropene with an alkyl-or aryl-substituted enol ether proceed readily in the presence of a stereogenic-at-Mo monopyrrolide-monoaryloxide. In some instances, as little as 0.15 mol % of the catalytically active alkylidene is sufficient to promote complete conversion within 10 min. The desired products are formed in up to 90% yield and >99:1 enantiomeric ratio (er) with the disubstituted enol ether generated in >90% Z selectivity. The enol ether of the enantiomerically enriched products can be easily differentiated from the terminal alkene through a number of functionalization procedures that lead to the formation of useful intermediates for chemical synthesis (e.g., efficient acid hydrolysis to afford the enantiomerically enriched carboxaldehyde). In certain cases, enantioselectivity is strongly dependent on enol ether concentration: larger equivalents of the cross partner leads to the formation of products of high enantiomeric purity (versus near racemic products with one equivalent). The length of reaction time can be critical to product enantiomeric purity; high enantioselectivity in reactions that proceed to >98% conversion in as brief a reaction time as 30 s can be nearly entirely eroded within 30 min. Mechanistic rationale that accounts for the above characteristics of the catalytic process is provided. © 2012 American Chemical Society.

  • 19.
    Ma, Guangning
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Afewerki, Samson
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Deiana, L.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Sweden .
    Palo-Nieto, C.
    Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Sweden .
    Liu, L.
    Berzelii Center EXSELENT, Stockholm University, Sweden .
    Sun, J.
    Berzelii Center EXSELENT, Stockholm University, Sweden .
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Chemical Engineering.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    A palladium/chiral amine co-catalyzed enantioselective dynamic cascade reaction: Synthesis of polysubstituted carbocycles with a quaternary carbon stereocenter2013In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 23, p. 6050-6054Article in journal (Refereed)
    Abstract [en]

    Polysubstituted 5- and 6-membered carbocycles were synthesized by the title reaction. The one-pot dynamic relay process generates four new stereocenters, including a quaternary carbon center, in a highly enantioselective fashion (99.5:0.5→99:0.5 e.r.) by using a simple combination of palladium and chiral amine co-catalysts. 

  • 20.
    Ma, Guangning
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Bartoszewicz, Agnieszka
    Stockholm Univ, Arrhenius Lab, Dept Organ Chem, SE-10691 Stockholm, Sweden .
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Highly Enantioselective Co-Catalytic Direct Aldol reactions by Combination of Hydrogen-Bond Donating and Acyclic Amino Acid Catalysts2011In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, no 17, p. 3114-3122Article in journal (Refereed)
    Abstract [en]

    Highly enantioselective co-catalytic direct aldol reactions by a combination of simple hydrophobic acyclic amino acid and hydrogen-bond donating catalysts are presented. The corresponding aldol products are formed in high yields with high regio-, diastereo- (anti or syn) and enantioselectivity (up to 99.5:0.5 er). The catalyst loadings can be decreased to as little as 2 mol%.

  • 21.
    Ma, Guangning
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Lin, Shuangzheng
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, S-10691 Stockholm, Sweden .
    Ibrahem, Ismail
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Kubik, Grzegorz
    Stockholm Univ, Dept Organ Chem, Arrhenius Lab, S-10691 Stockholm, Sweden .
    Liu, Leifeng
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden.
    Sun, Junliang
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden.
    Cordova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of applied science and design.
    Achiral Co-Catalyst Induced Switches in Catalytic Asymmetric Reactions on Racemic Mixtures (RRM): From Stereodivergent RRM to Stereoconvergent Deracemization by Combination of Hydrogen Bond Donating and Chiral Amine Catalysts2012In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, no 14-15, p. 2865-2872Article in journal (Refereed)
    Abstract [en]

    A stereochemical divergent approach for the highly enantioselective synthesis of distinct bicyclic products with multiple stereocenters from a racemate using a single chiral catalyst is disclosed. It is based on switches of the overall reaction pathways in the chiral amine-catalyzed cascade reactions between racemic ?-nitro ketones and a,beta-unsaturated aldehydes using different achiral co-catalysts. The utility of the method is exemplified by the highly diasteroselective switch and stereoconvergent deracemization process by combination of chiral amine and achiral hydrogen-bond-donating catalysts.

  • 22. Zhao, Gui-Ling
    et al.
    Ullah, Farman
    Deiana, Luca
    Lin, Shuangzheng
    Zhang, Qiong
    Sun, Junliang
    Ibrahem, Ismail
    Department of Organic Chemistry, The Arrhenius Laboratory, Stockholm University,.
    Dziedzic, Pawel
    Córdova, Armando
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Dynamic kinetic asymmetric transformation (DYKAT) by combined amine and transition metal catalyzed enantioselective cycloisomerization2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765Article in journal (Refereed)
1 - 22 of 22
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