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  • 1. Andersson, Samir
    et al.
    Zou, Dapeng
    Zhang, Rong
    Sun, Shiguo
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Selective positioning of CB[8] on two linked viologens and electrochemically driven movement of the host molecule2009In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 8, p. 1163-1172Article in journal (Refereed)
  • 2.
    Bogár, Krisztián
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krumlinde, Patrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bacsik, Zoltán
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hedin, Niklas
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Heterogenized Wilkinson's Catalyst for Transfer Hydrogenation of Carbonyl Compounds2011In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 23, p. 4409-4414Article in journal (Refereed)
    Abstract [en]

    Wilkinson’s catalyst [RhCl(PPh3)3] was heterogenized on common silica by the use of a grafting/anchoring technique. The immobilized catalyst showed high activity and selectivity in transfer hydrogenation reactions of a range of carbonyl compounds in 2-propanol. Reactions carried out in 2-propanol at reflux afforded the corresponding alcohols in high yields in short reaction times. The heterogeneous feature ofthe catalyst allows for easy recovery and efficient reuse in the same reaction up to 5 times without any detectible loss of catalytic activity.

  • 3. Chassagne, Pierre
    et al.
    Fontana, Carolina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Guerreiro, Catherine
    Gauthier, Charles
    Phalipon, Armelle
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mulard, Laurence A.
    Structural Studies of the O-Acetyl-Containing O-Antigen from a Shigella flexneri Serotype 6 Strain and Synthesis of Oligosaccharide Fragments Thereof2013In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 19, p. 4085-4106Article in journal (Refereed)
    Abstract [en]

    Extensive analysis by NMR spectroscopy of the delipidated lipopolysaccharide of Shigella flexneri serotype 6 strain MDC 2924-71 confirmed the most recently reported structure of the O-antigen repeating unit as {4)--D-GalpA-(13)--D-GalpNAc-(12)--L-Rhap3Ac/4Ac-(12)--L-Rhap-(1}, and revealed the non-stoichiometric acetylation at O-3C/4C. Input from the CASPER program helped to ascertain the fine distribution of the three possible patterns of O-acetylation. The non-O-acetylated repeating unit (ABCD) corresponded to about 2/3 of the population, while 1/4 was acetylated at O-3C (3AcCDAB), and 1/10 at O-4C (4AcCDAB). Di- to tetrasaccharides with a GalpA residue (A) at their reducing end were synthesized as their propyl glycosides following a multistep linear strategy relying on late-stage acetylation at O-3C. Thus, the 3C-O-acetylated and non-O-acetylated targets were synthesized from common protected intermediates. Rhamnosylation was most efficiently achieved by using imidate donors, including at O-4 of a benzyl galacturonate acceptor. In contrast, a thiophenyl 2-deoxy-2-trichloroacetamido-D-galactopyranoside precursor was preferred for chain elongation involving residue B. Final Pd/C-mediated deprotection ensured O-acetyl stability. All of the target molecules represent parts of the O-antigen of S. flexneri 6, a prevalent serotype. Non-O-acetylated oligosaccharides are also fragments of the Escherichia coli O147 O-antigen.

  • 4. Cosner, Casey C.
    et al.
    Iska, Vijaya Bhaskara Reddy
    Chatterjee, Anamitra
    Markiewicz, John T.
    Corden, Steven J.
    Löfstedt, Joakim
    Ankner, Tobias
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Richer, Joshua
    Hulett, Tyler
    Schauer, Douglas J.
    Wiest, Olaf
    Helquist, Paul
    Evolution of Concise and Flexible Synthetic Strategies for Trichostatic Acid and the Potent Histone Deacetylase Inhibitor Trichostatin A2013In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 1, p. 162-172Article in journal (Refereed)
    Abstract [en]

    (R)-(+)-Trichostatic acid and (R)-(+)-trichostatin A (TSA) are natural products that have attracted considerable attention in the field of epigenetic therapies. TSA in particular is a naturally occurring hydroxamic acid having potent activity as a histone deacetylase inhibitor (HDACi) and having significant potential for treatment of a myriad of genetically based diseases. Development of TSA and other trichostatic acid derivatives into useful small-molecule therapies has been hindered by the low natural abundance and high cost associated with these compounds. We report herein our collective efforts towards the development of concise and scalable routes for the synthesis of trichostatic acid and TSA in both racemic and enantioenriched forms. Three independent synthetic pathways were developed with varying degrees of efficiency and convergency. In the first synthesis, the key step was a vinylogous Horner-Wadsworth-Emmons condensation. A Marshall propargylation reaction was used as the key step in the second synthesis, and Pd-catalyzed a-alkenylation of a ketone zinc enolate by using various functionalized alkenyl or dienyl halides was developed for the third synthesis. The second pathway proved to be readily amenable to an enantioselective modification, and both the second and third pathways were straightforwardly adapted for the facile preparation of new analogues of trichostatic acid and TSA.

  • 5.
    Cumpstey, Ian
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ramstadius, Clinton
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Akhtar, Tashfeen
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Goldstein, Irwin J
    Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI .
    Winter, Harry C
    Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI .
    Non-glycosidically linked pseudodisaccharides: thioethers, sulfoxides, sulfones, ethers, selenoethers, and their binding to lectins2010In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 10, p. 1951-1970Article in journal (Refereed)
    Abstract [en]

    Hydrolytically stable non-glycosidically linked tail-to-tail pseudodisaccharides are linked by a single bridging atom remote from the anomeric centre of the constituent monosaccharides. Some such pseudodisaccharides with sulfur or oxygen bridges were found to act as disaccharide mimetics in their binding to the Banana Lectin and to Concanavalin A. A versatile synthetic route to a small library of such compounds is described

  • 6.
    Engström, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Shakeri, Mozaffar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dynamic Kinetic Resolution of β-Amino Esters by a Heterogeneous System of a Palladium Nanocatalyst and Candida antarctica Lipase A2011In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 10, p. 1827-1830Article in journal (Refereed)
    Abstract [en]

    A dynamic kinetic resolution (DKR) of β-amino esters have been developed by the use of a heterogeneous racemization catalyst and an immobilized enzyme that accepts aromatic, heteroaromatic and aliphatic substrates. The reaction conditions were optimized to yield an efficient catalytic system without by-product formation. The products are obtained in 96–99 % ee and high yields

  • 7.
    Eriksson, Kristofer
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nyholm, Leif
    Oscarsson, Sven
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dispersed Gold Nanoparticles Supported in the Pores of Siliceous Mesocellular Foam: A Catalyst for Cycloisomerization of Alkynoic Acids to gamma-Alkylidene Lactones2015In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 10, p. 2250-2255Article in journal (Refereed)
    Abstract [en]

    A versatile approach for the production of dispersed thiol-stabilized gold nanoparticles in the pores of siliceous mesocellular foam (MCF) is described. The reported method is based on an electrochemical oxidation of a gold surface generating oxidative Au-III species, which give rise to a surface-confined redox reaction yielding MCF-supported Au-I thiolates. By reducing the corresponding Au-I-S-MCF species with sodium borohydride, thiol-stabilized gold nanoparticles in the size range of 1-8 nm were obtained as determined by transmission electron microscopy. Elemental analysis indicated an Au loading of 3% (w/w) on the MCF. The surface-confined Au nanoparticles were used to catalyze the cycloisomerization of alkynoic acids to the corresponding -alkylidene lactones in high efficiency and complete 5-exo-dig selectivity under mild reaction conditions.

  • 8.
    Frigell, Jens
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pearcey, Jean A.
    Lowary, Todd L.
    Cumpstey, Ian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Carbasugar Analogues of Galactofuranosides: Pseudodisaccharide Mimics of Fragments of Mycobacterial Arabinogalactan2011In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 7, p. 1367-1375Article in journal (Refereed)
    Abstract [en]

    A partially protected carbasugar analogue of beta-galactofuranose was converted into an alpha-galacto-configured 1,2-epoxide, which was opened by alcohols under Lewis acid catalysis with regioselective attack at C-1 to give beta-galacto-configured C-1 ethers. Using OH-5 and OH-6 carbagalactofuranose derivatives as nucleophiles, we synthesised pseudodisaccharide analogues of substructures of the arabinogalactan from M. tuberculosis. The dicarba analogue of the disaccharide Galf(beta 1 -> 5) Galf was found to moderately inhibit the action of GlfT2 galactofuranosyl transferase from M. tuberculosis.

  • 9.
    Horváth, Attila
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Benner, Jessica
    Simple, Enantiocontrolled Synthesis of 3-Pyrrolines from α-Amino Allenes2004In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2004, no 15, p. 3240-3243Article in journal (Refereed)
    Abstract [en]

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

  • 10.
    Jiang, Yan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Deiana, Luca
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Alimohammadzadeh, Rana
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Leifeng
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cordova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Highly Diastereo- and Enantioselective Cascade Synthesis of Bicyclic Lactams in One-Pot2018In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 9, p. 1158-1164Article in journal (Refereed)
    Abstract [en]

    A versatile and highly stereoselective synthetic route to functionalized bi- and tricyclic lactams (up to > 20:1 dr and 99% ee) in one pot from simple starting materials (allylic alcohols, enals, diamines and amino alcohols) using cascade transformations promoted by chiral amine/BrOnsted or metal/chiral amine/BrOnsted relay catalysis is disclosed. Here molecular oxygen is employed as the terminal oxidant for the latter relay catalysis approach.

  • 11.
    Johnston, Eric V.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Karlsson, Erik A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tran, Lien-Hoa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient aerobic ruthenium-catalyzed oxidation of secondary alcohols by the use of a hybrid electron transfer catalyst2010In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 10, p. 1971-1976Article in journal (Refereed)
    Abstract [en]

    Biomimetic aerobic oxidation of secondary alcohols has been performed using hybrid catalyst 1 and Shvo's catalyst 2. This combination allows mild reaction conditions and low catalytic loading, due to the efficiency of intramolecular electron transfer. By this method a wide range of different alcohols have been converted into their corresponding ketones. Oxidation of benzylic as well as aliphatic, electron-rich, electron-deficient and sterically hindered alcohols could be oxidized in excellent yield and selectivity. Oxidation of (S)-1-phenyl-ethanol showed that no racemization occurred during the course of the reaction, indicating that the hydride 2b adds to the quinone much faster than it re-adds to the ketone product. The kinetic deuterium isotope effect of the oxidation was determined by the use of 1-phenylethanol (3a) and 1-deuterio-1-phenylethanol (3a-d1) in parallel and competitive manner, which gave the same isotope effect within experimental error (k(H)/k(D) approximate to 2.8). This indicates that there is no strong coordination of the substrate to the catalyst.

  • 12.
    Johnston, Eric V.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Karlsson, Erik A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tran, Lien-Hoa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient synthesis of hybrid (hydroquinone-Schiff base)cobalt oxidation catalysts2009In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 23, p. 3973-3976Article in journal (Refereed)
    Abstract [en]

    Hybrid catalysts A and B have recently been found to efficiently transfer electrons from a metal catalyst to molecular oxygen in biomimetic oxidations. In the present work hybrid catalysts A and B were synthesized in high yield from inexpensive starting materials. The key step is an efficient Suzuki cross-coupling, which allows the use of unprotected aldehyde 5. The new synthesis of the title hybrid catalysts is easy to carry out and can be scaled up.

  • 13.
    Kovalenko, Oleksandr O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lundberg, Helena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Huebner, Dennis
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tandem alpha-Alkylation/Asymmetric Transfer Hydrogenation of Acetophenones with Primary Alcohols2014In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 30, p. 6639-6642Article in journal (Refereed)
    Abstract [en]

    A tandem -alkylation/asymmetric transfer hydrogenation of acetophenones with primary alcohols, mediated by a single ruthenium catalyst, is described. Under optimized reaction conditions and with use of [Ru(p-cymene)Cl-2](2) in combination with an amino acid hydroxyamide ligand, the chiral secondary alcohol products were isolated in moderate yields and in moderate to good enantiomeric excess (up to 89% ee).

  • 14.
    Lavén, Gaston
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nilsson, Johan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Silylation-Mediated Transesterification of Phenyl H-Phosphonothioate: A New Entry to Nucleoside H-Phosphonothioate Monoesters2004In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 24, p. 5111-5114Article in journal (Refereed)
    Abstract [en]

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

  • 15.
    Lin, Shuangzheng
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Deiana, Luca
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tseggai, Abrehet
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cordova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Concise Total Synthesis of Dihydrocorynanthenol, Protoemetinol, Protoemetine, 3-epi-Protoemetinol and Emetine2012In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 2, p. 398-408Article in journal (Refereed)
    Abstract [en]

    A concise asymmetric assembly of secologanine tryptamine and dopamine alkaloids by means of a one-pot three-component cascade reaction methodology is disclosed. This is demonstrated by the expeditious total syntheses of (-)-dihydrocorynanthenol, (-)-protoemetinol, (-)-protoemetine, (-)-3-epi-protoemetinol, and emetine (3-6 steps). The biomimetic synthetic strategy involved the following key steps: (i) One-pot three-component highly enantioselective catalytic Michael/Pictet-Spengler/lactamization cascade reactions; (ii) One-pot tandem Swern oxidation/Wittig sequences; (iii) One-pot tandem hydrogenation sequences.

  • 16.
    Merritt, Eleanor A.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of a range of iodine(III) compounds directly from iodoarenes2011In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 20-21, p. 3690-3694Article in journal (Refereed)
    Abstract [en]

    The first direct synthesis of an alkynyl(phenyl)iodonium salt from iodobenzene and an unprotected alkyne is described. The synthesis of the corresponding alkenyl(phenyl)iodonium salt is achieved from the TMS-alkyne, simply by means of changing the solvent. The one-pot synthesis of 1-arylbenziodoxolones and other iodine(III) compounds from iodine(I) precursors is also presented.

  • 17.
    Quan, Xu
    et al.
    Uppsala University, Sweden.
    Parihar, Vijay Singh
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bera, Milan
    University of KwaZulu-Natal, South Africa.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. University of KwaZulu-Natal, South Africa.
    Iridium Catalysts with Chiral Bicyclic Pyridine-Phosphane Ligands for the Asymmetric Hydrogenation of Olefins2014In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, Vol. 2014, no 1, p. 140-146Article in journal (Refereed)
    Abstract [en]

    New bicyclic pyridine-phosphane ligands were prepared, and their iridium complexes were evaluated in asymmetric hydrogenation of trisubstituted olefins with non-coordinating and weakly coordinating substituents. The iridium catalysts showed high reactivity and enantioselectivity for both types of olefins.

  • 18.
    Ramstadius, Clinton
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Träff, Annika
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Krumlinde, Patrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cumpstey, Ian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ruthenium-catalysed epimerisation of carbohydrate lcohols as a method to determine the equilibria for epimer interconversion in hexopyranosides2011In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 23, p. 4455-4459Article in journal (Refereed)
    Abstract [en]

    Ruthenium-catalysed epimerisation of secondary carbohydrate alcohols was used to determine the thermodynamic equilibrium between non-anomeric epimers of partially protected glucose, mannose and allose derivatives. A cyclopentadienylruthenium catalyst was used to epimerise each of two pure epimeric alcohols in two separate experiments. The epimerisation reactions were run until the same ratio of epimers was obtained from the two experiments.

  • 19.
    Rönnols, Jerk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Burkhardt, Anja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cumpstey, Ian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    pK(a)-Determination and Conformational Studies by NMR Spectroscopy of D-Altrose-Containing and other Pseudodisaccharides as Glycosidase Inhibitor Candidates2012In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 1, p. 74-84Article in journal (Refereed)
    Abstract [en]

    The pK(a) values of six amine-linked pseudodisaccharides have been determined by using an NMR-based titration method. The pK(a) varies significantly depending on the linkage position and is inversely correlated with the number of electronegative groups in the beta-position to the amino group. Four of the pseudodisaccharides contain alpha-altroside moieties, the conformations of which were determined in the protonated and neutral states, again by using NMR techniques. In the neutral state, 2-amino-2-deoxyaltrosides and 3-amino-3-deoxyaltrosides were both found to occupy C-4(1) and S-O(2) conformations. On protonation, little change in the population distribution was seen for the 3-amino-3-deoxyaltrosides, but for the 2-amino-2-deoxyaltrosides, a shift in equilibrium position towards the skew conformer (more than 80% populated) takes place, and also a small amount of the other chair conformer (i.e., C-1(4), approximately 10% populated) was observed. 3-Amino-3-deoxyaltrosides have been shown to act as glycosidase inhibitors and insights into conformational equilibria as a function of protonation state should facilitate the design of better glycosidase inhibitors based on flexible monosaccharide amines.

  • 20.
    Sebelius, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kálmán J., Szabó
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Allylation of aldehyde and imine substrates with in situ generated allylboronates - a simple route to enantioenriched homoallyl alcohols2005In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 12, p. 2539-2547Article in journal (Refereed)
    Abstract [en]

    Allylation of aldehyde and imine substrates was achieved using easily available allylacetates and diboronate reagents in the presence of catalytic amounts of palladium. This operationally simple one-pot reaction has a broad synthetic scope, as many functionalities including, acetate, carbethoxy, amido and nitro groups are tolerated. The allylation reactions proceed with excellent regio- and stereoselectivity affording the branched allylic isomer. By employment of commercially available chiral diboronates enantioenriched homoallyl alcohols (up to 53% ee) could be obtained. The mechanistic studies revealed that the in situ generated allylboronates react directly with the aldehyde substrates, however the allylation of the sulfonylimine substrate requires palladium catalysis.

  • 21.
    Selander, Nicklas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sebelius, Sara
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Estay, Cesar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Highly Selective and Robust Palladium-Catalysed Carbon-Carbon Coupling between Allyl Alcohols and Aldehydes via Transient Allylboronic Acids2006In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 18, p. 4085-4087Article in journal (Refereed)
    Abstract [en]

    The highly regio- and stereoselective coupling of allyl alcohols with aldehydes could be achieved with 5 mol-% of SeCSe pincer complex catalyst and p-toluenesulfonic acid in the presence of diboronic acid. The transformations have a broad synthetic scope, and the high yields were obtained without the use of an inert atmosphere and carefully dried solvents.

  • 22.
    Tran, Lien-Hoa
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    An Efficient and Selective Oxidation of Alcohols to Carbonyl Compounds and Carboxylic Acids Catalyzed by A Dinuclear Ruthenium Complex Using Iodosobenzene as Terminal Oxidant2009In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690Article in journal (Refereed)
  • 23.
    Volkov, Alexey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Buitrago, Elina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Direct Hydrosilylation of Tertiary Amides to Amines by an In Situ Formed Iron/N-Heterocyclic Carbene Catalyst2013In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 11, p. 2066-2070Article in journal (Refereed)
    Abstract [en]

    Tertiary amides were efficiently reduced to their corresponding tertiary amines in high isolated yields by using the commercially available and inexpensive polymeric silane polymethylhydrosiloxane (PMHS) as the reducing agent. The reaction is efficiently catalyzed by an in situ generated iron/N-heterocyclic carbene complex (1 mol-%) obtained from iron(II) acetate and 1-(2-hydroxy-2-phenylethyl)-3-methylimidazolium triflate ([PhHEMIM][OTF]). A catalytic amount of lithium chloride (1 mol-%) present in the reaction mixture significantly reduced the reaction time and increased the chemoselectivity of the reduction process.

  • 24.
    Warner, Madeleine C.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Racemization of Olefinic Alcohols by a Carbonyl(cyclopentadienyl)ruthenium Complex: Inhibition by the Carbon-Carbon Double Bond2015In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 11, p. 2388-2393Article in journal (Refereed)
    Abstract [en]

    In this article, racemization of various olefinic sec-alcohols by Ru(CO)(2)((5)-C5Ph5)Cl was investigated. The racemization of three aliphatic sec-alcohols with different chain lengths containing terminal double bonds was studied. A dramatic decrease of the racemization rate was found for these sec-alcohols compared to that of the corresponding saturated substrates. The slow racemization rate of the former alcohols is ascribed to coordination of the double bond to the ruthenium centre, which blocks the free site needed for -hydride elimination. This mechanism was supported by a recent study, in which 5-hexen-2-ol was found to form an alkoxycarbonyl complex having the double bond coordinated to the ruthenium atom. Aliphatic sec-alcohol substrates with a di- or trisubstituted double bond were found to give a lower degree of inhibition of the racemization rate than the substrates with a monosubstituted double bond.

  • 25.
    Xu, Quan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diomedi, Simone
    Singh, Thishana
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Thiazole, Imidazole and Oxazoline Based N,P-Ligands for Palladium-Catalyzed Cycloisomerization of 1,6-Enynes2016In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 20, p. 3427-3433Article in journal (Refereed)
    Abstract [en]

    A series of N,P-ligands were prepared and evaluated in the asymmetric palladium-catalyzed cycloisomerization of allyl propargyl ether substrates. The reactivity and enantioselectivity of the reaction was shown to be highly dependent on the chiral skeleton of the ligand structures with ee's ranging from 22-99 %. The proton source had a significant impact on the enantioselectivity. The generation of palladium hydride from formic acid led to the highest ee. A selectivity model based on a proposed transition state was used to predict and explain the enantiomeric outcome of the reaction.

  • 26.
    Zaccheus, Mona
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pendrill, Robert
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jackson, Trudy A.
    Wang, An
    Auzanneau, France-Isabelle
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Conformational Dynamics of a Central Trisaccharide Fragment of the LeaLex Tumor Associated Antigen Studied by NMR Spectroscopy and Molecular Dynamics Simulations2012In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 25, p. 4705-4715Article in journal (Refereed)
    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.

  • 27.
    Éll, Alida H
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Csjernyik, Gábor
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Slagt, Vincent F
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Berner, Simon
    Puglia, Carla
    Greger, Ledung
    Oscarsson, Sven
    Synthesis os S-Thioacetate Functionalized Cobalt(II) Porphyrins and Heterogenization on gold Surface2006In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 5, p. 1193-1199Article in journal (Refereed)
    Abstract [en]

    Cobalt tetraarylporphyrins 1-Co and 2-Co with thioacetate-functionalized carbon chains on the aryl groups were synthesized. The cobalt porphyrin 2-Co was immobilized on a gold surface after deprotection of the S-acetyl group. The immobilized porphyrin was studied by X-ray Photoelectron Spectroscopy (XPS) and the results suggest that a complete monolayer of porphyrins is formed.

1 - 27 of 27
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