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  • 51.
    Angles d'Ortoli, Thibault
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Assembling and Unraveling Carbohydrates Structures: Conformational analysis of synthesized branched oligosaccharides2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

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

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

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

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

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

  • 52.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hamark, Christoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structure-Reactivity Relationships of Conformationally Armed Disaccharide Donors and Their Use in the Synthesis of a Hexasaccharide Related to the Capsular Polysaccharide from Streptococcus pneumoniae Type 372017Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, nr 15, s. 8123-8140Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 53.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mobarak, Hani
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ståhle, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Hamark, Christoffer
    Fontana, Carolina
    Engström, Olof
    Apostolica, Patricia
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Complete 1H and 13C NMR chemical shift assignments of mono- to tetrasaccharides as basis for NMR chemical shift predictions of oligo- and polysaccharides using the computer program CASPERManuskript (preprint) (Annet vitenskapelig)
  • 54.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sjöberg, Nils A.
    Vasiljeva, Polina
    Lindman, Jonas
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bergenstråhle-Wohlert, Malin
    Wohlert, Jakob
    Temperature Dependence of Hydroxymethyl Group Rotamer Populations in Cellooligomers2015Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 119, nr 30, s. 9559-9570Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 55.
    Angles d'Ortoli, Thibault
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of the tetrasaccharide glycoside moiety of Solaradixine and rapid NMR-based structure verification using the program CASPER2016Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 72, nr 7, s. 912-927Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 56.
    Arafa, Wael A. A.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kärkäs, Markus D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lee, Bao-Lin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Liao, Rong-Zhen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Berends, Hans-Martin
    Messinger, Johannes
    Siegbahn, Per E. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dinuclear manganese complexes for water oxidation: evaluation of electronic effects and catalytic activity2014Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, nr 24, s. 11950-11964Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

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

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

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

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

  • 59. Arukuusk, Piret
    et al.
    Pärnaste, Ly
    Hällbrink, Mattias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi.
    Langel, Ülo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi. Tartu University, Estonia.
    PepFects and NickFects for the Intracellular Delivery of Nucleic Acids2015Inngår i: Cell-Penetrating Peptides: Methods and Protocols / [ed] Ülo Langel, New York: Springer, 2015, Vol. 1324, s. 303-315Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    Nucleic acids can be utilized in gene therapy to restore, alter, or silence gene functions. In order to reveal the biological activity nucleic acids have to reach their intracellular targets by passing through the plasma membrane, which is impermeable for these large and negatively charged molecules. Cell-penetrating peptides (CPPs) condense nucleic acids into nanoparticles using non-covalent complexation strategy and mediate their delivery into the cell, whereas the physicochemical parameters of the nanoparticles determine the interactions with the membranes, uptake mechanism, and subsequent intracellular fate. The nanoparticles are mostly internalized by endocytosis that leads to the entrapment of them in endosomal vesicles. Therefore design of new CPPs that are applicable for non-covalent complex formation strategy and harness endosomolytic properties is highly vital. Here we demonstrate that PepFects and NickFects are efficient vectors for the intracellular delivery of various nucleic acids.This chapter describes how to form CPP/pDNA nanoparticles, evaluate stable nanoparticles formation, and assess gene delivery efficacy.

  • 60. Ashour, Radwa M.
    et al.
    Abdel-Magied, Ahmed F.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Nuclear Materials Authority, Egypt.
    Abdel-Khalek, Ahmed A.
    Helaly, O. S.
    Ali, M. M.
    Preparation and characterization of magnetic iron oxide nanoparticles functionalized by L-cysteine: Adsorption and desorption behavior for rare earth metal ions2016Inngår i: Journal of Environmental Chemical Engineering, ISSN 2160-6544, E-ISSN 2213-3437, Vol. 4, nr 3, s. 3114-3121Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 61.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Larsson, Johanna M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selander, Nicklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pincer complex-catalyzed redox coupling of alkenes with iodonium salts via presumed palladium(IV) intermediates2009Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 11, nr 13, s. 2852-2854Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 62.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantioselective palladium pincer complex catalyzed carbon carbon coupling reactions between tosylimines and various nucleophiles2008Inngår i: Abstracts of Papers, 236th ACS National Meeting, Philadelphia, PA, United States, August 17-21, 2008, Washington, DC: American Chemical Society , 2008Konferansepaper (Annet vitenskapelig)
  • 63.
    Aydin, Juhanes
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic considerations for the enantioselective palladium pincer complex catalyzed carbon-carbon coupling reactions2008Inngår i: Abstracts of Papers, 236th ACS National Meeting, Philadelphia, PA, United States, August 17-21, 2008, Washington, DC: American Chemical Society , 2008Konferansepaper (Annet vitenskapelig)
  • 64.
    Ayesa Alvarez, Susana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Design and Synthesis of Amine Building Blocks and Protease Inhibitors2008Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

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

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

  • 65.
    Ayesa, Susana
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Samuelsson, Bertil
    Classon, Björn
    A One-Pot, Solid-Phase Synthesis of Secondary Amines from Reactive Alkyl Halides and an Alkyl Azide2008Inngår i: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, nr 1, s. 77-79Artikkel i tidsskrift (Fagfellevurdert)
  • 66. Back, Marcus
    et al.
    Nyhlén, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kvarnström, Ingemar
    Rosenquist, Åsa
    Samuelsson, Bertil
    Design, synthesis and SAR of potent statin-based β-secretase inhibitors: Exploration of P1 phenoxy and benzyloxy residues2007Konferansepaper (Annet vitenskapelig)
  • 67.
    Balan, Daniela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    The three-component aza-Baylis-Hillman reaction: development and application2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The current thesis presents the optimization and generalization of the Baylis-Hillman reaction applied to in situ generated imines, i.e. a three-component aza- Baylis-Hillman reaction. We found that the title reaction proceeds most efficiently in the presence of a combination of catalysts, i.e. 3-hydroxyquinuclidine (0.15 equiv) and titanium isopropoxide (0.02 equiv), together with molecular sieves (4 Å; activated powder; 200 mg/mmol substrate) at ambient temperature.

    Our study of the scope and limitations of this reaction, revealed that arylaldehydes and sulfonamides are the only imine precursors which both generate the corresponding imines in situ and facilitate a further reaction with the Michael acceptor in a Baylis-Hillman fashion. Among the Michael acceptors tested, acrylates and acrylonitrile demonstrate high reactivity, while acrylamides and β-substituted acrylates do not participate in the reaction.

    The optimized conditions applied to the above range of substrates results in good-to-excellent yields of the desired amine-products (53-94%) and very high chemoselectivity (83- >99%). Furthermore, the reaction times observed under these conditions are considerably shorter than those previously reported for the aza-Baylis-Hillman reaction.

    In the development of a stereoselective version of the title reaction, the use of a chiral catalyst proved to be most effective. Thus, an enantiomeric excess up to 74% can be obtained with β-Isocupreidine. With chiral imine precursors or chiral acrylates, the diastereoselectivity attained was poor. No asymmetric induction was observed when chiral Lewis acids were employed as a co-catalyst.

    The α-methylene-β-amino acid derivatives obtained via the three-component aza-Baylis-Hillman reaction were subjected to further transformation. Carbon chain elongation at the olefinic end of the amine-adduct was attempted. For this purpose, the Miyaura borylation protocol could be successfully applied. The subsequent Suzuki-type cross-coupling reaction resulted predominantly in hydrolysis of the boronate intermediate, together with formation of the amine-adduct via β-hydride elimination. The optimal conditions for this latter reaction remain to be found.

    Finally, 2,5-dihydropyrroles have been synthesized from aza-Baylis-Hillman adducts, via a short and efficient route in which the key step is a microwave-assisted ring-closing metathesis of the N-allylated amine-adducts.

  • 68. Barbion, Julien
    et al.
    Sorin, Geoffroy
    Selkti, Mohamed
    Kellenberger, Esther
    Baati, Rachid
    Santoro, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pancrazi, Ange
    Lannou, Marie-Isabelle
    Ardisson, Janick
    Stereoselective functionalization of pyrrolidinone moiety towards the synthesis of salinosporamide A2012Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 68, nr 32, s. 6504-6512Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An important feature of the synthesis of salinosporamide A. a potent proteasome inhibitor, is the establishment of the quaternary stereocenter at C3. A new route has been developed based on the methylation of a functionalized pyrrolidinone. Direct methylation reaction led to the unwanted diastereomer: however, by means of a Corey-Chaykovsky reaction followed by LiAlH4 epoxide opening, the desired alcohol was obtained. The pyrrolidinone was elaborated through a key allylation reaction between a tertiary allyltitanium reagent and an aldehyde bearing a spiroketal moiety in alpha-position.

  • 69. Barlind, Jonas G.
    et al.
    Buckett, Linda K.
    Crosby, Sharon G.
    Davidsson, Ojvind
    Emtenas, Hans
    Ertan, Anne
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Jurva, Ulrik
    Lemurell, Malin
    Gutierrez, Pablo Morentin
    Nilsson, Karolina
    O'Mahony, Gavin
    Petersson, Annika U.
    Redzic, Alma
    Wagberg, Fredrik
    Yuan, Zhong-Qing
    Identification and design of a novel series of MGAT2 inhibitors2013Inngår i: Bioorganic & Medicinal Chemistry Letters, ISSN 0960-894X, E-ISSN 1090-2120, Vol. 23, nr 9, s. 2721-2726Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    [Acyl CoA]monoacylglycerol acyltransferase 2 (MGAT2) is of interest as a target for therapeutic treatment of diabetes, obesity and other diseases which together constitute the metabolic syndrome. In this Letter we report our discovery and optimisation of a novel series of MGAT2 inhibitors. The development of the SAR of the series and a detailed discussion around some key parameters monitored and addressed during the lead generation phase will be given. The in vivo results from an oral lipid tolerance test (OLTT) using the MGAT2 inhibitor (S)-10, shows a significant reduction (68% inhibition relative to naive, p < 0.01) in plasma triacylglycerol (TAG) concentration.

  • 70.
    Bartholomeyzik, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Investigation of Selectivity in Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes.Manuskript (preprint) (Annet vitenskapelig)
  • 71.
    Bartholomeyzik, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-Catalyzed Oxidative Carbocyclization/Functionalization of Allenynes2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The selective formation of carbon-carbon bonds constitutes a key transformation in organic synthesis with useful applications in pharmaceutical or material industry. A particularly versatile tool for carbon-carbon as well as carbon-heteroatom bond formation is palladium catalysis, which allows for mild and selective routes even towards complex structures.

    The work in this thesis describes the development and the mechanistic investigation of a palladium(II)-catalyzed oxidative carbocyclization/functionalization methodology, which converts 1,5-allenynes into either arylated or borylated carbocycles. To this end, either boronic acids or B2pin2 are employed and 1,4-benzoquinone serves as the stoichiometric oxidant. These protocols provide access to two products, a cyclic triene and a cyclic vinylallene. Their formation is dependent on the substrate structure as the latter product requires a propargylic C–H bond to be present in the substrate. Based on kinetic isotope effects, mechanisms involving either an initial allenic or propargylic C–H abstraction, respectively, were proposed. Full control of product selectivity to give either trienes or vinylallenes was achieved by modifying the reaction conditions with additives. Using substoichiometric amounts of BF3·OEt2 leads selectively to borylated or arylated vinylallenes. Under arylating conditions the reaction is zero order in allenyne and oxidant, and first order in phenylboronic acid. Transmetalation and, to some extent, propargylic C–H cleavage were found to be turnover-limiting. The selective reaction towards functionalized trienes was achieved by addition of either substoichiometric LiOAc·2H2O (borylation) or excess amounts of H2O (arylation). For the latter case, a kinetic study revealed an unusually slow catalyst activation. Lower concentrations of H2O gave product mixtures, and it was shown that vinylallenes are formed with either boronic acid or boroxine, whereas the formation of trienes requires boronic acid.

  • 72.
    Bartholomeyzik, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-Catalyzed Oxidative Carbocyclization/Functionalization of Allenynes2013Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Palladium catalysis has emerged as an outstanding tool in synthetic organic chemistry for the mild and selective formation of carbon-carbon and carbon-heteroatom bonds. This thesis has been directed towards the extension of palladium(II)-catalyzed carbocyclization chemistry under oxidative conditions. An oxidative carbocyclization/functionalization methodology utilizing boron-containing transmetalation reagents was exploited to convert 1,5-allenynes into either arylated or borylated carbocycles. Two protocols were developed that use minimal amounts of Pd(OAc)2, stoichiometric para-benzoquinone as the oxidant and either bis(pinacolato)diboron or different arylboronic acids under mild conditions. A wide substrate scope is applicable to both methods. When the allenyne substrate bears a propargylic hydrogen, two isomeric functionalized carbocycles can be formed. By controlling the reaction conditions the reaction can be directed towards either of these two isomeric products. Kinetic isotope effect studies suggest that the mechanism leading to the different products proceeds through allylic or propargylic C-H bond cleavage, respectively. Moreover, it was observed that water has an interesting effect on the product selectivity when arylboronic acids are used in the oxidative carbocyclization of allenynes.

  • 73.
    Bartholomeyzik, Teresa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mazuela, Javier
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Deng, Youqian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes: Control of Selectivity and Role of H2O2014Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, nr 33, s. 8696-8699Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Highly selective protocols for the carbocyclization/arylation of allenynes using arylboronic acids are reported. Arylated vinylallenes are obtained with the use of BF3 center dot Et2O as an additive, whereas addition of water leads to arylated trienes. These conditions provide the respective products with excellent selectivities (generally > 97:3) for a range of boronic acids and different allenynes. It has been revealed that water plays a crucial role for the product distribution.

  • 74.
    Bartholomeyzik, Teresa
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Complex Kinetics in a Palladium(II)-Catalyzed Oxidative Carbocyclization: Untangling of Competing Pathways, Pre-Catalyst Activation, and Product MixturesManuskript (preprint) (Annet vitenskapelig)
  • 75.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Building molecular complexity via tandem Ru-catalyzed reactions of allylic alcohols2009Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 76.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalysed hydrogen transfer processes for C-C and C-N bond formation: Synthetic studies and mechanistic investigations2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis focusses on synthetic studies and mechanistic investigations into reactions involving hydrogen-transfer processes.

    In the first part, the development of an efficient method for the synthesis of β-hydroxy ketones (aldols) and β-amino ketones (Mannich products) from allylic alcohols and aldehydes is described. These reactions use  Ru(η5-C5Ph5)(CO)2Cl as the catalyst. The reaction parameters were optimised in order to suppress the formation of undesired by-products. Neutral and mild reaction conditions enabled the synthesis of a variety of aldol products in up to 99% yield, with a good syn/anti ratio. The influence of the stereoelectronic properties of the catalyst on the reaction outcome was also studied. Based on the results obtained, a plausible reaction mechanism has been proposed, involving as the key steps the 1,4-addition of hydride to α,β-unsaturated ketones and the formation of ruthenium (Z)-enolates.

    In the second part of this thesis, a ruthenium-catalysed tandem isomerisation/C-H activation reaction is presented. A number of ruthenium complexes, phosphine ligands, and additives were evaluated in order to establish the optimal reaction conditions. It was found that the use of a stable ruthenium catalyst, Ru(PPh3)3Cl2, together with PtBu3 and HCO2Na resulted in an efficient tandem transformation. Using this procedure, a variety of ortho-alkylated ketones were obtained in excellent yields. Moreover, homoallylic alcohols could also be used as starting materials for the reaction, which further expands the substrate scope. Mechanistic investigations into the isomerisation part of the process were carried out.

    The last project described in the thesis deals with the design and preparation of novel bifunctional iridium complexes containing an N-(2-hydroxy-isobutyl)-N-Heterocyclic carbene ligand. These complexes were used as catalysts to alkylate amines using alcohols as latent electrophiles. The catalytic system developed here was found to be one of the most active systems reported to date, allowing the reaction to be performed at temperatures as low as 50 °C for the first time. A broad substrate scope was examined. Combined experimental and theoretical studies into the reaction mechanism are consistent with a metal-ligand bifunctional activity of the new catalyst.

  • 77.
    Bartoszewicz, Agnieszka
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    González Miera, Greco
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Marcos, Rocio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Norrby, Per-Ola
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic Studies on the Alkylation of Amines with Alcohols Catalyzed by a Bifunctional Iridium Complex2015Inngår i: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 5, nr 6, s. 3704-3716Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanism of the N-alkylation of amines with alcohols catalyzed by an iridium complex containing an N-heterocyclic carbene (NHC) ligand with a tethered alcohol/alkoxide functionality was investigated by a combination of experimental and computational methods. The catalyst resting state is an iridium hydride species containing the amine substrate as a ligand, and decoordination of the amine, followed by coordination of the imine intermediate to the iridium center, constitute the rate-determining step (rds) of the catalytic process. The alcohol/alkoxide that is tethered to the NHC participates in every step of the catalytic cycle by accepting or releasing protons and forming hydrogen bonds with the reacting species. Thus, the iridium complex with the alcohol/alkoxide tethered to the N-heterocyclic carbene ligand acts as a bifunctional catalyst.

  • 78.
    Bartoszewicz, Agnieszka
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jezowska, Martina M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Laymand, Kevin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mobus, Juri
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of β-Hydroxy and β-Amino Ketones from Allylic Alcohols Catalyzed by Ru(η5-C5Ph5)(CO)2Cl2012Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 9, s. 1517-1530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient method for the synthesis of beta-hydroxy and beta-amino ketones from allylic alcohols catalyzed by Ru(5-C5Ph5)(CO)2Cl is described. The influence of the stereoelectronic properties of the catalyst on the reaction outcome has been studied. Optimization of the reaction conditions supressed the formation of undesired side products such as saturated ketones, benzyl alcohols, and a,beta-unsaturated ketones. Several aromatic and aliphatic allylic alcohols have been reacted with a large variety of aldehydes or imines to produce beta-hydroxy ketones or beta-amino ketones, respectively, in yields up to 99%. Based on experimental data, a mechanism via ruthenium alkoxides and ruthenium aldoxides is proposed. In addition, a C-bound ruthenium enolate has been characterized.

  • 79.
    Bartoszewicz, Agnieszka
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Livendahl, Madeleine
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of b-Hydroxy Ketones from Allylic Alcohols via Catalytic Formation of Ruthenium Enolates2008Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, nr 34, s. 10547-10550Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 80.
    Bartoszewicz, Agnieszka
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Marcos, Rocio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sahoo, Suman
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Inge, A. Ken
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A Highly Active Bifunctional Iridium Complex with an Alcohol/Alkoxide-Tethered N-Heterocyclic Carbene for Alkylation of Amines with Alcohols2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 45, s. 14510-14519Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    A series of new iridium(III) complexes containing bidentate N-heterocyclic carbenes (NHC) functionalized with an alcohol or ether group (NHC?OR, R=H, Me) were prepared. The complexes catalyzed the alkylation of anilines with alcohols as latent electrophiles. In particular, biscationic IrIII complexes of the type [Cp*(NHC-OH)Ir(MeCN)]2+2[BF4-] afforded higher-order amine products with very high efficiency; up to >99?% yield using a 1:1 ratio of reactants and 12.5 mol?% of Ir, in short reaction times (216 h) and under base-free conditions. Quantitative yields were also obtained at 50?degrees C, although longer reaction times (4860 h) were needed. A large variety of aromatic amines have been alkylated with primary and secondary alcohols. The reactivity of structurally related iridium(III) complexes was also compared to obtain insights into the mechanism and into the structure of possible catalytic intermediates. The IrIII complexes were stable towards oxygen and moisture, and were characterized by NMR, HRMS, single-crystal X-ray diffraction, and elemental analyses.

  • 81.
    Bartoszewicz, Agnieszka
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Building molecular complexity via tandem Ru-catalyzed isomerization/C-H activation2009Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 11, nr 8, s. 1749-1752Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A tandem isomerization/C-H activation of allylic alcohols was performed using a catalytic amount of RUCl(2)(PPh(3))(3). A variety of ortho alkylated ketones have been obtained in excellent yields. This tandem process relies on an in situ generation of a carbonyl functional group that directs the ortho C-H bond activation.

  • 82. Barzegar, Hamid Reza
    et al.
    Nitze, Florian
    Malolepszy, Artur
    Stobinski, Leszek
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Wagberg, Thomas
    Water Assisted Growth of C-60 Rods and Tubes by Liquid-Liquid Interfacial Precipitation Method2012Inngår i: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 17, nr 6, s. 6840-6853Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    C-60 nanorods with hexagonal cross sections are grown using a static liquid-liquid interfacial precipitation method in a system of C-60/m-dichlorobenzene solution and ethanol. Adding water to the ethanol phase leads instead to C-60 tubes where both length and diameter of the C-60 tubes can be controlled by the water content in the ethanol. Based on our observations we find that the diameter of the rods/tubes strongly depends on the nucleation step. We propose a liquid-liquid interface growth model of C-60 rods and tubes based on the diffusion rate of the good C-60 containing solvent into the poor solvent as well as on the size of the crystal seeds formed at the interface between the two solvents. The grown rods and tubes exhibit a hexagonal solvate crystal structure with m-dichlorobenzene solvent molecules incorporated into the crystal structure, independent of the water content. An annealing step at 200 degrees C at a pressure <1 kPa transforms the grown structures into a solvent-free face centered cubic structure. Both the hexagonal and the face centered cubic structures are very stable and neither morphology nor structure shows any signs of degradation after three months of storage.

  • 83. Battistel, Marcos D.
    et al.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Freedberg, Daron I.
    Direct Evidence for Hydrogen Bonding in Glycans: A Combined NMR and Molecular Dynamics Study2013Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 117, nr 17, s. 4860-4869Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We introduce the abundant hydroxyl groups of glycans as NMR handle's and structural probes to expand the repertoire of tools for structure function studies on glycans in solution. To this end, we present the facile detection and assignment of hydroxyl groups in a Wide range of sample concentrations (0.5-1700 mM) and temperatures, ranging from -5 to 25 degrees C.,We then exploit this information to directly detect hydrogen bonds, well-known for their importance in molecular structural determination through NMR. Via HSQC-TOCSY, we were able to determine the directionality; of these hydrogen bonds in sucrose Furthermore, by means Of molecular dynamics simulations in conjunction with NMR, we establish that one Out of the three detected hydrogen bonds arises from intermolecular interactions. This finding may shed light on glycan glycan interactions and glycan recognition by proteins.

  • 84.
    Baumann, Herbert
    Stockholms universitet, Naturvetenskapliga fakulteten.
    Synthesis of and NMR and conformational studies on some 3-O-, 4-O- and 3,4-di-O-glycopyranosyl-substituted methyl d-glycopyranosides1988Doktoravhandling, med artikler (Annet vitenskapelig)
  • 85.
    Bedecs, Katarina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för neurokemi och neurotoxikologi.
    Galanin in the rat dorsal spinal cord: an inhibitor peptide in sensory processing1995Doktoravhandling, med artikler (Annet vitenskapelig)
  • 86.
    Belhomme, Marie-Charlotte
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wang, Dong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Formation of C(sp(3))-C(sp(3)) Bonds by Palladium Catalyzed Cross-Coupling of alpha-Diazoketones and Allylboronic Acids2016Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 18, nr 10, s. 2503-2506Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Palladium catalyzed cross-coupling of allylboronic acids with a-diazoketones was studied. The reaction selectively affords the linear allylic product. The reaction proceeds with formation of a new C(sp(3))-C(sp(3)) bond. The reaction was performed without an external oxidant, likely without the Pd-catalyst undergoing redox reactions.

  • 87. Bergenstråhle-Wohlert, Malin
    et al.
    Angles d'Ortoli, Thibault
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sjöberg, Nils A.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wohlert, Jakob
    On the anomalous temperature dependence of cellulose aqueous solubility2016Inngår i: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 23, nr 4, s. 2375-2387Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The solubility of cellulose in water-based media is promoted by low temperature, which may appear counter-intuitive. An explanation to this phenomenon has been proposed that is based on a temperature-dependent orientation of the hydroxymethyl group. In this paper, this hypothesis is investigated using molecular dynamics computer simulations and NMR spectroscopy, and is discussed in conjunction with alternative explanations based on solvent–solute and solvent–solvent hydrogen bond formation respectively. It is shown that neither simulations nor experiments lend support to the proposed mechanism based on the hydroxymethyl orientation, whereas the two alternative explanations give rise to two distinct contributions to the hydration free energy of cellooligomers.

  • 88. Berglund, Jennie
    et al.
    Angles d'Ortoli, Thibault
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vilaplana, Francisco
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bergenstråhle-Wohlert, Malin
    Lawoko, Martin
    Henriksson, Gunnar
    Lindström, Mikael
    Wohlert, Jakob
    A molecular dynamics study of the effect of glycosidic linkage type in the hemicellulose backbone on the molecular chain flexibility2016Inngår i: The Plant Journal, ISSN 0960-7412, E-ISSN 1365-313X, Vol. 88, nr 1, s. 56-70Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The macromolecular conformation of the constituent polysaccharides in lignocellulosic biomass influences their supramolecular interactions, and therefore their function in plants and their performance in technical products. The flexibility of glycosidic linkages from the backbone of hemicelluloses was studied by evaluating the conformational freedom of the φ and ψ dihedral angles using molecular dynamic simulations, additionally selected molecules were correlated with experimental data by NMR spectroscopy. Three types of β-(1→4) glycosidic linkages involving the monosaccharides (Glcp, Xylp and Manp) present in the backbone of hemicelluloses were defined. Different di- and tetrasaccharides with combinations of such sugar monomers from hemicelluloses were simulated and free energy maps of the φ - ψ space and hydrogen bonding patterns were obtained. The glycosidic linkage between Glc-Glc or Glc-Man (C-type) was the stiffest with mainly one probable conformation; the linkage from Man-Man or Man-Glc (M-type) was similar but with an increased probability for an alternative conformation making it more flexible, and the linkage between two Xyl-units (X-type) was the most flexible with two almost equally populated conformations. Glycosidic linkages of the same type showed essentially the same conformational space in both disaccharides and in the central region of tetrasaccharides. Different probabilities of glycosidic linkage conformations in the backbone of hemicelluloses can be directly estimated from the free energy maps, which to a large degree affect the overall macromolecular conformations of these polymers. The information gained contributes to an increased understanding of hemicelluloses’ function both in the cell wall and in technical products.

  • 89.
    Bermejo Gomez, Antonio
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Erbing, Elis
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Batuecas, Maria
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vazquez-Romero, Ana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martin-Matute, Belen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Iridium-Catalyzed Isomerization/Bromination of Allylic Alcohols: Synthesis of alpha-Bromocarbonyl Compounds2014Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, nr 34, s. 10703-10709Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    alpha-Brominated ketones and aldehydes, with two adjacent electrophilic carbon atoms, are highly valuable synthetic intermediates in organic synthesis, however, their synthesis from unsymmetrical ketones is very challenging, and current methods suffer from low selectivity. We present a new, reliable, and efficient method for the synthesis of alpha-bromocarbonyl compounds in excellent yields and with excellent selectivities. Starting from allylic alcohols as the carbonyl precursors, the combination of a 1,3-hydrogen shift catalyzed by iridium(III) with an electrophilic bromination gives alpha-bromoketones and aldehydes in good to excellent yields. The selectivity of the process is determined by the structure of the starting allylic alcohol; thus, alpha-bromoketones formally derived from unsymmetrical ketones can be synthesized in a straightforward and selective manner.

  • 90.
    Bermejo Gómez, Antonio
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Cortés González, Miguel A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lübcke, Marvin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Karolinska Institutet, Sweden.
    Johansson, Magnus J.
    Halldin, Christer
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Karolinska Insitutet, Sweden.
    Schou, Magnus
    Efficient DBU accelerated synthesis of F-18-labelled trifluoroacetamides2016Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 52, nr 97, s. 13963-13966Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nucleophilic F-18-fluorination of bromodifluoromethyl derivatives was performed using [F-18] Bu4NF in the presence of DBU(1,8-diazabicyclo[5.4.0]undec-7-ene). This novel procedure provided a diverse set of [F-18] trifluoroacetamides in good to excellent radiochemical conversions. A mechanism where DBU acts as organomediator in this transformation is proposed.

  • 91.
    Bermejo Gómez, Antonio
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Cortés González, Miguel A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lübcke, Marvin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Karolinska Intitutet, Sweden.
    Johansson, Magnus J.
    Schou, Magnus
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Karolinska Intitutet, Sweden.
    Synthesis of trifluoromethyl moieties by late-stage copper (I) mediated nucleophilic fluorination2017Inngår i: Journal of fluorine chemistry, ISSN 0022-1139, E-ISSN 1873-3328, Vol. 194, s. 51-57Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The nucleophilic fluorination of bromodifluoromethyl derivatives mediated by the complex (PPh3)(3)CuF is described. Under the reaction conditions, different trifluoroacetates, trifluorolcetones, trifluoroarenes and trifluoroacetamides were obtained in good yields.

  • 92.
    Bermejo Gómez, Antonio
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Holmberg, Pär
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martin-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalyzed redox isomerization of codeine and morphine in water2014Inngår i: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, nr 74, s. 39519-39522Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A water-soluble rhodium complex formed from commercially available [Rh(COD)(CH3CN)(2)]BF4 and 1,3,5-triaza-7-phosphaadamantane (PTA) catalyzes the isomerization of both codeine and morphine into hydrocodone and hydromorphone with very high efficiency. The reaction is performed in water, allowing isolation of the final products by simple filtration, which results in very high isolated yields. The reactions can be easily scaled up to 100 g.

  • 93.
    Bermejo-Gómez, Antonio
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ahlsten, Nanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of 4,5-disubstituted 2-amino-1,3-thiazoles from α,β-unsaturated ketones: Preparation of 5-Benzyl-4-methyl-1,3-thiazol-2-amine hydrochlorideManuskript (preprint) (Annet vitenskapelig)
  • 94.
    Bernlind, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten.
    Synthesis of LPS epitopes containing Kdo, L-, and D-Glycero-D-manno-heptose to be used in potential conjugate vaccines against Haemophilus species1998Doktoravhandling, med artikler (Annet vitenskapelig)
  • 95.
    Berthold, Malin
    Stockholms universitet, Naturvetenskapliga fakulteten.
    Galanin: ligand - receptor interactions1997Doktoravhandling, med artikler (Annet vitenskapelig)
  • 96.
    Bielawski, Marcin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Diaryliodonium Salts: Development of Synthetic Methodologies and α-Arylation of Enolates2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis describes novel reaction protocols for the synthesis of diaryliodonium salts and also provides an insight to the mechanism of α-arylation of carbonyl compounds with diaryliodonium salts.

     The first chapter gives a general introduction to the field of hypervalent iodine chemistry, mainly focusing on recent developments and applications of diaryliodonium salts.

    Chapter two describes the synthesis of electron-rich to electron-poor diaryliodonium triflates, in moderate to excellent yields from a range of arenes and iodoarenes.

    In chapter three, it is described that molecular iodine can be used together with arenes in a direct one-pot, three-step synthesis of symmetric diaryliodonium triflates. A large scale synthesis of bis(4-tert-butylphenyl)iodonium triflate is also described, controlled and verified by an external research group, further demonstrating the reliability of this methodology.

    The fourth chapter describes the development of a sequential one-pot synthesis of diaryliodonium salts from aryl iodides and boronic acids, furnishing symmetric and unsymmetric, electron-rich to electron-poor diaryliodonium tetrafluoroborates in moderate to excellent yields. This method was developed to overcome the regiochemical limitations imposed by the reaction mechanism in the protocols described in the preceding chapters.

    Chapter five describes a one-pot synthesis of heteroaromatic iodonium salts under similar conditions described in chapter two.

    The final chapter describes the reaction of enolates with chiral diaryliodonium salts or together with a phase transfer catalyst yielding racemic products. DFT calculations were performed, which revealed a low lying energy transition state (TS) between intermediates, which is believed to be responsible for the lack of selectivity observed in the experimental work. It is also proposed that a [2,3] rearrangement is preferred over a [1,2] rearrangement in the α-arylation of carbonyl compounds.

    The synthetic methodology described in this thesis is the most generally applicable, efficient and high-yielding to date for the synthesis of diaryliodonium salts, making these reagents readily available for various applications in synthesis.

  • 97.
    Bielawski, Marcin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Efficient and High-Yielding Routes to Diaryliodonium Salts2008Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis summarizes three novel and general reaction protocols for the synthesis of diaryliodonium salts. All protocols utilize mCPBA as oxidant and the acids used are either TfOH, to obtain triflate salts, or BF3•Et2O that gives the corresponding tetrafluoroborate salts in situ.

    Chapter two describes the reaction of various arenes and aryl iodides, delivering electron-rich and electron-deficient triflates in moderate to excellent yields.

    In chapter three, it is shown that the need of aryl iodides can be circumvented, as molecular iodine can be used together with arenes in a direct one-pot, three-step synthesis of symmetric diaryliodonium triflates.

    The final and fourth chapter describes the development of a sequential one-pot reaction from aryl iodides and boronic acids, delivering symmetric and unsymmetric, electron-rich and electron-deficient iodonium tetrafluoroborates in moderate to excellent yields. This protocol was developed to overcome mechanistic limitations existing in the protocols described in chapter two and three.

    The methodology described in this thesis is the most general, efficient and high-yielding existing up to date, making diaryliodonium salts easily available for various applications in synthesis.

  • 98.
    Bielawski, Marcin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Aili, David
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Regiospecific One-Pot Synthesis of Diaryliodonium Tetrafluoroborates from Arylboronic Acids and Aryl Iodides2008Inngår i: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 73, nr 12, s. 4602-4607Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

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

  • 99.
    Bielawski, Marcin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Efficient one-pot synthesis of bis(4-tert-butylphenyl)iodonium triflate2009Inngår i: Organic Syntheses, ISSN 0078-6209, Vol. 86, s. 308-314Artikkel i tidsskrift (Fagfellevurdert)
  • 100.
    Bielawski, Marcin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    High-Yielding One-Pot Synthesis of Diaryliodonium Triflates from Arenes and Iodine or Aryl Iodides2007Inngår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 24, s. 2521-2523Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Unsymmetric and symmetric diaryliodonium triflates are synthesized from both electron-deficient and electron-rich substrates in a fast, high yielding, and operationally simple protocol employing arenes and aryl iodides or iodine.

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