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  • 1.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    Jonsson, C.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Consecutive microcontact printing - ligands for asymmetric catalysis in silicon channels2001In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 79, no 1, p. 78-84Article in journal (Refereed)
    Abstract [en]

    Consecutive microcontact printing ( mu CP) has been developed to enable multiple functionalization of silicon surfaces, such as the immobilization of chiral ligands. The technique involves two subsequent printing steps using unstructured poly(methylsiloxane) stamps. The pattern is already defined on the substrate, consisting of etched channels. Hence, no precise alignment is needed between the two printing steps. A carboxylic acid group containing reagent was initially printed onto the silicon oxide surface and transformed to an anhydride. hi the second printing step an ester bond was formed with the hydroxy-functionalized ligand. The formed molecular layers were evaluated by contact angle measurements, scanning electron microscopy (SEM) and electron spectroscopy for chemical analysis (ESCA), indicating that the consecutive mu CP was successful. Initially, printing was performed on planar silicon surfaces but to realize a flow-through microfluidic device for high throughput screening a mu CP technique was developed for etched channels. To verify the technique, hydrophobic valves consisting of octadecyltrichlorosilane were formed using mu CP in deep reactive ion etched channels (50 mum wide and 50 mum deep). The printed hydrophobic patches were visualized by SEM and functioned well. Finally, the consecutive mu CP technique was applied to immobilize the ligand in the channels. The channels were then sealed with a low-temperature bonding technique using an adhesive PDMS film, which does not destroy the printed ligand. In this study mu CP is used in a novel manner. It enables a convenient method for performing complex surface modification of etched structures, which is a frequently appearing problem in biochemical microfluidic systems.

  • 2.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    Jonsson, C.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Patterned self-assembled beads in silicon channels2001In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 22, no 18, p. 3876-3882Article in journal (Refereed)
    Abstract [en]

    A novel technique enabling selective bead trapping in microfluidic devices without the use of physical barriers is presented in this paper. It is a fast, convenient and simple method, involving microcontact printing and self-assembly, that can be applied to silicon, quartz or plastic substrates. In the first step, channels are etched in the substrate. The surface chemistry of the internal walls of the channels is then modified by microcontact printing. The chip is submerged in a bead slurry where beads self-assemble based on surface chemistry and immobilize on the internal walls of the channels. Silicon channels (100 mum wide and 50 mum deep) have been covered with monolayers of streptavidin-, amino- and hydroxy-functionalized microspheres and resulted in good surface coverage of beads on the channel walls. A high-resolution pattern of lines of self-assembled streptavidin beads, as narrow as 5 mum, has also been generated on the bottom of a 500 mum wide and 50 mum deep channel. Flow tests were performed in sealed channels with the different immobilized beads to confirm that the immobilized beads could withstand the forces generated by water flowing in the channels. The presented results indicate that single beads can be precisely positioned within microfluidic devices based on self-assembly which is useful as screening and analysis tools within the field of biochemistry and organic chemistry.

  • 3.
    Andersson, Helene
    et al.
    KTH, Superseded Departments, Biotechnology.
    Jonsson, C.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Self-assembled and self-sorted array of chemically active beads for analytical and biochemical screening2002In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 56, no 2, p. 301-308Article in journal (Refereed)
    Abstract [en]

    A technique for generating a general screening platform consisting of dots of immobilized beads on silicon has been developed via self-sorting and -assembly of different kinds of beads. The dots are defined by a teflon-like film, which due to its hydrophobic characteristics also prevents cross-contamination of liquid from different dots. To enable functionalization of individual dots with different target molecules simultaneously a new way of microcontact printing has been explored where different target solutions are printed in parallel using one stamp. In order to show that this platform can be designed for both biochemical assays and organic chemistry, streptavidin-, amino- and hydroxy-functionalized beads have been self-sorted and -assembled both on separate and common platforms. The self-sorting and -arrangement are based on surface chemistry only, which has not previously been reported. Beads of different sizes and material have successfully been immobilized in line patterns as narrow as 5 mum. Besides silicon, quartz and polyethylene have also been used as substrates.

  • 4. Belda, O.
    et al.
    Kaiser, N. F.
    Bremberg, U.
    Larhed, M.
    Hallberg, A.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Highly stereo- and regioselective allylations catalyzed by Mo-pyridylamide complexes: Electronic and steric effects of the ligand2000In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 65, no 18, p. 5868-5870Article in journal (Refereed)
  • 5. Belda, O.
    et al.
    Lundgren, S.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Recoverable resin-supported pyridylamide ligand for microwave-accelerated molybdenum-catalyzed asymmetric allylic alkylations: Synthesis of baclofen2003In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 5, no 13, p. 2275-2278Article in journal (Refereed)
    Abstract [en]

    The syntheses of a series of 4-monosubstituted pyridylamides and a resin-supported pyridylamide are described. The ligands were evaluated in the microwave-accelerated molybdenum-catalyzed asymmetric allylic alkylation. The reaction afforded the product in high yield and with high regio- and enantioselectivity. The heterogeneous ligand could be reused several times with no change in the reaction outcome. The asymmetric allylic alkylation was employed as the key step in the enantioselective synthesis of (R)-baclofen.

  • 6. Belda, O.
    et al.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Bispyridylamides - coordination chemistry and applications in catalytic reactions2005In: Coordination chemistry reviews, ISSN 0010-8545, E-ISSN 1873-3840, Vol. 249, no 06-maj, p. 727-740Article, review/survey (Refereed)
    Abstract [en]

    Complexes of bis(2-pyridylamides) with most metal ions have been described. A variety of coordination modes, with the neutral or the deprotonated amide functions binding either via the carbonyl oxygen atom or the amide nitrogen atom have been identified. The modular technique used for the preparation of the compounds permits facile access to ligands with substituted pyridine nuclei and ligands with different backbones. Moreover, symmetric as well as asymmetric compounds, with equal or different pyridine rings and with symmetric or non-symmetric amines, can conveniently be prepared. Chiral derivatives are easily obtained starting from chiral diamines. Several metal complexes have been studied as mimics of biological systems. In recent years a variety of metal complexes have also been employed in catalysis. Oxidations of alkanes and alkenes have been particularly well studied, although modest reactivity has usually been encountered. Other applications include their use as ligands in Lewis acid catalyzed processes. Recently, it was shown that complexes with molybdenum catalyze highly regio- and enantioselective allylic alkylations.

  • 7. Belda, O.
    et al.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Substituted pyridylamide ligands in microwave-accelerated Mo(0)-catalysed allylic alkylations2002In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, no 11, p. 1601-1606Article in journal (Refereed)
    Abstract [en]

    Novel 4- and 6-substituted bis-pyridylamides were prepared by microwave accelerated nucleophilic substitution of the 4-and 6-halo substituted derivatives of the parent ligand la. The ligands were used in the asymmetric allylation of cinnamyl carbonate catalysed by Mo(0) in which the 4-chloro- and 4-pyrrolidyl substituted ligand derivatives exhibited high regioselectivity (74:1 and 88:1. respectively) and enantioselectivity (96% ee), whereas 6-substituted ligands afforded no product under the same conditions. Other allylic substrates were used to explore the generality of the procedure.

  • 8.
    Belda, Oscar
    et al.
    KTH, Superseded Departments, Chemistry.
    Duquesne, Sophie
    KTH, Superseded Departments, Chemistry.
    Fischer, A.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Chiral bispyridylamide metal complexes as catalysts for the enantioselective adddition of TMSCN to aldehydes2004In: Journal of Organometallic Chemistry, ISSN 0022-328X, E-ISSN 1872-8561, Vol. 689, no 23, p. 3750-3755Article in journal (Refereed)
    Abstract [en]

    The use of (1R,2R)-N,N'-bis(2-pyridinecarboxyamido)-1,2-diphenylethane metal complexes as catalysts for the enantioselective addition of trimethylsilyl cyanide to aldehydes is described. Enantioselectivities up to 70% ee were obtained with a Ti(IV) catalyst. Complexes with Zr(IV), Sc(III), Yb(III) and Cu(II) afforded less selective catalysts. For the Zr(IV) complex, a rate and selectivity enhancement was observed when adding 0.5 equiv. of water with respect to the catalyst. Studies of the metal complexes involved in the reaction were carried out by means of H-1 NMR spectroscopy. A Zr complex was shown by X-ray crystallography to exhibit distorted octahedral coordination, with the four nitrogen atoms of the doubly deprotonated ligand essentially in one plane.

  • 9.
    Belda, Oscar
    et al.
    KTH, Superseded Departments, Chemistry.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Molybdenum-catalyzed asymmetric allylic alkylations2004In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 37, no 3, p. 159-167Article in journal (Refereed)
    Abstract [en]

    The highly regio- and enantioselective molybdenum-catalyzed allylic alkylation reaction has become a powerful synthetic tool during the past few years. This Account describes the achievements gained so far in the area, with special attention directed to the different chiral ligands that have been used for inducing chirality in the products, the range of allylic substrates and nucleophiles employed, mechanistic studies, and applications of the reaction in asymmetric syntheses.

  • 10. Beletskaya, I.
    et al.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Element-element additions to unsaturated carbon-carbon bonds catalyzed by transition metal complexes2006In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 106, no 6, p. 2320-2354Article, review/survey (Refereed)
  • 11.
    Bellini, Rosalba
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Magre, Marc
    Biosca, Maria
    Norrby, Per-Ola
    Pamies, Oscar
    Dieguez, Montserrat
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Conformational Preferences of a Tropos Biphenyl Phosphinooxazoline-a Ligand with Wide Substrate Scope2016In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, no 3, p. 1701-1712Article in journal (Refereed)
    Abstract [en]

    Excellent enantioselectivities are observed in palladium-catalyzed allylic substitutions of a wide range of substrate types and nucleophiles using a bidentate ligand composed of oxazoline and chirally flexible biaryl phosphite elements. This unusually wide substrate scope is shown by experimental and theoretical studies of its eta(3)-allyl and eta(2)-olefin complexes not to be a result of configurational interconversion of the biaryl unit, since the ligand in all reactions adopts an S-a,S configuration on coordination to palladium, but rather the ability of the ligand to adapt the size of the substrate-binding pocket to the reacting substrate. This ability also serves as an explanation to its excellent performance in other types of catalytic processes.

  • 12. Bourguignon, J.
    et al.
    Bremberg, U.
    Dupas, G.
    Hallman, K.
    Hagberg, L.
    Hortala, L.
    Levacher, V.
    Lutsenko, S.
    Macedo, E.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Queguiner, G.
    Rahm, F.
    Chiral ditopic receptors. Application to palladium-catalyzed allylic alkylation2003In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 59, no 48, p. 9583-9589Article in journal (Refereed)
    Abstract [en]

    Chiral pyridinooxazoline, quinolinooxazoline, bis(oxazolino)pyridine (pybox), and bisoxazoline (box) derivatives containing crown ether residues were prepared. Some of the ligands were assessed in substrate binding studies and in palladium catalyzed allylic alkylations.

  • 13.
    Brule, Emile
    et al.
    KTH, Superseded Departments, Chemistry.
    Pei, Yuxin
    KTH, Superseded Departments, Chemistry.
    Lake, Fredrik
    KTH, Superseded Departments, Chemistry.
    Rahm, Fredrik
    KTH, Superseded Departments, Chemistry.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Chelating phosphines with C-2 and C-3 symmetry2004In: Mendeleev communications (Print), ISSN 0959-9436, E-ISSN 1364-551X, no 6, p. 276-277Article in journal (Refereed)
    Abstract [en]

    Antide formation between ring opened aziridines and 2-(diphenylphosphino)benzoic acid provides an easy access to chelating di- and triphosphines with C-2 and C-3 symmetry.

  • 14. Del Litto, Raffaella
    et al.
    Benessere, Vincenzo
    Ruffo, Francesco
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Carbohydrate-Based Pyridine-2-carboxamides for Mo-Catalyzed Asymmetric Allylic Alkylations2009In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 9, p. 1352-1356Article in journal (Refereed)
    Abstract [en]

    Bis(pyridine-2-carboxamides) were prepared from 1,2-diamines obtained from alpha-D-ghlcose and alpha-D-mannose. The ligands were assessed in molybdenum-catalyzed asymmetric allylic alkylations (AAA) by using both methyl (E)-3-phenyl-2-propenyl and methyl rac-1-phenyl-2-propenyl carbonates and dimethyl malonate as nucleophile under microwave irradiation. High enantioselectivity (99 % ee) and high regioselectivity (49:1 in favour of the branched isomer) were observed in reactions of the linear achiral substrate in the presence of 10 mol-% of a catalyst prepared from a ligand derived from glucose. Somewhat lower enantioselectivity (up to 96 % ee) was observed in reactions with the branched racemic carbonate by using the same ligand. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

  • 15.
    Durieux, Guillaume
    et al.
    CNRS, Ecole Normale Super, Dept Chim.
    Gerdin, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Jutand, Anny
    CNRS, Ecole Normale Super, Dept Chim.
    Rate and Mechanism of the Oxidative Addition of a Silylborane to Pt0 Complexes: Mechanism for the Pt-Catalyzed Silaboration of 1,3-Cyclohexadiene2008In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 27, p. 4236-4241Article in journal (Refereed)
    Abstract [en]

    The chemical reduction of Pt(acac)(2) by DIBALH in the presence of phosphanes, which is used to generate active Pt-0 complexes in the Pt-catalyzed silaboration of cyclohexadiene by 2-(diinethylphenylsilyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1) leading to the 1,4-silaborated product, was mimicked by the electrochemical reduction of Pt(acac)(2) in the presence of 2 equiv. of PR3 (R = Ph, nBu). The electrochemical reduction generates free acac anions and neutral Pt-0-(PR3)(2) complexes. The kinetics of the oxidative addition of bromobenzene (used first as a model molecule) and silylborane 1 to the Pt-0 complexes was investigated and the rate constants determined. Pt-0(PnBu(3))(2) is much more reactive than Pt-0(PPh3)(2) towards 1. From the electrochemical study, it emerges that the acac anions released in the reduction of Pt(acac)(2) do not coordinate to the Pt-0(PR3)(2) complexes. Consequently, the rate of the oxidative addition of 1 to Pt-0(PR3)(2), generated either by the electrochemical reduction or by the chemical reduction by DIBALH, is not affected by the acac anions and a posteriori not by aluminum cations. The oxidative addition and the further step of the catalytic cycle [insertion of the diene into the Pt-B bond of the Si-Pt-B complex generated in the oxidative addition, with formation of the eta(3)-allyl)Pt-Si complex] were monitored by NMR spectroscopy. Pt-0 and Pt-II complexes involved in the catalytic cycle were characterized. The oxidative addition is faster when the ligand is PMe2Ph relative to that obtained with PPh3, in agreement with the electrochemical data. No reductive elimination within the ((eta(3)-allyl))Pt-Si complex is observed when the ligand is PMe2Ph, whereas reactions in the presence of PPh3 proceeded to give the final product. As a consequence, PPh3 is a better ligand than PMe2Ph for the catalytic reaction, as observed experimentally.

  • 16.
    Fjellander, Ester
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Szabó, Zoltán
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Atropoisomerism in Phosphepines and Azepines2009In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 74, no 23, p. 9120-9125Article in journal (Refereed)
    Abstract [en]

    Free energy barriers to biaryl tropoinversion in metal complexes with tropos phosphepine and azepine ligands were determined by temperature-dependent P-31 NMR inversion-transfer experiments and line shape analysis of the temperature-dependent H-1 NMR spectra, respectively. The barrier in the PdCl2 complex of the azepine ligand was found to be slightly higher than that of the corresponding free ligand. Studies of a tridentate azepine ligand Suggested that Configurational change takes place without prior decoordination from the metal.

  • 17. Forcato, M.
    et al.
    Lake, F.
    Blazquez, M. M.
    Renner, P.
    Crisma, M.
    Gade, L. H.
    Licini, G.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Chiral, enantiopure aluminum(III) and titanium(IV) azatranes2006In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, no 5, p. 1032-1040Article in journal (Refereed)
    Abstract [en]

    Al-III and Ti-IV complexes of C-3-symmetric tetradentate trisamidoamme ligands with trigonal bipyramidal coordination geometry, containing chlorine or dialkylamido groups, or with a free coordination site in the apical position, have been synthesised by salt metathesis and amine elimination. Products with threefold symmetry were generally obtained for tetravalent titanium, whereas for the aluminium complexes either asymmetric structures with two of the three podand arms taking part in coordination to the metal or symmetric arrangements possessing the full threefold symmetry were formed depending on the steric properties of the ligands.

  • 18.
    Fransson, Linda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Biotechnology (BIO), Biochemistry. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Laurell, Anna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Widyan, Khalid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wingstrand, Erica
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Minor Enantiomer Recycling-Effect of Two Reinforcing Catalysts on Product Yield and Enantiomeric Excess2010In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 2, no 6, p. 683-693Article in journal (Refereed)
    Abstract [en]

    Kinetic modeling of a recycling procedure in which the minor product enantiomer from an enantioselective catalytic reaction is selectively retransformed to starting material by a second chiral catalyst demonstrates that the enantiomeric excess of the product is not affected by the relative amounts of the two catalysts, but that the yield increases when the amount of the catalyst for the product-forming reaction is increased. The yield, but not the enantiomeric excess, is also affected by the initial substrate concentration. The recycling process is compared to sequential processes in which either the second catalyst is added after completion of the first reaction or in which the two catalysts are added simultaneously. In the sequential processes, high enantioselectivity can be obtained at the expense of product yield, whereas under recycling conditions both high enantiomeric excess and high yield can be achieved. Experimental data from a recycling procedure providing qualitative support for results from kinetic modeling are presented.

  • 19.
    Fransson, Linda
    et al.
    KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Gaining Selectivity by Combining Catalysts: Sequential versus Recycling Processes2010In: CHEMCATCHEM, ISSN 1867-3880, Vol. 2, no 12, p. 1523-1532Article, review/survey (Refereed)
    Abstract [en]

    Highly enantioenriched chiral products may be obtained by using a combination of two moderately selective catalysts. Sequential enantioselective transformations comprising an asymmetric reaction followed by a kinetic resolution of the scalemic product mixture obtained in the first step are well known. In such processes, the minor, undesired enantiomer is transformed to a compound that can be more easily separated from the major enantiomer. Although chiral compounds may be obtained with high enantiopurity by such coupled processes, the yield of the desired product necessarily suffers. Recycling processes, whereby the minor enantiomer is transformed to prochiral starting material, avoid this limitation. In this Mini-review, different types of sequential catalytic processes using two reinforcing catalysts are surveyed and their advantages and limitations discussed in relation to recycling processes.

  • 20.
    Frölander, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Csöregh, Ingeborg
    KTH.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    OH–Pd Hydrogen Bonding in Pd(0)–Olefin Complexes Containing Hydroxy-Substituted LigandsManuscript (Other academic)
  • 21.
    Frölander, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lutsenko, Serghey
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Privalov, Timofei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Conformational preferences and enantiodiscrimination of phosphino-4-(1-hydroxyalkyl)oxazoline-metal-olefin complexes resulting from an OH-metal hydrogen bond2005In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 70, no 24, p. 9882-9891Article in journal (Refereed)
    Abstract [en]

    Phosphinooxazolines carrying (1-hydroxy-1-phenyl)methyl and (1-methoxy-1-phenyl)methyl substituents in the 4 position of the oxazoline ring exhibit contrasting behavior in Pd-and Ir-catalyzed allylic alkylations. Whereas catalysts with the methoxy-containing ligand generally provide products with high ee's, use of catalysts prepared from the hydroxy-containing ligand results in products with low ee's or even racemates. DFT calculations suggest the presence of a hydrogen bond with Pd(0) as the proton acceptor in the hydroxy-containing olefin-Pd(0) complexes, which induces a conformational change in the ligand, leading to different stereoselectivity.

  • 22.
    Frölander, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Lutsenko, Serghey
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Privalov, Timofei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    OH-Metal hydrogen bond in Pd- and Ir-catalyzed allylic alkylations2006In: ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2006, p. ORGN-259-Conference paper (Other academic)
    Abstract [en]

    Phosphinooxazolines carrying 4-hydroxybenzyl and 4-methoxybenzyl substituents exhibit contrasting behavior in Pd- and Ir-catalyzed allylic alkylations.  Whereas catalysts with the methoxy-contg. ligand generally provide products with high ee's, use of catalysts prepd. from the hydroxy contg. ligand results in products with low ee's or even racemates.  DFT calcns. suggest the presence of a hydrogen bond with Pd(0) as proton acceptor in the hydroxy contg. olefin Pd(0) complexes, which induces a conformational change in the ligand leading to different stereoselectivity.  We have previously obsd. the same kind of dramatic changes of enantioselectivities in palladium-catalyzed allylations upon methylation of hydroxy-contg. pyridinooxazolines and bisoxazolines.

  • 23.
    Frölander, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ag+-Assisted Hydrosilylation: Complementary Behavior of Rh and Ir Catalysts (Reversal of Enantioselectivity)2007In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 9, no 7, p. 1371-1374Article in journal (Refereed)
    Abstract [en]

    The presence of a suitably situated hydroxy function in a PHOX ligand leads to an enhancement of the enantioselectivity in Rh-catalyzed hydrosilylations of prochiral ketones in the presence of AgBF4 (95% ee for acetophenone as compared to 75% using i-Pr-phosphinooxazoline (PHOX)). Exchanging Rh for Ir affords the product with the opposite absolute configuration (78% ee).

  • 24.
    Frölander, Anders
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Tilliet, Mélanie
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Levacher, Vincent
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Bifunctional Pybox Ligands: Application in Cyanations of BenzaldehydeManuscript (Other academic)
  • 25.
    Gerdin, Martin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Enantioselective Platinum-Catalyzed Silicon-Boron Addition to 1,3-Cyclohexadiene2005In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 347, no 6, p. 749-753Article in journal (Refereed)
    Abstract [en]

    Silaboration of 1,3-cyclohexadiene in the presence of Pt(acac)(2), DIBALH, and a phosphoramidite prepared from (S)-1,1'-bi-2-naphthol and diisopropylamine led to (1R,4S)-1-(dimethylphenylsilyl)4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2-cyclohexene with 70% ee. Chiral catalysts based on Ni gave no or essentially racemic product, whereas complexes containing Pd were inactive.

     

     

     

     

  • 26.
    Gerdin, Martin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ni-Catalyzed Si-B Addition to 1,3-Dienes: Disproportionation in Lieu of Silaboration2006In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 8, no 14, p. 2929-2932Article in journal (Refereed)
    Abstract [en]

    Upon attempted silaboration of acyclic 1- and 1,4-substituted 1,3-dienes, a new disproportionation reaction was discovered, yielding 1:1 mixtures of allylsilanes and dienylboranes. It was demonstrated that, as a key step in this new catalytic process, hydrogen is being transferred from one diene moiety to another.

  • 27. Gerdin, Martin
    et al.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    ORGN 29-Silaboration of 1,6-enynes and 1,3-dienes2008In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 236, p. 29-ORGNArticle in journal (Refereed)
  • 28.
    Gerdin, Martin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Silaborative Carbocyclization of 1,6-EnynesManuscript (Other academic)
    Abstract [en]

    The silaboration of 1,6-enynes gives densely functionalized five-membered rings that offer promising reactivities for further synthetic manipulations. We have found that using silylborane 4 silaborative carbocyclization reactions proceed in good to excellent yields, giving the product as a single diastereomer. Attempts to extend this methodology to include terminally substituted enynes and developing asymmetric versions were largely unsuccessful. The vinylboronates formed were employed in Suzuki cross-coupling reactions with a range of aryl bromides, furnishing arylated product in good yields.

  • 29.
    Gerdin, Martin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Nadakudity, Sailendra Kumar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Worch, Christin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Regioselective Preparation of Functionalized exo-Methylene-cyclopentanes and exo-Methylenepyrrolidines via Silaborative Carbocyclization of 1,6-Enynes2010In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 352, no 14-15, p. 2559-2570Article in journal (Refereed)
    Abstract [en]

    Silaborative carbocyclization of 1,6-enynes catalyzed by Pd-PEPPSI-IPr {PEPPSI=pyridine-enhanced precatalyst preparation stabilization and initiation; IPr=N,N-bis[2,6-(diisopropyl)phenyl] imidazolium} employing either (dimethylphenylsilyl) pinacolborane or (chlorodimethylsilyl)pinacolborane provides access to densely functionalized five-membered rings as single diastereomers in excellent yields. The vinylboronate functions were employed in palladium-catalyzed Suzuki cross-coupling reactions with a range of aryl bromides, containing electron-with-drawing as well as electron-donating substituents, furnishing arylated exo-methylenecyclopentanes or exo-methylenepyrrolidines in good yields. Subsequent oxidation of the isopropoxydimethylsilyl function generated via addition of (chlorodimethylsilyl)-pinacolborane provided access to hydroxymethyl derivatives of the arylated compounds. Use of a chiral ester, bismenthyl (2-propenyl)(2-propynyl)malonate, afforded two diastereomeric products which could be separated, thereby giving access to the cyclized compounds as single isomers, with opposite absolute configurations at the newly formed stereocenter.

  • 30.
    Gerdin, Martin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Penhoat, Maël
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zalubovskis, Raivis
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Pétermann, Claire
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Enantioselective silicon-boron additions to cyclic 1,3-dienes catalyzed by the platinum group metal complexes2008In: Journal of Organometallic Chemistry, ISSN 0022-328X, E-ISSN 1872-8561, Vol. 693, no 23, p. 3519-3526Article in journal (Refereed)
    Abstract [en]

    Silaborations of 1,3-cyclohexadiene and 1,3-cycloheptadiene were achieved using catalysts prepared from different combinations of phosphorus ligands and group 10 metal compounds. For the six-membered compound, 1,4-adducts with up to 82% ee were obtained employing Pt(0) and phosphoramidite ligands. For the seven-membered diene optimal conditions were found using catalysts based on Ni(0), but the highest selectivity observed was merely 22% ee. No improvement of the chiral induction was obtained using chiral silylboranes in combination with chiral phosphoramidite ligands in the additions to 1,3-cyclohexadiene. The adduct obtained from cyclohexadiene was used in allylborations of aldehydes under microwave irradiation to produce homoallylic alcohols with moderate to good diastereoselectivity.

  • 31. Grutters, Michiel M. P.
    et al.
    van der Vlugt, Jarl Ivar
    Pei, Yuxin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Mills, Allison M.
    Lutz, Martin
    Spek, Anthony L.
    Muller, Christian
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Vogt, Dieter
    Highly Selective Cobalt-Catalyzed Hydrovinylation of Styrene2009In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 351, no 13, p. 2199-2208Article in journal (Refereed)
    Abstract [en]

    Phosphine complexes of cobalt halide salts activated by diethylaluminum chloride are shown to yield highly active catalysts in the hydrovinylation of styrene, with unprecedented high selectivity to the desired product 3-phenyl-1-butene (3P1B). Double-bond isomerization, a common problem in codimerization reactions, only occurs after full conversion with these catalyst systems, even at elevated temperature. The most active catalysts are based on cobalt halide species combined with either C-1- or C-2-bridged diphosphines, heterodonor P,N or P,O ligands, flexible bidentate phosphine ligands or monodentate phosphine ligands. Kinetic investigations show an order > 1 in catalyst, which indicates either the involvement of dinuclear species in the catalytic cycle or partial catalyst decomposition via a bimolecular pathway.

  • 32. Hallman, K.
    et al.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Palladium(II)-catalyzed oxidation of alcohols with air as reoxidant2001In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 343, no 3, p. 260-263Article in journal (Refereed)
    Abstract [en]

    Oxidation of primary and secondary aliphatic and secondary benzylic alcohols into their corresponding aldehydes and ketones was achieved in good yields with palladium catalysts using air as the reoxidant of palladium. The use of palladacycle 1 resulted in higher yields and a faster reaction than the use of Pd(OAc)(2) as the palladium source.

  • 33. Hallman, K.
    et al.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Polymer-bound bis(oxazoline) as a chiral catalyst2001In: Tetrahedron: asymmetry, ISSN 0957-4166, E-ISSN 1362-511X, Vol. 12, no 10, p. 1475-1478Article in journal (Refereed)
    Abstract [en]

    A chiral bis(oxazoline) was grafted on ArgoGel and used in the palladium-catalysed substitution of (+/-)-1,3-diphenyl-2-propenyl acetate with dimethyl malonate. The enantioselectivity was the same as that observed when the analogous monomeric catalyst was used (94-95% e.e.), despite the fact that the C-2 symmetry of the ligand was affected when coupled to the polymer. The polymer-supported catalyst could be recycled several times after removal of precipitated Pd(0). The polymer-bound bis(oxazoline) was also applied in a zinc-catalysed Diels-Alder reaction but lower selectivity and reactivity than the monomer was observed.

  • 34.
    Hallman, Kristina
    et al.
    KTH, Superseded Departments, Chemistry.
    Frölander, Anders
    KTH, Superseded Departments, Chemistry.
    Wondimagegn, Tebikie
    KTH, Superseded Departments, Chemistry.
    Svensson, Mats
    KTH, Superseded Departments, Chemistry.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    OH–Pd(0) Interaction as a Stabilizing Factor in Palladium-Catalyzed Allylic Alkylations2004In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 101, no 15, p. 5400-5404Article in journal (Refereed)
    Abstract [en]

    In palladium-catalyzed alkylations of allylic acetates with malonate as nucleophile, catalysts with oxazoline ligands bearing hydroxymethyl substituents in 4-position have been shown by density functional theory computations to undergo a conformational change on nucleophilic attack, which is accompanied by reduction of Pd(II) to Pd(0). The conformations of the Pd(0) complexes were shown to be governed by the presence of a hydrogen bond with the metal center acting as a hydrogen bond acceptor. The conformational change, which is absent in catalysts with O-alkylated analogs, largely affects the enantioselectivity of the catalytic process. This process is a previously uninvestigated example of where this type of weak hydrogen bond has been shown to influence the stereochemistry of a chemical reaction.

  • 35.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Penhoat, Maël
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    High-Throughput Enzymatic Method for Enantiomeric Excess Determination of O-Acetylated Cyanohydrins2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 7, p. 2234-2235Article in journal (Refereed)
  • 36.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Lundgren, Stina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wingstrand, Erica
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    High Throughput Synthesis and Analysis of Acylated Cyanohydrins2007In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, no 15, p. 4334-4341Article in journal (Refereed)
    Abstract [en]

    The yields and optical purities of products obtained from chiral Lewis acid/Lewis base-catalysed additions of alpha-ketonitriles to prochiral aldehydes could be accurately determined by an enzymatic method. The amount of remaining aldehyde was determined after its reduction to an alcohol, whilst the two product enantiomers were analysed after subsequent hydrolysis first by the (S)-selective Candida antarctica lipase B and then by the unselective pig liver esterase. The method could be used for analysis of products obtained from a number of aromatic aldehydes and aliphatic ketonitriles. Microreactor technology was successfully combined with high-throughput analysis for efficient catalyst optimization.

  • 37.
    Hertzberg, Robin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Dinér, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. Division of Organic Chemistry .
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Palladium-Catalyzed C(sp3)–C(sp2) Cross-Couplings of O-(α-Bromoacyl) Cyanohydrins with Boronic Acids: An Entry to Enantio­enriched N-Acylated β-Amino Alcohols2016In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, Vol. 48, no 19Article in journal (Refereed)
    Abstract [en]

    Suzuki-type cross-coupling of enantiomerically enriched O-(α-bromoacyl) cyanohydrins with aromatic boronic acids substituted with electron-withdrawing or electron-donating groups gave the expected coupling products in high yields without racemization. These substrates exhibit higher reactivities than analogous substrates lacking the nitrile function, probably as a result of π-coordination of the nitrile to palladium. Reduction of the nitrile group of the products, with accompanying intramolecular acyl transfer, provides access to biologically interesting N-acylated β-amino alcohols.

  • 38.
    Hertzberg, Robin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    One-step preparation of O-(α-bromoacyl) cyanohydrins by minor enantiomer recycling: Synthesis of 4-amino-2(5H)-furanones2013In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, no 18, p. 9174-9180Article in journal (Refereed)
    Abstract [en]

    O-(α-Bromoacyl) cyanohydrins were prepared in a single step from a range of different aldehydes in combination with α-bromoacyl cyanides. By the use of a cyclic procedure where the two minor diastereoisomers from a chiral Lewis acid-catalyzed reaction undergo Candida antarctica lipase B (CALB)-catalyzed hydrolysis followed by dehydrocyanation to regenerate the starting material, the products were obtained in good to high yields and in most cases with excellent diastereoselectivites. The synthetic importance of these compounds was demonstrated by the synthesis of 4-amino-2(5H)-furanones, a class of compounds that have shown both biological activity and utility as synthetic intermediates. This transformation was achieved by an intramolecular Blaise reaction, which gave the products in high to excellent yields and enantiomeric ratios.

  • 39.
    Hertzberg, Robin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Palladium-Catalyzed C(sp3)-C(sp2) Cross-Couplings BetweenO-(α-Bromoacyl) Cyanohydrins and Boronic AcidsManuscript (preprint) (Other academic)
  • 40.
    Hertzberg, Robin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Santiago, Guillermo Monreal
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Synthesis of the beta(3)-Adrenergic Receptor Agonist Solabegron and Analogous N-(2-Ethylamino)-beta-amino Alcohols from O-Acylated Cyanohydrins - Expanding the Scope of Minor Enantiomer Recycling2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 5, p. 2937-2941Article in journal (Refereed)
    Abstract [en]

    A novel methodology to produce highly enantioenriched N-(2-ethylamino)-beta-amino alcohols was developed. These compounds were obtained from O-(alpha-bromoacyl) cyanohydrins, which were synthesized by the minor enantiomer methodology employing a Lewis acid and a biocatalyst, followed by nucleophilic substitution with amines and reduction. The importance of the developed methodology was demonstrated by completing a highly enantioselective total synthesis of the beta(3)-adrenergic receptor agonist Solabegron.

  • 41.
    Hertzberg, Robin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wen, Ye-Qian
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Dual activation and minor enantiomer recycling: Asymmetric synthesis of O-acylated cyanohydrins and hydroxyphosphonates2014In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 248Article in journal (Refereed)
  • 42.
    Hertzberg, Robin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Widyan, Khalid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Heid, Berenice
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Enantioenriched ω-bromocyanohydrin derivatives. Improved selectivity by combination of two chiral catalysts2012In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 68, no 37, p. 7680-7684Article in journal (Refereed)
    Abstract [en]

    Highly enantioenriched (R)-4-bromo-1-cyanobutyl acetate and (R)-5-bromo-1-cyanopentyl acetate were prepared by acetylcyanation of 4-bromobutanal and 5-bromopentanal, respectively, catalyzed by (S,S)-[(4,6-bis(t-butyl)salen)Ti(Ό-O)] 2 and triethylamine followed by enzymatic hydrolysis of the minor enantiomer. A cyclic procedure employing the same two chiral catalysts provided inferior results due to a slowly reached steady state and, in reactions with the former substrate, to ring-closure of the free cyanohydrin formed as an intermediate in the reaction. Hydrolysis of the acylated cyanohydrins followed by AgClO 4-promoted cyclization provided (R)-2-cyanotetrahydrofuran and (R)-2-cyanotetrahydropyran in essentially enantiopure form.

  • 43. Hortala, L.
    et al.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Levacher, V.
    Bourguignon, J.
    Dupas, G.
    Acyl transfer of 8-acetoxy-2-oxazolinylquinoline assisted by hydrogen bonding formation2002In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 43, no 6, p. 1027-1029Article in journal (Refereed)
    Abstract [en]

    A significant acceleration of acyl transfer has been achieved on 8-acetoxy-2-oxazolinylquinoline in the presence of benzylamine. Comparison of the aminolysis by the new acylating reagent with that of 8-acetoxyquinoline and 8-acetoxyquinoline-2-carbonitrile has been carried out. The results of these experiments suggest that the proximity of a supplementary basic atom to the ester group increases the participation effect of the basic site mainly by formation of a possible second hydrogen bond. The association constant of benzylamine into the basic cavity of 8-methoxy-2-oxazolinylquinoline (K-d = 80 M-1) has been measured by H-1 NMR titration experiments.

  • 44.
    Jönsson, Christina
    et al.
    KTH, Superseded Departments, Chemistry.
    Hallman, Kristina
    KTH, Superseded Departments, Chemistry.
    Andersson, Helene
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stemme, Göran
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Malkoch, Michael
    KTH, Superseded Departments, Polymer Technology.
    Malmström, Eva
    KTH, Superseded Departments, Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Immobilized oxazoline-containing ligands in asymmetric catalysis - A review2002In: Bioorganic & Medicinal Chemistry Letters, ISSN 0960-894X, E-ISSN 1090-2120, Vol. 12, no 14, p. 1857-1861Article, review/survey (Refereed)
    Abstract [en]

    Metal complexes of chiral oxazoline derivatives immobilized on soluble as well as insoluble supports serve as versatile asymmetric catalysts in a variety of applications. In a few cases recovery and reuse of the chiral ligands have been achieved.

  • 45.
    Jönsson, Christina
    et al.
    KTH, Superseded Departments, Chemistry.
    Lundgren, Stina
    KTH, Superseded Departments, Chemistry.
    Haswell, S. J.
    Department of Chemistry, University of Hull.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Asymmetric Catalysis in a Micro Reactor: Ce, Yb and Lu Catalysed Enantioselective Addition of Trimethylsilyl Cyanide to Benzaldehyde2004In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 60, no 46, p. 10515-10520Article in journal (Refereed)
    Abstract [en]

    A T-shaped micro reactor was used for the optimisation of reaction conditions for the enantioselective silyleyanation of benzaldehyde catalysed by lanthanide-pybox complexes. Compared to a conventional batch procedure, higher conversion was observed within shorter reaction time. The micro reactor process involving Lu(III) afforded essentially the same enantioselectivity as the batch process (73 vs 76% ee), whereas the enantioselectivity was lower in the micro reactor for catalysts containing Yb(III) (53 compared to 72%). Ce(III) provided very low selectivity in both types of processes (1 and 11 % ee, respectively). A study of the effect of additives showed that the enantioselectivity in the Yb catalysed reaction performed in the micro reactor could be increased to 66%, whereas only a minor improvement, to 78% ee, was observed in the reaction with Lu.

  • 46. Kaiser, N. F. K.
    et al.
    Bremberg, U.
    Larhed, M.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Hallberg, A.
    Fast, convenient, and efficient molybdenum-catalyzed asymmetric allylic alkylation under noninert conditions: An example of microwave-promoted fast chemistry2000In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 39, no 20, p. 3596-3598Article in journal (Refereed)
  • 47. Kaiser, N. F. K.
    et al.
    Bremberg, U.
    Larhed, M.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Hallberg, A.
    Microwave-mediated palladium-catalyzed asymmetric allylic alkylation; an example of highly selective fast chemistry2000In: Journal of Organometallic Chemistry, ISSN 0022-328X, E-ISSN 1872-8561, Vol. 603, no 1, p. 2-5Article in journal (Refereed)
    Abstract [en]

    Highly enantioselective palladium-catalyzed microwave-mediated fast chemistry has been performed on dimethyl malonate alkylation of(rac)-1,3-diphenylallyl-1-acetate (1). Utilizing the recently developed palladium-phosphineoxazoline catalytic system, with general stability at elevated temperatures (less than or equal to 145 degrees C), quantitative yields of greater than or equal to 97% and ee values of up to >99% were obtained after very short irradiation times (15-300 s, TOF up to 7000 h(-1)).

  • 48. Lake, F.
    et al.
    Hagberg, L.
    Svensson, M.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    C-3-symmetric azaphosphatranes2000In: Collection of Czechoslovak Chemical Communications, ISSN 0010-0765, E-ISSN 1212-6950, Vol. 65, no 4, p. 570-576Article in journal (Refereed)
    Abstract [en]

    C-3-Symmetric azaphosphatranes, (3S, 7S,10S)-2,3,7,8,9,10-hexamethyl-2,8,9-triaza-5-azonial-lambda(5)-phosphabicyclo[3.3.3]undecane chloride and (3S,7S,10S)-3,7,10-triisopropyl-2,8,9-trimethyl -2,8,9-triaza-5-azonia-1-lambda(5)-phosphabicyclo[3.3.3]undecane chloride, have been prepared starting from the corresponding chiral tripodal tetraamines and chlorobis-(diethylamino)phosphane. The compounds are weak acids which are not fully deprotonated by potassium tert-butoxide. Density functional calculations of the compounds and their conjugate bases demonstrate that the weak acidity originates in a conformational change upon deprotonation leading to substantial steric repulsion.

  • 49. Lake, F.
    et al.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Application of bis-sulfonamides in asymmetric catalysis. Addition of diethylzinc to prochiral aldehydes2003In: Russian journal of organic chemistry, ISSN 1070-4280, E-ISSN 1608-3393, Vol. 39, no 3, p. 436-452Article, review/survey (Refereed)
    Abstract [en]

    The review summarizes the authors' and published data on the Ti(OPr-i)(4)-catalyzed addition of diethylzinc to prochiral aldehydes in the presence of bis-sulfonamides. The effect of bis-sulfonamide structure and other factors on the enantioselectivity of formation of secondary alcohols is discussed.

  • 50. Lake, F.
    et al.
    Moberg, Christina
    KTH, Superseded Departments, Chemistry.
    Sulfonamide ligands from chiral aziridines - Application to the titanium-mediated addition of diethylzinc to benzaldehyde2002In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 18, p. 3179-3188Article in journal (Refereed)
    Abstract [en]

    A modular approach was developed for the preparation of chiral, enantiopure sulfonamide ligands with C-1, C-2, and C-3 symmetry by ring opening of chiral N-sulfonylaziridines with ammonia, primary amines, and diamines. The new ligands were assessed in the titanium-mediated addition of diethylzinc to benzaldehyde, giving the product with selectivities up to 76% ee. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).

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