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  • 1.
    Peters, Byron K.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margarita, Cristiana
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Orebom, Alexander
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Morsch, Thomas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantio- and Regioselective Ir-Catalyzed Hydrogenation of Di- and Trisubstituted Cycloalkenes2016In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 138, no 36, p. 11930-11935Article in journal (Refereed)
    Abstract [en]

    A number of cyclic olefins Were prepared and evaluated for the asymmetric hydrogenation reaction using novel N,P-ligated iridium imidazote-based Catalysts (Crabtree type). The diversity of these cyclic olefins spanned those having little functionality to others bearing strongly coordinating substituents and heterocycles. Excellent enantioselectivities were observed both for substrates having little functionality (up to >99% ee) and for substrates possessing functional groups several carbons away from the olefin. Substrates having functionalities such as carboxyl groups, alcohols, or heterocycles in the vicinity of the C=C bond were hydrogenated in high enantiomeric excess (up to >99% ee). The hydrogenation was also found to be regioselective, and by controlling the reaction conditions, selective hydrogenation of one of two trisubstituted olefins can be achieved: Furthermore, trisubstituted olefins can be selectively hydrogenated in the presence of tetrasubstituted olefins.

  • 2.
    Peters, Byron K.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margarita, Cristiana
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Paptchikhine, Alexander
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantio- and Regioselective Hydrogenation of Minimally and Densely Decorated Unsaturated CarbocyclesManuscript (preprint) (Other academic)
    Abstract [en]

    Several cyclic prochiral olefins were successfully hydrogenated (>99 conv.,up to >99 % ee) using N,P-ligated iridium catalysts. Minimally functionalisedsubstrates (Class 1) were hydrogenated rapidly and in high ee, whichwas consistent with earlier reports. Substrates having functional groups(Class 2) and heterocycles (Class 3) attached to the unsaturated cycle, were43hydrogenated gradually over a period of time, however, high enantioselectivitywas still maintained (up to >99 % ee). This methodology is a highly practical,general and selective means of preparing chiral cyclohexanes.

  • 3.
    Peters, Byron K.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhou, Taigang
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rujirawanich, Janjira
    Cadu, Alban
    Singh, Thishana
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    An Enantioselective Approach to the Preparation of Chiral Sulfones by Ir-Catalyzed Asymmetric Hydrogenation2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 47, p. 16557-16562Article in journal (Refereed)
    Abstract [en]

    Several chiral sulfonyl compounds were prepared using the iridium catalyzed asymmetric hydrogenation reaction. Vinylic, allylic and homoallylic sulfone substitutions were investigated, and high enantioselectivity is maintained regardless of the location of the olefin with respect to the sulfone. Impressive stereoselectivity was obtained for dialkyl substitutions, which typically are challenging substrates in the hydrogenation. As expected, the more bulky Z-substrates were hydrogenated slower than the corresponding E isomers, and in slightly lower enantioselectivity.

  • 4.
    Quan, Xu
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diomedi, Simone
    Singh, Thishana
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Thiazole, Imidazole and Oxazoline Based N,P-Ligands for Palladium-Catalyzed Cycloisomerization of 1,6-Enynes2016In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 20, p. 3427-3433Article in journal (Refereed)
    Abstract [en]

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

  • 5.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Development of Ruthenium Complexes for Water Oxidation2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Development of a methodology to combat the world energy crisis can be one of the greatest challenges now facing mankind. Our research is focused on the development of versatile catalysts (WOCs) that oxidize water into molecular oxygen at neutral pH, driven by the mild one-electron oxidant [Ru(bpy)3]3+, using natural photosynthesis a sa model.

    The first part of the thesis describes the unexpected generation of a mononuclear Ru complex from a hexadentate ligand, which was envisioned to accommodate two metal atoms. The study of this mononuclear catalyst clearly demonstrated the importance of having strongly electron donating functional groups and their effect on catalytic water oxidation.

    The second part of thesis presents the preparation of a mononuclear Ru complex, which contains two amide groups in the ligand scaffold and the superior reactivity of this complex in catalytic water oxidation under neutral condition. When mild one-electronoxidant [Ru(bpy)3]3+ was employed, TONs of ∼ 6000 and TOFs of ∼20s-1 were achieved, which are the highest values reported so far, using this type of oxidant

  • 6.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The Use of N,P-Iridium and N,P-Palladium Complexes in Asymmetric Synthesis2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work presented in this thesis concerns asymmetric catalysis using chiral N,P-ligands and iridium or palladium transition metals. The first part  (Chapters 2 and 3) highlights the N,P-iridium catalyzed asymmetric hydrogenation of 1,4-cyclohexadienes having functionalized or unfunctionalized substituents, including allylsilane side chains. A series of N,P-iridium catalysts were synthesized and screened on a number of cyclohexadienes. The developed N,P-iridium catalysts have provided excellent chemo-, regio- and enantioselectivity for most of the products obtained. For substrates having an allylsilane sidechain, the chiral cyclic allylsilane products were used to induce stereocontrol in a subsequent Hosomi-Sakurai reaction using TiCl4 as Lewis acid and aldehydes as electrophiles. The corresponding homoallylic alcohols were obtained in good to excellent diastereoselectivity. 

    The second part (Chapter 4) describes the N,P-iridium catalyzed asymmetric hydrogenation of various vinyl fluorides. A number of tri- and tetrasubstituted vinyl fluorides were synthesized and evaluated for the asymmetric hydrogenation. The corresponding saturated chiral fluoro compounds were obtained in very high enantioselectivity (up to 99% ee). The defluorination, usually known to occur under the catalytic hydrogenation conditions, were not observed for the majority of the substrates. 

    Finally, Chapter 5 describes the application of N,P-ligands in the asymmetric cycloisomerization of 1,6-enynes using a palladium precatalyst. The enantioselectivities for the products were found to depend both on the substrate as well as the hydrogen source. These developed catalytic reactions provide attractive methods to create multiple stereogenic centers in a molecule in relatively few steps from readily available starting materials.

  • 7.
    Rabten, Wangchuk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Liao, Rong-Zhen
    Tinnis, Fredrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Siegbahn, Per E. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic Water Oxidation by a Molecular Ruthenium Complex: Unexpected Generation of a Single-Site Water Oxidation Catalyst2015In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 54, no 10, p. 4611-4620Article in journal (Refereed)
    Abstract [en]

    The increasing energy demand calls for the development of sustainable energy conversion processes. Here, the splitting of H2O to O-2 and H-2, or related fuels, constitutes an excellent example of solar-to-fuel conversion schemes. The critical component in such schemes has proven to be the catalyst responsible for mediating the four-electron oxidation of H2O to O-2. Herein, we report on the unexpected formation of a single-site Ru complex from a ligand envisioned to accommodate two metal centers. Surprising N-N bond cleavage of the designed dinuclear ligand during metal complexation resulted in a single-site Ru complex carrying a carboxylate amide motif. This ligand lowered the redox potential of the Ru complex sufficiently to permit H2O oxidation to be carried out by the mild one-electron oxidant [Ru(bpy)(3)](3+) (bpy = 2,2'-bipyridine). The work thus highlights that strongly electron-donating ligands are important elements in the design of novel, efficient H2O :oxidation catalysts.

  • 8.
    Rabten, Wangchuk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Margarita, Margarita
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ir-Catalyzed Asymmetric and Regioselective Hydrogenation of Cyclic Allylsilanes and Generation of Quaternary Stereocenters via the Hosomi-Sakurai Allylation2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 7, p. 1681-1685Article in journal (Refereed)
    Abstract [en]

    A number of cyclic dienes containing the allylsilane moiety were prepared via Birch reduction and subjected to iridium-catalyzed regioselective and asymmetric hydrogenation, which provided chiral allylsilanes in high conversion and enantiomeric excess (up to 99 % ee). The compounds were successively used in the Hosomi-Sakurai allylation with various aldehydes employing TiCl4 as Lewis acid, providing adducts with two additional stereogenic centers in excellent diastereoselectivity.

  • 9.
    Rabten, Wangchuk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ponra, Sudipta
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kerdphon, Sutthichat
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wu, Haibo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    N,P-Iridium Catalyzed Asymmetric Hydrogenation of Vinyl FluoridesManuscript (preprint) (Other academic)
  • 10.
    Rabten, Wangchuk
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). China University of Geosciences, China.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Peking University, China.
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A ruthenium water oxidation catalyst based on a carboxamide ligand2016In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 8, p. 3272-3276Article in journal (Refereed)
    Abstract [en]

    Herein is presented a single-site Ru complex bearing a carboxamide-based ligand that efficiently manages to carry out the fourelectron oxidation of H2O. The incorporation of the negatively charged ligand framework significantly lowered the redox potentials of the Ru complex, allowing H2O oxidation to be driven by the mild oxidant [Ru(bpy)(3)](3+). This work highlights that the inclusion of amide moieties into metal complexes thus offers access to highly active H2O oxidation catalysts.

  • 11.
    Shatskiy, Andrey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lomoth, Reiner
    Abdel-Magied, Ahmed F.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Nuclear Materials Authority, Egypt.
    Rabten, Wangchuk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Laine, Tanja M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chen, Hong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). KTH Royal Institute of Technology, Sweden.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Andersson, Pher G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalyst-solvent interactions in a dinuclear Ru-based water oxidation catalyst2016In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 47, p. 19024-19033Article in journal (Refereed)
    Abstract [en]

    Photocatalytic water oxidation represents a key process in conversion of solar energy into fuels and can be facilitated by the use of molecular transition metal-based catalysts. A novel straightforward approach for covalent linking of the catalytic units to other moieties is demonstrated by preparation of a dinuclear complex containing two [Ru(pdc)(pic)(3)]-derived units (pdc = 2,6-pyridinedicarboxylate, pic = 4-picoline). The activity of this complex towards chemical and photochemical oxidation of water was evaluated and a detailed insight is given into the interactions between the catalyst and acetonitrile, a common co-solvent employed to increase solubility of water oxidation catalysts. The solvent-induced transformations were studied by electrochemical and spectroscopic techniques and the relevant quantitative parameters were extracted.

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