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  • 1.
    Gustafsson, Mikaela
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bartoszewicz, Agnieszka
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhao, Tony
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Li, Zhongyue
    Zhu, Guangshan
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A family of highly stable lanthanide metal-organic frameworks: structural evolution and catalytic activity2010In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 22, no 11, p. 3316-3322Article in journal (Refereed)
    Abstract [en]

    A family of homeotypic porous lanthanide metal−organic frameworks (MOFs), [Ln(btc)(H2O)]·guest (Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), Ho (6), Er (7), and Yb (8); guest: DMF or H2O) was synthesized. The structures of the as-synthesized compounds are tetragonal and contain 1D channels with accessible lanthanide ions. In situ single crystal X-ray diffraction shows that 1 undergoes a single-crystal to polycrystalline to single-crystal transformation from room temperature to 180 °C. During the release of DMF and water molecules from the channels by evacuation and subsequent heating, the structures of 1 and 7 transformed from tetragonal to monoclinic, and then to tetragonal, while the structure of 8 remained tetragonal. The transformation between the monoclinic and the low temperature tetragonal phases is reversible. The Ln(btc) MOFs are stable to at least 480 °C and are among the most thermally stable MOFs. The Ln(btc) MOFs act as efficient Lewis acid catalysts for the cyanosilylation of aldehydes yielding cyanohydrins in high yields within short reaction times. 1 also catalyzes the cyanosilylation of less reactive substrates, such as ketones at room temperature. The Ln(btc) MOFs could be recycled and reused without loss of their crystallinity and activity.

  • 2.
    Larsson, Johanna M.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Tony S. N.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Oxidative Allylic C-H Silylation2011In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 13, no 7, p. 1888-1891Article in journal (Refereed)
    Abstract [en]

    Palladium-catalyzed allylic C−H silylation was performed with use of hexamethyldisilane as the silyl source. These C−H functionalization reactions occur only in the presence of hypervalent iodine reagents or other strong oxidants and proceed with excellent regioselectivity, providing the linear allylic isomer of the allylsilane products. In demonstrating the first oxidative allylic C−H silylation of alkenes, this study marks an important advance for the catalytic C−H functionalization method.

  • 3.
    Zhao, Tony
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of functionalized allylic, propargylic and allenylic compounds: Selective formation of C–B, C–C, C–CF3 and C-Si bonds2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is focused on the development of new palladium and copper- mediated reactions for functionalization of alkenes and propargylic alcohol derivatives. The synthetic utility of the 1,2-diborylated butadienes synthesized in one of these processes has also been demonstrated.

    We have developed an efficient procedure for the synthesis of allenyl boronates from propargylic carbonates and acetates. This was achieved by using a bimetallic system of palladium and copper or silver as co-catalyst. The reactions were performed under mild conditions for the synthesis of a variety of allenyl boronates. Furthermore, the synthesis of 1,2-diborylated butadienes was achieved with high diastereoselectivity from propargylic epoxides. The reactivity of the 1,2-diborylated butadienes with aldehydes was studied. It was found that the initial allylboration reaction proceeds via an allenylboronate intermediate. The allenylboronate reacts readily with an additional aldehyde to construct 2-ethynylbutane-1,4-diols with moderate to high diastereoselectivity.

    We have also studied the copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates. It was also shown that a transfer of chirality occurred when an enantioenriched starting material was used.

    In the last part of the thesis, we have described a method for palladium-catalyzed functionalization of allylic C-H bonds for the selective synthesis of allylic silanes. The protocol only works under highly oxidative conditions which suggest a mechanism involving high oxidation state palladium intermediates.

  • 4.
    Zhao, Tony S. N.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Copper and Palladium-Mediated Transformationsof Allylic and Propargylic Substrates2014Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This thesis is focused on the development of new palladium and copper-mediated reactions for functionalization of alkenes and propargylic alcohol derivatives. We have developed an efficient procedure for the synthesis of allenyl and propargyl boronate from propargylic carbonates and acetates. The reactions were performed under mild conditions for the synthesis of a variety of allenyl boronates. We have also observed a switch of regioselectivity for the formation of propargylic boronates using CuCl as a co-catalyst. This is, as far as we know, the first metal-catalyzed reaction for the synthesis of propargylic boronates. Furthermore, the synthesis of 1,2-diborylated butadienes was achieved with high diastereoselectivity from propargylic epoxides. A wide variety of propargylic epoxides could be converted to the corresponding dienes and this is the first catalytic protocol to form 1,2-diborylated butadienes.

    We have also studied the copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates. Depending on the temperature, two different regioselective outcomes were observed. It was also shown that a transfer of chirality occurred when an enantioenriched starting material was used.

    In the last part of the thesis, we have described a method for palladium-catalyzed functionalization of allylic C-H bonds for selective synthesis of allylic silanes. The reaction is regioselective and gives only the linear allylic silane. The protocol only works under highly oxidative conditions which suggest a mechanism involving high oxidation state palladium intermediates.

  • 5.
    Zhao, Tony S. N.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Trifluoromethylation of Propargylic Halides and Trifluoroacetates Using (Ph3P)(3)Cu(CF3) Reagent2012In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, no 15, p. 3966-3969Article in journal (Refereed)
    Abstract [en]

    A copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates was performed with high allenyl or propargyl selectivity. The reaction proceeds smoothly with aliphatic and aromatic substituents bearing either electron-withdrawing or -supplying groups. Preliminary mechanistic results indicate an ionic mechanism involving nucleophilic transfer of the CF3 group from the Cu complex to the propargylic substrate.

  • 6.
    Zhao, Tony S. N.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Yuzhu
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lessing, Timo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Borylation of Propargylic Substrates by Bimetallic Catalysis. Synthesis of Allenyl, Propargylic, and Butadienyl Bpin Derivatives2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 21, p. 7563-7566Article in journal (Refereed)
    Abstract [en]

    Bimetallic Pd/Cu and Pd/Ag catalytic systems were used for borylation of propargylic alcohol derivatives. The substrate scope includes even terminal alkynes. The reactions proceed stererospecifically with formal S(N)2' pathways to give allenyl boronates. Opening of propargyl epoxides leads to 1,2-diborylated butadienes probably via en allenylboronate intermediate.

  • 7.
    Zhao, Tony S. N.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Jian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stereoselective Synthesis of 1,4-Diols by a Tandem Allylboration–Allenylboration Sequence2015In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 17, no 9, p. 2290-2293Article in journal (Refereed)
    Abstract [en]

    The reaction of mono- and dialdehydes with bis-borodienes (incorporating an allylboronate unit) has been studied. It was found that the initial allylboration reaction results in an allenylboronate, which has two stereogenic units: one of them has axial chirality and the other one is a stereogenic carbon center. This reaction proceeds with high diastereoselectivity. The allenylboronate formed in the allylboration reacts with an additional aldehyde with fair to high stereoselectivity depending on the aldehyde substrate. Aromatic dialdehydes react with bis-boro-butadienes creating three new stereocenters with usually high diastereoselectivity.

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