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  • 1.
    Henry, Jeffrey L.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Posevins, Daniels
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Bin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Qiu, Youai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Highly Selective Olefin-Assisted Pd-II-Catalyzed Oxidative Alkynylation of Enallenes2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 33, p. 7896-7899Article in journal (Refereed)
    Abstract [en]

    An olefin-assisted, palladium-catalyzed oxidative alkynylation of enallenes for regio- and stereoselective synthesis of substituted trienynes has been developed. The reaction shows a broad substrate scope and good tolerance for various functional groups on the allene moiety, including carboxylic acid esters, free hydroxyls, imides, and alkyl groups. Also, a wide range of terminal alkynes with electron-donating and electron-withdrawing aryls, heteroaryls, alkyls, trimethylsilyl, and free hydroxyl groups are tolerated.

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  • 2.
    Li, Man-Bo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Inge, A. Ken
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Posevins, Daniels
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Qiu, Youai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chemodivergent and Diastereoselective Synthesis of gamma-Lactones and gamma-Lactams: A Heterogeneous Palladium-Catalyzed Oxidative Tandem Process2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 44, p. 14604-14608Article in journal (Refereed)
    Abstract [en]

    A palladium-catalyzed oxidative tandem process of enallenols was accomplished within a homogeneous/heterogeneous catalysis manifold, setting the stage for the highly chemodivergent and diaster-eoselective synthesis of gamma-lactones and gamma-lactams under mild conditions.

  • 3.
    Li, Man-Bo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Anhui University, P. R. China.
    Posevins, Daniels
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Geoffroy, Antoine
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhu, Can
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient Heterogeneous Palladium-Catalyzed Oxidative Cascade Reactions of Enallenols to Furan and Oxaborole Derivatives2020In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 59, no 5, p. 1992-1996Article in journal (Refereed)
    Abstract [en]

    A heterogeneous palladium-catalyzed oxidative cyclization of enallenols has been developed for the construction of highly substituted furan and oxaborole derivatives. The heterogeneous catalyst (Pd-AmP-MCF) exhibits high activity, high site- and stereoselectivity, and efficient palladium recyclability in the transformations.

  • 4.
    Li, Man-Bo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Posevins, Daniels
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Shchukarev, Andrey
    Qiu, Youai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diastereoselective Cyclobutenol Synthesis: A Heterogeneous Palladium-Catalyzed Oxidative Carbocyclization-Borylation of Enallenols2019In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 25, no 1, p. 210-215Article in journal (Refereed)
    Abstract [en]

    A highly selective and efficient oxidative carbocyclization/borylation of enallenols catalyzed by palladium immobilized on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was developed for diastereoselective cyclobutenol synthesis. The heterogeneous palladium catalyst can be recovered and recycled without any observed loss of activity or selectivity. The high diastereoselectivity of the reaction is proposed to originate from a directing effect of the enallenol hydroxyl group. Optically pure cyclobutenol synthesis was achieved by the heterogeneous strategy by using chiral enallenol obtained from kinetic resolution.

  • 5.
    Naidu, Veluru Ramesh
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Posevins, Daniels
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Volla, Chandra M. R.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selective Cascade Reaction of Bisallenes via Palladium-Catalyzed Aerobic Oxidative Carbocyclization-Borylation and Aldehyde Trapping2017In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, no 6, p. 1590-1594Article in journal (Refereed)
    Abstract [en]

    A cascade reaction, consisting of a palladium-catalyzed regioselective aerobic oxidative carbocyclization-borylation of bisallenes and a final aldehyde trapping, afforded triene alcohols with high diastereoselectivity. The cascade reaction occurs under mild reaction conditions and proceeds via an allylboron intermediate that is trapped by the aldehyde in a stereoselective manner.

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  • 6.
    Posevins, Daniels
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Advances in Stereoselective Palladium(ΙΙ)-Catalyzed Oxidative Transformations of Allenes2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Palladium(ΙΙ)-catalyzed carbon-carbon and carbon-heteroatom bond formation via selective C-H bond oxidation constitutes a step-economical and versatile approach towards complex target molecules. This thesis has been focused on the development of new selective palladium(ΙΙ)-catalyzed transformations of allenes under oxidative conditions catalyzed by either homogenous or heterogeneous palladium(ΙΙ) catalysts.

    The first part of this thesis describes carbocyclization-borylation of bisallenes, alkynylation of enallenes and preparation of [3]dendralenes from readily available allene starting materials. These homogenous palladium(ΙΙ)-catalyzed transformations involve selective allenic C-H cleavage under oxidative conditions. The aforementioned reactions can be carried out under aerobic biomimetic conditions by using electron transfer mediators (ETMs) and oxygen gas as the stoichiometric oxidant.

    The second part deals with highly diastereoselective palladium-catalyzed oxidative carbocyclization reactions of enallenes assisted by weakly coordinating functional groups, such as hydroxyl or sulfonamide groups. It was demonstrated, that this weak coordination is sufficient to trigger the allene attack on the metal center enabling formation of (vinyl)Pd(II) intermediates, previously achievable by the directing effect of unsaturated hydrocarbon groups. A broad range of borylated cyclohexanol derivatives, as well as cis-fused [5,5] bicyclic γ-lactones and γ-lactams were obtained with superb diastereoselectivity via palladium(ΙΙ)-catalyzed carbocyclization-functionalization reactions of enallenols.

    The final part of the thesis describes applications of the heterogenous catalyst Pd-AmP-MCF in oxidation reactions of allenes. Chemodivergent oxidative cascade reactions of enallenols were realized by switching between heterogeneous (Pd-AmP-MCF) and homogeneous (Pd(OAc)2) palladium catalysts. In separate cases, the heterogeneous catalyst Pd-AmP-MCF showed improved performance over its homogeneous counterpart, accompanied by high recyclability and no detectable metal leaching. Synthetically important cyclic skeletons such as cyclobutenols, furanes, oxaboroles, and fused γ-lactones/lactams were obtained via borylative or carbonylative carbocyclization reactions of enallenols in high yields and with excellent stereoselectivity.

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    Advances in Stereoselective Palladium(ΙΙ)-Catalyzed Oxidative Transformations of Allenes
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  • 7.
    Posevins, Daniels
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Li, Man-Bo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Svensson Grape, Erik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Inge, A. Ken
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Qiu, Youai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Highly Diastereoselective Palladium-Catalyzed Oxidative Cascade Carbonylative Carbocyclization of Enallenols2020In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 22, no 2, p. 417-421Article in journal (Refereed)
    Abstract [en]

    A palladium-catalyzed oxidative cascade carbonylative carbocyclization of enallenols was developed. Under mild reaction conditions, a range of cis-fused [5,5] bicyclic gamma-lactones and gamma-lactams with a 1,3-diene motif were obtained in good yields with high diastereoselectivity. The obtained lactone/lactam products are viable substrates for a stereoselective Diels-Alder reaction with N-phenylmaleimide, providing polycyclic compounds with increased molecular complexity.

  • 8.
    Posevins, Daniels
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Qiu, Youai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Highly Diastereoselective Palladium-Catalyzed Oxidative Carbocyclization of Enallenes Assisted by a Weakly Coordinating Hydroxyl Group2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 9, p. 3210-3214Article in journal (Refereed)
    Abstract [en]

    A highly diastereoselective palladium-catalyzed oxidative carbocyclization-borylation of enallenes assisted by a weakly coordinating hydroxyl group was developed. The reaction afforded functionalized cyclo-hexenol derivatives, in which the 1,3-relative stereo chemistry is controlled (d.r. > 50:1). Other weakly coordinating oxygen-containing groups (ketone, alkoxide, acetate) also assisted the carbocyclization toward cyclo-hexenes. The reaction proceeds via a ligand exchange on Pd of the weakly coordinating group with a distant olefin group. The high diastereoselectivity of the hydroxyl directed reaction could be rationalized by a face-selective coordination of the distant olefin. It was demonstrated that the primary coordination of the close-by oxygen containing functionality was necessary for the reaction to occur and removal of this functionality shut down the reaction.

  • 9.
    Qiu, Youai
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mendoza, Abraham
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Posevins, Daniels
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kalek, Marcin
    Bäckvall, Jan E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanistic Insight into Enantioselective Palladium-Catalyzed Oxidative Carbocyclization-Borylation of Enallenes2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 10, p. 2433-2439Article in journal (Refereed)
    Abstract [en]

    The asymmetric palladium-catalyzed oxidative carbocyclization-borylation of enallenes, employing a chiral phosphoric acid as co-catalyst, constitutes an efficient and convenient entry into functionalized building blocks with cyclopentene scaffolds in high enantiopurity. Up till now there has been a lack of knowledge concerning the origin of enantioselectivity of this reaction as well as the absolute configuration of the product. Herein, we report the crystal structure of one of the compounds generated via this carbocyclization, providing the link between the configuration of the products and the configuration of the chiral phosphoric acid used in the reaction. Furthermore, the origin of the enantioselectivity is thoroughly investigated with density functional theory (DFT) calculations. By careful examination of different possible coordination modes, it is shown that the chiral phosphoric acid and the corresponding phosphate anion serve as ligands for palladium during the key stereoselectivity-determining cyclization step. In addition, we examine reactions wherein an extra chiral reagent, a p-benzoquinone containing a chiral sulfoxide, is used. The combined experimental and theoretical studies provide insight into the details of complexation of palladium with various species present in the reaction mixture, furnishing a general understanding of the factors governing the stereoselectivity of this and related catalytic reactions.

  • 10.
    Qiu, Youai
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Posevins, Daniels
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selective Palladium-Catalyzed Allenic C-H Bond Oxidation for the Synthesis of [3]Dendralenes2017In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, no 42, p. 13112-13116Article in journal (Refereed)
    Abstract [en]

    A highly selective palladium-catalyzed allenic C-H bond oxidation was developed, and it provides a novel and straightforward synthesis of [3]dendralene derivatives. A variety of [3]dendralenes with diverse substitution patterns are accessible with good efficiency and high stereoselectivity. The reaction tolerates a broad substrate scope containing various functional groups on the allene moiety, including ketone, aldehyde, ester, and phenyl groups. Also, a wide range of olefins with both electron-donating and electron-withdrawing aryls, acrylate, sulfone, and phosphonate groups are tolerated.

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1 - 10 of 10
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