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  • 101.
    Karlsson, Erik A.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanism of the palladium-catalyzed carbohydroxylation of allene-substituted conjugated dienes: rationalization of the recently observed nucleophilic attack by water on a (pi-allyl)palladium intermediate2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 30, p. 9175-9180Article in journal (Refereed)
    Abstract [en]

    The mechanism of the palladium-catalyzed oxidative carbohydroxylation of allene-substituted 1,3-cyclohexadiene was studied by DFT calculations. All intermediates and transition states of the reaction were identified and their structures were calculated. The calculations confirm the mechanism previously proposed and show that the CC bond-forming step occurs via insertion of one of the double bonds of 1,3-cyclohexadiene into a Pdvinyl bond of a vinylpalladium intermediate. This reaction leads to a (π-allyl)palladium intermediate, and coordination of benzoquinone and a double bond in the molecule to Pd creates a highly reactive cationic π-allyl complex, which is readily attacked by water according to the calculations.

  • 102.
    Karlsson, Erik A.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lee, Bao-Lin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Hansson, Örjan
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Photosensitized water oxidation by use of a bioinspired manganese catalyst2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 49, p. 11715-11718Article in journal (Refereed)
  • 103.
    Kasrayan, Alex
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bocola, Marco
    Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
    Sandström, Anders G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lavén, Gaston
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Prediction of the Candida antarctica lipase A protein structure by comparative modeling and site-directed mutagenesis2007In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 8, no 12, p. 1409-1415Article in journal (Refereed)
    Abstract [en]

    A number of model structures of the CalA suggested by comparative modeling were tested by site-directed mutagenesis. Enzyme variants were created where amino acids predicted to play key roles for the lipase activity in the different models were replaced by an inert amino acid (alanine). The results from activity measurements of the overproduced and purified mutant enzymes indicate a structure where the active site consists of amino acid residues Ser184, His366, and Asp334 and in which there is no lid. This model can be used for future targeted modifications of the enzyme to obtain new substrate acceptance, better thermostability, and higher enantioselectivity.

  • 104.
    Kessler, Simon N.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iron-catalyzed Cross-Coupling of Propargyl Carboxylates and Grignard Reagents: Synthesis of Substituted Allenes2016In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, no 11, p. 3734-3738Article in journal (Refereed)
    Abstract [en]

    Presented herein is a mild, facile, and efficient iron-catalyzed synthesis of substituted allenes from propargyl carboxylates and Grignard reagents. Only 1-5mol% of the inexpensive and environmentally benign [Fe(acac)(3)] at -20 degrees C was sufficient to afford a broad range of substituted allenes in excellent yields. The method tolerates a variety of functional groups.

  • 105.
    Kessler, Simon N.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hundemer, Fabian
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Stockholm Univ, Arrhenius Lab, Dept Organ Chem, SE-10691 Stockholm, Sweden.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    A Synthesis of Substituted alpha-Allenols via Iron-Catalyzed Cross-Coupling of Propargyl Carboxylates with Grignard Reagents2016In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, no 11, p. 7448-7451Article in journal (Refereed)
    Abstract [en]

    alpha-Allenols are attractive and versatile compounds whose preparation can be a nontrivial task. In this Letter, we provide a method for the prompt synthesis of substituted alpha-allenols via a catalytic cross-coupling reaction which makes use of a nontoxic and cost-effective iron catalyst. The catalyst loading is typically as low as 1-5 mol %. The mild reaction conditions (-20 degrees C) and the short reaction time (15 min) allow for the presence of a variety of functional groups. Moreover, the reaction was shown to be scalable up to gram scale and the propargyl substrates are readily accessible by a one-pot synthesis.

  • 106.
    Kocovsky, Pavel
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Academy of Sciences of the Czech Republic, Czech Republic; Charles University, Czech Republic.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The syn/anti-Dichotomy in the Palladium-Catalyzed Addition of Nucleophiles to Alkenes2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 51, p. 36-56Article in journal (Refereed)
    Abstract [en]

    In this review the stereochemistry of palladium-catalyzed addition of nucleophiles to alkenes is discussed, and examples of these reactions in organic synthesis are given. Most of the reactions discussed involve oxygen and nitrogen nucleophiles; the Wacker oxidation of ethylene has been reviewed in detail. An anti-hydroxypalladation in the Wacker oxidation has strong support from both experimental and computational studies. From the reviewed material it is clear that anti-addition of oxygen and nitrogen nucleophiles is strongly favored in intermolecular addition to olefin-palladium complexes even if the nucleophile is coordinated to the metal. On the other hand, syn-addition is common in the case of intramolecular oxy- and amidopalladation as a result of the initial coordination of the internal nucleophile to the metal.

  • 107.
    Kong, Wei-Jun
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kessler, Simon N.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wu, Haibo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iron-Catalyzed Cross-Coupling of α-Allenyl Esters with Grignard Reagents for the Synthesis of 1,3-Dienes2023In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 25, no 1, p. 120-124Article in journal (Refereed)
    Abstract [en]

    Structurally diverse 1,3-dienes are valuable building blocks in organic synthesis. Herein we report the iron-catalyzed coupling between α-allenyl esters and Grignard reagents, which provides a fast and practical approach to a variety of complex substituted 1,3-dienes. The reaction involves an inexpensive iron catalyst, mild reaction conditions, and provides easy scale up. 

  • 108.
    Kong, Wei-Jun
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Reil, Michaela
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Feng, Lei
    Li, Man-Bo
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid Sweden University, Sweden.
    Aerobic Heterogeneous Palladium-Catalyzed Oxidative Allenic C−H Arylation: Benzoquinone as a Direct Redox Mediator between O2 and Pd2021In: CCS Chemistry, ISSN 2096-5745, Vol. 3, no 6, p. 1127-1137Article in journal (Refereed)
    Abstract [en]

    Transition metal-catalyzed aerobic oxidative reactions using molecular oxygen as the terminal oxidant play a significant role in organic synthesis. Benzoquinone (BQ) has been widely used as an electron-transfer mediator (ETM) in biomimetic palladium-catalyzed aerobic oxidative reactions, but always together with an ETM between O2 and BQ, such as a macrocyclic metal complex. Herein, we report on a heterogeneous palladium-catalyzed allenic C(sp3)–H arylation with only catalytic amounts of BQ under air without the need of an additional ETM. A range of multisubstituted 1,3-dienes were synthesized under mild reaction conditions. Mechanistic studies reveal the bifunctional role of BQ as a ligand for reductive elimination and as an ETM between Pd(0) and O2. This new regime of oxidation has important implications for further development of other transition metal-catalyzed aerobic oxidative reactions. 

  • 109.
    Krumlinde, Patrik
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bogár, Krisztián
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Asymmetric synthesis of bicyclic diol derivatives through metal and enzyme catalysis: Application to the formal synthesis of sertraline2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 13, p. 4031-4036Article in journal (Refereed)
    Abstract [en]

    Enzyme- and ruthenium-catalyzed dynamic kinetic asymmetric transformation (DYKAT) of bicyclic diols to their diacetates was highly enantio- and diastereoselective to give the corresponding diacetates in high yield with high enantioselectivity (99.9 % ee). The enantiomerically pure diols are accessible by simple hydrolysis (NaOH, MeOH), but an alternative enzyme-catalyzed ester cleavage was also used to give the trans-diol (R,R)-1 b in extremely high diastereomeric purity (trans/cis=99.9:0.1, >99.9 % ee). It was demonstrated that the diols can be selectively oxidized to the ketoalcohols in a ruthenium-catalyzed Oppenauer-type reaction. A formal enantioselective synthesis of sertraline from a simple racemic cis/trans diol 1 b was demonstrated.

  • 110.
    Krumlinde, Patrik
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bogár, Krisztián
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of a neonicotinoide pesticide derivative via chemoenzymatic dynamic kinetic resolution2009In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 74, no 19, p. 7407-7410Article in journal (Refereed)
  • 111.
    Kärkäs, Markus D.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Karlsson, Erik A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lee, Bao-Lin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Shariatgorji, Mohammadreza
    Ilag, Leopold
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Hansson, Örjan
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Light-Induced Water Oxidation by a Ru-complex Containing a Bio-Inspired Ligand2011In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 17, no 28, p. 7953-7959Article in journal (Refereed)
    Abstract [en]

    The new Ru-complex 8 containing the bio-inspired ligand 7 was successfully synthesized and characterized. Complex 8 could efficiently catalyze water oxidation using CeIV and RuIII as chemical oxidants. More importantly, this complex has sufficiently low overpotential to utilize ruthenium polypyridyl-type complexes as photosensitizers.

  • 112.
    Leijondahl, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Borén, Linnéa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Braun, Roland
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantiopure 1,5-diols from dynamic kinetic asymmetric transformation: Useful synthetic intermediates for the preparation of chiral heterocycles2008Conference paper (Other academic)
  • 113.
    Leijondahl, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Borén, Linnéa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Braun, Roland
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantiopure 1,5-diols from dynamic kinetic asymmetric transformation: Useful synthetic intermediates for the preparation of heterocycles2008In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 10, no 10, p. 2027-2030Article in journal (Refereed)
    Abstract [en]

    Dynamic kinetic asymmetric transformation (DYKAT) of a series of 1,5-diols has been performed in the presence of Candida antarctica lipase B (CALB), Pseudomonas cepacia lipase H (PS-C II), and ruthenium catalyst 4. The resulting optically pure 1,5-diacetates are useful synthetic intermediates, which was demonstrated by the syntheses of both an enantiopure 2,6-disubstituted piperidine and an enantiopure 3,5-disubstituted morpholine.

  • 114.
    Leijondahl, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Borén, Linnéa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Braun, Roland
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enzyme- and ruthenium-catalyzed dynamic kinetic asymmetric transformation of 1,5-diols: Application to the synthesis of (+)-Solenopsin A2009In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 74, no 5, p. 1988-1993Article in journal (Refereed)
    Abstract [en]

    Dynamic kinetic asymmetric transformation (DYKAT) of 1,5-diols via combined lipase and ruthenium catalysis provides enantiomerically pure diacetates in high diastereoselectivity, which can serve as intermediates in natural product synthesis. This is demonstrated by the synthesis of (+)-Solenopsin A.

  • 115. Li, Man-Bo
    et al.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid Sweden University, Sweden.
    Efficient Heterogeneous Palladium Catalysts in Oxidative Cascade Reactions2021In: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 54, no 9, p. 2275-2286Article, review/survey (Refereed)
    Abstract [en]

    CONSPECTUS: Palladium-catalyzed oxidations involving cascade processes provide a versatile platform for streamlined conversion of simple feedstocks into functional molecules with high atom and step economy. However, the achievement of high palladium efficiency and selectivity in Pd-catalyzed oxidative cascade reactions is still challenging in many cases, as a result of the aggregation of active palladium species to Pd black and the possible side reactions during each bond-forming step. The two current solutions for addressing these issues are either to utilize oxidant-stable ligands or to use electron transfer mediators (ETMs). The former solution, which includes the use of amines, pyridines, sulfoxides, and carbene derivatives, inhibits aggregation of Pd-0 during the catalytic cycle, while the latter solution facilitates reoxidation of Pd-0 to Pd-II to improve the activity and selectivity. Following our long-standing interest in Pd-catalyzed oxidations, very recently we developed heterogeneous catalysts to resolve the issues mentioned above in oxidative cascade reactions. The heterogeneous palladium catalysts (Pd-AmP-MCF or Pd-AmP-CNC) comprise palladium nanoclusters (1-2 nm) immobilized on amino-functionalized siliceous mesocellular foam (MCF) or on crystalline nanocellulose (CNC), exhibiting high activity, selectivity as well as excellent recycling ability. In this Account, we will discuss the synthesis and characterizations of the heterogeneous palladium catalysts, as well as their catalytic behaviors, and the mechanisms involved in their reactions. An important aspect of these catalysts in oxidation reactions is the generation of active Pd(II) species within the heterogeneous phase. Typical oxidative cascade reactions of our recent research on this topic include oxidative carbocyclization-carbonylation, oxidative carbocyclization-borylation, oxidative alkynylation-cyclization, oxidative carbonylation-cyclization, and oxidative carbocyclization-alkynylation. These reactions provide access to important compounds attractive in medicinal chemistry and functional materials, such as gamma-lactone/gamma-lactam-based poly rings, cyclobutenols, highly substituted furans, and oxaboroles. During these processes, the heterogeneous catalysts exhibited much higher turnover numbers (TONs) than their homogeneous counterparts (e.g., Pd(OAc)(2)) as well as unique selectivity that cannot be achieved by homogeneous palladium catalysts. The origin of the high efficiency and unique selectivity of the heterogeneous catalysts was also investigated. Asymmetric syntheses for the construction of optically pure compounds were realized based on the excellent selectivity in these heterogeneous processes. Kinetic studies revealed that the rate and yield of the reactions were essentially maintained during recycling, which demonstrates that Pd-AmP-MCF and Pd-AmP-CNC are robust and highly active in these oxidative cascade reactions. In addition, inductively coupled plasma optical emisson spectroscopy (ICP-OES) analysis and hot filtration test suggest that these processes most likely proceed via a heterogeneous pathway. Recent progress in our group has shown that the activity of Pd-AmP-MCF and Pd-AmP-CNC could be improved even further by the addition of Ag+ to generate cationic Pd(II). Furthermore, intriguing solvent effects were observed in a Pd-AmP-MCF-catalyzed oxidative cascade process, and solvent-controlled chemoselective transformations were developed based on this property of the catalyst. The heterogeneous strategy of this Account provides solutions to palladium deactivation and selectivity issues in Pd(II)catalyzed oxidative cascade reactions and enables efficient catalyst recycling, which will open up new opportunities in oxidative cascade reactions.

  • 116.
    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.

  • 117.
    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.

  • 118.
    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.

  • 119.
    Li, Man-Bo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Svensson Grape, Erik
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Stereospecific Oxidative Cascade Reaction of Allenes for the Construction of Pyrrole Rings: Control of Reactivity and Selectivity2019In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 9, no 6, p. 5184-5190Article in journal (Refereed)
    Abstract [en]

    A palladium-catalyzed oxidative cascade reaction of alpha-tosylamide allenes has been developed. The reactivity of the allenes is controlled by the tosylamide group. In the presence of terminal alkynes the reaction proceeds via a pathway leading to a one-pot construction of pyrrole rings. Moreover, a solvent-controlled chemoselectivity of the cascade reaction was realized, leading to a stereospecific and divergent synthesis of (Z)-tetrasubstituted olefins, 2,5-dihydropyrroles, and pyrroles. Enantioenriched (Z)-tetrasubstituted olefins and 2,5-dihydropyrroles are readily synthesized by chirality transfer using this approach.

  • 120. Li, Man-Bo
    et al.
    Yang, Jie
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Ying
    Xu, Guo-Yong
    Luo, Gen
    Yang, Jianping
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid Sweden University, Sweden.
    Amino-Supported Palladium Catalyst for Chemo- and Stereoselective Domino Reactions2021In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 60, no 2, p. 670-674Article in journal (Refereed)
    Abstract [en]

    A solid amino-supported palladium catalyst is used in an oxidative domino reaction for the diastereoselective construction of alkyne-substituted cyclopentenol compounds. This heterogeneous catalyst exhibits high efficiency and excellent chemoselectivity, as well as good recyclability. The chemoselectivity of the domino reactions was readily controlled by switching the solvent and catalyst. Asymmetric syntheses and an oxidative carbocyclization-borylation reaction have also been developed based on the heterogeneous palladium catalyst.

  • 121.
    Li, Man-Bo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Anhui University, P. R. China.
    Yang, Ying
    Rafi, Abdolrahim A.
    Oschmann, Michael
    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).
    Córdova, Armando
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid Sweden University, Sweden.
    Silver-Triggered Activity of a Heterogeneous Palladium Catalyst in Oxidative Carbonylation Reactions2020In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 59, no 26, p. 10391-10395Article in journal (Refereed)
    Abstract [en]

    A silver-triggered heterogeneous Pd-catalyzed oxidative carbonylation has been developed. This heterogeneous process exhibits high efficiency and good recyclability, and was utilized for the one-pot construction of polycyclic compounds with multiple chiral centers. AgOTf was used to remove chloride ions in the heterogeneous catalyst Pd-AmP-CNC, thereby generating highly active Pd-II, which results in high efficiency of the heterogeneous catalytic system.

  • 122.
    Lihammar, Richard
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Millet, Renaud
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    An Efficient Dynamic Kinetic Resolution of N-Heterocyclic 1,2-Amino Alcohols2011In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, no 13, p. 2321-2327Article in journal (Refereed)
    Abstract [en]

    A chemoenzymatic dynamic kinetic resolution (DKR) of N-heterocyclic amino alcohols is described. Various lipases were studied as biocatalysts for the kinetic resolution of N-heterocyclic 1,2-amino alcohols. The influence of the support of the enzymes on the enantioselectivity in the resolution of different substrates is highlighted. Various 3-acetoxypyrrolidines and -piperidines were obtained in high yield and high enantiomeric excess in efficient DKR reactions.

  • 123.
    Lihammar, Richard
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Millet, Renaud
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enzyme- and Ruthenium-Catalyzed Dynamic Kinetic Resolution of Functionalized Cyclic Allylic Alcohols2013In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, no 23, p. 12114-12120Article in journal (Refereed)
    Abstract [en]

    Enantioselective synthesis of functionalized cyclic allylic alcohols via dynamic kinetic resolution has been developed. Cyclopentadienylruthenium catalysts were used for the racemization, and lipase PS-IM or CALB was employed for the resolution. By optimization of the reaction conditions the formation of the enone byproduct was minimized, making it possible to prepare a range of optically active functionalized allylic alcohols in good yields and high ee's.

  • 124.
    Lihammar, Richard
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rönnols, Jerk
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Epimerization of Glycal Derivatives by a Cyclopentadienylruthenium Catalyst: Application to Metalloenzymatic DYKAT2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 45, p. 14756-14762Article in journal (Refereed)
    Abstract [en]

    Epimerization of a non-anomeric stereogenic center in carbohydrates is an important transformation in the synthesis of natural products. In this study an epimerization procedure of the allylic alcohols of glycals by cyclopentadienylruthenium catalyst 1 is presented. The epimerization of 4,6-O-benzylidene-D-glucal 4 in toluene is rapid, and an equlibrium with its D-allal epimer 5 is established within 5min at room temperature. Exchange rates for allal and glucal formation were determined by 1D H-1 EXSY NMR experiments to be 0.055s(-1) and 0.075s(-1), respectively. For 4-O-benzyl-L-rhamnal 8 the epimerization was less rapid and four days of epimerization was required to achieve equilibration of the epimers at room temperature. The epimerization methodology was subsequently combined with acylating enzymes in a dynamic kinetic asymmetric transformation (DYKAT), giving stereoselective acylation to the desired stereoisomers 12, 13, and 15. The net effect of this process is an inversion of a stereogenic center on the glycal, and yields ranging from 71% to 83% of the epimer were obtained.

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  • 125.
    Liu, Jie
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Hunan University, China.
    Guđmundsson, Arnar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid Sweden University, Sweden.
    Efficient Aerobic Oxidation of Organic Molecules by Multistep Electron Transfer2021In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 60, no 29, p. 15686-15704Article, review/survey (Refereed)
    Abstract [en]

    This Minireview presents recent important homogenous aerobic oxidative reactions which are assisted by electron transfer mediators (ETMs). Compared with direct oxidation by molecular oxygen (O-2), the use of a coupled catalyst system with ETMs leads to a lower overall energy barrier via stepwise electron transfer. This cooperative catalytic process significantly facilitates the transport of electrons from the reduced form of the substrate-selective redox catalyst (SSRCred) to O-2, thereby increasing the efficiency of the aerobic oxidation. In this Minireview, we have summarized the advances accomplished in recent years in transition-metal-catalyzed as well as metal-free aerobic oxidations of organic molecules in the presence of ETMs. In addition, the recent progress of photochemical and electrochemical oxidative functionalization using ETMs and O-2 as the terminal oxidant is also highlighted. Furthermore, the mechanisms of these transformations are showcased.

  • 126.
    Liu, Jie
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ricke, Alexander
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Bin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient Palladium-Catalyzed Aerobic Arylative Carbocyclization of Enallenynes2018In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 57, no 51, p. 16842-16846Article in journal (Refereed)
    Abstract [en]

    Herein, we communicate a selective and efficient protocol for oxidative arylating carbocyclization of enallenynes using O-2 as the oxidant. The key to success for this aerobic transformation is the application of a specific electron transfer mediator (ETM), a bifunctional catalyst consisting of a metal-macrocycle and quinone moieties. This catalyst significantly facilitates the reoxidation of Pd-0 to Pd-II under atmospheric pressure of O-2. Diverse functionalized enallenynes react with aryl boronic acids to afford the corresponding cyclic tetraenes in moderate to good yields.

  • 127.
    Löfgren, Johanna
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Görbe, Tamás
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oschmann, Michael
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Svedendahl Humble, Maria
    Bäckvall, Jan-E
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Transesterification of a Tertiary Alcohol by Engineered Candida antarctica Lipase A2019In: ChemBioChem (Print), ISSN 1439-4227, E-ISSN 1439-7633, Vol. 20, no 11, p. 1438-1443Article in journal (Refereed)
    Abstract [en]

    Tertiary alcohols are known to be challenging substrates for applications in asymmetric synthesis due to their complexity and steric hinderance. The occurrence of tertiary alcohols and their esters in nature indicates the presence of natural biocatalytic synthetic routes for their preparation. Lipase A from Candida antarctica (CalA) is a hydrolase that has previously been shown to catalyze the transesterification of racemic 2-phenylbut-3-yn-2-ol at a low rate. In this work, the activity of that enzyme was improved by protein engineering through a semi-rational design strategy. An enzyme library was created and screened for transesterification activity towards racemic 2-phenylbut-3-yn-2-ol in an organic solvent. One successful enzyme variant (L367G) showed a tenfold increased reaction rate compared to the wild-type enzyme, while maintaining a high enantioselectivity.

  • 128. Löfstedt, Joakim
    et al.
    Franzén, Johan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Carbon-Carbon Bond Formation in Regio- and Stereoselective Palladium-Catalyzed Cyclization of Allene-Substituted Conjugated Dienes2001In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 66, no 24, p. 8015-8025Article in journal (Refereed)
  • 129.
    Malmgren, Joel
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    C-2 Selective Arylation of Indoles with Heterogeneous Nanopalladium and Diaryliodonium Salts2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 42, p. 13531-13535Article in journal (Refereed)
    Abstract [en]

    A simple and efficient method to prepare synthetically useful 2-arylindoles is presented, using a heterogeneous Pd catalyst and diaryliodonium salts in water under mild conditions. A remarkably low leaching of metal catalyst was observed under the applied conditions. The developed protocol is highly C-2 selective and tolerates structural variations both in the indole and in the diaryliodonium salt. Arylations of both NH indoles and N-protected indoles with ortho-substituted, electron-rich, electron-deficient, or halogenated diaryliodonium salts were achieved to give the desired products in high to excellent isolated yields within 6 to 15 h at room temperature or 40 °C.

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  • 130.
    Manna, Srimanta
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kong, Wei-Jun
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid Sweden University, Sweden.
    Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles2021In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 27, no 55, p. 13725-13729Article in journal (Refereed)
    Abstract [en]

    Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.

  • 131.
    Manna, Srimanta
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kong, Wei-Jun
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Metal-catalyzed biomimetic aerobic oxidation of organic substrates2021In: Advances in Catalysis: Volume 69 / [ed] Montserrat Diéguez; Oscar Pàmies, Cambridge: Academic Press, 2021, Vol. 69, p. 1-57Chapter in book (Refereed)
    Abstract [en]

    The use of molecular oxygen (O2) as terminal oxidant in transition metal-catalyzed oxidative reactions is an appealing and challenging approach in organic chemistry. In these oxidations, the reoxidation of the reduced form of the metal catalyst by O2 is the key and challenging step, due to the triplet ground state of O2 and the high energy barrier for electron transfer. Inspired by (i) the electron transfer chain (ETC) in aerobic respiration and (ii) metalloenzymes for oxidations in Nature, organic chemists have developed metal-catalyzed biomimetic oxidations. In this chapter, two biomimetic approaches for transition metal-catalyzed aerobic oxidations are summarized, including: (i) biomimetic oxidation by multistep electron transfer pathways inspired by the respiratory chain and (ii) biomimetic oxidation by rational design of metal complexes that mimic metalloenzymes. The first type of aerobic oxidative transformations discussed include Wacker oxidations, alkyne oxidations, C—H functionalizations, and dehydrogenative oxidations of alcohols and amines. The second type of aerobic oxidations include iron-, copper- and manganese- osmium- and vanadium-catalyzed reactions.

  • 132.
    Manna, Srimanta
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Peters, Joannes
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bermejo-López, Aitor
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanistic Studies on Iron-Catalyzed Dehydrogenation of Amines Involving Cyclopentadienone Iron Complexes-Evidence for Stepwise Hydride and Proton Transfer2023In: ACS Catalysis, E-ISSN 2155-5435, Vol. 13, no 13, p. 8477-8484Article in journal (Refereed)
    Abstract [en]

    The mechanism of dehydrogenation of amines catalyzedby (cyclopentadienone)ironcarbonyl complexes was studied by means of kinetic isotope effect(KIE) measurements, intermediate isolation, and density functionaltheory calculations. The (cyclopentadienone)iron-amine intermediateswere isolated and characterized by H-1 and C-13 NMR spectroscopy as well as X-ray crystallography. The isolatediron-amine complexes are quite stable and undergo a formal beta-hydride elimination to produce imine and iron hydride complexes.The KIEs observed for the iron-catalyzed dehydrogenation of 4-methoxy-N-(4-methylbenzyl)aniline are in accordance with stepwisedehydrogenation. The density functional calculations corroborate astepwise mechanism involving a rate-determining hydride transfer fromamine to iron to yield a metal hydride and an iminium intermediate,followed by a proton transfer from the iminium ion to the oxygen ofthe cyclopentadienone ligand.

  • 133.
    Martín-Matute, Belén
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bogár, Krisztián
    Edin, Michaela
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kaynak, F. Betül
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Highly efficient redox isomerization of allylic alcohols at ambient temperature catalyzed by novel ruthenium cyclopentadienyl complexes: New insight into the mechanism2005In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 11, no 20, p. 5832-5842Article in journal (Refereed)
    Abstract [en]

    A range of ruthenium cyclopentadienyl (Cp) complexes have been prepared and used for isomerization of allylic alcohols to the corresponding saturated carbonyl compounds. Complexes bearing CO ligands show higher activity than those with PPh3 ligands. The isomerization rate is highly affected by the substituents on the Cp ring. Tetra(phenyl)methyl-substituted catalysts rapidly isomerize allylic alcohols under very mild reaction conditions (ambient temperature) with short reaction times. Substituted allylic alcohols have been isomerized by employing Ru–Cp complexes. A study of the isomerization catalyzed by [Ru(Ph5Cp)(CO)2H] (14) indicates that the isomerization catalyzed by ruthenium hydrides partly follows a different mechanism than that of ruthenium halides activated by KOtBu. Furthermore, the lack of ketone exchange when the isomerization was performed in the presence of an unsaturated ketone (1 equiv), different from that obtained by dehydrogenation of the starting allylic alcohol, supports a mechanism in which the isomerization takes place within the coordination sphere of the ruthenium catalyst.

  • 134.
    Martín-Matute, Belén
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Edin, Michaela
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bogár, Krisztián
    Kaynak, F. Betül
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Combined ruthenium(II)- and lipase catalysis for efficient dynamic kinetic resolution of sec-alcohols. Insight into a new racemization mechanism2005In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, no 24, p. 8817-8825Article in journal (Refereed)
    Abstract [en]

     

    Pentaphenylcyclopentadienyl ruthenium complexes (3) are excellent catalysts for the racemization of secondary alcohols at ambient temperature. The combination of this process with enzymatic resolution of the alcohols results in a highly efficient synthesis of enantiomerically pure acetates at room temperature with short reaction times for most substrates. This new reaction was applied to a wide range of functionalized alcohols including heteroaromatic alcohols, and for many of the latter, enantiopure acetates were efficiently prepared for the first time via dynamic kinetic resolution (DKR). Different substituted cyclopentadienyl ruthenium complexes were prepared and studied as catalysts for racemization of alcohols. Pentaaryl-substituted cyclopentadienyl complexes were found to be highly efficient catalysts for the racemization. Substitution of one of the aryl groups by an alkyl group considerably slows down the racemization process. A study of the racemization of (S)-1-phenylethanol catalyzed by ruthenium hydride η5-Ph5CpRu(CO)2H (8) indicates that the racemization takes place within the coordination sphere of the ruthenium catalyst. This conclusion was supported by the lack of ketone exchange in the racemization of (S)-1-phenylethanol performed in the presence of p-tolyl methyl ketone (1 equiv), which gave <1% of 1-(p-tolyl)ethanol. The structures of ruthenium chloride and iodide complexes 3a and 3c and of ruthenium hydride complex 8 were confirmed by X-ray analysis.

  • 135.
    Mazuela, Javier
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Banerjee, Debasis
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium(II)-Catalyzed Tandem Oxidative Acetoxylation/ortho C-H Activation/Carbocyclization of Arylallenes2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 30, p. 9559-9562Article in journal (Refereed)
    Abstract [en]

    Herein we report an example of tandem. oxidative acetoxylation/carbocyclization of arylallenes 1 using Pd(OAc)(2). The catalytic protocol is highly selective and provides access to new C-C and C-O bonds leading to a carbocyclization. The reaction proceeds via C-H activation by Pd. Mechanistic investigations show that the C-H activation is not the rate-limiting step and indicate that the reaction proceeds via acetoxylation of the allene.

  • 136.
    Millet, Renaud
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Träff, Annika M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Petrus, Michiel L.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantioselective synthesis of syn- and anti-1,3-aminoalcohols via β-aminoketones and subsequent reduction/dynamic kinetic asymmetric transformation2010In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 132, no 43, p. 15182-15184Article in journal (Refereed)
    Abstract [en]

    β-Aminoketones obtained from imines in an organocatalytic Mannich reaction were transformed to enantio- and diastereomerically pure 1,3-aminoalcohols with two stereogenic centers via a combined reduction/dynamic kinetic asymmetric transformation. Both syn and anti diastereomers were obtained in high yield, dr, and ee.

  • 137.
    Nagendiran, Anuja
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pascanu, Vlad
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bermejo Gómez, Antonio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    González Miera, Greco
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mild and Selective Catalytic Hydrogenation of the C=C Bond in a,b-Unsaturated Carbonyl Compounds Using Supported Palladium Nanoparticles2016In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 22, no 21, p. 7184-7189Article in journal (Refereed)
    Abstract [en]

    Chemoselective reduction of the C=C bond in a variety of α,β-unsaturated carbonyl compounds using supported palladium nanoparticles is reported. Three different heterogeneous catalysts were compared using 1 atm of H2: 1) nano-Pd on a metal–organic framework (MOF: Pd0-MIL-101-NH2(Cr)), 2) nano-Pd on a siliceous mesocellular foam (MCF: Pd0-AmP-MCF), and 3) commercially available palladium on carbon (Pd/C). Initial studies showed that the Pd@MOF and Pd@MCF nanocatalysts were superior in activity and selectivity compared to commercial Pd/C. Both Pd0-MIL-101-NH2(Cr) and Pd0-AmP-MCF were capable of delivering the desired products in very short reaction times (10–90 min) with low loadings of Pd (0.5–1 mol %). Additionally, the two catalytic systems exhibited high recyclability and very low levels of metal leaching.

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  • 138.
    Nagendiran, Anuja
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sörensen, Henrik
    Johansson, Magnus J.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nanopalladium-catalyzed conjugate reduction of Michael acceptors - application in flow2016In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 18, no 9, p. 2632-2637Article in journal (Refereed)
    Abstract [en]

    A continuous-flow approach towards the selective nanopalladium-catalyzed hydrogenation of the olefinic bond in various Michael acceptors, which could lead to a greener and more sustainable process, has been developed. The nanopalladium is supported on aminofunctionalized mesocellular foam. Both aromatic and aliphatic substrates, covering a variation of functional groups such as acids, aldehydes, esters, ketones, and nitriles were selectively hydrogenated in high to excellent yields using two different flow-devices (H-Cube (R) and Vapourtec). The catalyst was able to hydrogenate cinnamaldehyde continuously for 24 h (in total hydrogenating 19 g cinnanmaldehyde using 70 mg of catalyst in the H-cube (R)) without showing any significant decrease in activity or selectivity. Furthermore, the metal leaching of the catalyst was found to be very low (ppb amounts) in the two flow devices.

  • 139.
    Nagendiran, Anuja
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Haller, Clemence
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cycloisomerization of Acetylenic Acids to gamma-Alkylidene Lactones using a Palladium(II) Catalyst Supported on Amino-Functionalized Siliceous Mesocellular Foam2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 3, p. 1399-1405Article in journal (Refereed)
    Abstract [en]

    Cycloisomerization of various gamma-acetylenic acids to their corresponding gamma-alkylidene lactones by the use of a heterogeneous Pd(II) catalyst supported on amino-functionalized siliceous mesocellular foam is described. Substrates containing terminal as well as internal alkynes were cyclized in high to excellent yields within 2-24 h under mild reaction conditions. The protocol exhibited high regio- and stereoselectivity, favoring the exo-dig product with high Z selectivity. Moreover, the catalyst displayed excellent stability under the employed reaction conditions, as demonstrated by its good recyclability and low leaching.

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  • 140.
    Naidu, Veluru Ramesh
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Mid Sweden University, Sweden.
    Synthesis of Cross-Conjugated Polyenes via Palladium-Catalyzed Oxidative C-C Bond Forming Cascade Reactions of Allenes2020In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 85, no 8, p. 5428-5437Article in journal (Refereed)
    Abstract [en]

    An efficient palladium-catalyzed oxidative C-C bond forming cascade reaction of allenes involving a coupling between an enallene and an allenyne followed by a carbocyclization of the generated Pd-intermediate was developed. This cascade reaction afforded functionalized cross-conjugated polyenes. The enallene is initially activated by palladium and reacts with the allenyne to give the cross-conjugated polyenes.

  • 141.
    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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  • 142.
    Norinder, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bogár, Krisztián
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kanupp, Lisa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    An enantioselective route to alpha-methyl carboxylic acids via metal and enzyme catalysis2007In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 9, no 24, p. 5095-5098Article in journal (Refereed)
    Abstract [en]

    Dynamic kinetic resolution of allylic alcohols to allylic acetates followed by copper-catalyzed allylic substitution gave alkenes in high yields and high optical purity. Subsequent oxidative C-C double bond cleavage afforded pharmaceutically important alpha-methyl substituted carboxylic acids in high ee.

  • 143.
    Norinder, Jakob
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dynamic processes in the copper-catalyzed substitution of chiral allylic acetates leading to loss of chiral information2007In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 13, p. 4094-4102Article in journal (Refereed)
    Abstract [en]

    Copper-catalyzed α-substitution of enantiomerically pure secondary allylic esters with Grignard reagents was studied with the aim to find conditions that give racemic products. It was observed that the degree of chiral transfer is strongly dependent on the temperature. The loss of chiral information is consistent with an equilibration of the CuIII(allyl) intermediates prior to product formation. Equilibration of the reaction intermediates is of importance for a possible development of a dynamic kinetic asymmetric transformation (DYKAT) process, in which a chiral catalyst is used to produce an optically active product from a racemic substrate, by means of a dynamic equilibrium of the diastereomeric reaction intermediates.

  • 144.
    Nyhlén, Jonas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Privalov, Timofei
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Racemization of alcohols catalyzed by [RuCl(CO)25-pentaphenylcyclopentadienyl)] – Mechanistic insights from theoretical modeling2009In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 21, p. 5220-5229Article in journal (Refereed)
    Abstract [en]

    Two possible pathways of inner-sphere racemization of sec-alcohols by using the [RuCl(CO)(2)(eta(5)-pentaphenylcyclopentadienyl)] catalyst (1) have been thoroughly investigated by means of density function calculations. To be able to racemize alcohols, catalyst 1 needs to have a free coordination site on the metal. This can be achieved either by a eta(5)-->eta(3) ring slippage or by dissociation of a carbon monoxide (CO) ligand. The eta(5)-->eta(3) ring-slip pathway was found to have a high potential energy barrier, 42 kcal mol(-1), which can be explained by steric congestion in the transition state. On the other hand, CO dissociation to give a 16-electron complex has a barrier of only 22.6 kcal mol(-1). We have computationally discovered a mechanism involving CO participation that does not require eta(5)-->eta(3) ring slippage. The key features of this mechanism are 1) CO-assisted exchange of chloride for alkoxide, 2) alcohol-alkoxide exchange, and 3) generation of an active 16-electron complex through CO dissociation with subsequent beta-hydride elimination as the racemization step. We have found a low-energy pathway for reaction of 1 with potassium tert-butoxide and a pathway for fast alkoxide exchange with interaction between the incoming/leaving alcohol and one of the two CO ligands. We predict that dissociation of a Ru-bound CO ligand does not occur in these exchange reactions. Dissociation of one of the two Ru-bound CO ligands has been found necessary only at a later stage of the reaction. Though this barrier is still quite high, our results indicate that it is not necessary to cross the CO dissociation barrier for the racemization of each new alcohol. Thus, the dissociation of a CO ligand is interpreted as a rate-limiting reaction step in order to create a catalytically active 16-electron complex.

  • 145.
    Olofsson, Berit
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bogár, Krisztián
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Fransson, Ann-Britt L
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Divergent asymmetric synthesis of 3,5-disubstituted piperidines.2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 21, p. 8256-60Article in journal (Refereed)
    Abstract [en]

    A divergent synthesis of various 3,5-dioxygenated piperidines with interesting pharmacological properties is described. A mixture of the achiral cis- and racemic trans-3,5-piperidine diol could be efficiently obtained from N-benzylglycinate in five steps by the use of chemoenzymatic methods. In the subsequent enzyme- and Ru-catalyzed reaction, the rac/meso diol mixture was efficiently transformed to the cis-(3R,5S)-diacetate with excellent diastereoselectivity and in high yield. Further transformations of the cis-diacetate selectively delivered the cis-piperidine diol and the cis-(3R,5S)-hydroxy acetate. Alternatively, the DYKAT could be stopped at the monoacetate stage to give the trans-(3R,5R)-hydroxy acetate.

  • 146.
    Oschmann, Michael
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Placais, Clotilde
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nagendiran, Anuja
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient 1,3-Oxazolidin-2-one Synthesis through Heterogeneous Pd-II-Catalyzed Intramolecular Hydroamination of Propargylic Carbamates2019In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 25, no 25, p. 6295-6299Article in journal (Refereed)
    Abstract [en]

    Herein, we present an operationally simple protocol for the cycloisomerization of propargylic carbamates in which a heterogeneous catalyst consisting of Pd species immobilized on amino-functionalized siliceous mesocellular foam (Pd-II-AmP-MCF) is used. This Pd nanocatalyst displayed high efficiency at low catalyst loading and reaction temperatures, which allowed for the efficient and mild synthesis of a wide range of 1,3-oxazolidin-2-one derivatives and related compounds. Moreover, it proved possible to re-use the Pd nanocatalyst for several reactions, although a gradual decrease in activity was observed in the subsequent cycles.

  • 147.
    Persson, Andreas K. A.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jiang, Tuo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnson, Magnus T.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Oxidative Borylative Carbocyclization of Enallenes2011In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 50, no 27, p. 6155-6159Article in journal (Refereed)
    Abstract [en]

    An efficient oxidative carbocyclization/borylation of enallenes uses Pd(OAc)2 as the catalyst, B2pin2 as the boron-transfer reagent, and 1,4-benzoquinone (BQ) as the oxidant (see scheme). The reaction seems to take place through activation of the allene by a PdII complex to give an alkenyl–PdII intermediate followed by carbopalladation of the olefin and subsequent cleavage of the intermediate palladium–carbon bond by the boron reagent.

  • 148.
    Persson, Andreas K. Å.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium(II)-catalyzed oxidative carbocyclization of aza-enallenes2010In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, no 27, p. 4624-4627Article in journal (Refereed)
    Abstract [en]

    Live and let diene: A palladium(II)-catalyzed oxidative carbocyclization reaction of aza-enallenes provides access to potentially valuable heterocyclic dienes. In the presence of a dieneophile during the carbocyclization step, the products can react further in a one-pot cyclization/Diels–Alder sequence to give polycyclic products. BQ=para-benzoquinone

  • 149.
    Persson, Andreas K. Å.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Copper-catalyzed N-allenylation of allylic sulfonamides2009In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 11, no 17, p. 3814-3817Article in journal (Refereed)
    Abstract [en]

    Allylic allenic amides have been synthesized via a copper-catalyzed cross-coupling between allylic sulfonamides and bromoallenes in moderate to good yields. Copper(I) thiophene-2-carboxylate (CuTC) was used a source of copper with DMEDA as the ligand. The allenylated products obtained are potential substrates for palladium-catalyzed carbocyclizations.

  • 150.
    Piera, Julio
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Persson, Andreas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Caldentey, Xisco
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Water as nucleophile in palladium-catalyzed oxidative carbohydroxylation of allene-substituted conjugated dienes2007In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 46, p. 14120-14121Article in journal (Refereed)
    Abstract [en]

    An efficient palladium(II)-catalyzed oxidative carbohydroxylation of allene-substituted conjugated dienes in aqueous media has been developed. The reaction is conducted employing p-benzoquinone as the stoichiometric reoxidant for the palladium or under aerobic conditions with essentially the same outcome. It is worth mentioning that this is the first example of a palladium(II)-catalyzed oxidation where a carbon−carbon bond is formed in water and also one of the few cases of nucleophilic attack by water on a (π-allyl)palladium complex.

12345 101 - 150 of 234
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