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  • 1.
    Abdel-Magied, Ahmed F.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Arafa, Wael A. A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Laine, Tanja M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Shatskiy, Andrey
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Substituent Effects in Molecular Ruthenium Water Oxidation Catalysts Based on Amide Ligands2017In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 9, no 9, p. 1583-1587Article in journal (Refereed)
    Abstract [en]

    The production of clean and sustainable energy is considered as one of the most urgent issues for our society. Mastering the oxidation of water to dioxygen is essential for the production of solar fuels. A study of the influence of the substituents on the catalytic activity of a series of mononuclear Ru complexes (2a-e) based on a tetradentate ligand framework is presented. At neutral pH, using [Ru(bpy)(3)](PF6)(3) (bpy=2,2'-bipyridine) as the terminal oxidant, a good correlation between the turnover frequency (TOF) and the Hammett sigma(meta) parameters was obtained. Additionally, a general pathway for the deactivation of Ru-based catalysts 2a-e during the catalytic oxidation of water through poisoning by carbon monoxide was demonstrated. These results highlight the importance of ligand design for fine-tuning the catalytic activity of water oxidation catalysts.

  • 2. An, Wei
    et al.
    Baber, Ashleigh E.
    Xu, Fang
    Soldemo, Markus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Weissenrieder, Jonas
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Stacchiola, Dario
    Liu, Ping
    Mechanistic Study of CO Titration on CuxO/Cu(111) (x <= 2) Surfaces2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 8, p. 2364-2372Article in journal (Refereed)
    Abstract [en]

    The reducibility of metal oxides is of great importance to their catalytic behavior. Herein, we combined ambient-pressure scanning tunneling microscopy (AP-STM), X-ray photoemission spectroscopy (AP-XPS), and DFT calculations to study the CO titration of CuxO thin films supported on Cu(111) (CuxO/Cu(111)) aiming to gain a better understanding of the roles that the Cu(111) support and surface defects play in tuning catalytic performances. Different conformations have been observed during the reduction, namely, the 44 structure and a recently identified (5-7-7-5) Stone-Wales defects (5-7 structure). The DFT calculations revealed that the Cu(111) support is important to the reducibility of supported CuxO thin films. Compared with the case for the Cu2O(111) bulk surface, at the initial stage CO titration is less favorable on both the 44 and 5-7 structures. The strong CuxO <-> Cu interaction accompanied with the charge transfer from Cu to CuxO is able to stabilize the oxide film and hinder the removal of O. However, with the formation of more oxygen vacancies, the binding between CuxO and Cu(111) is weakened and the oxide film is destabilized, and Cu2O(111) is likely to become the most stable system under the reaction conditions. In addition, the surface defects also play an essential role. With the proceeding of the CO titration reaction, the 5-7 structure displays the highest activity among all three systems. Stone-Wales defects on the surface of the 5-7 structure exhibit a large difference from the 44 structure and Cu2O(111) in CO binding energy, stability of lattice oxygen, and, therefore, the reduction activity. The DFT results agree well with the experimental measurements, demonstrating that by adopting the unique conformation, the 5-7 structure is the active phase of CuxO, which is able to facilitate the redox reaction and the Cu2O/Cu(111)<-> Cu transition.

  • 3.
    An, Wei
    et al.
    Brookhaven National Laboratory, USA.
    Baber, Ashleigh E.
    Brookhaven National Laboratory, USA.
    Xu, Fang
    Stony Brook University, USA.
    Soldemo, Markus
    KTH.
    Weissenrieder, Jonas
    KTH.
    Stacchiola, Dario
    Brookhaven National Laboratory, USA.
    Liu, Ping
    Brookhaven National Laboratory, USA.
    Mechanistic Study of CO Titration on CuxO/Cu(111) (x <= 2) Surfaces2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 8, p. 2364-2372Article in journal (Refereed)
    Abstract [en]

    The reducibility of metal oxides is of great importance to their catalytic behavior. Herein, we combined ambient-pressure scanning tunneling microscopy (AP-STM), X-ray photoemission spectroscopy (AP-XPS), and DFT calculations to study the CO titration of CuxO thin films supported on Cu(111) (CuxO/Cu(111)) aiming to gain a better understanding of the roles that the Cu(111) support and surface defects play in tuning catalytic performances. Different conformations have been observed during the reduction, namely, the 44 structure and a recently identified (5-7-7-5) Stone-Wales defects (5-7 structure). The DFT calculations revealed that the Cu(111) support is important to the reducibility of supported CuxO thin films. Compared with the case for the Cu2O(111) bulk surface, at the initial stage CO titration is less favorable on both the 44 and 5-7 structures. The strong CuxO <-> Cu interaction accompanied with the charge transfer from Cu to CuxO is able to stabilize the oxide film and hinder the removal of O. However, with the formation of more oxygen vacancies, the binding between CuxO and Cu(111) is weakened and the oxide film is destabilized, and Cu2O(111) is likely to become the most stable system under the reaction conditions. In addition, the surface defects also play an essential role. With the proceeding of the CO titration reaction, the 5-7 structure displays the highest activity among all three systems. Stone-Wales defects on the surface of the 5-7 structure exhibit a large difference from the 44 structure and Cu2O(111) in CO binding energy, stability of lattice oxygen, and, therefore, the reduction activity. The DFT results agree well with the experimental measurements, demonstrating that by adopting the unique conformation, the 5-7 structure is the active phase of CuxO, which is able to facilitate the redox reaction and the Cu2O/Cu(111)<-> Cu transition.

  • 4. Asahina, Shunsuke
    et al.
    Takami, Seiichi
    Otsuka, Takeshi
    Adschiri, Tadafumi
    Terasaki, Osamu
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Exploitation of Surface-Sensitive Electrons in Scanning Electron Microscopy Reveals the Formation Mechanism of New Cubic and Truncated Octahedral CeO(2) Nanoparticles2011In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 3, no 6, p. 1038-1044Article in journal (Refereed)
    Abstract [en]

    Development of new analytical tools for nanostructures directly contributes to the study of catalysts. By using scanning electron microscopy (SEM) with a newly designed signal enhancer, we study cubic and truncated octahedral cerium oxide (CeO(2)) nanoparticles, which are composed of smaller primary octahedral CeO(2) and are formed through bond formation with hexanedioic acid. The signal enhancer is designed to efficiently collect secondary electrons of kinetic energy less than 10 eV; thus, it greatly improves the S/N ratio. On the basis of the observed SEM images and electron backscattered diffraction patterns of the cross section of the nanoparticles, we discuss the formation mechanism of the nanoparticles and speculate that the primary CeO(2) nanocrystals share their edges in the cubic nanoparticles and truncated octahedral nanoparticles. These results will contribute to the preparation of nanostructured metal oxide surfaces with controlled morphologies that could enhance catalytic activity.

  • 5.
    Buitrago, Elina
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lundberg, Helena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Andersson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ryberg, Per
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    High Throughput Screening of a Catalyst Library for the Asymmetric Transfer Hydrogenation of Heteroaromatic Ketones: Formal Syntheses of (R)-Fluoxetine and (S)-Duloxetine2012In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, no 12, p. 2082-2089Article in journal (Refereed)
    Abstract [en]

    A total of 21 amino acid based ligands including hydroxy amide, thioamide, and hydroxamic acid functionalities, respectively, were combined with [Ru(p-cymene)Cl2]2 and [RhCp*Cl2]2, and used as catalysts for the asymmetric transfer hydrogenation of four different heteroaromatic ketones in 2-propanol. The reactions were performed on a Chemspeed automated high-throughput screening robotic platform. Optimal catalysts were identified for the individual heterocyclic substrate classes. Based on these results, the formal syntheses of the antidepressant drugs (R)-fluoxetine and (S)-duloxetine were conducted by using the found catalysts in the key reaction step, which results in high isolated yields (94?%) and excellent product enantioselectivities (>99?% ee) of the formed 1,3-amino alcohols.

  • 6.
    Chan, Fan Liang
    et al.
    Catalysis for Green Chemicals Group, Department of Chemical Engineering, Monash University.
    Umeki, Kentaro
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Tanksale, Akshat
    Catalysis for Green Chemicals Group, Department of Chemical Engineering, Monash University.
    Kinetic Study of Catalytic Steam Gasification of Biomass by Using Reactive Flash Volatilisation2015In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 8, p. 1329-1337Article in journal (Refereed)
    Abstract [en]

    Reactive flash volatilisation is an autothermal process to convert biomass into tar-free synthesis gas under steam-rich conditions. This article studies the kinetics of reactive flash volatilisation by using Ni, Pt[BOND]Ni, Ru[BOND]Ni, Re[BOND]Ni, and Rh[BOND]Ni catalysts supported on alumina. The rates of mass loss of cellulose, xylan, and lignin were measured and compared with those of the synthetic biomass mixture and pinewood sawdust. The kinetic parameters were calculated with and without catalysts by using a wire-mesh isothermal thermogravimetric analyser in an equimolar steam/N2 atmosphere and high heating rates of 8.6×102, 1.1×103, and 1.3×104 °C min−1 at 700, 750, and 800 °C, respectively. The results revealed three distinct regimes of the rate of mass loss: pyrolytic decomposition, reforming, and char gasification. The catalysts increased the rate of mass loss in the reforming regime. Rh[BOND]Ni and Ru[BOND]Ni supported catalysts showed higher reforming rates than other catalysts. This study provides direct evidence of the in situ catalytic removal of tar during gasification of biomass

  • 7. Chen, Hu
    et al.
    Gao, Yan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    A Cobalt-Based Film for Highly Efficient Electrocatalytic Water Oxidation in Neutral Aqueous Solution2016In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 8, no 17, p. 2757-2760Article in journal (Refereed)
    Abstract [en]

    A cobalt-based film (Co-Hi) for water oxidation was prepared in 2-[4-(2-hydroxyethyl) piperazin-1-yl]ethanesulfonic acid buffer at pH 7.0 through a unique cyclic voltammetry electrodeposition method by applying a wide scan range from 1.40 to -1.00 V versus normal hydrogen electrode (NHE). This catalyst film displayed highly efficient activity during oxygen evolution in neutral aqueous solution. An impressive current density of more than 1.5 mAcm(-2) that was stable over a prolonged time period was obtained with a remarkably low onset overpotential of 230 mV in 0.1 M phosphate buffer (pH 7.0).

  • 8. Coll, Mercedes
    et al.
    Pamies, Oscar
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dieguez, Montserrat
    Second-Generation Amino Acid Furanoside Based Ligands from D-Glucose for the Asymmetric Transfer Hydrogenation of Ketones2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 12, p. 3821-3828Article in journal (Refereed)
    Abstract [en]

    A novel series of modular amino acid thioamide ligands functionalized with carbohydrates were introduced and employed in the rhodium-catalyzed asymmetric transfer hydrogenation (ATH) of aryl alkyl ketones, including the less-studied heteroaromatic ketones. The ligands are based on amino acid hydroxyamides (pseudodipeptides), which are the most successful ligands previously used in asymmetric hydrogen transfer reactions. High enantioselectivities [up to 99% enantiomeric excess (ee)] were achieved in the ATH of a wide range of aryl alkyl ketones by using catalysts generated insitu from [RhCl2Cp*](2) (Cp*=C5Me5) and thioamide ligands comprising a 3-benzyl glucofuranoside backbone and a bulky isopropyl group in the -amino acid moiety. Interestingly, both enantiomers of the alcohol products can readily be obtained with high enantioselectivity by simply changing the absolute configuration of the -amino acid. The good performance can be extended to a very challenging class of industrially interesting heteroaromatic ketones (up to 99%ee).

  • 9.
    Dawange, Monali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Galkin, Maxim V.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Selective Aerobic Benzylic Alcohol Oxidation of Lignin Model Compounds: Route to Aryl Ketones2015In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 3, p. 401-404Article in journal (Refereed)
    Abstract [en]

    A mild and chemoselective oxidation of the -alcohol in -O-4-ethanoaryl and -O-4-glycerolaryl ethers has been developed. The benzylic alcohols were selectively dehydrogenated to the corresponding ketones in 60-93% yield. A one-pot selective route to aryl ethyl ketones was performed. The catalytic system comprises recyclable heterogeneous palladium, mild reaction conditions, green solvents, and oxygen in air as oxidant. Catalytic amounts of a coordinating polyol were found pivotal for an efficient aerobic oxidation.

  • 10.
    Dinér, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sadhukhan, Arghya
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Blomkvist, Björn
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Chiral Sulfinamides as Highly Enantioselective Organocatalysts2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 11, p. 3063-3066Article in journal (Refereed)
  • 11.
    Fatih Polat, Muhammed
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hettmanczyk, Lara
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Zhang, Wei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Szabo, Zoltan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Franzén, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    One-Pot, Two-Step Protocol for the Catalytic Asymmetric Synthesis of Optically Active N,O- and O,O-Acetals2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 6, p. 1334-1339Article in journal (Refereed)
  • 12.
    Fransson, Linda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Biotechnology (BIO), Biochemistry. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Laurell, Anna
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Widyan, Khalid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Wingstrand, Erica
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Minor Enantiomer Recycling-Effect of Two Reinforcing Catalysts on Product Yield and Enantiomeric Excess2010In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 2, no 6, p. 683-693Article in journal (Refereed)
    Abstract [en]

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

  • 13.
    Galkin, Maxim V.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Sawadjoon, Supaporn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Rohde, Volker
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Dawange, Monali
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Synthetical Organic Chemistry.
    Mild Heterogeneous Palladium-Catalyzed Cleavage of beta-O-4 '-Ether Linkages of Lignin Model Compounds and Native Lignin in Air2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 1, p. 179-184Article in journal (Refereed)
    Abstract [en]

    A mild and robust heterogeneous palladium-catalyzed CO bond cleavage of 2-aryloxy-1-arylethanols using formic acid as reducing agent in air was developed. The cleaved products were isolated in 92-98% yield; and by slightly varying the reaction conditions, a ketone, an alcohol, or an alkane can be generated in near-quantitative yield. This reaction is applicable to cleaving the -O-4-ether bond found in lignin polymers of different origin. The reaction was performed on a lignin polymer model to generate either the monomeric aryl ketone or alkane in a quantitative yield. Moderate depolymerization was achieved with native lignin at similar reaction conditions. Mechanistic studies under kinetic control indicate that an initial palladium-catalyzed dehydrogenation of the alcohol is followed by insertion of palladium to an enol equivalent. A palladium-formato complex reductively cleaves the palladium-enolate complex to generate the ketone.

  • 14. Garcia-Martinez, Javier
    et al.
    Xiao, Changhong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Cychosz, Katie A.
    Li, Kunhao
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Thommes, Matthias
    Evidence of Intracrystalline Mesostructured Porosity in Zeolites by Advanced Gas Sorption, Electron Tomography and Rotation Electron Diffraction2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 11, p. 3110-3115Article in journal (Refereed)
    Abstract [en]

    The small size of micropores (typically <1 nm) in zeolites causes slow diffusion of reactant and product molecules in and out of the pores and negatively impacts the product selectivity of zeolite based catalysts, for example, fluid catalytic cracking (FCC) catalysts. Size-tailored mesoporosity was introduced into commercial zeolite Y crystals by a simple surfactant-templating post-synthetic mesostructuring process. The resulting mesoporous zeolite Y showed significantly improved product selectivity in both laboratory testing and refinery trials. Advanced characterization techniques such as electron tomography, three-dimensional rotation electron diffraction, and high resolution gas adsorption coupled with hysteresis scanning and density functional theory, unambiguously revealed the intracystalline nature and connectivity of the introduced mesopores. They can be considered as molecular highways that help reactant and product molecules diffuse quickly to and away from the catalytically active sites within the zeolite crystals and, thus, shift the selectivity to favor the production of more of the valuable liquid fuels at reduced yields of coke and unconverted feed.

  • 15. Ghobril, Cynthia
    et al.
    Hammar, Peter
    Kodepelly, Sanjeevarao
    Spiess, Bernard
    Wagner, Alain
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Baati, Rachid
    Structure-Reactivity Relationship Studies for Guanidine-Organocatalyzed Direct Intramolecular Aldolization of Ketoaldehydes2010In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 2, no 12, p. 1573-1581Article in journal (Refereed)
    Abstract [en]

    Structure-reactivity studies are performed to explore the reaction mechanism of the guanidine-catalyzed intramolecular aldol reaction of ketoaldehydes. A large number of guanidine and guanidine-like catalysts are synthesized and their properties studied. Kinetic profiles and pK(a) values of the catalysts are measured and correlated to reaction barriers calculated using density functional theory (DFT). The DFT calculations show that structural rigidity influences the pKa of the guanidines. Although the basicity is a very important factor in the catalysis, it is not sufficient to fully account for its catalytic efficiency. The availability of two aligned nitrogen reaction sites for proton shuttling in the transition state is an essential feature that helps to rationalize the reactivity pattern and the activation mode for this family of organocatalysts.

  • 16.
    Gizinski, Damian
    et al.
    Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Blachucki, Wojciech
    Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Srebowata, Anna
    Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Zienkiewicz-Machnik, Malgorzata
    Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Goszewska, Ilona
    Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Matus, Krzysztof
    Silesian Tech Univ, Inst Engn Mat & Biomat, Konarskiego 18 A, PL-44100 Gliwice, Poland.
    Lisovytskiy, Dmytro
    Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Pisarek, Marcin
    Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Szlachetko, Jakub
    Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland;Polish Acad Sci, Inst Nucl Phys, Ul Radzikowskiego 152, PL-31342 Krakow, Poland.
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    On-the-fly Catalyst Accretion and Screening in Chemoselective Flow Hydrogenation2018In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 10, no 17, p. 3641-3646Article in journal (Refereed)
    Abstract [en]

    Herein, it is reported an on-the-fly accretion/reaction protocol to evaluate the structure-performance relationship in the chemoselective flow citral hydrogenation over Ni-based catalysts. Based on the methodology one was able to determine Ni nanoparticles ideal average size (ca. 9nm), in a rapid and facile manner. The methodology offers a simple workflow, cost-effective and adaptable strategy for process intensification and optimization.

  • 17.
    Hamberg, Anders
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Magnusson, Anders
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hu, Francis J.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Selective Monoacylation of Diols by Substrate Assisted Catalysis in T40A Candida antarctica Lipase B2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 3, p. 743-747Article in journal (Refereed)
    Abstract [en]

    The selectivity towards diols over monoesters in the esterification of diols catalysed by lipase B from Candida antarctica (CALB) was improved by the single point mutation T40A in the enzyme's oxyanion hole. Substrate-assisted catalysis was suggested from molecular modelling of the tetrahedral intermediate in esterification of 1,2-ethanediol catalysed by T40A CALB. The non-reacting hydroxyl group of the diol forms a hydrogen bond to the oxyanion in the transition state, replacing that deleted in mutation. Monoester yields in transacylation reactions were monitored over time to compare the selectivities for wild-type and T40A CALB. The results showed increased selectivities towards the diols tested over their corresponding monoesters as a result of the T40A mutation with substrate-assisted catalysis as a plausible explanation.

  • 18. Kartusch, Christiane
    et al.
    Makosch, Martin
    Sa, Jacinto
    Hungerbuehler, Konrad
    van Bokhoven, Jeroen A.
    The Dynamic Structure of Gold Supported on Ceria in the Liquid Phase Hydrogenation of Nitrobenzene2012In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, no 2, p. 236-242Article in journal (Refereed)
  • 19.
    Laurell Nash, Anna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Widyan, Khalid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Moberg, Christina
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Recycling Powered by Release of Carbon Dioxide2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 12, p. 3314-3317Article in journal (Refereed)
    Abstract [en]

    In a cyclic process, fed with external chemical energy generated by the transformation of a compound with high chemical potential to carbon dioxide, the undesired enantiomer from a catalytic asymmetric reaction is continuously recycled to starting reagent. This minor enantiomer recycling is characterized by gradually increasing yields and product enantiomeric ratios. The requirements for maintaining a cyclic procedure are discussed; the necessity of a coupled exergonic process is demonstrated experimentally.

  • 20.
    Liu, Jian-Quan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry. Jiangsu Normal Univ, Jiangsu Key Lab Green Synth Funct Mat, Sch Chem & Chem Engn, Xuzhou 221116, Jiangsu, Peoples R China.
    Shen, Xuanyu
    Jiangsu Normal Univ, Jiangsu Key Lab Green Synth Funct Mat, Sch Chem & Chem Engn, Xuzhou 221116, Jiangsu, Peoples R China..
    Shatskiy, Andrey
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Zhou, Enlong
    Shandong Agr Univ, Coll Chem & Mat Sci, Tai An 271000, Shandong, Peoples R China..
    Kärkäs, Markus D.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Wang, Xiang-Shan
    Jiangsu Normal Univ, Jiangsu Key Lab Green Synth Funct Mat, Sch Chem & Chem Engn, Xuzhou 221116, Jiangsu, Peoples R China..
    Silver-Induced [3+2] Cycloaddition of Isocyanides with Acyl Chlorides: Regioselective Synthesis of 2,5-Disubstituted Oxazoles2019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899Article in journal (Refereed)
    Abstract [en]

    A silver-induced cycloaddition of isocyanides with acyl chlorides has been developed. This transition metal-catalyzed strategy provides an effective and scalable approach for the formation of 2,5-disubstituted oxazoles in good to high yields. The employed silver-based MOF catalyst can be efficiently recycled without compromising the yield.

  • 21.
    Maier, Annika Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Herceglija Iglebaek, Ena
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Confirming the formation of hydroxyl radicals in the catalytic decomposition of H2O2 on metal oxides using coumarin as a probe2019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899Article in journal (Refereed)
    Abstract [en]

    Hydrogen peroxide can be catalytically decomposed to O2 and H2O on metal oxide surfaces in contact with aqueous solutions containing H2O2. The initial step in this process has been proposed to be the formation of surface‐bound hydroxyl radicals which has recently been verified using tris as a radical scavenger. Here, we make use of the unique fluorescent product 7‐hydroxycoumarin formed in the reaction between hydroxyl radicals and coumarin to probe the formation of surface‐bound hydroxyl radicals. The experiments clearly show that 7‐hydroxycoumarin is formed upon catalytic decomposition of H2O2 in aqueous suspensions containing ZrO2‐particles and coumarin, thereby confirming the formation of surface‐bound hydroxyl radicals in this process. The results are quantitatively compared to results on the same system using tris as a probe for hydroxyl radicals. The effects of the two probes on the system under study are compared and it is concluded that coumarin has a significantly lower impact on the system.

  • 22.
    Maier, Annika Carolin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Pd‐Catalyzed Surface Reactions of Importance in Radiation Induced Dissolution of Spent Nuclear Fuel Involving H22019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899Article in journal (Refereed)
    Abstract [en]

    To assess the influence of metallic inclusions (ϵ‐particles) on the dissolution of spent nuclear fuel under deep repository conditions, Pd‐catalyzed reactions of H2O2, O2 and UO22+ with H2 were studied using Pd‐powder suspensions. U(VI) can efficiently be reduced to less soluble U(IV) on Pd‐particles in the presence of H2. The kinetics of the reaction was found to depend on the H2 partial pressure at pH2≤5.1×10−2 bar. In comparison, the H2 pressure dependence for the reduction of H2O2 on Pd also becomes evident below 5.1×10−2 bar. Surface bound hydroxyl radicals are formed as intermediate species produced during the catalytic decomposition of H2O2 on oxide surfaces. While a significant amount of surface bound hydroxyl radicals were scavenged during the catalytic decomposition of H2O2 on ZrO2, no scavenging was observed in the same reaction on Pd. This indicates a different reaction mechanism for H2O2 decomposition on Pd compared to metal oxides and is in contrast to current literature. While Pd is an excellent catalyst for the synthesis of H2O2 from H2 and O2, a similar catalytic activity that was previously proposed for ZrO2 could not be confirmed.

  • 23. Makosch, Martin
    et al.
    Sa, Jacinto
    Kartusch, Christiane
    Richner, Gilles
    van Bokhoven, Jeroen A.
    Hungerbuehler, Konrad
    Hydrogenation of Nitrobenzene Over Au/MeOx CatalystsuA Matter of the Support2012In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, no 1, p. 59-63Article in journal (Refereed)
  • 24.
    Naidu, Veluru Ramesh
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Ni, Shengjun
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Franzén, Johan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    The Carbocation: A Forgotten Lewis Acid Catalyst2015In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 13, p. 1896-1905Article in journal (Refereed)
    Abstract [en]

    A Lewis acid that has received negligible attention as a catalyst is the carbocation. The carbocation is isoelectronic to boron and owes its Lewis acidity to a low-lying empty p(C) orbital. In terms of reactivity and stability carbocations are very versatile Lewis acids, from the extremely unstable methylium cation to the water-stable tris(N,N-dimethylaniline) methylium ion (crystal violet). Although the Lewis acid properties of carbocations have been extensively studied since the discovery of the tropolium ion more than 130years ago there is only a handful examples on the application of carbocations as Lewis acid catalysts. Herein, the research on triarylmethylium (trityl)-cation catalysis is summarized. In light of the reports the trityl ion emerges as a highly efficient and highly versatile Lewis acid catalyst capable of catalyzing different classes of reactions often with high selectivity and low catalyst loadings (for some reactions down to ppm levels).

  • 25. Nobili, Alberto
    et al.
    Steffen-Munsberg, Fabian
    KTH, School of Biotechnology (BIO), Industrial Biotechnology. University of Greifswald, Germany .
    Kohls, Hannes
    Trentin, Ivan
    Schulzke, Carola
    Höhne, Matthias
    Bornscheuer, Uwe T.
    Engineering the Active Site of the Amine Transaminase from Vibrio fluvialis for the Asymmetric Synthesis of Aryl-Alkyl Amines and Amino Alcohols2015In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 5, p. 757-760Article in journal (Refereed)
    Abstract [en]

    Although the amine transaminase from Vibrio fluvialis has often been applied as a catalyst for the biocatalytic preparation of various chiral primary amines, it is not suitable for the transamination of a-hydroxy ketones and aryl-alkyl ketones bearing an alkyl substituent larger than a methyl group. We addressed this problem through a systematic mutagenesis study of active site residues to expand its substrate scope towards two bulky ketones. We identified two mutants (F85L/V153A and Y150F/V153A) showing 30-fold increased activity in the conversion of (S)-phenylbutylamine and (R)-phenylglycinol, respectively. Notably, they facilitated asymmetric synthesis of these amines with excellent enantiomeric purities of 98% ee.

  • 26.
    Nordin, Mikael
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liao, Rong-Zhen
    Ahlford, Katrin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Theoretical study of asymmetric transfer hydrogenation of ketones catalyzed by amino acid derived rhodium complexes2012In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, no 8, p. 1095-1104Article in journal (Refereed)
    Abstract [en]

    Density functional theory calculations are employed to study the asymmetric transfer hydrogenation of ketones catalyzed by rhodiumarene complexes containing hydroxamic acid-functionalized amino acid ligands. Firstly, the ligandmetal binding is investigated and it is shown that both the N,N and O,O binding modes Are viable. For each of these, the full free energy profile for the transfer hydrogenation is calculated according to the outer-sphere reaction mechanism. Three factors are demonstrated to influence the stereoselectivity of the process, namely the energy difference between the metalligand binding modes, the energy difference between the intermediate hydrogenated catalyst, and the existence of a stabilizing CHp interaction between the Cp* ligand of the catalyst and the phenyl moiety of the substrate. Theoretical reproduction of the selectivity of a slightly modified ligand that is shown experimentally to yield the opposite enantioselectivity corroborates these results. Finally, a technical observation made is that inclusion of dispersion interactions (using the B3LYP-D2 correction or the M06 functional) proved to be very important for reproducing the enantioselectivity.

  • 27. Orrego, Alejandro H.
    et al.
    Lopez-Gallego, Fernando
    Espaillat, Akbar
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Cava, Felipe
    Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR).
    Guisan, Jose M.
    Rocha-Martin, Javier
    One‐step Synthesis of α‐Keto Acids from Racemic Amino Acids by A Versatile Immobilized Multienzyme Cell‐free System2018In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 10, no 14, p. 3002-3011Article in journal (Refereed)
    Abstract [en]

    The elevated value of α‐keto acids has pushed scientists to explore more efficient and less expensive alternatives for their synthesis. In this work, an immobilized tri‐enzyme system that produced α‐keto acids in “one‐pot” from l‐ or racemic mixtures of diverse amino acids was presented. The system combined a broad‐spectrum amino acid racemase (BsrV), a d‐amino acid oxidase (DAAO) and catalase (CAT). BsrV racemized l‐amino acids into their d‐enantiomers, DAAO catalyzed the stereospecific oxidative deamination of the d‐amino acids into their corresponding α‐keto acids, ammonium ion, and H2O2. Finally, CAT converted the inactivating H2O2 into H2O and O2, which can be reused by the oxidase reaction. BsrV thermal stability was improved 3,300‐fold by immobilizing the enzyme on glyoxyl‐activated agarose beads. DAAO and CAT were co‐immobilized on agarose beads functionalized with glutaraldehyde groups for enhancing their stabilities and eliminating H2O2 in a much more effective way. To show the versatility of this system, racemic mixtures of amino acids were converted in their corresponding α‐keto acids. The coupling of the three immobilized enzymes permitted conversions of approximately 99 % through a dynamic kinetic resolution process. This system conserved 100 % of its initial effectiveness after 8 reaction cycles. Collectively, our innovative tri‐enzyme system for the synthesis of α‐keto acids opens the door for a cheapening in the production of many pharmaceutical and cosmetics.

  • 28.
    Ozer, Lütfiye Y.
    et al.
    Khalifa Univ Sci & Technol, Masdar Inst Masdar City, Dept Chem Engn, POB 54224, Abu Dhabi, U Arab Emirates.
    Apostoleris, Harry
    Khalifa Univ Sci & Technol, Masdar Inst Masdar City, Dept Mech Engn, POB 54224, Abu Dhabi, U Arab Emirates.
    Ravaux, Florent
    Khalifa Univ Sci & Technol, Masdar Inst Masdar City, Dept Mech Engn, POB 54224, Abu Dhabi, U Arab Emirates.
    Shylin, Sergii I.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Mamedov, Fikret
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Chiesa, Matteo
    Khalifa Univ Sci & Technol, Masdar Inst Masdar City, Dept Mech Engn, POB 54224, Abu Dhabi, U Arab Emirates; Arctic Univ Norway UiT, Arctic Renewable Energy Ctr ARC, Dept Phys & Technol, Tromso, Norway.
    Sá, Jacinto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Warsaw, Poland.
    Palmisano, Giovanni
    Khalifa Univ Sci & Technol, Masdar Inst Masdar City, Dept Chem Engn, POB 54224, Abu Dhabi, U Arab Emirates.
    Long-Lasting Non-hydrogenated Dark Titanium Dioxide: Medium Vacuum Anneal for Enhanced Visible Activity of Modified Multiphase Photocatalysts2018In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 10, no 14, p. 2949-2954Article in journal (Refereed)
    Abstract [en]

    Multiphase TiO2 was stably modified by vacuum treatment for a dramatic improvement in visible-light absorption and photocatalytic reactivity. The samples were made of rutile-brookite, bare or N doped, and were grown on reduced graphene oxide. The stable introduction of Ti3+ species and oxygen vacancies resulting in mitigated electron?hole recombination was identified as the main responsible factor, along with a change in surface charges.

  • 29. Roberts, F. Sloan
    et al.
    Kuhl, Kendra P.
    Nilsson, Anders
    Stockholm University, Faculty of Science, Department of Physics. SLAC National Accelerator Laboratory, USA.
    Electroreduction of Carbon Monoxide Over a Copper Nanocube Catalyst: Surface Structure and pH Dependence on Selectivity2016In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 8, no 6, p. 1119-1124Article in journal (Refereed)
    Abstract [en]

    The activity and selectivity for CO2/CO reduction over Cu electrodes is strongly dependent on the local surface structure of the catalyst and the pH of the electrolyte. Here we investigate a unique, Cu nanocube surface (CuCube) as a CO reduction electrode under neutral and basic pH by using online electrochemical mass spectroscopy (OLEMS) to determine the onset potentials and relative intensities of methane and ethylene production. To relate the unique selectivity to the surface structure, the CuCube surface reactivity is compared to polycrystalline Cu and three single crystals under the same reaction conditions. We find that the high selectivity for ethylene over the CuCube surface is most comparable to the Cu(100) surface, which has a cubic unit cell. However, the suppression of methane production over CuCube is unique to that particular surface. A basic pH is shown to enhance ethylene selectivity on all surfaces, and again the CuCube surface is unique.

  • 30.
    Rodrigues, Diogo
    et al.
    Novartis Pharma AG, 4002 Basel, Switzerland.
    Kittelmann, M.
    Eggimann, F.
    Bachler, T.
    Abad, S.
    Camattari, A.
    Glieder, A.
    Winkler, M.
    Lütz, S.
    Production of recombinant human aldehyde oxidase in Escherichia coli and optimization of its application for the preparative synthesis of oxidized drug metabolites2014In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 6, no 4, p. 1028-1042Article in journal (Refereed)
    Abstract [en]

    Recombinant human aldehyde oxidase (AO) was expressed in Escherichia coli. Different cell disruption methods and conditions of cell culture in shake flasks and bioreactors and of biotransformation on an analytical scale were tested to optimize the synthesis of oxidized AO drug metabolites. The volumetric productivity was increased 24-fold by optimizing the cell culture conditions. The highest yield was achieved in a 25 L stirred tank bioreactor under non-oxygen-limited conditions and high lactose feed rate. Suspensions of highly concentrated and well-aerated whole cells at neutral pH and relatively low temperatures led to the best conversion. The solvent for the substrate and the buffering agent for the biotransformation had an important effect. In a biotransformation with AO, 210 mg of famciclovir was converted to diacetyl penciclovir a yield of 82 %. The optimized protocol represents a viable method for the preparative synthesis of oxidized AO metabolites of drugs. Drug metabolites: Recombinant human aldehyde oxidase is expressed in Escherichia coli. The highest volumetric productivity is achieved in a 25 L stirred tank bioreactor under non-oxygen-limited conditions and high lactose feed rate. In a biotransformation with concentrated whole cells at pH 7.4 and 30 °C, 210 mg of famciclovir is converted to diacetyl penciclovir in a yield of 82 %. The optimized protocol enables the preparative synthesis of oxidized aldehyde oxidase metabolites of drugs.

  • 31.
    Ruggieri, Federica
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Industrial Biotechnology. SARom Biostruct AB, SE-22381 Lund, Sweden.
    van Langen, Luuk M.
    Logan, Derek T.
    Walse, Björn
    Berglund, Per
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Industrial Biotechnology.
    Transaminase-catalyzed racemization with potential for dynamic kinetic resolutions2018In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 10, no 21, p. 5026-5032Article in journal (Refereed)
    Abstract [en]

    Dynamic kinetic resolution (DKR) reactions in which a stereoselective enzyme and a racemization step are coupled in one‐pot would represent powerful tools for the production of enantiopure amines through enantioconvergence of racemates. The exploitation of DKR strategies is currently hampered by the lack of effective, enzyme‐compatible and scalable racemization strategies for amines. In the present work, the proof of concept of a fully biocatalytic method for amine racemization is presented. Both enantiomers of the model compound 1‐methyl‐3‐phenylpropylamine could be racemized in water and at room temperature using a couple of wild‐type, non‐proprietary, enantiocomplementary amine transaminases and a minimum amount of pyruvate/alanine as a co‐substrate couple. The biocatalytic simultaneous parallel cascade reaction presented here poses itself as a customizable amine racemization system with potential for the chemical industry in competition with traditional transition‐metal catalysis.

  • 32. Sa, Jacinto
    et al.
    Ace, Matthew
    Jose Delgado, Juan
    Goguet, Alexandre
    Hardacre, Christopher
    Morgan, Kevin
    Activation of Alkanes by Gold-Modified Lanthanum Oxide2011In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 3, no 2, p. 394-398Article in journal (Refereed)
  • 33.
    Sahoo, Suman
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Lundberg, Helena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Edén, Mattias
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Physical Chemistry.
    Ahlsten, Nanna
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wan, Wei
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Single Site Supported Cationic Rhodium(I) Complexes for the Selective Redox Isomerization of Allylic Alcohols2012In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, no 2, p. 243-250Article in journal (Refereed)
    Abstract [en]

    The isomerization of allylic alcohols to carbonyl compounds by a heterogeneous rhodium complex is reported. Different silica material supports and catalyst/ligand systems were evaluated. The most efficient catalyst in terms of catalytic activity and stability was found to be a cationic rhodium(I) complex with sulfonated phosphine ligands anchored on a mesoporous aluminosilica AlSBA-15. The heterogeneous complex catalyzed the isomerization of a variety of allylic alcohols in excellent yields with very low catalyst loadings (0.5 mol %). The catalyst could be recycled without significant loss of activity or selectivity. The optimized catalyst was characterized by N2 sorption, powder X-ray diffraction, transmission electron microscopy, as well as solution and solid-state nuclear magnetic resonance, and Fourier Transform infrared spectroscopies.

  • 34.
    Shatskiy, Andrey
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kivijärvi, Tove
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lundberg, Helena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tinnis, Fredrik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ruthenium-Catalyzed Asymmetric Transfer Hydrogenation of Propargylic Ketones2015In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 23, p. 3818-3821Article in journal (Refereed)
    Abstract [en]

    The asymmetric transfer hydrogenation of alpha,beta-propargyl ketones catalyzed by an in situ formed ruthenium-hydroxyamide complex was explored. The acetylenic alcohols were isolated in good to excellent yields with excellent ee values (typically >90%) after short reaction times at room temperature.

  • 35.
    Singh, Prem
    et al.
    Indian Inst Technol Mandi, India.
    Sonika,
    Indian Inst Technol Mandi, India.
    Gangadharan, Pranav K.
    CSIR Natl Chem Lab, India; Acad Sci and Innovat Res AcSIR, India.
    Khan, Ziyauddin
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Kurungot, Sreekumar
    CSIR Natl Chem Lab, India; Acad Sci and Innovat Res AcSIR, India.
    Jaiswal, Amit
    Indian Inst Technol Mandi, India.
    Cubic Palladium Nanorattles with Solid Octahedron Gold Core for Catalysis and Alkaline Membrane Fuel Cell Applications2019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 11, no 17, p. 4383-4392Article in journal (Refereed)
    Abstract [en]

    Herein, we report the synthesis of palladium nanorattles (Au-Pd NRTs) comprising of a gold octahedral core caged within a thin porous cubic palladium shell. The introduction of core-shell and porous architecture was realized by combining seed mediated and galvanic replacement reaction techniques. Next, we examined the catalytic efficiency of the nanocatalyst in comparison with solid palladium nanocube (Pd-NC) of similar size for the degradation of p-nitrophenol and organic dyes. The rate constant of Au-Pd NRTs was found nearly 12 times higher than the Pd-NCs. Further, we exploited our catalyst for electrochemical oxygen reduction reaction (ORR) and observed its high intrinsic ORR activity. Compared with commercialized Pt/C, the Au-Pd NRT displayed nearly comparable onset and half-wave potential values and excellent durability upon potential cycling. The system level validation in a single-cell mode of alkaline exchange membrane fuel cell also confirms the efficiency of the present catalyst to serve as a potential cathode catalyst for realistic device applications.

  • 36. Sjöblom, Magnus
    et al.
    Risberg, Per
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Filippova, Alfia
    Öhrman, Olov G. W.
    Rova, Ulrika
    Christakopoulos, Paul
    In Situ Biocatalytic Synthesis of Butyl Butyrate in Diesel and Engine Evaluations2017In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 9, no 24, p. 4529-4537Article in journal (Refereed)
    Abstract [en]

    Blending petroleum fuels with biofuels is likely to become increasingly important over the years to come. Butyl butyrate has promising characteristics as a blend component in diesel and can be synthesized by lipase-catalyzed esterification of 1-butanol and butyric acid, which both can be derived from fermentation technologies. In the current study, the enzyme load and reaction temperature were optimized for the production of butyl butyrate with Novozyme 435 ( immobilized Candida antarctica lipase B) directly in diesel at a substrate concentration of 1m using a molar ratio of 1:1 between n-butanol and butyric acid. Optimum conditions were found by using a central composite design at an enzyme load of 12% of substrate weight and a temperature of 57 degrees C, giving 90% yield conversion in 30 min, corresponding to a butyl butyrate productivity of 1.8 mol L(-1)h(-1). Diesel blended with 5, 10, and 30% butyl butyrate was tested in a heavy-duty diesel engine under two load cases. The ignition properties of the blended fuels were very similar to pure diesel, making butyl butyrate an interesting diesel substitute. The emission analysis demonstrated lower soot and CO emissions, similar hydrocarbons levels and slightly increased NOx levels compared with using pure diesel. The high activity of lipase in diesel and the compatibility between diesel and butyl butyrate opens up the possibility to develop fuel blending systems where the synthesis of the blendin component occurs directly in the fuel.

  • 37.
    Sjöblom, Magnus
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Risberg, Per
    Internal Combustion Engines, Department of Machine Design, Royal Institute of Technology, Stockholm..
    Filippova, Alfia
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Öhrman, Olov G W
    RISE Energy Technology Center, Piteå.
    Rova, Ulrika
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    Christakopoulos, Paul
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.
    In Situ Biocatalytic Synthesis of Butyl Butyrate in Diesel and Engine Evaluations2017In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 9, no 24, p. 4529-4537Article in journal (Refereed)
    Abstract [en]

    Blending petroleum fuels with biofuels is likely to become increasingly important over the years to come. Butyl butyrate has promising characteristics as a blend component in diesel and can be synthesized by lipase-catalyzed esterification of 1-butanol and butyric acid, which both can be derived from fermentation technologies. In the current study, the enzyme load and reaction temperature were optimized for the production of butyl butyrate with Novozyme435 (immobilized Candida antarctica lipaseB) directly in diesel at a substrate concentration of 1m using a molar ratio of 1:1 between n-butanol and butyric acid. Optimum conditions were found by using a central composite design at an enzyme load of 12% of substrate weight and a temperature of 57°C, giving 90% yield conversion in 30min, corresponding to a butyl butyrate productivity of 1.8molL-1h-1. Diesel blended with 5, 10, and 30% butyl butyrate was tested in a heavy-duty diesel engine under two load cases. The ignition properties of the blended fuels were very similar to pure diesel, making butyl butyrate an interesting diesel substitute. The emission analysis demonstrated lower soot and CO emissions, similar hydrocarbons levels and slightly increased NOx levels compared with using pure diesel. The high activity of lipase in diesel and the compatibility between diesel and butyl butyrate opens up the possibility to develop fuel blending systems where the synthesis of the blend-in component occurs directly in the fuel.

  • 38.
    Sjöblom, Magnus
    et al.
    Luleå University of Technology, Sweden.
    Risberg, Per
    KTH Royal Institute of Technology, Sweden.
    Filippova, Alfia
    Luleå University of Technology, Sweden.
    Öhrman, Olov G.W.
    RISE - Research Institutes of Sweden, Bioeconomy, ETC Energy Technology Center.
    Rova, Ulrika
    Luleå University of Technology, Sweden.
    Christakopoulos, Paul
    Luleå University of Technology, Sweden.
    In Situ Biocatalytic Synthesis of Butyl Butyrate in Diesel and Engine Evaluations2017In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 9, no 24, p. 4529-4537Article in journal (Refereed)
    Abstract [en]

    Blending petroleum fuels with biofuels is likely to become increasingly important over the years to come. Butyl butyrate has promising characteristics as a blend component in diesel and can be synthesized by lipase-catalyzed esterification of 1-butanol and butyric acid, which both can be derived from fermentation technologies. In the current study, the enzyme load and reaction temperature were optimized for the production of butyl butyrate with Novozyme 435 (immobilized Candida antarctica lipase B) directly in diesel at a substrate concentration of 1 m using a molar ratio of 1:1 between n-butanol and butyric acid. Optimum conditions were found by using a central composite design at an enzyme load of 12 % of substrate weight and a temperature of 57 °C, giving 90 % yield conversion in 30 min, corresponding to a butyl butyrate productivity of 1.8 mol L−1 h−1. Diesel blended with 5, 10, and 30 % butyl butyrate was tested in a heavy-duty diesel engine under two load cases. The ignition properties of the blended fuels were very similar to pure diesel, making butyl butyrate an interesting diesel substitute. The emission analysis demonstrated lower soot and CO emissions, similar hydrocarbons levels and slightly increased NOx levels compared with using pure diesel. The high activity of lipase in diesel and the compatibility between diesel and butyl butyrate opens up the possibility to develop fuel blending systems where the synthesis of the blend-in component occurs directly in the fuel.

  • 39.
    Slagbrand, Tove
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kivijärvi, Tove
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Adolfsson, Hans
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bimetallic Catalysis: Asymmetric Transfer Hydrogenation of Sterically Hindered Ketones Catalyzed by Ruthenium and Potassium2015In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 7, no 21, p. 3445-3449Article in journal (Refereed)
    Abstract [en]

    An efficient protocol for the asymmetric reduction of sterically hindered ketones under transfer-hydrogenation conditions was developed. The corresponding chiral alcohols were obtained in good to excellent yields with enantiomeric excess values up to 99%. The role of the cation associated with the base present in the reduction reaction was investigated. In contrast to previous studies on this catalyst system, potassium ions rather than lithium ions significantly enhanced the reaction outcome.

  • 40. Steffen-Munsberg, F.
    et al.
    Vickers, C.
    Thontowi, A.
    Schätzle, S.
    Meinhardt, T.
    Svedendahl Humble, M.
    Land, Henrik
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Bornscheuer, U. T.
    Höhne, M.
    Revealing the Structural Basis of Promiscuous Amine Transaminase Activity2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 1, p. 154-157Article in journal (Refereed)
  • 41. Steffen-Munsberg, F.
    et al.
    Vickers, C.
    Thontowi, A.
    Schätzle, S.
    Tumlirsch, T.
    Svedendahl Humble, M.
    Land, Henrik
    KTH, School of Biotechnology (BIO), Biochemistry.
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Bornscheuer, U. T.
    Höhne, M.
    Connecting Unexplored Protein Crystal Structures to Enzymatic Function2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 1, p. 150-153Article in journal (Refereed)
  • 42. Steffen-Munsberg, Fabian
    et al.
    Vickers, Clare
    Thontowi, Ahmad
    Schaetzle, Sebastian
    Meinhardt, Tina
    Humble, Maria Svedendahl
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Land, Henrik
    Berglund, Per
    Bornscheuer, Uwe T.
    Hoehne, Matthias
    Revealing the structural basis of promiscuous amine transaminase activity2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 1, p. 154-157Article in journal (Refereed)
  • 43. Steffen-Munsberg, Fabian
    et al.
    Vickers, Clare
    Thontowi, Ahmad
    Schaetzle, Sebastian
    Tumlirsch, Tony
    Humble, Maria Svedendahl
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Land, Henrik
    Berglund, Per
    Bornscheuer, Uwe T.
    Hoehne, Matthias
    Connecting unexplored protein crystal structures to enzymatic function2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 1, p. 150-153Article in journal (Refereed)
  • 44. Sterchele, Stefano
    et al.
    Biasi, Pierdomenico
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Abo Akad Univ, Johan Gadolin Proc Chem Ctr, Lab Ind Chem & React Engn, Dept Chem Engn, Biskopsgatan 8, FI-20500 Abo Turku, Finland.
    Centomo, Paolo
    Shchukarev, Andrey
    Kordás, Krisztian
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Univ Oulu, EMPART Res Grp Infotech Oulu, Microelect & Mat Phys Labs, Fac Technol, FI-90014 Oulu, Finland.
    Rautio, Anne-Riika
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Abo Akad Univ, Johan Gadolin Proc Chem Ctr, Lab Ind Chem & React Engn, Dept Chem Engn, Biskopsgatan 8, FI-20500 Abo Turku, Finland.
    Salmi, Tapio
    Canton, Patrizia
    Zecca, Marco
    Influence of Metal Precursors and Reduction Protocols on the Chloride-Free Preparation of Catalysts for the Direct Synthesis of Hydrogen Peroxide without Selectivity Enhancers2016In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 8, no 8, p. 1564-1574Article in journal (Refereed)
    Abstract [en]

    Different metal precursors and reducing agents were applied in the preparation of 1 wt % Pd catalysts supported on commercial ion-exchange resin (Lewatit K2621) and used in the direct synthesis of H2O2. The catalysts were characterized by using TEM and their performance was evaluated in the direct synthesis of H2O2 (in a batch and semi-batch reactor) to investigate the relationship between the catalyst preparation methods, morphology, and catalytic performance. As expected, both the choice of the Pd precursor and the reduction conditions had a strong influence on the size and size distribution of the resulting supported nanostructured metal nanoparticles and, consequently, on the catalytic performance. The best combination of metal precursor and reduction agent was [Pd(NH3)4]SO4 reduced with hydrogen. This catalyst had the largest average size of the Pd nanoparticles and the broadest size distribution.

  • 45. Sugano, Yasuhito
    et al.
    Kumar, Narendra
    Peurla, Markus
    Roine, Jorma
    Aho, Atte
    Bobacka, Johan
    Mikkola, Jyri-Pekka
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Åbo Akademi, University Faculty of Science and Engineering, Turku, Finland.
    Specific Electrocatalytic Oxidation of Cellulose at Carbon Electrodes Modified by Gold Nanoparticles2016In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 8, no 14, p. 2401-2405Article in journal (Refereed)
    Abstract [en]

    The influence of the size and oxidation state of Au nanoparticles (AuNPs) as electrocatalysts for the electro-oxidation of cellulose was studied. Carbon paper electrodes modified with AuNPs were used as the electrocatalysts for the electro-oxidation of cellulose dissolved in 1.3 m NaOH. The size and oxidation state of the AuNPs were determined by using SEM, TEM, and X-ray photoelectron spectroscopy. Both the size and the oxidation state of the AuNPs were found to influence the electrocatalytic properties of the electrode, as studied by using cyclic voltammetry, square wave voltammetry, and electrochemical impedance spectroscopy. The carbon paper electrodes decorated with AuNPs (less than 25 nm) that consist of metallic Au gave rise to a significantly higher electrocatalytic activity than a bare polycrystalline Au electrode.

  • 46.
    Svedendahl Humble, Maria
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Engelmark Cassimjee, Karim
    KTH, School of Biotechnology (BIO), Biochemistry.
    Abedu, Vahak
    Federsel, Hans-Jürgen
    Berglund, Per
    KTH, School of Biotechnology (BIO), Biochemistry.
    Key Amino Acid Residues for Reversed or Improved Enantiospecificity of an omega-Transaminase2012In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, no 8, p. 1167-1172Article in journal (Refereed)
    Abstract [en]

    Transaminases inherently possess high enantiospecificity and are valuable tools for stereoselective synthesis of chiral amines in high yield from a ketone and a simple amino donor such as 2-propylamine. Most known ?-transaminases are (S)-selective and there is, therefore, a need of (R)-selective enzymes. We report the successful rational design of an (S)-selective ?-transaminase for reversed and improved enantioselectivity. Previously, engineering performed on this enzyme group was mainly based on directed evolution, with few exceptions. One reason for this is the current lack of 3D structures. We have explored the ?-transaminase from Chromobacterium violaceum and have used a homology modeling/rational design approach to create enzyme variants for which the activity was increased and the enantioselectivity reversed. This work led to the identification of key amino acid residues that control the activity and enantiomeric preference. To increase the enantiospecificity of the C. violaceum ?-transaminase, a possible single point mutation (W60C) in the active site was identified by homology modeling. By site-directed mutagenesis this enzyme variant was created and it displayed an E value improved up to 15-fold. In addition, to reverse the enantiomeric preference of the enzyme, two other point mutations (F88A/A231F) were identified. This double mutation created an enzyme variant, which displayed substrate dependent reversed enantiomeric preference with an E value shifted from 3.9 (S) to 63 (R) for 2-aminotetralin.

  • 47.
    Syrén, Per-Olof
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Le Joubioux, Florian
    Ben Henda, Yesmine
    Maugard, Thierry
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Graber, Marianne
    Proton Shuttle Mechanism in the Transition State of Lipase-Catalyzed N-Acylation of Amino Alcohols2013In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 5, no 7, p. 1842-1853Article in journal (Refereed)
    Abstract [en]

    An increased reaction rate for lipase-catalyzed N-acylation of amino alcohols relative to that of monofunctionalized amines can be explained by a hydrogen shuttling mechanism that avoids nitrogen inversion in the transition state. The mechanism does not involve acyl migration from an ester intermediate that would be formed first, an explanation that permeates the literature. Our suggested reaction mechanism is dependent on the preference of amino alcohols to form intramolecular hydrogen bonds and the capability of the enzyme to accommodate and exploit the specific hydrogen bonding pattern provided by the ligand during catalysis. Our proposed proton shuttle mechanism involves the transfer of two protons in the transition state concomitant with a nucleophilic attack on the acyl enzyme and provides an explanation for the high reaction rate and chemoselectivity for lipase-catalyzed N-acylation of amino alcohols. Moreover, the proton shuttle mechanism explains the increased reaction rate for the enzyme-catalyzed N-acylation of diamines and of methoxy-2-propylamine, for which O- to N-acyl migration is impossible. A linear free-energy relationship analysis based on the experimental results showed that all of our investigated difunctionalized amine substrates afforded a substrate-assisted rate acceleration of the N-acylation by the same reaction mechanism. Furthermore, the results of the analysis were consistent with partial proton transfer in the rate-limiting transition state, which further supports our suggested proton shuttle mechanism.

  • 48.
    Sá, Jacinto
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Polish Acad Sci, Inst Phys Chem, Ul Kasprzaka 44-52, PL-01224 Warsaw, Poland.
    Medlin, J. Will
    Univ Colorado, Dept Chem & Biol Engn, JSCBB D125 3415 Colorado Ave, Boulder, CO 80303 USA.
    On-the-fly Catalyst Modification: Strategy to Improve Catalytic Processes Selectivity and Understanding2019In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 11, no 15, p. 3355-3365Article, review/survey (Refereed)
    Abstract [en]

    Hydrogenation is a quintessential process to the chemical industry. It is heavily involved in organic synthesis and fuel production, among other processes. Preferentially the reactions are carried out with heterogeneous catalysts and when possible in flow mode. Herein, we provide a retrospective on selective surface modification of catalysts for improved selectivity and understanding of catalytic reactivity. In addition, we provide a prospectus for an emerging strategy of carrying out surface modification on-the-fly to produce novel catalysts in a fast and reproducible way and to understand catalytic phenomena.

  • 49. Taylor, Sarah F. R.
    et al.
    Sa, Jacinto
    Hardacre, Christopher
    Friedel-Crafts Alkylation of Aromatics with Benzyl Alcohol over Gold-Modified Silica2011In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 3, no 1, p. 119-121Article in journal (Refereed)
  • 50.
    Tsupova, Svetlana
    et al.
    Heidelberg Univ, Organ Chem Inst, Neuenheimer Feld 270, D-69120 Heidelberg, Germany..
    Cadu, Alban
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry. Heidelberg Univ, Organ Chem Inst, Neuenheimer Feld 270, D-69120 Heidelberg, Germany..
    Stuck, Fabian
    Heidelberg Univ, Organ Chem Inst, Neuenheimer Feld 270, D-69120 Heidelberg, Germany..
    Rominger, Frank
    Heidelberg Univ, Organ Chem Inst, Neuenheimer Feld 270, D-69120 Heidelberg, Germany..
    Rudolph, Matthias
    Heidelberg Univ, Organ Chem Inst, Neuenheimer Feld 270, D-69120 Heidelberg, Germany..
    Samec, Joseph S. M.
    Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Hashmi, A. Stephen K.
    Heidelberg Univ, Organ Chem Inst, Neuenheimer Feld 270, D-69120 Heidelberg, Germany.;King Abdulaziz Univ, Fac Sci, Dept Chem, Jeddah 21589, Saudi Arabia..
    Dual Gold(I)-catalyzed Cyclization of Dialkynyl Pyridinium Salts2017In: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 9, no 11, p. 1915-1920Article in journal (Refereed)
    Abstract [en]

    Novel dialkynyl pyridines were synthesized and protected as alkyl salts for dual gold(I)-catalyzed cycloisomerization. Different alkyl groups and counter ions were screened for the salts, with benzyl and hexafluorophosphate providing the best results. The cyclization led to NMR yields of >95% being obtained for a number of substrates. Step-wise hydrogenation of products could be performed in one-pot by Pd/C, with selective reduction of the double bonds, followed by deprotection of the benzyl group.

12 1 - 50 of 61
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