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  • 1. Afewerki, Samson
    et al.
    Ibrahem, Ismail
    Rydfjord, Jonas
    Breistein, Palle
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Direct Regiospecific and Highly Enantioselective Intermolecular α-Allylic Alkylation of Aldehydes by a Combination of Transition-Metal and Chiral Amine Catalysts2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 10, s. 2972-2977Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first direct intermolecular regiospecific and highly enantioselective a-allylic alkylation of linear aldehydes by a combination of achiral bench-stable Pd0 complexes and simple chiral amines as co-catalysts is disclosed. The co-catalytic asymmetric chemoselective and regiospecific a-allylic alkylation reaction is linked in tandem with in situ reduction to give the corresponding 2-alkyl alcohols with high enantiomeric ratios (up to 98:2 e.r.; e.r.=enantiomeric ratio). It is also an expeditious entry to valuable 2-alkyl substituted hemiacetals, 2-alkyl-butane-1,4-diols, and amines. The concise co-catalytic asymmetric total syntheses of biologically active natural products (e.g., Arundic acid) are disclosed.

  • 2.
    Agrawal, Santosh
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lenormand, Maud
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martin-Matute, Belen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Selective Alkylation of (Hetero)Aromatic Amines with Alcohols Catalyzed by a Ruthenium Pincer Complex2012Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, nr 6, s. 1456-1459Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A readily available pincer ruthenium(II) complex catalyzes the selective monoalkylation of (hetero)aromatic amines with a wide range of primary alcohols (including pyridine-, furan-, and thiophene-substituted alcohols) with high efficiency when used in low catalyst loadings (1 mol %). Tertiary amine formation via polyalkylation does not occur, making this ruthenium system an excellent catalyst for the synthesis of sec-amines.

  • 3.
    Ahlsten, Nanna
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Allylic alcohols as synthetic enolate equivalents: Isomerisation and tandem reactions catalysed by transition metal complexes2012Inngår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, nr 6, s. 1660-1670Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Allylic alcohols can be isomerised into carbonyl compounds by transition metal complexes. In the last few years, catalyst design and development have resulted in highly efficient isomerisations under mild reaction conditions, including enantioselective versions. In addition, the isomerisation of allylic alcohols has been combined with C-C bond forming reactions when electrophiles such as aldehydes or imines were present in the reaction mixture. Also, C-F bonds can be formed when electrophilic fluorinating reagents are used. Thus, allylic alcohols can be treated as latent enol(ate)s. In this article, we highlight the latest developments concerning the isomerisation of allylic alcohols into carbonyl compounds, focusing in particular on tandem isomerisation/C-C or C-heteroatom bond formation processes. Significant attention is given to the mechanistic aspects of the reactions.

  • 4.
    Alam, Rauful
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pilarski, Lukasz T.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pershagen, Elias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabo, Kalman J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stereoselective intermolecular allylic C-H trifluoroacetoxylation of functionalized alkenes2012Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, nr 21, s. 8778-8781Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Pd-catalyzed allylic C-H trifluoroacetoxylation of substituted alkenes was performed using PhI(OCOCF3)(2) as the oxidant and acyloxy source. Trifluoroacetoxylation of monosubstituted cyclopentenes and cyclohexenes proceeds with excellent regio- and diastereoselectivity. Studies with one of the possible (eta(3)-allyl)Pd(II) intermediates suggest that the reaction proceeds via stereoselective formation of Pd(IV) intermediates and subsequent stereo- and regioselective reductive elimination of the product.

  • 5.
    Babu, Beneesh P.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Endo, Yoshinori
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Biomimetic Aerobic Oxidation of Amino Alcohols to Lactams2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 37, s. 11524-11527Artikkel i tidsskrift (Fagfellevurdert)
  • 6. Barbion, Julien
    et al.
    Sorin, Geoffroy
    Selkti, Mohamed
    Kellenberger, Esther
    Baati, Rachid
    Santoro, Stefano
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pancrazi, Ange
    Lannou, Marie-Isabelle
    Ardisson, Janick
    Stereoselective functionalization of pyrrolidinone moiety towards the synthesis of salinosporamide A2012Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 68, nr 32, s. 6504-6512Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An important feature of the synthesis of salinosporamide A. a potent proteasome inhibitor, is the establishment of the quaternary stereocenter at C3. A new route has been developed based on the methylation of a functionalized pyrrolidinone. Direct methylation reaction led to the unwanted diastereomer: however, by means of a Corey-Chaykovsky reaction followed by LiAlH4 epoxide opening, the desired alcohol was obtained. The pyrrolidinone was elaborated through a key allylation reaction between a tertiary allyltitanium reagent and an aldehyde bearing a spiroketal moiety in alpha-position.

  • 7.
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalysed hydrogen transfer processes for C-C and C-N bond formation: Synthetic studies and mechanistic investigations2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis focusses on synthetic studies and mechanistic investigations into reactions involving hydrogen-transfer processes.

    In the first part, the development of an efficient method for the synthesis of β-hydroxy ketones (aldols) and β-amino ketones (Mannich products) from allylic alcohols and aldehydes is described. These reactions use  Ru(η5-C5Ph5)(CO)2Cl as the catalyst. The reaction parameters were optimised in order to suppress the formation of undesired by-products. Neutral and mild reaction conditions enabled the synthesis of a variety of aldol products in up to 99% yield, with a good syn/anti ratio. The influence of the stereoelectronic properties of the catalyst on the reaction outcome was also studied. Based on the results obtained, a plausible reaction mechanism has been proposed, involving as the key steps the 1,4-addition of hydride to α,β-unsaturated ketones and the formation of ruthenium (Z)-enolates.

    In the second part of this thesis, a ruthenium-catalysed tandem isomerisation/C-H activation reaction is presented. A number of ruthenium complexes, phosphine ligands, and additives were evaluated in order to establish the optimal reaction conditions. It was found that the use of a stable ruthenium catalyst, Ru(PPh3)3Cl2, together with PtBu3 and HCO2Na resulted in an efficient tandem transformation. Using this procedure, a variety of ortho-alkylated ketones were obtained in excellent yields. Moreover, homoallylic alcohols could also be used as starting materials for the reaction, which further expands the substrate scope. Mechanistic investigations into the isomerisation part of the process were carried out.

    The last project described in the thesis deals with the design and preparation of novel bifunctional iridium complexes containing an N-(2-hydroxy-isobutyl)-N-Heterocyclic carbene ligand. These complexes were used as catalysts to alkylate amines using alcohols as latent electrophiles. The catalytic system developed here was found to be one of the most active systems reported to date, allowing the reaction to be performed at temperatures as low as 50 °C for the first time. A broad substrate scope was examined. Combined experimental and theoretical studies into the reaction mechanism are consistent with a metal-ligand bifunctional activity of the new catalyst.

  • 8.
    Bartoszewicz, Agnieszka
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jezowska, Martina M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Laymand, Kevin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mobus, Juri
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Synthesis of β-Hydroxy and β-Amino Ketones from Allylic Alcohols Catalyzed by Ru(η5-C5Ph5)(CO)2Cl2012Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 9, s. 1517-1530Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An efficient method for the synthesis of beta-hydroxy and beta-amino ketones from allylic alcohols catalyzed by Ru(5-C5Ph5)(CO)2Cl is described. The influence of the stereoelectronic properties of the catalyst on the reaction outcome has been studied. Optimization of the reaction conditions supressed the formation of undesired side products such as saturated ketones, benzyl alcohols, and a,beta-unsaturated ketones. Several aromatic and aliphatic allylic alcohols have been reacted with a large variety of aldehydes or imines to produce beta-hydroxy ketones or beta-amino ketones, respectively, in yields up to 99%. Based on experimental data, a mechanism via ruthenium alkoxides and ruthenium aldoxides is proposed. In addition, a C-bound ruthenium enolate has been characterized.

  • 9.
    Bartoszewicz, Agnieszka
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Marcos, Rocio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sahoo, Suman
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Inge, A. Ken
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A Highly Active Bifunctional Iridium Complex with an Alcohol/Alkoxide-Tethered N-Heterocyclic Carbene for Alkylation of Amines with Alcohols2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 45, s. 14510-14519Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    A series of new iridium(III) complexes containing bidentate N-heterocyclic carbenes (NHC) functionalized with an alcohol or ether group (NHC?OR, R=H, Me) were prepared. The complexes catalyzed the alkylation of anilines with alcohols as latent electrophiles. In particular, biscationic IrIII complexes of the type [Cp*(NHC-OH)Ir(MeCN)]2+2[BF4-] afforded higher-order amine products with very high efficiency; up to >99?% yield using a 1:1 ratio of reactants and 12.5 mol?% of Ir, in short reaction times (216 h) and under base-free conditions. Quantitative yields were also obtained at 50?degrees C, although longer reaction times (4860 h) were needed. A large variety of aromatic amines have been alkylated with primary and secondary alcohols. The reactivity of structurally related iridium(III) complexes was also compared to obtain insights into the mechanism and into the structure of possible catalytic intermediates. The IrIII complexes were stable towards oxygen and moisture, and were characterized by NMR, HRMS, single-crystal X-ray diffraction, and elemental analyses.

  • 10.
    Bouma, Marinus J.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    General One-Pot Synthesis of Alkynyliodonium Salts and Alkynyl Benziodoxolones from Aryl Iodides2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 45, s. 14242-14245Artikkel i tidsskrift (Fagfellevurdert)
  • 11. Breistein, Palle
    et al.
    Johansson, Jonas
    Ibrahem, Ismail
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Deiana, Luca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Cordova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    One-Step Catalytic Enantioselective a-Quaternary 5-Hydroxyproline Synthesis: An Asymmetric Entry to Highly Functionalized a-Quaternary Proline Derivatives2012Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, nr 6, s. 1156-1162Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The highly enantioselective cascade reaction between N-protected a-cyanoglycine esters and a,beta-unsaturated aldehydes is disclosed. The reaction represents a one-step entry to polysubstituted 5-hydroxyproline derivatives having a quaternary a-stereocenter generally in high yields with up to >95:5 dr and 99:1 er. It is also a direct catalytic two-step entry to functionalized a-quaternary proline derivatives.

  • 12.
    Buitrago, Elina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Transition metal-catalyzed reduction of carbonyl compounds: Fe, Ru and Rh complexes as powerful hydride mediators2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    A detailed mechanistic investigation of the previously reported ruthenium pseudo-dipeptide-catalyzed asymmetric transfer hydrogenation (ATH) of aromatic ketones was performed. It was found that the addition of alkali metals has a large influence on both the reaction rate and the selectivity, and that the rate of the reaction was substantially increased when THF was used as a co-solvent. A novel bimetallic mechanism for the ruthenium pseudo-dipeptide-catalyzed asymmetric reduction of prochiral ketones was proposed.

    There is a demand for a larger substrate scope in the ATH reaction, and heteroaromatic ketones are traditionally more challenging substrates. Normally a catalyst is developed for one benchmark substrate, and a substrate screen is carried out with the best performing catalyst. There is a high probability that for different substrates, another catalyst could outperform the one used. To circumvent this issue, a multiple screen was executed, employing a variety of ligands from different families within our group’s ligand library, and different heteroaromatic ketones to fine-tune and to find the optimum catalyst depending on the substrate. The acquired information was used in the formal total syntheses of (R)-fluoxetine and (S)-duloxetine, where the key reduction step was performed with high enantioselectivities and high yield, in each case.

    Furthermore, a new iron-N-heterocyclic carbene (NHC)-catalyzed hydrosilylation (HS) protocol was developed. An active catalyst was formed in situ from readily available imidazolium salts together with an iron source, and the inexpensive and benign polymethylhydrosiloxane (PMHS) was used as hydride donor. A set of sterically less demanding, potentially bidentate NHC precursors was prepared. The effect proved to be remarkable, and an unprecedented activity was observed when combining them with iron. The same system was also explored in the reduction of amides to amines with satisfactory results.

  • 13.
    Buitrago, Elina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lundberg, Helena
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ryberg, Per
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    High Throughput Screening of a Catalyst Library for the Asymmetric Transfer Hydrogenation of Heteroaromatic Ketones: Formal Syntheses of (R)-Fluoxetine and (S)-Duloxetine2012Inngår i: ChemCatChem, ISSN 1867-3880, E-ISSN 1867-3899, Vol. 4, nr 12, s. 2082-2089Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 14.
    Buitrago, Elina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Tinnis, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Efficient and Selective Hydrosilylation of Carbonyls Catalyzed by Iron Acetate and N-Hydroxyethylimidazolium Salts2012Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, nr 1, s. 217-222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aromatic aldehydes, along with aryl alkyl, heteroaryl alkyl, and dialkyl ketones were efficiently reduced to their corresponding primary and secondary alcohols, respectively, in high yields, using the commercially available and inexpensive polymeric silane, polymethylhydrosiloxane (PMHS), as reducing agent. The reaction is catalyzed by in situ generated iron complexes containing hydroxyethyl-functionalized NHC ligands. Turnover frequencies up to 600 h−1 were obtained

  • 15.
    Carson, Fabian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Agrawal, Santosh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Gustafsson, Mikaela
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bartoszewicz, Agnieszka
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Moraga, Francisca
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zou, Xiaodong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ruthenium Complexation in an Aluminium Metal-Organic Framework and its Application in Alcohol Oxidation Catalysis2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 48, s. 15337-15344Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    A ruthenium trichloride complex has been loaded into an aluminium metalorganic framework (MOF), MOF-253, by post-synthetic modification to give MOF-253-Ru. MOF-253 contains open bipyridine sites that are available to bind with the ruthenium complex. MOF-253-Ru was characterised by elemental analysis, N2 sorption and X-ray powder diffraction. This is the first time that a Ru complex has been coordinated to a MOF through post-synthetic modification and used as a heterogeneous catalyst. MOF-253-Ru catalysed the oxidation of primary and secondary alcohols, including allylic alcohols, with PhI(OAc)2 as the oxidant under very mild reaction conditions (ambient temperature to 40 degrees C). High conversions (up to >99%) were achieved in short reaction times (13 h) by using low catalyst loadings (0.5 mol% Ru). In addition, high selectivities (>90%) for aldehydes were obtained at room temperature. MOF-253-Ru can be recycled up to six times with only a moderate decrease in substrate conversion.

  • 16. Chow, Winnie W. Y.
    et al.
    Herwik, Stanislav
    Ruther, Patrick
    Gothelid, Emmanuelle
    Oscarsson, Sven
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bio-polymer coatings on neural probe surfaces: Influence of the initial sample composition2012Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, nr 20, s. 7864-7871Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper presents the results of the study of hyaluronic acid (HyA) coating on two structural materials, silicon oxide (dielectric) surface and platinum (Pt) surface used for fabrication of probes developed for neurological investigations in the framework of the EU-project NeuroProbes. The silicon-based neural probes consist of multiple Pt electrodes on the probe shafts for neural recording applications. HyA coatings were proposed to apply on the probe surfaces to enhance the biocompatibility [1]. This study aims at understanding the influence of the initial composition of the probe surface on the structure and morphology of HyA coating. HyA was chemically functionalized by SS-pyridin using (N-Succinimidyl 3-[2-pyridyldithio]-propionate) (SPDP) and was immobilized on the surfaces via a covalent bond. The dielectric and Pt surfaces were derivatized by use of (3-mercaptopropyl) methyldimethoxysilane (MPMDMS). The silanol groups in MPMDMS bind to the dielectric surface, leaving the thiol groups at the uppermost surface and the thiol groups then bind covalently to the functionalized HyA. On the Pt surface, it is the thiol group which binds on the Pt surface. The coated surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). A well-defined HyA layer was observed on both dielectric and Pt surfaces. The coating of two molecular weights (340 kDa and 1.3 MDa) of HyA was examined. The influence of the silanized layer on the HyA coating was also investigated.

  • 17. Coll, Mercedes
    et al.
    Ahlford, Katrin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pamies, Oscar
    Adolfsson, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dieguez, Montserrat
    Modular Furanoside Pseudodipeptides and Thioamides, Readily Available Ligand Libraries for Metal-Catalyzed Transfer Hydrogenation Reactions: Scope and Limitations2012Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, nr 2-3, s. 415-427Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two new highly modular carbohydrate-based, pseudodipeptide and thioamide ligand libraries have been synthesized for the rhodium- and ruthenium-catalyzed asymmetric transfer hydrogenation (ATH) of prochiral ketones. These series of ligands can be prepared efficiently from easily accessible D-xylose and D-glucose. The ligand libraries contain two main ligand structures (pseudodipeptide and thioamide) that have been designed by making systematic modifications to one of the most successful ligand families developed for the ATH. As well as studying the effect of these two ligand structures on the catalytic performance, we also evaluated the effect of modifying several of the ligand parameters. We found that the effectiveness of the ligands at transferring the chiral information in the product can be tuned by correctly choosing the ligand components (ligand structure and ligand parameters). Excellent enantioselectivities (ees up to 99%) were therefore obtained in both enantiomers of the alcohol products using a wide range of substrates.

  • 18.
    Cordova, Armando
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Tseggai, Abrehet
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Concise catalytic asymmetric total synthesis of biologically active tropane alkaloids2012Inngår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 354, nr 7, s. 1363-1372Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A general strategy for the total asymmetric synthesis of valuable tropane alkaloids by catalytic stereoselective transformations is disclosed. The power of this approach is exemplified by the concise catalytic enantioselective total syntheses of (+)-methylecgonine, (-)-cocaine and (+)-cocaine as well as the first catalytic asymmetric total syntheses of a cocaine C-1 derivative and (+)-ferruginine starting from 5-oxo-protected-a,beta-unsaturated enals using only two and three column chromatographic purification steps, respectively.

  • 19.
    Deiana, Luca
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Afewerki, Samson
    Palo-Nieto, Carlos
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Verho, Oscar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johnston, Eric V.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Cordova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Mid Sweden University.
    Highly Enantioselective Cascade Transformations by Merging Heterogeneous Transition Metal Catalysis with Asymmetric Aminocatalysis2012Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 2, s. 851-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The concept of combining heterogeneous transition metal and amine catalysis for enantioselective cascade reactions has not yet been realized. This is of great advantage since it would allow for the recycling of expensive and non-environmentally friendly transition metals. We disclose that the use of a heterogeneous Pd-catalyst in combination with a simple chiral amine co-catalyst allows for highly enantioselective cascade transformations. The preparative power of this process has been demonstrated in the context of asymmetric cascade Michael/carbocyclization transformations that delivers cyclopentenes bearing an all carbon quaternary stereocenters in high yields with up to 30: 1 dr and 99% ee. Moreover, a variety of highly enantioselective cascade hetero-Michael/carbocyclizations were developed for the one-pot synthesis of valuable dihydrofurans and pyrrolidines (up to 98% ee) by using bench-stable heterogeneous Pd and chiral amines as co-catalysts.

  • 20.
    Deiana, Luca
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhao, Gui-Ling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Leijonmarck, Hans
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lehmann, Christian
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, Avdelningen för strukturkemi.
    Lehmann, Christian W.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Mid Sweden University.
    Direct Catalytic Asymmetric Synthesis of Pyrazolidine Derivatives2012Inngår i: ChemistryOpen, ISSN 2191-1363, Vol. 1, nr 3, s. 134-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A highly enantioselective, metal-free cascade reaction between di-1,2-N-protected hydrazine and α,β-unsaturated aldehydes is disclosed. The catalytic, asymmetric cascade transformation is a direct entry to 3-hydroxypyrazolidine and 3-allylpyrazolidine derivatives in one step and two steps, respectively, with >19:1 d.r. and 98–99 % ee using simple chiral pyrrolidines as catalysts.

  • 21.
    Deng, Youqian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bartholomeyzik, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Persson, Andreas K. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes2012Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 51, nr 11, s. 2703-2707Artikkel i tidsskrift (Fagfellevurdert)
  • 22.
    Deng, Youqian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Persson, Andreas K. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Oxidative Carbocyclizations2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 37, s. 11498-11523Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Palladium-catalyzed oxidative carboncarbon bond-forming annulations, that is, carbocyclization reactions, have recently emerged as efficient and atom-economical routes to carbo- and heterocycles, whereby less functionalized substrates and fewer synthetic steps are needed to obtain a target molecule compared with traditional non-oxidative carboncarbon bond-forming reactions. In this review, the synthetic efforts in palladium-catalyzed oxidative carbocyclization reactions are summarized.

  • 23. Duan, Lele
    et al.
    Bozoglian, Fernando
    Mandal, Sukanta
    Stewart, Beverly
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Privalov, Timofei
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Llobet, Antoni
    Sun, Licheng
    A molecular ruthenium catalyst with water-oxidation activity comparable to that of photosystem II2012Inngår i: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 4, nr 5, s. 418-423Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Across chemical disciplines, an interest in developing artificial water splitting to O-2 and H-2, driven by sunlight, has been motivated by the need for practical and environmentally friendly power generation without the consumption of fossil fuels. The central issue in light-driven water splitting is the efficiency of the water oxidation, which in the best-known catalysts falls short of the desired level by approximately two orders of magnitude. Here, we show that it is possible to close that 'two orders of magnitude' gap with a rationally designed molecular catalyst [Ru(bda)(isoq)(2)] (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; isoq = isoquinoline). This speeds up the water oxidation to an unprecedentedly high reaction rate with a turnover frequency of >300 s(-1). This value is, for the first time, moderately comparable with the reaction rate of 100-400 s(-1) of the oxygen-evolving complex of photosystem II in vivo.

  • 24.
    Endo, Yoshinori
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Biomimetic Oxidative Coupling of Benzylamines and 2-Aminophenols: Synthesis of Benzoxazoles2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 43, s. 13609-13613Artikkel i tidsskrift (Fagfellevurdert)
  • 25.
    Engström, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Enantioselective biotransformations using engineered lipases from Candida antarctica2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Enzymes are attractive catalysts in organic synthesis since they are efficient, selective and environmentally friendly. A large number of enzyme-catalyzed transformations have been described in the literature. If no natural enzyme can carry out a desirable reaction, one possibility is to modify an existing enzyme by protein engineering and thereby obtain a catalyst with the desired properties. In this thesis, the development of enantioselective enzymes and their use in synthetic applications is described. 

    In the first part of this thesis, enantioselective variants of Candida antarctica lipase A (CALA) towards α-substituted p-nitrophenyl esters were developed by directed evolution. A highly selective variant of CALA towards p-nitrophenyl 2-phenylpropanoate was developed by pairwise randomization of amino acid residues close to the active site. The E value of this variant was 276 compared to 3 for the wild type.

    An approach where nine residues were altered simultaneously was used to discover another highly enantioselective CALA variant (E = 100) towards an ibuprofen ester. The sterical demands of this substrate made it necessary to vary several residues at the same time in order to reach a variant with improved properties.

    In the second part of the thesis, a designed variant of Candida antarctica lipase B (CALB) was employed in kinetic resolution (KR) and dynamic kinetic resolution (DKR) of secondary alcohols. The designed CALB variant (W104A) accepts larger substrates compared to the wild type, and by the application of CALB W104A, the scope of these resolutions was extended.

    First, a DKR of phenylalkanols was developed using CALB W104A. An enzymatic resolution was combined with in situ racemization of the substrate, to yield the products in up to 97% ee. Secondly, the KR of diarylmethanols with CALB W104A was developed. By the use of diarylmethanols with two different aryl groups, highly enantioselective transformations were achieved.

  • 26.
    Engström, Karin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vallin, Michaela
    Hult, Karl
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kinetic resolution of diarylmethanols using a mutated variant of lipase CALB2012Inngår i: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 68, nr 37, s. 7613-7618Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An enzymatic kinetic resolution of diarylmethanols via acylation has been developed. This was achieved by the use of a mutated variant of CALB that accepts larger substrates compared to the wild type. By the use of diarylmethanols with two differently sized aryl groups, enantioselective transformations were achieved. A larger size-difference led to a higher enantioselectivity. In addition, substrates with electronically different aryl groups, such as phenyl and pyridyl, also gave an enantioselective reaction. The highest E value was observed with a substrate where steric and electronic effects were combined.

  • 27.
    Eriksson, Kristofer
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johansson, Lars Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Göthelid, Emmanuelle
    Department of Physics and Astroniomy Uppsala University.
    Nyholm, Leif
    Department of Chemistry, Uppsala Univeristy.
    Oscarsson, Sven
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Manufacturing of Anisotropic Particles by Site Specific Oxidation of Thiols2012Inngår i: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, nr 16, s. 7681-7683Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel method for the manufacturing of functional anisotropic particles based on an inexpensive and straightforward electrochemical approach is presented. The method enables large-scale manufacturing of anisotropic particles as well as fabrication of multifunctional beads which may be used in the design of barcodes for multiplex diagnostics.

  • 28.
    Eriksson, Kristofer
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palmgren, Pal
    Nyholm, Leif
    Oscarsson, Sven
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Electrochemical Synthesis of Gold and Protein Gradients on Particle Surfaces2012Inngår i: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 28, nr 28, s. 10318-10323Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A straightforward, versatile approach to the production of protein gradients on planar and spherical particle surfaces is described. The method is based on the spatially controlled oxidation of thiolated surfaces by Au(III) ions generated via the electrochemical oxidation of a gold electrode in a phosphate-buffered saline solution (10 mM PBS, pH 7.2, 150 mM NaCl). Because the gold electrode is in direct contact with the thiolated surfaces, the released Au(III) ions, which are present as Au(III) chloride complexes, give rise to the formation of a surface gradient of Au(I)-thiolate complexes depending on the local redox potential given by the local Au(III) concentration. As is shown on the basis of the use of X-ray photoelectron spectroscopy and fluorescently labeled proteins, the Au(I)-thiolate complexes can subsequently be functionalized with thiolated proteins, yielding surface density protein gradients on micrometer-sized nonconducting polymer beads as well as linear Au(I)-thiolate gradients on planar silicon surfaces.

  • 29.
    Eriksson, Lars
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Methyl 3-O-alpha-L-fucopyranosyl alpha-D-galactopyranoside: a synchrotron study2012Inngår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 68, s. o528-U1770Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The title compound, C13H24O10 is the methyl glycoside of a structural element alpha-L-Fucp-(1 -> 3)-alpha-D-Galp making up two thirds of the repeating unit in the capsular polysaccharide of Klebsiella K63. The conformation of the title compound is described by the glycosidic torsion angles phi(H) = 55 (1)degrees and psi H = -24 (1)degrees. The hydroxymethyl group in the galactose residue is present in the gauche-trans conformation. In the crystal, O-H center dot center dot center dot O hydrogen bonds connect the disaccharide units into chains along the a-axis direction and further hydrogen bonds cross-link the chains.

  • 30.
    Eriksson, Lars
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Methyl 3-O-α-l-fucopyranosyl β-d-glucopyranoside tetrahydrate2012Inngår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 68, s. o3180-o3181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The title compound, C13H24O10·4H2O, is the methyl glycoside of a disaccharide structural element present in the backbone of the capsular polysaccharide from Klebsiella K1, which contains only three sugars and a substituent in the polysaccharide repeating unit. The conformation of the title disaccharide is described by the glycosidic torsion angles ϕH = 51.1 (1)° and ψH = 25.8 (1)°. In the crystal, a number of O—HO hydrogen bonds link the methyl glycoside and water mol­ecules, forming a three-dimensional network. One water mol­ecule is disordered over two positions with occupancies of 0.748 (4) and 0.252 (4).

  • 31. Eriksson, Lars
    et al.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Methyl α-l-rhamnosyl-(1→2)[α-l-rhamnosyl-(1→3)]-α-l-rhamnoside penta­hydrate: synchrotron study2012Inngår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 68, nr 7, s. o2221-o2222Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The title hydrate, C19H34O13·5H2O, contains a vicinally disubstituted tris­accharide in which the two terminal rhamnosyl sugar groups are positioned adjacent to each other. The conformation of the tris­accharide is described by the glycosidic torsion angles ϕ2 = 48 (1)°, ψ2 = −29 (1)°, ϕ3 = 44 (1)° and ψ3 = 4 (1)°, whereas the ψ2 torsion angle represents a conformation from the major state in solution, the ψ3 torsion angle conformation may have been caught near a potential energy saddle-point when compared to its solution structure, in which at least two but probably three conformational states are populated. Extensive inter­molecular O—HO hydrogen bonding is present in the crystal and a water-containing channel is formed along the b-axis direction.

  • 32. Ertem, Mehmed Z.
    et al.
    Cramer, Christopher J.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Siegbahn, Per E. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    N-O bond cleavage mechanism(s) in nitrous oxide reductase2012Inngår i: Journal of Biological Inorganic Chemistry, ISSN 0949-8257, E-ISSN 1432-1327, Vol. 17, nr 5, s. 687-698Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quantum chemical calculations of active-site models of nitrous oxide reductase (N2OR) have been undertaken to elucidate the mechanism of N-O bond cleavage mediated by the supported tetranuclear Cu4S core (Cu-Z) found in the enzymatic active site. Using either a minimal model previously employed by Gorelsky et al. (J. Am. Chem. Soc. 128:278-290, 2006) or a more extended model including key residue side chains in the active-site second shell, we found two distinct mechanisms. In the first model, N2O binds to the fully reduced Cu-Z in a bent mu-(1,3)-O,N bridging fashion between the Cu-I and Cu-IV centers and subsequently extrudes N-2 while generating the corresponding bridged mu-oxo species. In the second model, substrate N2O binds loosely to one of the coppers of Cu-Z in a terminal fashion, i.e., using only the oxygen atom; loss of N-2 generates the same mu-oxo copper core. The free energies of activation predicted for these two alternative pathways are sufficiently close to one another that theory does not provide decisive support for one over the other, posing an interesting problem with respect to experiments that might be designed to distinguish between the two. Effects of nearby residues and active-site water molecules are also explored.

  • 33.
    Fontana, Carolina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural studies of glycans by NMR spectroscopy2012Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 34.
    Fontana, Carolina
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lundborg, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Weintraub, Andrej
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Structural studies and biosynthetic aspects of the o antigen polysaccharide from Escherichia coli o1742012Inngår i: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 354, s. 102-105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure of the repeating unit of the O-antigenic polysaccharide (PS) from Escherichia coli O174 has been determined. Component analysis together with H-1 and C-13 NMR spectroscopy experiments were employed to elucidate the structure. Inter-residue correlations were determined by H-1, C-13-heteronuclear multiple-bond correlation and H-1, H-1-NOESY experiments. The PS is composed of tetrasaccharide repeating units with the following structure: -> 4)-beta-D-GlcpA-(1 -> 3)-beta-D-Galp-(1 -> 3)-beta-D-GalpNAc-(1 -> vertical bar beta-D-GlcpNAc-(1 -> 2) Cross-peaks of low intensity were present in the NMR spectra consistent with a beta-D-GlcpNAc-(1 -> 2)-beta-D-GlcpA(1 -> structural element at the terminal part of the polysaccharide, which on average is composed of similar to 15 repeating units. Consequently the biological repeating unit has a 3-substituted N-acetyl-D-galactosamine residue at its reducing end.

  • 35. Girgis, Adel S.
    et al.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ismail, Nasser S. M.
    Farag, Hanaa
    Synthesis and QSAR study of novel cytotoxic spiro[3H-indole-3,2 '(1 ' H)-pyrrolo[3,4-c]pyrrole]-2,3 ',5 '(1H,2 ' aH,4 ' H)-triones2012Inngår i: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 47, s. 312-322Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1,3-Dipolar cycloaddition reaction of 1-aryl-1H-pyrrole-2,5-diones 1a-e with non-stabilized azomethine ylides, generated in situ via decarboxylative condensation of isatins 2a-c and sarcosine (3) in refluxing ethanol, afforded 4'-aryl-5'a,6'-dihydro-1'-methyl-spiro[3H-indole-3,2'(1 ' H)-pyrrolo[3,4-c]pyrrole]-2,3',5'(1H,2'aH,4'H)-triones 4a-o in good yields. Compound 4I exhibited high anti-tumor activity against HEPG2 (liver cancer) cell line (IC50 = 12.16 mu M) compared to that of Doxorubicin (IC50= 7.36 mu M), and the other synthesized compounds revealed moderate anti-tumor properties against HCT116 (colon), MCF7 (breast) and HEPG2 (liver) human tumor cell lines. 3D-Pharmacophore modeling and quantitative structure-activity relationship (QSAR) analysis were combined to explore the structural requirements controlling the observed anti-tumor properties. It was found that the major structural factors affecting potency of these compounds were related to their basic skeleton.

  • 36. Huang, Yong
    et al.
    Gao, Weiming
    Åkermark, Torbjörn
    Li, Mingrun
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    An Air-Stable Fe3S4 Complex with Properties Similar to Those of the HOXair State of the Diiron Hydrogenases2012Inngår i: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, nr 27, s. 4259-4263Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A Fe3S4 complex bridged by azapropanedithiolate (adt), complex 6, was prepared as a potential model of the HOXair state of [FeFe]-hydrogenases. Complex 6 was characterized by IR and 1H NMR spectroscopy, and its structure was determined by X-ray crystallography. The electrochemical studies show that complex 6 is redox-active under acidic conditions, which provides insight into the catalytic mechanism. Hydrogen evolution, driven by visible light, was observed in CH3CN/D2O solution by online mass spectroscopy.

  • 37. Ibrahem, Ismail
    et al.
    Breistein, Palle
    Cordova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    One-Pot Three-Component Highly Selective Synthesis of Homoallylboronates by Using Metal-Free Catalysis2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 17, s. 5175-5179Artikkel i tidsskrift (Fagfellevurdert)
  • 38.
    Jalalian, Nazli
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Development and Applications of Hypervalent Iodine Compounds: Powerful Arylation and Oxidation Reagents2012Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The first part of this thesis describes the efficient synthesis of several hypervalent iodine(III) compounds. Electron-rich diaryliodonium salts have been synthesized in a one-pot procedure, employing mCPBA as the oxidant. Both symmetric and unsymmetric diaryliodonium tosylates can be isolated in high yields. An in situ anion exchange also enables the synthesis of previously unobtainable diaryliodonium triflates.

    A large-scale protocol for the synthesis of a derivative of Koser’s reagent, that is an isolable intermediate in the diaryliodonium tosylate synthesis, is furthermore described. The large-scale synthesis is performed in neat TFE, which can be recovered and recycled. This is very desirable from an environmental point of view.

    One of the few described syntheses of enantiopure diaryliodonium salts is discussed. Three different enantiopure diaryliodonium salts bearing electron-rich substituents are synthesized in moderate to high yields. The synthesis of these three salts shows the challenge in the preparation of electron-rich substituted unsymmetric salts.

    The second part of the thesis describes the application of both symmetric and unsymmetric diaryliodonium salts in organic synthesis. A metal-free efficient and fast method for the synthesis of diaryl ethers from diaryliodonium salts has been developed. The substrate scope is wide as both the phenol and the diaryliodonium salt can be varied. Products such as halogenated ethers, ortho-substituted ethers and bulky ethers, that are difficult to obtain with metal-catalyzed procedures, are readily prepared. The mild protocol allows arylation of racemization-prone a-amino acid derivatives without loss of enantiomeric excess.

    A chemoselectivity investigation was conducted, in which unsymmetric diaryliodonium salts were employed in the arylation of three different nucleophiles in order to understand the different factors that influence which aryl moiety that is transferred to the nucleophile.

  • 39.
    Jalalian, Nazli
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Petersen, Tue B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Metal-Free Arylation of Oxygen Nucleophiles with Diaryliodonium Salts2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 44, s. 14140-14149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phenols and carboxylic acids are efficiently arylated with diaryliodonium salts. The reaction conditions are mild, metal free, and avoid the use of halogenated solvents, additives, and excess reagents. The products are obtained in good-to-excellent yields after short reaction times. Steric hindrance is very well tolerated, both in the nucleophile and diaryliodonium salt. The scope includes ortho-and halo-substituted products, which are difficult to obtain by metal-catalyzed protocols. Many functional groups are tolerated, including carbonyl groups, heteroatoms, and alkenes. Unsymmetric salts can be chemoselectively utilized to obtain products with hitherto unreported levels of steric congestion. The arylation has been extended to sulfonic acids, which can be converted to sulfonate esters by two different approaches. With recent advances in efficient synthetic procedures for diaryliodonium salts the reagents are now inexpensive and readily available. The iodoarene byproduct formed from the iodonium reagent can be recovered quantitatively and used to regenerate the diaryliodonium salt, which improves the atom economy.

  • 40.
    Janson, Pär G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Metal-catalyzed oxidative formation of C-CF3 and C-O bonds in alkenes and alkynes2012Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 41.
    Janson, Pär G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ghoneim, Ibrahim
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ilchenko, Nadia O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Electrophilic Trifluoromethylation by Copper-Catalyzed Addition of CF3-Transfer Reagents to Alkenes and Alkynes2012Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, nr 11, s. 2882-2885Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Regio- and stereoselective Cu-catalyzed addition of the above hypervalent iodine reagent to alkynes and alkenes was achieved. In the presence of Cul, the reaction is suitable to perform trifluoromethyl-benzoyloxylation and trifluoromethyl-halogenation of alkenes and alkynes. Electron-donating substituents accelerate the process, and alkenes react faster than alkynes emphasizing the electrophilic character of the addition reaction.

  • 42.
    Jiang, Min
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium-Catalyzed Oxidative Diarylating Carbocyclization of Enynes2012Inngår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, nr 13, s. 3538-3541Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A mild and efficient palladium-catalyzed oxidative diarylating carbocyclization of enynes is described. The reaction tolerates a range of functionalized arylboronic acids to give diarylated products in good yields. Control experiments suggest that the reaction starts with an arylpalladation of the alkyne, followed by carbocyclization, transmetalation, and reductive elimination to afford the diarylated product.

  • 43.
    Jiang, Tuo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-catalyzed oxidativecarbocyclization: Functionalization with Boron-Containing Reagents2012Licentiatavhandling, med artikler (Annet vitenskapelig)
  • 44.
    Jimenez-Halla, J. Oscar C.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kalek, Marcin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stawinski, Jacek
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Computational study of the mechanism and selectivity of palladium catalyzed propargylic substitution with phosphorus nucleophiles2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 39, s. 12424-12436Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The mechanism and sources of selectivity in the palladium-catalyzed propargylic substitution reaction that involves phosphorus nucleophiles, and which yields predominantly allenylphosphonates and related compounds, have been studied computationally by means of density functional theory. Full free-energy profiles are computed for both H-phosphonate and H-phosphonothioate substrates. The calculations show that the special behavior of H-phosphonates among other heteroatom nucleophiles is indeed reflected in higher energy barriers for the attack on the central carbon atom of the allenyl/propargyl ligand relative to the ligand-exchange pathway, which leads to the experimentally observed products. It is argued that, to explain the preference of allenyl- versus propargyl-phosphonate/phosphonothioate formation in reactions that involve H-phosphonates and H-phosphonothioates, analysis of the complete free-energy surfaces is necessary, because the product ratio is determined by different transition states in the respective branches of the catalytic cycle. In addition, these transition states change in going from a H-phosphonate to a H-phosphonothioate nucleophile.

  • 45.
    Johnston, Eric V.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Verho, Oscar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kärkäs, Markus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Shakeri, Mozaffar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Tai, Cheuk-Wai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Palmgren, Pål
    Eriksson, Kristofer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Oscarsson, Sven
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly dispersed palladium nanoparticles on mesocellular foam: an efficient and recyclable heterogeneous catalyst for alcohol oxidation2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 39, s. 12202-12206Artikkel i tidsskrift (Fagfellevurdert)
  • 46.
    Jonsson, K. Hanna M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Säwén, Elin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Studies on the conformational flexibility of alpha-L-rhamnose-containing oligosaccharides using C-13-site-specific labeling, NMR spectroscopy and molecular simulations: implications for the three-dimensional structure of bacterial rhamnan polysaccharides2012Inngår i: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 10, nr 12, s. 2453-2463Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bacterial polysaccharides are comprised of a variety of monosaccharides, L-rhamnose (6-deoxy-L-mannose) being one of them. This sugar is often part of alpha-(1 -> 2)- and/or alpha-(1 -> 3)-linkages and we have therefore studied the disaccharide alpha-L-Rhap-(1 -> 2)-alpha-L-Rhap-OMe to obtain information on conformational preferences at this glycosidic linkage. The target disaccharide was synthesized with C-13 site-specific labeling at C1' and at C2', i.e., in the terminal group. 2D H-1, C-13-HSQC-HECADE and H-1, C-13-J-HMBC NMR experiments, 1D C-13 and H-1 NMR spectra together with total line-shape analysis were used to extract conformationally dependent hetero- and homonuclear spin-spin coupling constants. This resulted in the determination of (2)JC(2',H1'), (3)J(C1',C1), (3)J(C1',C3), (3)J(C2',C2), (2)J(C1',C2), (1)JC(1',C2'), and (1)J(C1',H1'). These data together with previously determined J(CH) and H-1, H-1 NOEs result in fourteen conformationally dependent NMR parameters that are available for analysis of glycosidic linkage flexibility and conformational preferences. A 100 ns molecular dynamics (MD) simulation of the disaccharide with explicit water molecules as solvent showed a major conformational state at phi(H) approximate to 40 degrees and psi(H) approximate to -35 degrees, consistent with experimental NMR data. In addition, MD simulations were carried out also for alpha-L-Rhap-(1 -> 3)-alpha-L-Rhap-OMe and a rhamnan hexasaccharide. The gathered information on the oligosaccharides was used to address conformational preferences for a larger structure, a 2- and 3-linked nonasaccharide, with implications for the 3D structure of rhamnan polysaccharides, which should be regarded as flexible polymers.

  • 47.
    Joosten, Antoine
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Persson, Andreas K. A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Millet, Renaud
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johnson, Magnus T.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palladium(II)-Catalyzed Oxidative Cyclization of Allylic Tosylcarbamates: Scope, Derivatization, and Mechanistic Aspects2012Inngår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 18, nr 47, s. 15151-15157Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    A highly selective oxidative palladium(II)-catalyzed (Wacker-type) cyclization of readily available allylic tosylcarbamates is reported. This operationally simple catalytic reaction furnishes tosyl-protected vinyl-oxazolidinones, common precursors to syn-1,2-amino alcohols, in high yield and excellent diasteroselectivity (>20:1). It is demonstrated that both stoichiometric amounts of benzoquinone (BQ) as well as aerobic reoxidation (molecular oxygen) is suitable for this transformation. The title reaction is shown to proceed through overall trans-amidopalladation of the olefin followed by beta-hydride elimination. This process is scalable and the products are suitable for a range of subsequent transformations such as: kinetic resolution (KR) and oxidative Heck-, Wacker-, and metathesis reactions.

  • 48.
    Kalek, Marcin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Combining Meyer-Schuster Rearrangement with Aldol and Mannich Reactions: Theoretical Study of the Intermediate Interception Strategy2012Inngår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, nr 46, s. 19159-19169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Interception of the transient allenyl enolate intermediate of the vanadium-catalyzed Meyer-Schuster rearrangement with aldehydes and imines has been studied computationally using density functional theory. Mechanistic details of the catalytic cycles for each of the reaction variants are established. In particular, it is shown that the active form of I the catalyst contains two triphenylsiloxy ligands, the transesterification of vanadate occurs via sigma-bond metathesis, and vanadium enolate is directly involved in the key C-C bond formation. The calculations also provide support for the dissociative course of the key 1,3-shift step. The stereochemistry of the reaction is thoroughly investigated, and the obtained energy barriers reproduce and rationalize the experimentally observed (Z)-, (E)-selectivity. The calculated free energy profiles are analyzed in terms of efficiency of the intermediate enolate interception. It is shown that the investigated reactions represent borderline cases, in which the intermediate trapping is only slightly favored over the undesired isomerization pathway.

  • 49. Kotsyubynskyy, Dmytro
    et al.
    Zerbetto, Mirco
    Šoltésová, Mária
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Charles University Prague .
    Engström, Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Pendrill, Robert
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Kowalewski, Josef
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Polimeno, Antonin
    Stochastic Modeling of Flexible Biomolecules Applied to NMR Relaxation: 2. Interpretation of Complex Dynamics in Linear Oligosaccharides2012Inngår i: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 116, nr 50, s. 14541-14555Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A computational stochastic approach is applied to the description of flexible molecules. By combining (i) molecular dynamics simulations, (ii) hydrodynamics approaches, and (iii) a multidimensional diffusive description for internal and global dynamics, it is possible to build an efficient integrated approach to the interpretation of relaxation processes in flexible systems. In particular, the model is applied to the interpretation of nuclear magnetic relaxation measurements of linear oligosaccharides, namely a mannose-containing trisaccharide and the pentasaccharide LNF-1. Experimental data are reproduced with sufficient accuracy without free model parameters.

  • 50.
    Kärkäs, Markus D.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Johnston, Eric V.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Karim, Shams R.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Laine, Tanja M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lee, Bao-Lin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Tobias
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Privalov, Timofei
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Water Oxidation by Single-Site Ruthenium Complexes: Using Ligands as Redox and Proton Transfer Mediators2012Inngår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 51, nr 46, s. 11589-11593Artikkel i tidsskrift (Fagfellevurdert)
12 1 - 50 of 89
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