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  • 301.
    Färnbäck, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Söderman, Peter
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Methyl 3,4,6-tri-O-acetyl-2-deoxy-2-azido-alpha-D-galactopyranosyl-(1-2)-: [3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-glucopyranosyl-(1-3)]-4-O-benzoyl-alpha-L-rhamnopyranoside n-hexane 0.1-solvate2007In: Acta Crystallographica: Section E, Vol. E63, p. o1581-o1583Article in journal (Refereed)
  • 302. Gagliardo, Marcella
    et al.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mehendale, Nilesh C.
    van Koten, Gerard
    Klein Gebbink, Robertus J. M.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic performance of symmetrical and unsymmetrical sulfur-containing pincer complexes: synthesis and tandem catalytic activity of the first PCS-pincer palladium complex2008In: Chemistry: a European journal, ISSN 0947-6539, Vol. 14, no 16, p. 4800-4809Article in journal (Refereed)
  • 303.
    Galkin, Maxim V.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Smit, Arjan T.
    Subbotina, Elena
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Artemenko, Konstantin A.
    Bergquist, Jonas
    Huijgen, Wouter J. J.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hydrogen-free catalytic fractionation of woody biomass2016In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 9, no 23, p. 3280-3287Article in journal (Refereed)
    Abstract [en]

    The pulping industry could become a biorefinery if the lignin and hemicellulose components of the lignocellulose are valorized. Conversion of lignin into well-defined aromatic chemicals is still a major challenge. Lignin depolymerization reactions often occur in parallel with irreversible condensation reactions of the formed fragments. Here, we describe a strategy that markedly suppresses the undesired condensation pathways and allows to selectively transform lignin into a few aromatic compounds. Notably, applying this strategy to woody biomass at organosolv pulping conditions, the hemicellulose, cellulose, and lignin were separated and in parallel the lignin was transformed into aromatic monomers. In addition, we were able to utilize a part of the lignocellulose as an internal source of hydrogen for the reductive lignin transformations. We hope that the presented methodology will inspire researchers in the field of lignin valorization as well as pulp producers to develop more efficient biomass fractionation processes in the future.

  • 304. Gao, Weiming
    et al.
    Ekström, Jesper
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianhui
    Chen, Changneng
    Eriksson, Lars
    Department of Physical, Inorganic and Structural Chemistry.
    Weng, Linhong
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Binuclear iron-sulfur complexes with bidentate phosphine ligands as active site models of Fe-hydrogenase and their catalytic proton reduction2007In: Inorganic Chemistry, ISSN 0020-1669, Vol. 46, no 6, p. 1981-1991Article in journal (Refereed)
  • 305. Gao, Weiming
    et al.
    Liu, Jianhui
    Jiang, Weina
    Wang, Mei
    Weng, Linhong
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    An azadithiolate bridged Fe2S2 complex as active site model of FeFe-hydrogenase covalently linked to a Re(CO)3(bpy)(py) photosensitizer aiming for light-driven hydrogen production2008In: Comptes Rendus Chimie, ISSN 1631-0748, Vol. 11, no 8, p. 915-921Article in journal (Refereed)
  • 306. Gao, Weiming
    et al.
    Liu, Jianhui
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Bidentate phosphine ligand based Fe2S2-containing macromolecules: synthesis, characterization, and catalytic electrochemical hydrogen production2006In: Inorganic Chemistry, ISSN 0020-1669, Vol. 45, no 23, p. 9169-9171Article in journal (Refereed)
  • 307. Gao, Weiming
    et al.
    Liu, Jianhui
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Facile and highly efficient light-induced PR3/CO ligand exchange: a novel approach to the synthesis of [(mu-SCH2NnPrCH2S)Fe2(CO)4(PR3)2]2007In: Journal of Organometallic Chemistry, ISSN 0022-328X, Vol. 692, p. 1579-1583Article in journal (Refereed)
  • 308.
    Gao, Weiming
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Li, Mingrun
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Åkermark, Torbjörn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Romare, Kristina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Royal Institute of Technology (KTH), Department of Organic Chemistry.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of a [3Fe2S] cluster with low redox potential from [2Fe2S] hydrogenase models: electrochemical and photochemical generation of hydrogen2011In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-1948, Vol. 2011, no 7, p. 1100-1105Article in journal (Refereed)
    Abstract [en]

    In the attempted replacement of carbon monoxide by the bis(phosphane) dppv in a dinuclear [2Fe2S] complex, a trinuclear [3Fe2S] complex with two bis(phosphane) ligands was unexpectedly obtained. On protonation, this gave a bridged hydride complex with an unusually low potential for the reduction of protons to molecular hydrogen. The redox potential also appears sufficiently positive for direct electron transfer from an excited [Ru(bpy)(3)](2+) sensitizer.

  • 309.
    Gao, Weiming
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Åkermark, Torbjörn
    Li, Mingrun
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry, Structural Chemistry.
    Sun, Licheng
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Attachment of a hydrogen-bonding carboxylate side chain to an [FeFe]-hydrogenase model complex: Influence on the catalytic mechanism2010In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 16, no 8, p. 2537-2546Article in journal (Refereed)
    Abstract [en]

    Azapropanedithiolate (adt)-bridged model complexes of [FeFe]-hydrogenase bearing a carboxylic acid functionality have been designed with the aim of decreasing the potential for reduction of protons to hydrogen. Protonation of the bisphosphine complexes 46 has been studied by in situ IR and NMR spectroscopy, which revealed that protonation with triflic acid most likely takes place first at the N-bridge for complex 4 but at the FeFe bond for complexes 5 and 6. Using an excess of acid, the diprotonated species could also be observed, but none of the protonated species was sufficiently stable to be isolated in a pure state. Electrochemical studies have provided an insight into the catalytic mechanisms under strongly acidic conditions, and have also shown that complexes 3 and 6 are electro-active in aqueous solution even in the absence of acid, presumably due to hydrogen bonding. Hydrogen evolution, driven by visible light, has been observed for three-component systems consisting of [Ru(bpy)3]2+, complex 1, 2, or 3, and ascorbic acid in CH3CN/D2O solution by on-line mass spectrometry.

  • 310.
    Gao, Yan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Liu, Jianhui
    Jiang, Wenfeng
    Xia, Ming
    Zhang, Wei
    Li, Minna
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Synthesis and photophysical and electrochemical properties of a binuclear Ru(bpy)3-Cu(III) corrole complex2007In: Journal of Porphyrins and Phthalocyanines, ISSN 1088-4246, Vol. 11, no 5-6, p. 463-469Article in journal (Refereed)
  • 311. Gao, Yan
    et al.
    Liu, Jianhui
    Na, Yong
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Licheng
    Synthesis and characterization of manganese and copper corrole xanthene complexes as catalysts for water oxidation2007In: Tetrahedron, ISSN 0040-4020, Vol. 63, no 9, p. 1987-1994Article in journal (Refereed)
  • 312.
    Gao, Yan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Åkermark, Torbjörn
    Liu, Jianhui
    Sun, Licheng
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nucleophilic attack of hydroxide on a MnV oxo complex: a model of the O-O bond formation in the oxygen evolving complex of photosystem II2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 25, p. 8726-8727Article in journal (Refereed)
  • 313.
    Gemma, Emiliano
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lahmann, Martina
    Oscarson, Stefan
    Synthesis of the tetrasaccharide α-D-Glcp-(1→3)-α-D-Manp-(1→2)-α-D-Manp-(1→2)-α-D-Manp recognised by Calreticulin/Calnexin2005In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 340, no 16, p. 2558-2562Article in journal (Refereed)
    Abstract [en]

    The title compound as its methyl glycoside was efficiently synthesized using a block synthesis approach. Halide-assisted glycosidations between 6-O-acetyl-2,3,4-tri-O-benzyl-α-d-glucopyranosyl iodide and ethyl 2-O-acetyl-4,6-di-O-benzyl-1-thio-α-d-mannopyranoside using triphenylphosphine oxide as promoter yielded, with complete α-selectivity, a disaccharide building block in high yield. The perbenzylated derivative of this proved to be an excellent donor affording 88% of the protected target tetrasaccharide in an NIS/AgOTf-promoted coupling to a known methyl dimannoside acceptor. Deprotection through catalytic hydrogenolysis then gave the target compound in 47% overall yield.

  • 314. George, Riham F.
    et al.
    Ismail, Nasser S. M.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Girgis, Adel S.
    Design, synthesis and QSAR studies of dispiroindole derivatives as new antiproliferative agents2013In: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 68, p. 339-351Article in journal (Refereed)
    Abstract [en]

    A variety of 4'-ary1-3-(arylmethylidene)-1 ''-[(cyclic-amino)methylene]-1'-methyl-dispiro[cyclohexane-1,3'-pyrrolidine-2',3 ''-[3H]indole]-2,2 ''(1H)-diones 4a-u were prepared via reaction of 2E,6E-bis(arylidene)-1-cyclohexanones 1a-i with azomethine ylides, generated in situ via a decarboxylative condensation of isatins 2a-c and sarcosine (3). Single crystal X-ray study of 4a, revealed structural and stereochemical features of these derivatives. While most of the synthesized compounds exhibit mild antitumor properties when tested against various human tumor cell lines (HEPG2 liver, HELA cervical and PD prostate cancers), three of them, 4d and 4p (active against HEPG2), and compound 4g (active against HELA), demonstrated higher activities, that were close or even higher than that of the reference standard Doxorubicin. QSAR studies revealed good predictive and statistically significant 3 descriptor models (r(2) = 0.903-0.812, r(adjusted)(2) = 0.855-0.672, r(prediction)(2) = 0.773-0.605).

  • 315.
    Georgieva, Polina
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Quantum chemical modeling of enzymatic reactions: The Case of histone lysine methyltransferase2010In: Journal of Computational Chemistry, ISSN 0192-8651, E-ISSN 1096-987X, Vol. 31, no 8, p. 1707-1714Article in journal (Refereed)
    Abstract [en]

    Quantum chemical cluster models of enzyme active sites are today an important and powerful tool in the study of various aspects of enzymatic reactivity. This methodology has been applied to a wide spectrum of reactions and many important mechanistic problems have been solved. Herein, we report a systematic study of the reaction mechanism of the histone lysine methyltransferase (HKMT) SET7/9 enzyme, which catalyzes the methylation of the N-terminal histone tail of the chromatin structure. In this study, HKMT SET7/9 serves as a representative case to examine the modeling approach for the important class of methyl transfer enzymes. Active site models of different sizes are used to evaluate the methodology. In particular, the dependence of the calculated energies on the model size, the influence of the dielectric medium, and the particular choice of the dielectric constant are discussed. In addition, we examine the validity of some technical aspects, such as geometry optimization in solvent or with a large basis set, and the use of different density functional methods.

  • 316. Georgieva, Polina
    et al.
    Wu, Qian
    McLeish, Michael J.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The reaction mechanism of phenylethanolamine N-methyltransferase: A density functional theory study2009In: Biochimica et Biophysica Acta, ISSN 0006-3002, E-ISSN 1878-2434, Vol. 1794, no 12, p. 1831-1837Article in journal (Refereed)
  • 317. Ghanem, Raed
    et al.
    Xu, Yunhua
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    pan, Jie
    Hoffmann, Tobias
    Andersson, Johan
    Polivka, Tomas
    Pascher, Torbjörn
    Styring, Stenbjörn
    Sun, Licheng
    Sundström, Villy
    Light-driven Tyrosine Radical Formation in a Ruthenium-Tyrosine Complex Attached to Nanoparticle TiO22002In: Inorganic Chemistry, ISSN 0020-1669, Vol. 41, no 24, p. 6258-6266Article in journal (Refereed)
  • 318. 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.

  • 319.
    Ghosh, Raju
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lindstedt, Erik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jalalian, Nazli
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Room Temperature, Metal-Free Arylation of Aliphatic Alcohols2014In: ChemistryOpen, ISSN 2191-1363, Vol. 3, no 2, p. 54-57Article in journal (Refereed)
    Abstract [en]

    Diaryliodonium salts are demonstrated as efficient arylating agents of aliphatic alcohols under metal-free conditions. The reaction proceeds at room temperature within 90min to give alkyl aryl ethers in good to excellent yields. Aryl groups with electron-withdrawing substituents are transferred most efficiently, and unsymmetric iodonium salts give chemoselective arylations. The methodology has been applied to the formal synthesis of butoxycaine.

  • 320.
    Ghosh, Raju
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Metal-Free Synthesis of N-Aryloxyimides and Aryloxyamines2014In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 6, p. 1830-1832Article in journal (Refereed)
    Abstract [en]

    N-Hydroxyphthalimide and N-hydroxysuccinimide have been arylated with diaryliodonium salts to provide N-aryloxyimides in excellent yields in short reaction times. A novel hydrolysis under mild and hydrazine-free conditions yielded aryloxyamines, which are valuable building blocks in the synthesis of oxime ethers and benzofurans.

  • 321.
    Ghosh, Raju
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stridfeldt, Elin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olofsson, Berit
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Metal-Free One-Pot Synthesis of Benzofurans2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 29, p. 8888-8892Article in journal (Refereed)
    Abstract [en]

    Ethyl acetohydroxamate was efficiently arylated with diaryliodonium salts at room temperature under transition-metal-free conditions. The obtained O-arylated products were reacted in situ with ketones under acidic conditions to yield substituted benzo[b]furans through oxime formation, [3,3]-rearrangement, and cyclization in a fast and operationally simple one-pot fashion without using excess reagents. Alternatively, the O-arylated products could be isolated or transformed in situ to aryloxyamines or O-arylaldoximes. The methodology was applied to the synthesis of Stemofuran A and the formal syntheses of Coumestan, Eupomatenoid 6, and (+)-machaeriol B.

  • 322.
    Gigant, Nicolas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Conjugated Dienes via a Biomimetic Aerobic Oxidative Coupling of Two CvinylH Bonds2013In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 33, p. 10799-10803Article in journal (Refereed)
    Abstract [en]

    A time to dienes: A highly efficient and general method has been developed to prepare conjugated dienes through a biomimetic approach. This aerobic oxidative coupling, involving two CvinylH bonds, proceeds under low Pd catalyst loading and employs catalytic amounts of p-benzoquinone and iron phthalocyanine as electron-transfer mediators (ETMs) under ambient oxygen pressure (see scheme).

  • 323.
    Gigant, Nicolas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Access to Cinnamyl Derivatives from Arenes and Allyl Esters by a Biomimetic Aerobic Oxidative Dehydrogenative Coupling2014In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 6, p. 1664-1667Article in journal (Refereed)
    Abstract [en]

    An efficient biomimetic aerobic oxidative dehydrogenative alkenylation of arenes with allyl esters is presented. The reaction proceeds under an ambient pressure of oxygen with relatively low catalyst loading of palladium acetate, employing catalytic amounts of electron-transfer mediators (ETMs). This study represents a new environmentally friendly method for the synthesis of cinnamyl derivatives.

  • 324.
    Gigant, Nicolas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aerobic Direct C-H Arylation of Nonbiased Olefins2014In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 17, p. 4432-4435Article in journal (Refereed)
    Abstract [en]

    An efficient ligand-promoted biomimetic aerobic oxidative dehydrogenative cross-coupling between arenes and nonbiased olefins is presented. Acridine as a ligand was found to significantly enhance the rate, the yield, and the scope of the reaction under ambient oxygen pressure, providing a variety of alkenylarenes via an environmentally friendly procedure.

  • 325.
    Gigant, Nicolas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aerobic Double Dehydrogenative Cross Coupling between Cyclic Saturated Ketones and Simple Arenes2014In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 20, p. 5890-5894Article in journal (Refereed)
    Abstract [en]

    The synthesis of 3-aryl-2-cyclohexenones is a topic of current interest as they are not only privileged structures in bioactive molecules, but they are also relevant feedstocks for the synthesis of substituted phenols or anilines, which are ubiquitous structural elements both in drug design and medicinal chemistry. A simple and sustainable one-pot aerobic double dehydrogenative reaction under mild conditions for the introduction of arenes in the -position of cyclic ketones has been developed. Starting from the corresponding saturated ketone, this reaction sequence proceeds under relatively low Pd catalyst loading and involves catalytic amounts of electron-transfer mediators (ETMs) under ambient oxygen pressure.

  • 326.
    Gigant, Nicolas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Université Paris-Sud, France.
    Quintin, Francois
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Preparation of Tetrasubstituted Olefins Using Mono or Double Aerobic Direct C-H Functionalization Strategies: Importance of Steric Effects2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 5, p. 2796-2803Article in journal (Refereed)
    Abstract [en]

    A novel protocol for the synthesis of tetrasubstituted olefins through a biomimetic approach has been explored. Both mono- and diarylations were performed under ambient oxygen pressure, giving a range of highly hindered tetrasubstituted alkenes. For diarylation of disubstituted substrates, it was demonstrated that the second arylation is the rate-limiting step of the overall transformation.

  • 327. Girgis, Adel S.
    et al.
    Mabied, Ahmed F.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hegazy, Lamees
    George, Riham F.
    Farag, Hanaa
    Shalaby, ElSayed M.
    Farag, I. S. Ahmed
    Synthesis and DFT studies of an antitumor active spiro-oxindole2015In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 39, no 10, p. 8017-8027Article in journal (Refereed)
    Abstract [en]

    An anti-oncological active spiro-oxindole 7 was synthesized regioselectively via a [3+2]-cycloaddition reaction of azomethine ylide to exocyclic olefinic linkage of 4-piperidone 6, exhibiting properties against diverse tumor cell lines including leukemia, melanoma and cancers of the lung, colon, brain, ovary, breast, prostate, and kidney. Compound 7 crystallizes in the monoclinic system and P21/c space group with four molecules in the unit cell. The structure was also studied by AM1, PM3 and DFT techniques. DFT studies support the stereochemical selectivity of the reaction and determine the molecular electrostatic potential and frontier molecular orbitals.

  • 328. Girgis, Adel S.
    et al.
    Stawinski, Jacek
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    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)-triones2012In: European Journal of Medicinal Chemistry, ISSN 0223-5234, E-ISSN 1768-3254, Vol. 47, p. 312-322Article in journal (Refereed)
    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.

  • 329. Godefroid, Marie
    et al.
    Svensson, Mona V
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cambier, Pierre
    Uzureau, Sophie
    Mirabella, Aurélie
    De Bolle, Xavier
    Van Cutsem, Pierre
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Letesson, Jean-Jacques
    Brucella melitensis 16M produces a mannan and other extracellular matrix components typical of a biofilm2010In: FEMS Immunology and Medical Microbiology, ISSN 0928-8244, E-ISSN 1574-695X, Vol. 59, no 3, p. 364-377Article in journal (Refereed)
  • 330.
    Goncalves, Sylvie
    et al.
    Universite de Strasbourg, Faculte de Pharmacie UMR/CNRS 7199, Laboratoire des Systemes Chimiques Fonctionnels, Illkirch, France.
    Santoro, Stefano
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nicolas, Marc
    Les Laboratoires Pierre Fabre, Centre de Developpement Chimique et Industriel, Gaillac, France.
    Wagner, Alain
    Universite de Strasbourg, Faculte de Pharmacie UMR/CNRS 7199, Laboratoire des Systemes Chimiques Fonctionnels, Illkirch, France.
    Maillos, Philippe
    Les Laboratoires Pierre Fabre, Centre de Developpement Chimique et Industriel, Gaillac, France.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Baati, Rachid
    Universite de Strasbourg, Faculte de Pharmacie UMR/CNRS 7199, Laboratoire des Systemes Chimiques Fonctionnels, Illkirch, France.
    Cationic cyclization of 2-alkenyl-1,3-dithiolanes: DiastereoselectiveSynthesis of trans-decalins2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 9, p. 3274-3285Article in journal (Refereed)
    Abstract [en]

    An unprecedented and highly diastereoselective 6-endo-trig cyclization of 2-alkenyl-1,3-dithiolanes has beendeveloped yielding trans-decalins, an important scaffold present in numerous di- and triterpenes. The novelty of this 6-endo-trigc yclization stands in the stepwise mechanism involving 2-alkenyl-1,3-dithiolane, acting as a novel latent initiator. It is suggested that the thioketal opens temporarily under the influence of TMSOTf, triggering the cationic 6-endo-trig cyclization, andcloses after C−C bond formation and diastereoselective protonation to terminate the process. DFT calculations confirm this mechanistic proposal and provide a rationale for the observed diastereoselectivity. The reaction tolerates a wide range of functionalities and nucleophilic partners within the substrate. We have also shown that the one-pot 6-endo-trig cyclization followedby in situ 1,3-dithiolane deprotection afford directly the corresponding ketone. This improvement allowed the achievement of the shortest total synthesis of triptophenolide and the shortest formal synthesis of triptolide.

  • 331. González, David
    et al.
    Grilló, María-Jesús
    De Miguel, María-Jesús
    Ali, Tara
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Arce-Gorvel, Vilma
    Delrue, Rose-May
    Conde-Álvarez, Raquel
    Munoz, Pilar
    López-Goni, Ignacio
    Iriarte, Maite
    Marín, Clara-M.
    Weintraub, Andrej
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zygmunt, Michel
    Letesson, Jean-Jacques
    Gorvel, Jean-Pierre
    Blasco, José-María
    Moriyón, Ignacio
    Brucellosis vaccines: assessment of Brucella melitensis lipopolysaccharide rough mutants defective in core and O-polysaccharide synthesis and export2008In: PLoS ONE, ISSN 1932-6203, Vol. 3, no 7, p. e2760 (1-15)Article in journal (Refereed)
  • 332.
    González Miera, Greco
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nonclassical cyclodehydration of diols assisted by metal-ligand cooperation2017Article in journal (Refereed)
  • 333.
    González Miera, Greco
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bermejo Gómez, Antonio
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chupas, Peter J.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chapman, Karena W.
    Platero-Prats, Ana E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Topological Transformation of a Metal–Organic Framework Triggered by Ligand Exchange2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 8, p. 4576-4583Article in journal (Refereed)
    Abstract [en]

    Here we describe the topological transformation of the pores of a new framework in the bio-MOF-100 family (dia-c) into the known isomer (lcs) by doubling the pore volume, which occurs during postsynthesis modifications. During this transformation, reassembling of the metal–organic framework (MOF) building blocks into a completely different framework occurs, involving breaking/forming of metal–ligand bonds. MOF crystallinity and local structure are retained, as determined by powder X-ray diffraction (PXRD) and pair distribution function (PDF) analyses, respectively. We exploited the inherent dynamism of bio-MOF-100 by coupling chemical decorations of the framework using solvent-assisted ligand exchange to the topological change. Following this method and starting from the pristine dense dia-c phase, open lcs-bio-MOF-100 was prepared and functionalized in situ with an iridium complex (IrL). Alternatively, the dia-c MOF could be modified with wide-ranging amounts of IrL up to ca. 50 mol %, as determined by solution 1H NMR spectroscopy, by tuning the concentration of the solutions used and with no evidence for isomer transformation. The single-site nature of the iridium complexes within the MOFs was assessed by X-ray absorption spectroscopy (XAS) and PDF analyses. Ligand exchanges occurred quantitatively at room temperature, with no need of excess of the iridium metallolinker.

  • 334.
    González Miera, Greco
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martínez-Castro, Elisa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Acceptorless Alcohol Dehydrogenation: OH vs NH Effect in Bifunctional NHC–Ir(III) Complexes2018In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 37, no 5, p. 636-644Article in journal (Refereed)
    Abstract [en]

    Bifunctional complexes bearing N-heterocyclic carbene (NHC) ligands functionalized with hydroxy or amine groups were synthesized to measure the beneficial effect of different modes of metal–ligand cooperation in the acceptorless dehydrogenation of alcohols. In comparison to complexes with an amine moiety, hydroxy-functionalized iridium catalysts showed superior activity. In contrast to alcohols, 1,4-diols underwent cyclization to give the corresponding tetrahydrofurans without involving dehydrogenation processes. Mechanistic investigations to rationalize the “OH effect” in these types of complexes have been undertaken.

  • 335. Goulart, Paula N.
    et al.
    da Silva, Clarissa O.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    The importance of orientation of exocyclic groups in a naphthoxyloside: A specific rotation calculation study2017In: Journal of Physical Organic Chemistry, ISSN 0894-3230, E-ISSN 1099-1395, Vol. 30, no 12, article id e3708Article in journal (Refereed)
    Abstract [en]

    2-Naphthyl -d-xylopyranoside (XylNap) inhibits -1,4-galactosyltransferase 7 (4GalT7) and thereby growth of tumor cells both in vitro and in vivo. The binding pocket of 4GalT7 has a defined orientation of hydrogen bond acceptors and hydrophobic moiety. Knowing the orientation of the hydroxyl and naphthyl groups of this molecule would help in the development of more efficient inhibitors. In this work, we have tried, for the first time, to determine the exocyclic hydroxyl and aglycon groups orientation of XylNap, using ab initio descriptions, and calculation of the specific rotation values, in methanol solutions, using 2 different solvent descriptions: a dielectric continuum approach (polarizable continuum model [PCM]) and a microsolvated+continuum approach (MS+PCM). In the PCM approach, [](D)=-59 deg/(dm(g/cm(3))) whereas for the MS+PCM approach [](D)=-29 deg/(dm(g/cm(3))). The latter is in excellent agreement with the experimentally determined value in methanol solution, viz, [](D)=-30 deg/(dm(g/cm(3))). This agreement allows us to say that the hydroxyl groups have similar orientations in xylose and XylNap, and the naphthyl group has a very well-defined dihedral angle value in the most abundant conformations.

  • 336.
    Gudmundsson, Arnar
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Bin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient Formation of 2,3-Dihydrofurans via Iron-Catalyzed Cycloisomerization of alpha-Allenols2018In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 1, p. 12-16Article in journal (Refereed)
    Abstract [en]

    Herein, we report a highly efficient iron-catalyzed intramolecular nucleophilic cyclization of alpha-allenols to furnish substituted 2,3-dihydrofurans under mild reaction conditions. A highly diastereoselective variant of the reaction was developed as well, giving diastereomeric ratios of up to 98:2. The combination of the iron-catalyzed cycloisomerization with enzymatic resolution afforded the 2,3-dihydrofuran in high ee. A detailed DFT study provides insight into the reaction mechanism and gives a rationalization for the high chemo-and diastereoselectivity.

  • 337. Gupta, Arvind Kumar
    et al.
    Akkarasamiyo, Sunisa
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Orthaber, Andreas
    Rich Coordination Chemistry of pi-Acceptor Dibenzoarsole Ligands2017In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 56, no 8, p. 4504-4511Article in journal (Refereed)
    Abstract [en]

    A series of dibenzoarsole (also known as 9-arsafluorene) derivatives have been prepared, and their coordination chemistry has been investigated. The different ligand topology and the arsenic substituents govern the reactivity of the ligands. We report various crystal structures of palladium and platinum complexes derived from this family of ligands. The biphenyl backbone of the bridged bidentate ligands allows very flexible coordination. We have also studied the application of an allylic Pd complex in nucleophilic substitution reactions, revealing that the benzoarsole substituent is susceptible to metal insertion.

  • 338. Gupta, Garima
    et al.
    Gemma, Emiliano
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oscarson, Stefan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Surolia, Avadhesha
    Defining substrate interactions with calreticulin: an isothermal titration calorimetric study2008In: Glycoconjugate Journal, ISSN 0282-0080, Vol. 25, no 8, p. 797-802Article in journal (Refereed)
  • 339.
    Gustafson, Karl P. J.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gudmundsson, Arnar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lewis, Kayla
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chemoenzymatic Dynamic Kinetic Resolution of Secondary Alcohols Using an Air- and Moisture-Stable Iron Racemization Catalyst2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 5, p. 1048-1051Article in journal (Refereed)
    Abstract [en]

    Herein, we report on a metalloenzymatic dynamic kinetic resolution of sec-alcohols employing an iron-based racemization catalyst together with a lipase. The iron catalyst was evaluated in racemization and then used in dynamic kinetic resolution of a number of sec-alcohols to give enantiomerically pure products in good to high yields. The iron catalyst is air and moisture stable and is readily accessible.

  • 340.
    Gustafson, Karl P. J.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lihammar, Richard
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Engström, Karin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Chemoenzymatic Dynamic Kinetic Resolution of Primary Amines Using a Recyclable Palladium Nanoparticle Catalyst Together with Lipases2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 9, p. 3747-3751Article in journal (Refereed)
    Abstract [en]

    A catalyst consisting of palladium nanoparticles supported on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was used in chemoenzymatic dynamic kinetic resolution (DKR) to convert primary amines to amides in high yields and excellent ee's. The efficiency of the nanocatalyst at temperatures below 70 degrees C enables reaction conditions that are more suitable for enzymes. In the present study, this is exemplified by subjecting 1-phenylethylamine (1a) and analogous benzylic amines to DKR reactions using two commercially available lipases, Novozyme-435 (Candida antartica Lipase B) and Amano Lipase PS-C1 (lipase from Burkholderia cepacia) as biocatalysts. The latter enzyme has not previously been used in the DKR of amines because of its low stability at temperatures over 60 degrees C. The viability of the heterogeneous Pd-AmP-MCF was further demonstrated in a recycling study, which shows that the catalyst can be reused up to five times.

  • 341.
    Gustafson, Karl P. J.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Shatskiy, Andrey
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kärkäs, Markus D.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Schluschass, Bastian
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Water oxidation mediated by ruthenium oxide nanoparticles supported on siliceous mesocellular foam2017In: Catalysis Science & Technology, ISSN 2044-4753, E-ISSN 2044-4761, Vol. 7, no 1, p. 293-299Article in journal (Refereed)
    Abstract [en]

    Artificial photosynthesis is an attractive strategy for converting solar energy into fuel. In this context, development of catalysts for oxidation of water to molecular oxygen remains a critical bottleneck. Herein, we describe the preparation of a well-defined nanostructured RuO2 catalyst, which is able to carry out the oxidation of water both chemically and photochemically. The developed heterogeneous RuO2 nanocatalyst was found to be highly active, exceeding the performance of most known heterogeneous water oxidation catalysts when driven by chemical or photogenerated oxidants.

  • 342.
    Gustafsson, Mikaela
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Bartoszewicz, Agnieszka
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sun, Junliang
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Grins, Jekabs
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Zhao, Tony
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Li, Zhongyue
    Zhu, Guangshan
    Zou, Xiaodong
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    A family of highly stable lanthanide metal-organic frameworks: structural evolution and catalytic activity2010In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 22, no 11, p. 3316-3322Article in journal (Refereed)
    Abstract [en]

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

  • 343. Gustafsson, Nina M. S.
    et al.
    Färnegårdh, Katarina
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Stockholm University, Science for Life Laboratory (SciLifeLab). Kancera AB, Sweden.
    Bonagas, Nadilly
    Ninou, Anna Huguet
    Groth, Petra
    Wiita, Elisee
    Jönsson, Mattias
    Hallberg, Kenth
    Lehto, Jemina
    Pennisi, Rosa
    Martinsson, Jessica
    Norström, Carina
    Hollers, Jessica
    Schultz, Johan
    Andersson, Martin
    Markova, Natalia
    Marttila, Petra
    Kim, Baek
    Norin, Martin
    Olin, Thomas
    Helleday, Thomas
    Targeting PFKFB3 radiosensitizes cancer cells and suppresses homologous recombination2018In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, article id 3872Article in journal (Refereed)
    Abstract [en]

    The glycolytic PFKFB3 enzyme is widely overexpressed in cancer cells and an emerging anticancer target. Here, we identify PFKFB3 as a critical factor in homologous recombination (HR) repair of DNA double-strand breaks. PFKFB3 rapidly relocates into ionizing radiation (IR)-induced nuclear foci in an MRN-ATM-gamma H2AX-MDC1-dependent manner and co-localizes with DNA damage and HR repair proteins. PFKFB3 relocalization is critical for recruitment of HR proteins, HR activity, and cell survival upon IR. We develop KAN0438757, a small molecule inhibitor that potently targets PFKFB3. Pharmacological PFKFB3 inhibition impairs recruitment of ribonucleotide reductase M2 and deoxynucleotide incorporation upon DNA repair, and reduces dNTP levels. Importantly, KAN0438757 induces radiosensitization in transformed cells while leaving non-transformed cells unaffected. In summary, we identify a key role for PFKFB3 enzymatic activity in HR repair and present KAN0438757, a selective PFKFB3 inhibitor that could potentially be used as a strategy for the treatment of cancer.

  • 344.
    Gustafsson, Robert
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Jemth, Ann-Sofie
    Gustafsson, Nina M. S.
    Färnegårdh, Katarina
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Loseva, Olga
    Wiita, Elisée
    Bonagas, Nadilly
    Dahllund, Leif
    Llona-Minguez, Sabin
    Häggblad, Maria
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Henriksson, Martin
    Andersson, Yasmin
    Homan, Evert
    Helleday, Thomas
    Stenmark, Pal
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Crystal Structure of the Emerging Cancer Target MTHFD2 in Complex with a Substrate-Based Inhibitor2017In: Cancer Research, ISSN 0008-5472, E-ISSN 1538-7445, Vol. 77, no 4, p. 937-948Article in journal (Refereed)
    Abstract [en]

    To sustain their proliferation, cancer cells become dependent on one-carbon metabolism to support purine and thymidylate synthesis. Indeed, one of the most highly upregulated enzymes during neoplastic transformation is MTHFD2, a mitochondrial methylenetetrahydrofolate dehydrogenase and cyclohydrolase involved in one-carbon metabolism. Because MTHFD2 is expressed normally only during embryonic development, it offers a disease-selective therapeutic target for eradicating cancer cells while sparing healthy cells. Here we report the synthesis and preclinical characterization of the first inhibitor of human MTHFD2. We also disclose the first crystal structure of MTHFD2 in complex with a substrate-based inhibitor and the enzyme cofactors NAD(+) and inorganic phosphate. Our work provides a rationale for continued development of a structural framework for the generation of potent and selective MTHFD2 inhibitors for cancer treatment.

  • 345.
    Görbe, Tamás
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Gustafson, Karl P. J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Verho, Oscar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kervefors, Gabriella
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zheng, Haoquan
    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).
    Johnston, Eric V.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Design of a Pd(0)-CalB CLEA Biohybrid Catalyst and Its Application in a One-Pot Cascade Reaction2017In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 7, no 3, p. 1601-1605Article in journal (Refereed)
    Abstract [en]

    Herein, a design of a biohybrid catalyst is described, consisting of Pd nanoparticles and a cross-linked network of aggregated lipase B enzyme of Candida antarctica (CalB CLEA) functioning as an active support for the Pd nanoparticles. Both entities of the hybrid catalyst showed good catalytic activity. The applicability was demonstrated in a one-pot reaction, where the Pd-catalyzed cycloisomerization of 4-pentynoic acid afforded a lactone that serves as an acyl donor in a subsequent selective enzymatic kinetic resolution of a set of sec-alcohols. The catalyst proved to be robust and could be recycled five times without a significant loss of activity.

  • 346.
    Görbe, Tamás
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lihammar, Richard
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-E.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Heterogeneous Acid-Catalyzed Racemization of Tertiary Alcohols2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 1, p. 77-80Article in journal (Refereed)
    Abstract [en]

    Tertiary alcohols are important structural motifs in natural products and building blocks in organic synthesis but only few methods are known for their enantioselective preparation. Chiral resolution is one of these approaches that leaves one enantiomer (50% of the material) unaffected. An attractive method to increase the efficiency of those resolutions is to racemize the unaffected enantiomer. In the present work, we have developed a practical racemization protocol for tertiary alcohols. Five different acidic resin materials were tested. The Dowex 50WX8 was the resin of choice since it was capable of racemizing tertiary alcohols without any byproduct formation. Suitable solvents and a biphasic system were investigated, and the optimized system was capable of racemizing differently substituted tertiary alcohols.

  • 347. Hafrén, Jonas
    et al.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Direct Bronsted acid-catalyzed derivatization of cellulose with poly(L-lactic acid) and D-mandelic acid2007In: Nordic Pulp and Paper Research Journal, ISSN 0283-2631, Vol. 22, no 2, p. 184-187Article in journal (Refereed)
  • 348. Hakkarainen, Birgit
    et al.
    Kenne, Lennart
    Lahmann, Martina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Oscarson, Stefan
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sandström, Corine
    Spectral assignments and reference data: NMR study of hydroxy protons of di- and trimannosides, substructures of Man-92007In: Magnetic Resonance in Chemistry, ISSN 0749-1581, Vol. 45, no 12, p. 1076-1080Article in journal (Refereed)
  • 349.
    Hamark, Christoffer
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Berntsson, Ronnie P. -A.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Masuyer, Geoffrey
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Henriksson, Linda M.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Gustafsson, Robert
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Stenmark, Pål
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Glycans Confer Specificity to the Recognition of Ganglioside Receptors by Botulinum Neurotoxin A2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 1, p. 218-230Article in journal (Refereed)
    Abstract [en]

    The highly poisonous botulinum neurotoxins, produced by the bacterium Clostridium botulinum, act on their hosts by a high-affinity association to two receptors on neuronal cell surfaces as the first step of invasion. The glycan motifs of gangliosides serve as initial coreceptors for these protein complexes, whereby a membrane protein receptor is bound. Herein we set out to characterize the carbohydrate minimal binding epitope of the botulinum neurotoxin serotype A. By means of ligand-based NMR spectroscopy, X-ray crystallography, computer simulations, and isothermal titration calorimetry, a screening of ganglioside analogues together with a detailed characterization of various carbohydrate ligand complexes with the toxin were accomplished. We show that the representation of the glycan epitope to the protein affects the details of binding. Notably, both branches of the oligosaccharide GD la can associate to botulinum neurotoxin serotype A when expressed as individual trisaccharides. It is, however, the terminal branch of GD1a as well as this trisaccharide motif alone, corresponding to the sialyl-Thomsen-Friedenreich antigen, that represents the active ligand epitope, and these compounds bind to the neurotoxin with a high degree of predisposition but with low affinities. This finding does not correlate with the oligosaccharide moieties having a strong contribution to the total affinity, which was expected to be the case. We here propose that the glycan part of the ganglioside receptors mainly provides abundance and specificity, whereas the interaction with the membrane itself and protein receptor brings about the strong total binding of the toxin to the neuronal membrane.

  • 350.
    Hamark, Christoffer
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Landström, Jens
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ethyl 3,6-di-O-benzyl-2-deoxy-N-phthalimido-1-thio-β-D-glucopyranoside2010In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. E66, p. o3250-o3251Article in journal (Refereed)
    Abstract [en]

    In the title compound, C30H31NO6S, the plane of the N-phthalimido group is nearly orthogonal to the least-squares plane of the sugar ring (defined by atoms C2, C3, C5 and O5 using standard glucose nomenclature), making a dihedral angle of 72.8 (1)°. The thioethyl group has the exo-anomeric conformation. The hydroxy group forms an intermolecular hydrogen bond to the O atom in the sugar ring, generating [100] chains. There are four close - contacts with centroid-centroid distances less than 4.0 Å, all with dihedral angles between the interacting systems of only 8°, supporting energetically favourable stacking interactions

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