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  • 1701.
    Zhao, Tony S. N.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Trifluoromethylation of Propargylic Halides and Trifluoroacetates Using (Ph3P)(3)Cu(CF3) Reagent2012Ingår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, nr 15, s. 3966-3969Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A copper-mediated trifluoromethylation of propargylic halides and trifluoroacetates was performed with high allenyl or propargyl selectivity. The reaction proceeds smoothly with aliphatic and aromatic substituents bearing either electron-withdrawing or -supplying groups. Preliminary mechanistic results indicate an ionic mechanism involving nucleophilic transfer of the CF3 group from the Cu complex to the propargylic substrate.

  • 1702.
    Zhao, Tony S. N.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Yuzhu
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lessing, Timo
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Borylation of Propargylic Substrates by Bimetallic Catalysis. Synthesis of Allenyl, Propargylic, and Butadienyl Bpin Derivatives2014Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, nr 21, s. 7563-7566Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bimetallic Pd/Cu and Pd/Ag catalytic systems were used for borylation of propargylic alcohol derivatives. The substrate scope includes even terminal alkynes. The reactions proceed stererospecifically with formal S(N)2' pathways to give allenyl boronates. Opening of propargyl epoxides leads to 1,2-diborylated butadienes probably via en allenylboronate intermediate.

  • 1703.
    Zhao, Tony S. N.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhao, Jian
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Szabó, Kálmán J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Stereoselective Synthesis of 1,4-Diols by a Tandem Allylboration–Allenylboration Sequence2015Ingår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 17, nr 9, s. 2290-2293Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The reaction of mono- and dialdehydes with bis-borodienes (incorporating an allylboronate unit) has been studied. It was found that the initial allylboration reaction results in an allenylboronate, which has two stereogenic units: one of them has axial chirality and the other one is a stereogenic carbon center. This reaction proceeds with high diastereoselectivity. The allenylboronate formed in the allylboration reacts with an additional aldehyde with fair to high stereoselectivity depending on the aldehyde substrate. Aromatic dialdehydes react with bis-boro-butadienes creating three new stereocenters with usually high diastereoselectivity.

  • 1704.
    Zheng, Jia
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Margarita, Cristiana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Krajangsri, Suppachai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Andersson, Pher G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Asymmetric Total Synthesis of (-)-Juvabione via Sequential Ir-Catalyzed Hydrogenations2018Ingår i: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 20, nr 18, s. 5676-5679Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    (-)-Juvabione, a natural sesquiterpene exhibiting juvenile insect hormone activity, was synthesized constructing the two adjacent stereogenic centers via sequential Ir-catalyzed hydrogenations. The first center is generated by hydrogenation of a styrene-type double bond (99% ee). The successive monohydrogenation of a diene intermediate constitutes the key step, granting high levels of regio- and stereocontrol (94:6 dr). This novel strategy allowed the preparation of (-)-juvabione from simple starting materials in 9 steps and 17% total yield.

  • 1705.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    An Efficient Approach to Regio- and Stereodefined Fully-Substituted Alkenylsilanes by Pd-Catalyzed Allenic C(sp(3))-H Oxidation2019Ingår i: Chemistry: A European Journal, ISSN 0947-6539, Vol. 25, nr 49, s. 11566-11573Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A highly efficient palladium-catalyzed functionalization of allenylsilanes to give regio- and stereodefined fully-substituted alkenylsilanes has been developed. This oxidative coupling reaction showed good functional group compatibility with exclusive regio- and stereoselectivity. The pending olefin on the silyl group was shown to be an indispensable element for the initial allenic C(sp(3))-H bond cleavage, and performs as the directing group to control the overall selectivity. The addition of substoichiometric amounts of Et3N was found to increase the reaction rate leading to a higher reaction yield. The reaction can be easily scaled up and applied for the late-stage functionalization of natural products and pharmaceutical compounds, including amino acids and steroid derivatives. The newly introduced functional groups include aryl, alkynyl, and boryl groups. The highly strained four-membered ring, silacyclobutene was obtained when B(2)pin(2) was employed as the coupling partner. Mechanistic studies, including kinetic isotope effects, showed that the allenic C(sp(3))-H bond cleavage is the rate-limiting step.

  • 1706.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Selective Cascade C-C Bond Formation via Palladium-Catalyzed Oxidative Carbonylation-Carbocyclization-Carbonylation-Alkynylation of Enallenes2015Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, nr 37, s. 11868-11871Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A highly efficient palladium-catalyzed oxidative cascade reaction of enallenes undergoing overall four C-C bond formations has been developed. The insertion cascade proceeds via carbonylation carbocyclization carbonylation alkynylation involving sequential insertion of carbon monoxide, olefin, and carbon monoxide. Furthermore, different types of terminal alkynes and functionalized enallenes have been investigated and found to undergo the cascade reaction under mild reaction conditions.

  • 1707.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    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.
    Olefin-Directed Palladium-Catalyzed Regio- and Stereoselective Oxidative Arylation of Allenes2015Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, nr 31, s. 9066-9069Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An olefin-directed palladium-catalyzed oxidative regio- and stereoselective arylation of allenes to afford 1,3,6-trienes has been established. A number of functionalized allenes, including 2,3- and 3,4-dienoates and 3,4-dienol derivatives, have been investigated and found to undergo the olefin-directed allene arylation. The olefin moiety has been proven to be a crucial element for the arylating transformation.

  • 1708.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Khanh Mai, Binh
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Palazzotto, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Gudmundsson, Arnar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Ricke, Alexander
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Himo, Fahmi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Selective Palladium-Catalyzed Hydroborylative Carbocyclization of Bisallenes to Seven-Membered Rings2018Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, nr 43, s. 14324-14333Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A highly selective palladium-catalyzed hydroborylative carbocyclization of bisallenes to afford seven-membered rings has been established. This ring-closing coupling reaction showed good functional group compatibility with high chemo- and regioselectivity, as seven-membered ring 3 was the only product obtained. The extensive use of different linkers, including nitrogen, oxygen, malononitrile, and malonate, showed a broad substrate scope for this approach. A one-pot cascade reaction was realized by trapping the primary allylboron compound with an aldehyde, affording a diastereomerically pure alcohol and a quaternary carbon center by formation of a new C-C bond. A comprehensive mechanistic DFT investigation is also presented. The calculations suggest that the reaction proceeds via a concerted hydropalladation pathway from a Pd(0)-olefin complex rather than via a pathway involving a defined palladium hydride species. The reaction was significantly accelerated by the coordination of the pendant olefin, as well as the introduction of suitable substituents in the bridge, due to the Thorpe-Ingold effect.

  • 1709.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Highly Selective Construction of Seven-Membered Carbocycles by Olefin-Assisted Palladium-Catalyzed Oxidative Carbocyclization-Alkoxycarbonylation of Bisallenes2016Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, nr 46, s. 14405-14408Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An olefin-assisted palladium-catalyzed oxidative carbocyclization-alkoxycarbonylation of bisallenes to afford seven-membered carbocycles has been established. This dehydrogenative coupling reaction showed excellent substrate scope and functional group compatibility. The reaction exhibited high chemo-and regioselectivity, and ester 3 was the only product obtained. The olefin unit has been proven to be indispensable during the reaction. Moreover, intramolecular oxidative coupling suggests that the reaction proceeds via a (pallyl)palladium intermediate.

  • 1710.
    Zhu, Can
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yang, Bin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Qiu, Youai
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olefin-Directed Palladium-Catalyzed Regio- and Stereoselective Hydroboration of Allenes2016Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 22, nr 9, s. 2939-2943Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An olefin-directed palladium-catalyzed regio- and stereoselective hydroboration of allenes has been developed to afford fully substituted alkenylboron compounds. The reaction showed a broad substrate scope: a number of functionalized allenes, including 2,3-dienoate, 3,4-dienoate, 3,4-dienol, 1,2-allenylphosphonate, and alkyl-substituted allenes, could be used in this olefin-directed allene hydroboration. The olefin unit was proven to be an indispensable element for this transformation.

  • 1711.
    Zhu, Mingzhao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Jalalian, Nazli
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Olofsson, Berit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    One-pot synthesis of diaryliodonium salts using toluenesulfonic acid - a fast entry to electron-rich diaryliodonium tosylates and triflates2008Ingår i: Synlett: Accounts and Rapid Communications in Synthetic Organic Chemistry, ISSN 0936-5214, E-ISSN 1437-2096, nr 4, s. 592-596Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A direct synthesis of symmetric and unsymmetric electron-rich diaryliodonium salts is described. The use of MCPBA and toluenesulfonic acid delivers diaryliodonium tosylates in high yields. An in situ anion exchange has also been developed, giving access to the corresponding triflate salts.

  • 1712.
    Zhu, Mingzhao
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Lin, Shuangzheng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Zhao, Gui-Ling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Junliang
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Organocatalytic diastereoselective dibromination of alkenes2010Ingår i: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 51, nr 20, s. 2708-2712Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A highly diastereoselective pyrrolidine-promoted dibromination of alkenes by combination of NBS and succinimide is presented. The pyrrolidine-mediated dibromination of alkenes is higly anti-selective and gives the corresponding products in moderate to high yields and up to >25:1 dr.

  • 1713.
    Zmudzka, Katarzyna
    et al.
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Johansson, Tommy
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Wojcik, Marzena
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Janicka, Magdalena
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Nowak, Marian
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Stawinski, Jacek
    Nawrot, Barbara
    Polish Acad Sci, Ctr Mol & Macromol Studies.
    Novel DNA Analogues with 2-, 3- and 4-Pyridylphosphonate Internucleotide Bonds: Synthesis and Hybridisation Properties2003Ingår i: New Journal of Chemistry, ISSN 1144-0546, Vol. 27, nr 12, s. 1698-1705Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Oligothymidylates modified with stereodefined 2-pyridyl-, 3-pyridyl- and 4-pyridylphosphonate moieties at one or two juxtaposed internucleotide positions were prepared, and their avidity towards complementary single stranded DNA and RNA, as well as toward double stranded DNA were evaluated by UV melting temperature and CD studies. It was found that the sense of chirality at the phosphorus centre and the position of the nitrogen atom in the pyridyl ring of a pyridylphosphonate moiety are important factors governing stability of double- and triple-stranded complexes formed by these oligonucleotides. DNA/DNA and DNA/RNA duplexes containing oligothymidylate strands with R-P-pyridylphosphonate units differed only slightly from unmodified reference complexes. In contrast to this, the S-P-pyridylphosphonate derivatives exhibited lower binding affinity than both their R-P-counterparts and the unmodified reference oligonucleotide T-20. Triplexes of oligo(thymidyl pyridylphosphonate)s with hairpin oligomer d(A(21)C(4)T(21)) were found mostly to be thermodynamically slightly more stable in pH 7.4 and less stable in pH 5.0 than non-modified complexes. As expected, oligonucleotides with pyridylphosphonate internucleotide bonds were recognised by 3'- and 5'-exonucleases but the chimeric oligonucleotide chains were not cleaved at the modi. cation sites.

  • 1714. Zou, Dapeng
    et al.
    Andersson, Samir
    Zhang, Rong
    Sun, Shiguo
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    A host-induced intramolecular charge-transfer complex and light-driven radical cation formation of a molecular triad with cucurbit[8]uril2008Ingår i: The Journal of Organic Chemistry, ISSN 0022-3263, Vol. 73, nr 10, s. 3775-3783Artikel i tidskrift (Refereegranskat)
  • 1715. Zou, Dapeng
    et al.
    Andersson, Samir
    Zhang, Rong
    Sun, Shiguo
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sun, Licheng
    Selective binding of cucurbit[7]uril and beta-cyclodextrin with a redox-active molecular triad Ru(bpy)3-MV2+-naphthol2007Ingår i: Chemical Communications, ISSN 1359-7345, nr 45, s. 4734-4736Artikel i tidskrift (Refereegranskat)
  • 1716.
    Zou, Xiaodong
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Yao, Qingxia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Bermejo Gómez, Antonio
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Su, Jie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Pascanu, Vlad
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Yifeng, Yun
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Zheng, Haoquan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Chen, Hong
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Liu, Leifeng
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Abdelhamid, Hani N.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    A series of highly stable isoreticular lanthanide metal-organic frameworks with tunable luminescence properties solved by rotation electron diffraction and X-ray diffraction2016Ingår i: Acta Crystallographica Section A: Foundations of Crystallography, ISSN 0108-7673, E-ISSN 1600-5724, Vol. A72, s. 136-136Artikel i tidskrift (Refereegranskat)
  • 1717. Zovko, Ana
    et al.
    Novak, Metka
    Hååg, Petra
    Kovalerchick, Dimitry
    Holmlund, Teresa
    Färnegårdh, Katarina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi. Stockholms universitet, Science for Life Laboratory (SciLifeLab).
    Ilan, Micha
    Carmeli, Shmuel
    Lewensohn, Rolf
    Viktorsson, Kristina
    Compounds from the marine sponge Cribrochalina vasculum offer a way to target IGF-1R mediated signaling in tumor cells2016Ingår i: OncoTarget, ISSN 1949-2553, E-ISSN 1949-2553, Vol. 7, nr 31, s. 50258-50276Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work two acetylene alcohols, compound 1 and compound 2, which were isolated and identified from the sponge Cribrochalina vasculum, and which showed antitumor effects were further studied with respect to targets and action mechanisms. Gene expression analyses suggested insulin like growth factor receptor (IGF-1R) signaling to be instrumental in controlling anti-tumor efficacy of these compounds in non-small cell lung cancer (NSCLC). Indeed compounds 1 and 2 inhibited phosphorylation of IGF-1R beta as well as reduced its target signaling molecules IRS-1 and PDK1 allowing inhibition of pro-survival signaling. In silico docking indicated that compound 1 binds to the kinase domain of IGF-1R at the same binding site as the well known tyrosine kinase inhibitor AG1024. Indeed, cellular thermal shift assay (CETSA) confirmed that C. vasculum compound 1 binds to IGF-1R but not to the membrane localized tyrosine kinase receptor EGFR. Importantly, we demonstrate that compound 1 causes IGF-1R beta but not Insulin Receptor degradation specifically in tumor cells with no effects seen in normal diploid fibroblasts. Thus, these compounds hold potential as novel therapeutic agents targeting IGF-1R signaling for anti-tumor treatment.

  • 1718. Zovko, Ana
    et al.
    Viktorsson, Kristina
    Haag, Petra
    Kovalerchick, Dimitry
    Farnegardh, Katarina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Alimonti, Andrea
    Ilan, Micha
    Carmeli, Shmuel
    Lewensohn, Rolf
    Marine Sponge Cribrochalina vasculum Compounds Activate Intrinsic Apoptotic Signaling and Inhibit Growth Factor Signaling Cascades in Non-Small Cell Lung Carcinoma2014Ingår i: Molecular Cancer Therapeutics, ISSN 1535-7163, E-ISSN 1538-8514, Vol. 13, nr 12, s. 2941-2954Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Marine-derived compounds have been explored and considered as possible antitumor agents. In this study, we analyzed extracts of the sponge Cribrochalina vasculum for their ability to inhibit tumor cell proliferation. Screening identified two acetylenic compounds of similar structure that showed strong tumor-specific toxicity in non-small cell lung carcinoma (NSCLC) cells and small-cell lung carcinoma cells, and less prominent toxicity in ovarian carcinoma, while having no effect on normal cells. These acetylenic compounds were found to cause a time-dependent increase in activation of apoptotic signaling involving cleavage of caspase-9, caspase-3, and PARP, as well as apoptotic cell morphology in NSCLC cells, but not in normal fibroblasts. Further analysis demonstrated that these compounds caused conformational change in Bak and Bax, and resulted in loss of mitochondrial potential and cytochrome c release in NSCLC cells. Moreover, a decreased phosphorylation of the growth factor signaling kinases Akt, mTOR, and ERK was evident and an increased phosphorylation of JNK was observed. Thus, these acetylenic compounds hold potential as novel therapeutic agents that should be further explored for NSCLC and other tumor malignancies.

  • 1719.
    Åberg, Jenny B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic Studies on Ruthenium-Catalyzed Hydrogen Transfer Reactions2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Mechanistic studies on three different ruthenium-based catalysts have been performed. The catalysts have in common that they have been employed in hydrogen transfer reactions involving alcohols and ketones, amines and imines or both.

    Bäckvall’s catalyst, η5-(Ph5C5)Ru(CO)2Cl, finds its application as racemization catalyst in dynamic kinetic resolution, where racemic alcohols are converted to enantiopure acetates in high yields. The mechanism of the racemization has been investigated and both alkoxide and alkoxyacyl intermediates have been characterized by NMR spectroscopy and in situ FT-IR measurements. The presence of acyl intermediates supports a mechanism via CO assistance. Substantial support for coordination of the substrate during the racemization cycle is provided, including exchange studies with both external and internal potential ketone traps. We also detected an unexpected alkoxycarbonyl complex from 5-hydroxy-1-hexene, which has the double bond coordinated to ruthenium.

    Shvo’s catalyst, [Ru2(CO)4(μ-H)(C4Ph4COHOCC4Ph4)] is a powerful catalyst for transfer hydrogenation as well as for dynamic kinetic resolution. The mechanism of this catalyst is still under debate, even though a great number of studies have been published during the past decade. In the present work, the mechanism of the reaction with imines has been investigated. Exchange studies with both an external and an internal amine as potential traps have been performed and the results can be explained by a stepwise inner-sphere mechanism. However, if there is e.g. a solvent cage effect, the results can also be explained by an outer-sphere mechanism. We have found that there is no cage effect in the reduction of a ketone containing a potential internal amine trap. If the mechanism is outer-sphere, an explanation as to why the solvent cage effect is much stronger in the case of imines than ketones is needed.

    Noyori’s catalyst, [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3), has successfully been used to produce chiral alcohols and amines via transfer hydrogenation. The present study shows that the mechanism for the reduction of imines is different from that of ketones and aldehydes. Acidic activation of the imine was found necessary and an ionic mechanism was proposed.

  • 1720.
    Åberg, Jenny B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic studies on three different ruthenium based hydrogen transfer catalysts2006Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 1721.
    Åberg, Jenny B.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Investigation of a possible solvent cage effect in the reduction of 4-aminocyclohexanone by a hydroxycyclopentadienyl ruthenium hydride2008Ingår i: Chemistry: a European Journal, ISSN 0947-6539, Vol. 14, nr 30, s. 9169-9174Artikel i tidskrift (Refereegranskat)
  • 1722.
    Åberg, Jenny B.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Nyhlén, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Martín-Matute, Belén
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Privalov, Timofei
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    CO Assistance in ligand exchange of a ruthenium racemization catalyst: identification of an acyl intermediate2009Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, nr 27, s. 9500-9501Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An acyl intermediate in the activation of eta(5)-(Ph(5)Cp)Ru(CO)(2)Cl by t-BuOK was identified by means of in situ FT-IR measurements and NMR spectroscopy. This strongly supports the conclusion that the ligand exchange takes place via CO assistance, i.e., that the activation occurs via nucleophilic attack by tert-butoxide on one of the CO ligands. The tert-butoxycarbonyl intermediate shows stretching vibrations at 1933 and 1596 cm(-1), corresponding to the CO and COOt-Bu groups, respectively. In the (13)C NMR spectrum, the CO group appears at 209.5 ppm and the COOt-Bu group at 208.7 ppm. The NMR assignments were confirmed by density functional theory calculations. The subsequent alcohol-alkoxide exchange is also thought to take place via CO assistance. However, no intermediate in that step could be detected.

  • 1723.
    Åberg, Jenny B.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Warner, Madeleine C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Unexpected formation of a cyclopentadienylruthenium alkoxycarbonyl complex with a coordinated C=C bond2009Ingår i: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, nr 38, s. 13622-13624Artikel i tidskrift (Refereegranskat)
  • 1724.
    Åberg, Jenny
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Samec, Joseph S. M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Mechanistic Investigation on the Hydrogenation of Imines by [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3). Experimental support for an  Ionic Pathway2006Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, nr 26, s. 2771-2773Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The need for acidic activation in the stoichiometric hydrogenation of benzyl-[1-phenyl-ethylidene]-amine ( 6a) or [1-(4-methoxy-phenyl)-ethylidene]-methyl-amine ( 6b) by Noyori's catalyst [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3)( 2) is inconsistent with the proposed concerted mechanism and supports an ionic mechanism.

  • 1725.
    Åkermark, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Vätgas från solljus och vatten, en dröm som närmar sig sin uppfyllelse2008Ingår i: Sveriges Energiting, 13-14 mars 2008, 2008, s. xxxx-Konferensbidrag (Övrigt vetenskapligt)
  • 1726.
    Åkermark, Björn
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Sjögren, Magnus P.T.
    Iron-catalyzed nucleophilic substitution of allylic acetate2007Ingår i: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 349, nr 17-18, s. 2641-2646Artikel i tidskrift (Refereegranskat)
  • 1727.
    Éll, Alida H
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Csjernyik, Gábor
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Slagt, Vincent F
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Bäckvall, Jan-Erling
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Berner, Simon
    Puglia, Carla
    Greger, Ledung
    Oscarsson, Sven
    Synthesis os S-Thioacetate Functionalized Cobalt(II) Porphyrins and Heterogenization on gold Surface2006Ingår i: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, nr 5, s. 1193-1199Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cobalt tetraarylporphyrins 1-Co and 2-Co with thioacetate-functionalized carbon chains on the aryl groups were synthesized. The cobalt porphyrin 2-Co was immobilized on a gold surface after deprotection of the S-acetyl group. The immobilized porphyrin was studied by X-ray Photoelectron Spectroscopy (XPS) and the results suggest that a complete monolayer of porphyrins is formed.

  • 1728. Éll, Alida H
    et al.
    Samec, Joseph S M
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Brasse, Claudia
    Bäckvall, Jan-E
    Dehydrogenation of aromatic amines to imines via ruthenium-catalyzed hydrogen transfer2002Ingår i: Chemical Communications, ISSN 1359-7345, nr 10, s. 1144 - 1145Artikel i tidskrift (Refereegranskat)
  • 1729. Öksnes Dalheim, Marianne
    et al.
    Björk Arnfinnsdottir, Nina
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Christensen, Björn E.
    The size and shape of three water-soluble, non-ionic polysaccharides produced by lactic acid bacteria: A comparative study2016Ingår i: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 142, s. 91-97Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three water-soluble, non-ionic extracellular polysaccharides (EPS) obtained from lactic acid bacteria (S. thermophilus THS, L. helveticus K16 and S. thermophilus ST1) were subjected to a comparative study by means of multidetector size-exclusion chromatography, providing distributions and averages of molar masses, radii of gyration and intrinsic viscosities. All polysaccharides displayed random coil character. Further analysis of the data reveals differences in chain stiffness and extension that could be well correlated to structural features. The calculated persistence lengths ranged from 5 to 10 nm and fall within the range typical for many single-stranded bacterial or plant polysaccharides. The ST1 polysaccharide had the highest molar mass but the lowest persistence length, which is attributed to the presence of the flexible (1→6)-linkage in the main chain.

  • 1730.
    Östervall, Jennie
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Conformational Dynamics of Carbohydrates Studied by NMR Spectroscopy and Molecular Simulations2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Carbohydrates play important roles in biological processes. Their function is closely related to their conformation. In this thesis, conformational studies of carbohydrates by NMR spectroscopy and molecular dynamics computer simulations are described.

    The first two papers discuss the anomalous solubility of β-cyclodextrin compared to other cyclodextrins. Time correlation functions revealed flexibility in all cyclodextrins. Molecular dynamics computer simulations showed that the glycosidic linkages were rather rigid and the flexibility was suggested to be macrocyclic. From spatial distribution functions β-cyclodextrin was found to have greater ability to order the surrounding water than the other cyclodextrins. Paper III deals with some of the difficulties of conformational studies. In Paper IV, a new method, Additative Potential Maximum Entropy, APME, is applied to a disaccharide. Conformational distribution functions are derived from NOEs, J-couplings and residual dipolar couplings and calculated from computer simulations. All distribution functions were found to be in good agreement. In papers V and VI oligosaccharides from human milk are studied. Residual dipolar coupling, J-couplings and cross relaxation rates were measured by NMR spectroscopy and molecular dynamics computer simulations were carried out. Both oligosaccharides showed high flexibility for the β-D-GlcpNAc-(1→3)-β-D-Galp linkage.

  • 1731.
    Östervall, Jennie
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Maliniak, Arnold
    Widmalm, Göran
    Conformational dynamics of the pentasaccharide LNF-1 from NMR spectroscopy and molecular dynamics simulationsManuskript (Övrigt vetenskapligt)
  • 1732.
    Östervall, Jennie
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Naidoo, Kevin J.
    Chen, Jeff Yu-Jen
    Widmalm, Göran
    Maliniak, Arnold
    Molecular structure and dynamics of α, β and γ-cyclodextrinsManuskript (Övrigt vetenskapligt)
  • 1733. Číhalová, Sylva
    et al.
    Dziedzic, Pawel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Córdova, Armando
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Veselý, Jan
    Asymmetric Aza-Morita–Baylis–Hillman-type reactions: The highly enantioselective reaction between unmodified α,β-unsaturated aldehydes and N-acylimines by organo-co-catal2011Ingår i: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, nr 7, s. 1096-1108Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The highly enantioselective organo-co-catalytic aza-Morita–Baylis–Hillman (MBH)-type reaction between N-carbamate-protected imines and α,β-unsaturated aldehydes has been developed. The organic co-catalytic system of proline and 1,4-diazabicyclo[2.2.2]octane (DABCO) enables the asymmetric synthesis of the corresponding N-Boc- and N-Cbz-protected β-amino-α-alkylidene-aldehydes in good to high yields and up to 99% ee. In the case of aza-MBH-type addition of enals to phenylprop-2-ene-1-imines, the co-catalytic reaction exhibits excellent 1,2-selectivity. The organo-co-catalytic aza-MBH-type reaction can also be performed by the direct highly enantioselective addition of α,β-unsaturated aldehydes to bench-stableN-carbamate-protected α-amidosulfones to give the corresponding β-amino-α-alkylidene-aldehydes with up to 99% ee.The organo-co-catalytic aza-MBH-type reaction is also an expeditious entry to nearly enantiomerically pure β-amino-α-alkylidene-amino acids and β-amino-α-alkylidene-lactams (99% ee). The mechanism and stereochemistry of the chiral amine and DABCO co-catalyzed aza-MBH-type reaction arealso discussed.

  • 1734.
    Šoltésová, Mária
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK). Charles University in Prague.
    Kowalewski, Jozef
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Widmalm, Göran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för organisk kemi.
    Dynamics of exocyclic groups in the Escherichia coli O91 O-antigen polysaccharide in solution studied by carbon-13 NMR relaxation2013Ingår i: Journal of Biomolecular NMR, ISSN 0925-2738, E-ISSN 1573-5001, Vol. 57, nr 1, s. 37-45Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carbon-13 relaxation data are reported for exocyclic groups of hexopyranosyl sugar residues in the repeating unit within the Escherichia coli O91 O-antigen polysaccharide in a dilute D2O solution. The measurements of T 1, T 2 and heteronuclear nuclear Overhauser enhancements were carried out at 310 K at two magnetic fields (16.4 T, 21.1 T). The data were analyzed using the standard and extended Lipari–Szabo models, as well as a conformational jump model. The extended version of the Lipari–Szabo and the two-site jump models were most successful for the hydroxymethyl groups of Gal and GlcNAc sugar residues. Different dynamics was found for the hydroxymethyl groups associated with different configurations (d-gluco, d-galacto) of the sugar residues, the latter being faster than the former.

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