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  • 1.
    Ilchenko, Nadia O.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Novel Applications of Benziodoxole Reagents in the Synthesis of Organofluorine Compounds2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns method development of new synthetic routes by applying electrophilic hypervalent iodine reagents, such as trifluoromethyl-benziodoxole (Togni reagent) and fluoro-benziodoxole. The first project involved the addition of an oxygen moiety and trifluoromethyl group across double and triple bonds (both groups derived from the hypervalent iodine reagent). We observed that electron donating substituents on the aromatic ring of the substrate accelerated the oxytrifluoromethylation reaction. This transformation was further expanded to halo-trifluoromethylation reaction of a vinyl silane substrate. We also developed a copper mediated cyanotrifluoromethylation reaction, which was accelerated by PCy3 additive. This transformation allowed for the creation of two new C-C bonds in a single addition reaction. The direct C-H trifluoromethylation reaction of quinones was achived using the Togni-reagent in the presence of B2pin2 additive. The intriguing additive effects of both B2pin2 and PCy3 inspired us to examine the mechanism of these transformations.

    Fluoro-benziodoxole is the fluoroiodane analogue of the trifluoromethylating Togni reagent. We developed a AgBF4 mediated geminal difluorination of styrenes using this fluoroiodine reagent. In this process one fluorine atom came from the fluoroiodane, while the other fluorine was derived from the tetrafluoroborate ion. A similar approach was applied for the 1,3-oxyfluorination and difluorination of cyclopropanes. Similarly, this fluorinative ring opening of unactivated cyclopropanes involved the introduction of an electrophilic fluorine atom from the fluoroiodane reagent and a nucleophilic one from the tetrafluoroborate ion. This reaction was extended to synthesis of 1,3-oxyfluorinated products. When alkenes reacted with the fluoro-benziodoxole reagent in the presence of palladium catalyst the iodofluorination reaction occurred.  Both the iodine and fluorine atoms were derived from the fluoroiodane reagent. The iodofluorination reaction with disubstituted and cyclic alkenes proceeded with high regio- and stereoselectivity.

  • 2.
    Ilchenko, Nadia O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cortes, Miguel Angel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed lodofluorination of Alkenes Using Fluorolodoxole Reagent2016In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 6, no 1, p. 447-450Article in journal (Refereed)
    Abstract [en]

    The application of an air- and moisture-stable fluoroiodane reagent was investigated in the palladium-catalyzed iodofluorination reaction of alkenes. Both the iodo and fluoro substituents arise from the fluoroiodane reagent. In the case of certain palladium catalysts, the alkene substrates undergo allylic rearrangement prior to the iodofluorination process. The reaction is faster for electron-rich alkenes than for electron-deficient ones.

  • 3.
    Ilchenko, Nadia O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Hedberg, Martin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Fluorinative ring-opening of cyclopropanes by hypervalent iodine reagents. An efficient method for 1,3-oxyfluorination and 1,3-difluorination2017In: Chemical Sience, ISSN 2041-6520, Vol. 8, no 2, p. 1056-1061Article in journal (Refereed)
    Abstract [en]

    A new method is presented for 1,3-difluorination and 1,3-oxyfluorination reactions. The process is based on iodonium mediated opening of 1,1-disubstituted cyclopropanes. The reaction proceeds with high chemo- and regioselectivity under mild reaction conditions typically at room temperature in a couple of hours. The reaction probably occurs via electrophilic ring-opening of cyclopropanes.

  • 4.
    Ilchenko, Nadia O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Janson, Pär G.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Copper-Mediated Cyanotrifluoromethylation of Styrenes Using the Togni Reagent2013In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, no 21, p. 11087-11091Article in journal (Refereed)
    Abstract [en]

    Styrenes with an electron-deficient double bond undergo cyanotrifluoromethylation with a trifluoromethylated hypervalent iodine reagent in the presence of CuCN. The reaction proceeds under mild conditions in the presence of bulky phosphines or B(2)pin(2) additives. The process is highly regioselective and involves the consecutive formation of two C-C bonds in a single addition reaction. In the presence of a p-methoxy substituent in the styrene, oxytrifluoromethylation occurs instead of the cyanotrifluoromethylation.

  • 5.
    Ilchenko, Nadia O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Janson, Pär
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Copper-mediated C-H trifluoromethylation of quinones2013In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, no 59, p. 6614-6616Article in journal (Refereed)
    Abstract [en]

    Quinones undergo copper-mediated C-H trifluoromethylation reactions using a hypervalent iodine reagent. The reactions have a broad synthetic scope involving naphtho, alkyl, chloro and methoxy quinones.

  • 6.
    Ilchenko, Nadia O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Tasch, Boris O. A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mild Silver-Mediated Geminal Difluorination of Styrenes Using an Air- and Moisture-Stable Fluoroiodane Reagent2014In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 53, no 47, p. 12897-12901Article in journal (Refereed)
    Abstract [en]

    An air-and moisture-stable fluoroiodane in the presence of AgBF4 is suitable for selective geminal difluorination of styrenes under mild reaction conditions. One of the C-F bonds is formed by transfer of electrophilic fluorine from the hypervalent iodine reagent, while the other one arises from the tetrafluoroborate counterion of silver. Deuterium-isotope-labelling experiments and rearrangement of methyl styrene substrates suggest that the reaction proceeds through a phenonium ion intermediate.

  • 7.
    Janson, Pär G.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ghoneim, Ibrahim
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ilchenko, Nadia O.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Electrophilic Trifluoromethylation by Copper-Catalyzed Addition of CF3-Transfer Reagents to Alkenes and Alkynes2012In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, no 11, p. 2882-2885Article in journal (Refereed)
    Abstract [en]

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

  • 8.
    Janson, Pär G.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Ilchenko, Nadia O.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diez-Varga, Alberto
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Effects of B(2)pin(2) and PCy3 on copper-catalyzed trifluoromethylation of substituted alkenes and alkynes with the Togni reagent2015In: Tetrahedron, ISSN 0040-4020, E-ISSN 1464-5416, Vol. 71, no 6, p. 922-931Article in journal (Refereed)
    Abstract [en]

    The copper-catalyzed oxytrifluoromethylation of phenylacetylenes and C-H trifluoromethylation of quinones were studied. It was found that both reactions are accelerated by B(2)pin(2) and PCy3 additives. The two reactions have different substituent effects. The oxytrifluoromethylation is faster in the presence of electron-donating groups, while the C-H trifluoromethylation is faster with electron-withdrawing substituents. The Hammett plot for oxytrifluoromethylation gave a rho value of 0.76 indicating electron demand in the rate determining step of the reaction. According to the absolute value of rho the reaction probably does not proceed through a rate determining formation of a carbocation intermediate. The kinetic isotope effect measurements indicate that in C-H trifluoromethylation of quinones the cleavage of the C-H bond is not the rate determining step of the reaction.

  • 9. Szijjarto, Csongor
    et al.
    Pershagen, Elias
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    Ilchenko, Nadia O.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Borbas, K. Eszter
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Uppsala University, Sweden.
    A Versatile Long-Wavelength-Absorbing Scaffold for Eu-Based Responsive Probes2013In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 19, no 9, p. 3099-3109Article, review/survey (Refereed)
    Abstract [en]

    Coumarin-sensitized, long-wavelength-absorbing luminescent EuIII-complexes have been synthesized and characterized. The lanthanide binding site consists of a cyclen-based chelating framework that is attached through a short linker to a 7-hydroxycoumarin, a 7-B(OH)2-coumarin, a 7-O-(4-pinacolatoboronbenzyl)-coumarin or a 7-O-(4-methoxybenzyl)-coumarin. The syntheses are straightforward, use readily available building blocks, and proceed through a small number of high-yielding steps. The sensitivity of coumarin photophysics to the 7-substituent enables modulation of the antenna-absorption properties, and thus the lanthanide excitation spectrum. Reactions of the boronate-based functionalities (cages) with H2O2 yielded the corresponding 7-hydroxycoumarin species. The same species was produced with peroxynitrite in a x106107-fold faster reaction. Both reactions resulted in the emergence of a strong approximate to 407nm excitation band, with concomitant decrease of the 366nm band of the caged probe. In aqueous solution the methoxybenzyl caged Eu-complex was quenched by ONOO. We have shown that preliminary screening of simple coumarin-based antennae through UV/Vis absorption spectroscopy is possible as the changes in absorption profile translate with good fidelity to changes in EuIII-excitation profile in the fully elaborated complex. Taken together, our results show that the 7-hydroxycoumarin antenna is a viable scaffold for the construction of turn-on and ratiometric luminescent probes.

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