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  • 1.
    Andersson, Hanna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Organic Chemistry. University of Gothenburg, SE-412 96 Gothenburg, Sweden.
    Gräfenstein, Jürgen
    National Sun Yat-Sen University, Kaohsiung, Taiwan.
    Isobe, Minoru
    National Sun Yat-Sen University, Kaohsiung, Taiwan.
    Erdélyi, Máté
    University of Gothenburg, SE-412 96 Gothenburg, Sweden; The Swedish NMR Centre, SE-413 96 Gothenburg, Sweden.
    Sydnes, Magne O
    University of Stavanger, NO-4036 Stavanger, Norway.
    Photochemically Induced Aryl Azide Rearrangement: Solution NMR Spectroscopic Identification of the Rearrangement Product2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 3, p. 1812-1816Article in journal (Refereed)
    Abstract [en]

    Photolysis of ethyl 3-azido-4,6-difluorobenzoate at room temperature in the presence of oxygen results in the regioselective formation of ethyl 5,7-difluoro-4-azaspiro[2.4]hepta-1,4,6-triene-1-carboxylate, presumably via the corresponding ketenimine intermediate which undergoes a photochemical four-electron electrocyclization followed by a rearrangement. The photorearrangement product was identified by multinuclear solution NMR spectroscopic techniques supported by DFT calculations.

  • 2.
    Andersson, Pher G.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Regio- and Stereoselective Deuteration of Allylic Chlorides Controlled by Neighboring Alcohol or Ether Groups1996In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 61, no 12, p. 4154-4156Article in journal (Refereed)
  • 3.
    Arefalk, Anna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Wannberg, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Larhed, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Hallberg, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Stereoselective Synthesis of 3-Aminoindan-1-ones and Subsequent Incorporation into HIV-1 Protease Inhibitors2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 3, p. 1265-1268Article in journal (Refereed)
    Abstract [en]

    A new method for the stereoselective synthesis of 3-aminoindan-1-ones from triflates of salicylic sulfinyl imines and ethylene glycol vinyl ether has been developed. The reaction sequence starts with a regioselective Heck reaction followed by stereoselective Lewis acid mediated annulation. Acidic cleavage of the sulfinamides produced pure (R)- and (S)-3-aminoindan-1-ones, which were successfully isolated and incorporated into active HIV-1 protease inhibitors.

  • 4.
    Arvela, Riina K
    et al.
    Department of Chemistry, University of Connecticut.
    Leadbeater, Nicholas E
    Department of Chemistry, University of Connecticut.
    Microwave-promoted Heck coupling using ultralow metal catalyst concentrations.2005In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 70, no 5, p. 1786-1790Article in journal (Refereed)
    Abstract [en]

    We show that Heck couplings can be performed in water using microwave heating and Pd catalyst concentrations as low as 500 ppb. The methodology is simple; all that is required as the catalyst is a stock solution of palladium.

  • 5.
    Arvela, Riina K
    et al.
    University of Connecticut, Department of Chemistry.
    Leadbeater, Nicholas E
    University of Connecticut, Department of Chemistry.
    Sangi, Michael S
    University of Connecticut, Department of Chemistry.
    Williams, Victoria A
    University of Connecticut, Department of Chemistry.
    Granados, Patricia
    Saint Mary's University, Department of Chemistry.
    Singer, Robert D
    Saint Mary's University, Department of Chemistry.
    A reassessment of the transition-metal free suzuki-type coupling methodology.2005In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 70, no 1, p. 161-168Article in journal (Refereed)
    Abstract [en]

    We present here a reassessment of our transition-metal free Suzuki-type coupling protocol. We believe that, although the reaction can be run without the need for addition of a metal catalyst, palladium contaminants down to a level of 50 ppb found in commercially available sodium carbonate are responsible for the generation of the biaryl rather than, as previously suggested, an alternative non-palladium-mediated pathway. We present a revised methodology for Suzuki couplings using ultralow palladium concentrations for use with aryl and vinyl boronic acids and discuss the effects of the purity of the boronic acid on the reaction.

  • 6.
    Arvela, Riina K.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Pasquini, Serena
    Università degli Studi di Siena, Dipartimento Farmaco Chimico Tecnologico.
    Larhed, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Highly regioselective internal heck arylation of hydroxyalkyl vinyl ethers by aryl halides in water2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 17, p. 6390-6396Article in journal (Refereed)
    Abstract [en]

    Highly regioselective and fast Pd(0)-catalyzed internal α-arylation of ethylene glycol vinyl ether with aryl halides was shown to be possible in water without the need for any halide scavengers or ionic liquid additives. This presents, to our knowledge, the first case of water being utilized in the selective arylation of electron-rich olefins. Resulting α-products were hydrolyzed and isolated as corresponding acetophenones in good to excellent yields when using aryl bromides and with good to moderate yields in the case of aryl iodides. Microwave irradiation was shown to be beneficial in activation of aryl chlorides toward the internal Heck arylation. The scope of the protocol was further increased to include different hydroxyalkyl vinyl ethers, these all giving selectively only branched α-products. Finally, the active role of the hydroxy group in directing the regioselectivity toward internal arylation of electron-rich olefins, even in nonpolar toluene, was revealed.

  • 7.
    Aune, Marie
    et al.
    Uppsala University.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Matsson, Olle
    Uppsala University.
    Solvent Dependence of Enantioselectivity for a Base Catalyzed 1,3-Hydron Transfer Reaction: A Kinetic Isotope Effect and NMR Spectroscopic Study.1995In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 60, no 5, p. 1356-1364p. 1356-1364Article in journal (Refereed)
    Abstract [en]

    The base-catalyzed rearrangement of 1-methylindene (1) to 3-methylindene (2) has been studied. The reaction proceeds with substrate enantioselectivity (kinetic resolution) when chiral tertiary amines are used as catalysts. When dihydroquinidine (DHQD) (3

  • 8.
    Ayub, Rabia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    El Bakouri, Ouissam
    Univ Girona, IQCC, C Maria Aurelia Capmany 6, Girona 17003, Catalonia, Spain..
    Jorner, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Sola, Miguel
    Univ Girona, IQCC, C Maria Aurelia Capmany 6, Girona 17003, Catalonia, Spain..
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Can Baird's and Clar's Rules Combined Explain Triplet State Energies of Polycyclic Conjugated Hydrocarbons with Fused 4n pi- and (4n+2)pi-Rings?2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 12, p. 6327-6340Article in journal (Refereed)
    Abstract [en]

    Compounds that can be labeled as "aromatic chameleons" are pi-conjugated compounds that are able to adjust their pi-electron distributions so as to comply with the different rules of aromaticity in different electronic states. We used quantum chemical calculations to explore how the fusion of benzene rings onto aromatic chameleonic units represented by biphenylene, dibenbzocyclooctatetraene, and dibenzo[a,e]pentalene modifies the first triplet excited states (T-1) of the compounds. Decreases in T-1 energies are observed when going from isomers with linear connectivity of the fused benzene rings to those with cis- or transbent connectivities. The T-1 energies decreased down to those of the parent (isolated) 4n pi-electron units. Simultaneously, we observe an increased influence of triplet State aromaticity of the central 4n ring as given by Baird's rule and evidenced by geometric, magnetic, and electron density based aromaticity indices (HOMA, NICS-XY, ACID, and FLU). Because of an influence of,triplet state aromaticity in the central 4n pi-electron units,, the most stabilized, compounds, retain the triplet excitation in Baird pi-quartets or octets, enabling the outer benzene rings to adapt closed-shell singlet Clar pi-sextet character. Interestingly, the T-1 energies go down as the total number of aromatic cycles within a molecule in the T-1 state increases.

  • 9.
    Ayub, Rabia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. uppsala university.
    El Bakouri, Ouissam
    Univ Girona, IQCC, C Maria Aurelia Capmany 6, Girona 17003, Catalonia, Spain.
    Jorner, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. uppsala university.
    Sola, Miquel
    Univ Girona, IQCC, C Maria Aurelia Capmany 6, Girona 17003, Catalonia, Spain.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. uppsala university.
    Can Baird’s and Clar’s Rules Combined Explain Triplet State Energies of Polycyclic Conjugated Hydrocarbons with Fused 4nπ- and (4n + 2)π-Rings?2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 12, p. 6327-6340Article in journal (Refereed)
  • 10. Belda, O
    et al.
    Kaiser, N F
    Bremberg, U
    Larhed, M
    Hallberg, A
    Moberg, C
    Highly stereo- and regioselective allylations catalyzed by Mo-pyridylamide complexes: Electronic and steric effects of the ligand2000In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 65, no 18, p. 5868-5870Article in journal (Refereed)
  • 11. Bengtson, A
    et al.
    Larhed, M
    Hallberg, A
    Protected indanones by a Heck-Aldol annulation reaction2002In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 67, no 16, p. 5854-5856Article in journal (Refereed)
    Abstract [en]

    Monoprotected 3-hydroxyindan-1-ones have been prepared in moderate to good yields by a new tandem reaction involving salicylaldehyde triflates and commercially available 2-hydroxyethyl vinyl ether. This one-pot annulation reaction proceeds in the presence of a palladium bidentate catalyst and results in the formation of two new ring systems.

  • 12.
    Bornhof, Anna-Bea
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Xiong, Ruisheng
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Borbas, K. Eszter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Rational Synthesis of 2-Bromoporphyrins and 2,12-Dibromoporphyrins2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 23, p. 12908-12913Article in journal (Refereed)
    Abstract [en]

    Bromoporphyrins were prepared by the metal-mediated self-condensation of brominated 1-formyldipyrromethanes. Depending on the conditions, Mg(II)-2,12-dibromoporphyrin and Mg(II)-2-bromoporphyrin could be obtained in up to 11% and 17% isolated yield, respectively. Zn(II) was also a viable templating metal. The positions of the bromine substituents were confirmed by 2D-NMR spectroscopic analysis and the X-ray crystal structure of a derivative. Suzuki and Sonogashira reactions of the bromoporphyrins yielded 2-substituted or 2,12-disubstituted porphyrins with red-shifted absorption and emission spectra. This method provides access to the minimalist core of beta-mono- and beta,beta'-disubstituted porphyrins from readily available starting materials.

  • 13. Bremberg, U
    et al.
    Larhed, M
    Moberg, C
    Hallberg, A
    Rapid microwave-induced palladium-catalyzed asymmetric allylic alkylation1999In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 64, no 4, p. 1082-1083Article in journal (Refereed)
  • 14.
    Bunrit, Anon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Sawadjoon, Supaporn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Tsupova, Svetlana
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Samec, Joseph S. M.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    A General Route to beta-Substituted Pyrroles by Transition-Metal Catalysis2016In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, no 4, p. 1450-1460Article in journal (Refereed)
    Abstract [en]

    An atom-efficient route to pyrroles substituted in the beta-position has been achieved in four high yielding steps by a combination of Pd, Ru, and Fe catalysis with only water and ethene as side-products. The reaction is general and gives pyrroles substituted in the beta-position with linear and branched alkyl, benzyl, or aryl groups in overall good yields. The synthetic route includes a Pd-catalyzed monoallylation step of amines with substituted allylic alcohols that proceeds to yield the monoallylated products in moderate to excellent yields. In a second step, unsymmetrical diallylated aromatic amines are generated from the reaction of a second allylic alcohol with high selectivity in moderate to good yields by control of the reaction temperature. Ru-catalyzed ring-closing metathesis performed on the diallylated aromatic amines yields the pyrrolines substituted in the beta-position in excellent yields. By addition of ferric chloride to the reaction mixture, a selective aromatization to yield the corresponding pyrroles substituted in the beta-position was achieved. A reaction mechanism involving a palladium hydride, generated from insertion of palladium to O-H of an allyl alcohol, that is responsible for the C-O bond cleavage to generate the pi-allyl intermediate is proposed.

  • 15.
    Bäckvall, Jan-E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Granberg, Kennth L.
    Andersson, Pher
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Gatti, Roberto
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Stereocontrolled Lactonization Reactions via Palladium-Catalyzed 1,4-Addittion to Conjugated Dienes1993In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 58, no 20, p. 5445-5451Article in journal (Refereed)
    Abstract [en]

    Stereocontrolledp alladium(I1)-catalyzed1 ,4-chloro-and 1,4-acetoxylactonizations o f conjugated cyclic dienes have been developed to give stereodefined fused lactones. The stereochemistry of the 1,4- acetoxylactonization was controlled by the ligand on the metal catalyst, and in this way either a cisor truns-acetoxylactonization was obtained. This dual stereoselectivity is explained by a stereocontrolled acetate attack (trans or cis, respectively) on the allyl group in the catalytic (π-allyl)- palladium intermediate. To further strengthen the mechanism the intermediate (π-ally1)palladium complex was isolated and fully characterized. A stereospecific synthesis of cis-  and truns-2-[6- (benzyloxy)-2,4-heptadien-l-yllacetic a cid (cis-  and truns-9) followed by stereoselective Pd(I1)- catalyzed chloro- and acetoxylactonization in acetonelacetic acid resulted in highly functionalized fused lactones with control of the relative stereochemistry at four different carbons.

  • 16.
    Bäckvall, Jan-Erling
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Andersson, Pher
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Stone, Guy
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Organic Chemistry.
    Syntheses of (±)-α- and (±)- γ- Lycorane via a Stereocontrolled Organopalladium Route1991In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 56, no 9, p. 2988-2993Article in journal (Refereed)
    Abstract [en]

    Total syntheses of (+/-)-alpha-and (+/-)-gamma-lycorane are described. The key steps in the syntheses are the stereocontrolled palladium-catalyzed intramolecular 1,4-chloroamidation of 12 to 13 and the subsequent anti-stereoselective copper-catalyzed S(N)2' reaction of allylic chloride 13 with [3,4-(methylenedioxy)phenyl]magnesium bromide to give 14. Hexahydroindole 14 has the required relative stereochemistry between carbons 3a, 7, and 7a for alpha-lycorane (1a) and was transformed to the latter via 15 and 16. The epimeric gamma-lycorane (2) was obtained by performing the Bischler-Napieralski cyclization on 14, which led to a highly stereoselective isomerization to give exclusively 17. Compound 17 was subsequently transformed to 2. The overall yield from ester 8 to (+/-)-alpha- and (+/-)-gamma-lycorane was 40 and 36%, respectively.

  • 17.
    Chow, Shiao
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Stevens, Marc
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Odell, Luke
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Sulfonyl Azides as Precursors in Ligand-free Palladium-Catalyzed Synthesis of Sulfonyl Carbamates and Sulfonyl Ureas and Synthesis of Sulfonamides2016In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, no 7, p. 2681-2691Article in journal (Refereed)
    Abstract [en]

    An efficient synthesis of sulfonyl carbamates and sulfonyl ureas from sulfonyl azides employing a palladium-catalyzed carbonylation protocol has been developed. Using a two-chamber system, sulfonyl azides, PdCl2, and CO gas, released ex situ from Mo(CO)(6), were assembled to generate sulfonyl isocyanates in situ, and alcohols and aryl amines were exploited as nucleophiles to afford a broad range of sulfonyl carbamates and sulfonyl ureas. A protocol for the direct formation of substituted sulfonamides from sulfonyl azides and amines via nucleophilic substitution was also developed.

  • 18.
    Chow, Shiao Y.
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Odell, Luke R.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Synthesis of N-Sulfonyl Amidines and Acyl Sulfonyl Ureas from Sulfonyl Azides, Carbon Monoxide, and Amides2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 5, p. 2515-2522Article in journal (Refereed)
    Abstract [en]

    A Pd-catalyzed and ligand-free carbonylation/cycloaddition/decarboxylation cascade synthesis of sulfonyl amidines from sulfonyl azides and substituted amides at low CO pressure is reported. The reaction proceeds via an initial Pd-catalyzed carbonylative generation of sulfonyl isocyanates from sulfonyl azides, followed by a [2 + 2] cycloaddition with amides and subsequent decarboxylation, which liberates the desired sulfonyl amidines, generating N-2 and CO2 as the only reaction byproducts. Using this simple protocol, a diverse range of sulfonyl amidines was obtained in moderate to excellent yields. In addition, the reaction can also be directed through a more conventional amidocarbonylation pathway by employing N-monosubstituted amide nucleophiles to afford acyl sulfonyl ureas in good yields.

  • 19.
    Dahlstrand, Christian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Yamazaki, Kaoru
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Kilså, Kristine
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Substituent Effects on the Electron Affinities and Ionization Energies of Tria-, Penta-, and Heptafulvenes: A Computational Investigation2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 23, p. 8060-8068Article in journal (Refereed)
    Abstract [en]

    The extent of substituent influence on the vertical electron affinities (EAs) and ionization energies (IEs) of 43 substituted tria-, penta-, and heptafulvenes was examined computationally at the OVGF/6-311G(d)//B3LYP/6-311G(d) level of theory and compared with those of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) as representing strong electron-acceptor and -donor compounds, respectively. The substituents X at the exocyclic positions of the fulvenes were either NH2, H, or CN, while the substituents Y at the ring positions were H, CI, F, CN, or NH2. The variations of the EAs and lEs were rationalized by qualitative arguments based on frontier orbital symmetries for the different fulvene classes with either X or Y being constant. The minimum and maximum values found for the calculated EAs of the tria-, penta-, and heptafulvenes were 0.51-2.05, 0.24-3.63, and 0.53-3.14 eV, respectively, and for the IEs 5.27-9.96, 7.07-10.31, and 6.35-10.59 eV, respectively. Two of the investigated fulvenes outperform TCNQ (calcd EA = 2.63 eV) and one outperforms TTF (calcd IE = 6.25 eV) with regard to acceptor and donor abilities, respectively. We also evaluated the properties of bis(fulvene)s, i.e., compounds composed of a donor-type heptafulvene fused with an acceptor-type pentafulvene, and it was revealed that these bis(fulvene)s can be designed so that the IE and EA of the two separate fulvene segments are retained, potentially allowing for the design of compact donor-acceptor dyads.

  • 20.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Geng, Ting
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Marloie, Gaël
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Al Hussain, Adel O.
    Williams, Nicholas H.
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    The Alkaline Hydrolysis of Sulfonate Esters: Challenges in Interpreting Experimental and Theoretical Data2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 7, p. 2816-2828Article in journal (Refereed)
    Abstract [en]

    Sulfonate ester hydrolysis has been the subject of recent debate, with experimental evidence interpreted in terms of both stepwise and concerted mechanisms. In particular, a recent study of the alkaline hydrolysis of a series of benzene arylsulfonates (Babtie et al., Org. Biomol. Chem. 10, 2012, 8095) presented a nonlinear Bronsted plot, which was explained in terms of a change from a stepwise mechanism involving a pentavalent intermediate for poorer leaving groups to a fully concerted mechanism for good leaving groups and supported by a theoretical study. In the present work, we have performed a detailed computational study of the hydrolysis of these compounds and find no computational evidence for a thermodynamically stable intermediate for any of these compounds. Additionally, we have extended the experimental data to include pyridine-3-yl benzene sulfonate and its N-oxide and N-methylpyridinium derivatives. Inclusion of these compounds converts the Bronsted plot to a moderately scattered but linear correlation and gives a very good Hammett correlation. These data suggest a concerted pathway for this reaction that proceeds via an early transition state with little bond cleavage to the leaving group, highlighting the care that needs to be taken with the interpretation of experimental and especially theoretical data.

  • 21.
    Duarte, Fernanda
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Gronert, Scott
    Kamerlin, Shina Caroline Lynn
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational and Systems Biology.
    Concerted or Stepwise: How Much Do Free-Energy Landscapes Tell Us about the Mechanisms of Elimination Reactions?2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 3, p. 1280-1288Article in journal (Refereed)
    Abstract [en]

    The base-catalyzed dehydration of benzene cis-1,2-dihydrodiols is driven by formation of an aromatic product as well as intermediates potentially stabilized by hyperaromaticity. Experiments exhibit surprising shifts in isotope effects, indicating an unusual mechanistic balance on the E2-E1cB continuum. In this study, both land 2-dimensional free energy surfaces are generated for these compounds with various substituents, using density functional theory and a mixed implicit/explicit solvation model. The computational data help unravel hidden intermediates along the reaction coordinate and provide a novel conceptual framework for distinguishing between competing pathways in this and any other system with borderline reaction mechanisms.

  • 22.
    Enquist, Per-Anders
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Nilsson, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Sjöberg, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Larhed, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    ESI-MS Detection of Proposed Reaction Intermediates in the Air-Promoted and Ligand-Modulated Oxidative Heck Reaction2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 23, p. 8779-8786Article in journal (Refereed)
    Abstract [en]

    Electrospray ionization mass spectrometry (ESI-MS) and subsequent MS/MS analyses were used to directly detect palladium-containing cationic reaction intermediates in a ligand controlled palladium(II)-catalyzed oxidative Heck arylation. All potential intermediates were observed as dmphen-ligated palladium(II) species, suggesting that the dmphen bidentate ligand is attached to the metal center during the entire catalytic cycle. The study supports previous mechanistic propositions and provides new information regarding the composition of aryl-containing Pd(II) complexes in an ongoing oxidative Heck reaction. In addition, sodium acetate was found to be a useful base alternative to previously used tertiary amines.

  • 23.
    Erdélyi, Máté
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Rapid homogeneous-phase Sonogashira coupling reactions using controlled microwave heating2001In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 66, no 12, p. 4165-4169Article in journal (Refereed)
    Abstract [en]

    A microwave-enhanced, rapid and efficient homogeneous-phase version of the Sonogashira reaction is presented. It has been applied to the coupling of aryl iodides, bromides, triflates, and aryl chloride, as well as pyridine and thiophene derivatives with trimethylsilylacetylene. Excellent yields (80−95%) for substrates containing a large variety of substituents in different positions are obtained in 5−25 min.

  • 24. Garg, N
    et al.
    Larhed, M
    Hallberg, A
    Heck arylation of 1,2-cyclohexanedione and 2-ethoxy-2-cyclohexenone1998In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 63, no 12, p. 4158-4162Article in journal (Refereed)
  • 25.
    Grennberg, Helena
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry.
    Bäckvall, Jan-Erling
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry.
    Use of Sulfoxides as Co‑catalysts in the Palladium‑Quinone‑Catalyzed 1,4‑Diacetoxylation of 1,3‑Dienes: An Example of Ligand‑Accelerated Catalysis1991In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 56, no 20, p. 5811-5811Article in journal (Refereed)
  • 26. Grigorjeva, Liene
    et al.
    Liepinsh, Edvards
    Razafimahefa, Solofoniaina
    Yahorau, Aleh
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Yahorava, Sviatlana
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Rasoanaivo, Philippe
    Jirgensons, Aigars
    Wikberg, Jar E. S.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Semisynthesis of Libiguin A and Its Analogues by Trans-Lactonization of Phragmalin2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 9, p. 4148-4153Article in journal (Refereed)
    Abstract [en]

    Libiguins are limonoids with highly potent sexual activity enhancing effects, originally isolated from the Madagascarian Meliaceae species Neobeguea mahafalensis, where they exist in only minute quantities. Their low natural abundance has hampered mapping of their biological effects. Here we describe an approach to the semisynthesis of libiguin A and its close analogues 1-3 starting from phragmalin, which is a limonoid present in high amounts in a commercially cultivated Meliaceae species, Chukrasia tabularis, allowing the preparation of libiguins in appreciable quantities.

  • 27.
    Hartikka, Antti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Arvidsson, Per. I
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Tetrazolic Acid Functionalized Dihydroindol: Rational Design of a Highly Selective Cyclopropanation Organocatalyst2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 15, p. 5874-5877Article in journal (Refereed)
    Abstract [en]

    Herein we wish to report our development of an improved catalyst (S)-(-)-indoline-2-yl-1H-tetrazole (1) for the enantioselective organocatalyzed cyclopropanation of α,β-unsaturated aldehydes with sulfur ylides. The new organocatalyst readily facilitates the enantioselective organocatalytic cyclopropanation, providing cyclized product in excellent diastereoselectivities ranging from 96% to 98% along with enantioselectivities exceeding 99% enantiomeric excess for all reacted α,β-unsaturated aldehydes. The new catalyst provides the best results so far reported for intermolecular enantioselective organocatalyzed cyclopropanation.

  • 28.
    Honcharenko, Dmytro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Bioorganic Chemistry.
    Varghese, Oommen P.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Bioorganic Chemistry.
    Plashkevych, Oleksandr
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Bioorganic Chemistry.
    Barman, Jharna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Bioorganic Chemistry.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Bioorganic Chemistry.
    Synthesis and Structure of Novel Conformationally Constrained 1‘,2‘-Azetidine-Fused Bicyclic Pyrimidine Nucleosides: Their Incorporation into Oligo-DNAs and Thermal Stability of the Heteroduplexes2006In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 71, no 1, p. 299-314Article in journal (Refereed)
  • 29.
    Honcharenko, Dmytro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Zhou, Chuanzheng
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Modulation of Pyrene Fluorescence in DNA Probes Depends upon the Nature of the Conformationally Restricted Nucleotide2008In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 73, no 7, p. 2829-2842Article in journal (Refereed)
    Abstract [en]

    The DNA probes (ODNs) containing a 2'-N-(pyren-1-yl)-group on the conformationally locked nucleosides [2'-N-(pyren-1-yl)carbonyl-azetidine thymidine, Aze-pyr (X), and 2'-N-(pyren-1-yl)carbonyl-aza-ENA thymidine, Aza-ENA-pyr (Y)], show that they can bind to complementary RNA more strongly than to the DNA. The Aze-pyr (X) containing ODNs with the complementary DNA and RNA duplexes showed an increase in the fluorescence intensity (measured at lambda em approximately 376 nm) depending upon the nearest neighbor at the 3'-end to X [dA ( approximately 12-20-fold) > dG ( approximately 9-20-fold) > dT ( approximately 2.5-20-fold) > dC ( approximately 6-13-fold)]. They give high fluorescence quantum yields (Phi F = 0.13-0.89) as compared to those of the single-stranded ODNs. The Aza-ENA-pyr (Y)-modified ODNs, on the other hand, showed an enhancement of the fluorescence intensity only with the complementary DNA (1.4-3.9-fold, Phi F = 0.16-0.47); a very small increase in fluorescence is also observed with the complementary RNA (1.1-1.7-fold, Phi F = 0.17-0.22), depending both upon the site of the Y modification introduced as well as on the chemical nature of the nucleobase adjacent to the modification site into the ODN. The fluorescence properties, thermal denaturation experiments, absorption, and circular dichroism (CD) studies with the X- and Y-modified ODNs in the form of matched homo- and heteroduplexes consistently suggested (i) that the orientation of the pyrene moiety is outside the helix of the nucleic acid duplexes containing a dT-d/rA base pair at the 3'-end of the modification site for both X and Y types of modifications, and (ii) that the microenvironment around the pyrene moiety in the ODN/DNA and ODN/RNA duplexes is dictated by the chemical nature of the conformational constraint in the sugar moiety, as well as by the nature of neighboring nucleobases. The pyrene fluorescence emission in both X and Y types of the conformationally restricted nucleotides is found to be sensitive to a mismatched base present in the target RNA: (i) The X-modified ODN showed a decrease ( approximately 37-fold) in the fluorescence intensity (measured at lambda em approximately 376 nm) upon duplex formation with RNA containing a G nucleobase mismatch (dT-rG pair instead of dT-rA) opposite to the modification site. (ii) In contrast, the Y-modified ODN in the heteroduplex resulted in a approximately 3-fold increase in the fluorescence intensity upon dT-rG mismatch, instead of matched dT-rA pair, in the RNA strand. Our data corroborate that the pyrene moiety is intercalated in the X-modified mismatched ODN/RNA (G mismatch) heteroduplex as compared to that of the Y-modified ODN/RNA (G mismatch) heteroduplex, in which it is located outside the helix.

  • 30.
    Johansson, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Shanks, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Engman, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Amorati, Riccardo
    Pedulli, Gian Franco
    Valgimigli, Luca
    Long-lasting Antioxidant Protection: A Regenerable BHA-Analogue2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 22, p. 7535-7541Article in journal (Refereed)
    Abstract [en]

    Introduction of an octyltelluro group ortho to the phenolic moiety in 3-tert-butyl-4-hydroxyanisole (BHA) was found to significantly improve the antioxidant characteristics of the material. In contrast to BHA and the corresponding ortho-substituted octylthio- (9c) and octylseleno (9b) derivatives, the organotellurium 9a was regenerable when assayed for its capacity to inhibit azo-initiated peroxidation of linoleic acid in a chlorobenzene/water two-phase system containing N-acetylcysteine as a stoichiometric reducing agent, and peroxyl radicals were quenched more efficiently than with α-tocopherol. In the homogeneous phase, inhibition of styrene autoxidation occurred with a rate constant kinh as large as 1 × 107 M-1 s-1 but with a low (n = 0.4) stoichiometric factor. Evans-Polanij plots of log (kinh) versus BDE(O-H), which are usually linear for phenols with similar steric crowding reacting by H-atom transfer, revealed that compound 9a was more than 2 orders of magnitude more reactive than expected. Although further mechanistic investigations are needed, it seems that the ortho-arrangement of an alkyltelluro group and hydroxyl should be considered a privileged structure for phenolic antioxidants.

  • 31.
    Jäger, Michael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Eriksson, Lars
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Johansson, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Synthesis and Characterization of 2,6-Di(quinolin-8-yl)pyridines: New Ligands for Bistridentate RuII Complexes with Microsecond Luminescent Lifetimes2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 26, p. 10227-10230Article in journal (Refereed)
    Abstract [en]

    The synthesis of 4-substituted and 4-aryl-substituted 2,6-di(quinolin-8-yl)pyridines is described. The tridentate ligands were prepared via a palladium-catalyzed Suzuki−Miyaura cross-coupling reaction or via a one-step ring-forming reaction generating the central pyridine ring. X-ray crystal structures and 1H NMR shifts are discussed and compared to the corresponding data for a RuII bistridentate complex. Intramolecular stacking of two quinoline units in the RuII complex is suggested by 1H NMR data and also observed in the X-ray structure.

  • 32.
    Kamerlin, Shina Caroline Lynn
    Stockholm University, Department of Organic Chemistry, Arrhenius Laboratory.
    Theoretical comparison of p-nitrophenyl phosphate and sulfate hydrolysis in aqueous solution: implications for enzyme-catalyzed sulfuryl transfer2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 22, p. 9228-9238Article in journal (Refereed)
    Abstract [en]

    Both phosphoryl and sulfuryl transfers are ubiquitous in biology, being involved in a wide range of processes, ranging from cell division to apoptosis. Additionally, it is becoming increasingly clear that enzymes that can catalyze phosphoryl transfer can often cross-catalyze sulfuryl transfer (and vice versa). However, while there have been extensive experimental and theoretical studies performed on phosphoryl transfer, the body of available research on sulfuryl transfer is comparatively much smaller. The present work presents a direct theoretical comparison of p-nitrophenyl phosphate and sulfate monoester hydrolysis, both of which are considered prototype systems for probing phosphoryl and sulfuryl transfer, respectively. Specifically, free energy surfaces have been generated using density functional theory, by initial geometry optimization in PCM using the 6-31+G* basis set and the B3LYP density functional, followed by single-point calculations using the larger 6-311+G** basis set and the COSMO continuum model. The resulting surfaces have been then used to identify the relevant transition states, either by further unconstrained geometry optimization or from the surface itself where possible. Additionally, configurational entropies were evaluated using a combination of the quasiharmonic approximation and the restraint release approach and added to the calculated activation barriers as a correction. Finally, the overall activation entropy was estimated by approximating the solvent contribution to the total activation entropy using the Langevin dipoles solvation model. We have reproduced both the experimentally observed activation barriers and the observed trend in the activation entropies with reasonable accuracy, as well as providing a comparison of calculated and observed (15)N and (18)O kinetic isotope effects. We demonstrate that, counterintuitively, the hydrolysis of the p-nitrophenyl sulfate proceeds through a more expansive pathway than its phosphate analogue. Additionally, we show that the solvation effects upon moving from the ground state to the transition state are quite different for both reactions, suggesting that the enzymes that catalyze these reactions would need active sites with quite different electrostatic preorganization for the efficient catalysis of either reaction (despite which many enzymes can catalyze both phosphoryl and sulfuryl transfer). We believe that such a comparative study is an important foundation for understanding the molecular basis for phosphate-sulfate cross-promiscuity within members of the alkaline phosphatase superfamily.

  • 33.
    Karimi, Mansoureh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Erfan, Sayeh
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Földesi, András
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Steric Effects in the Tuning of the Diastereoselectivity of the Intramolecular Free-Radical Cyclization to an Olefin As Exemplified through the Synthesis of a Carba-Pentofuranose Scaffold2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 16, p. 6855-6872Article in journal (Refereed)
    Abstract [en]

    Two free-radical cyclization reactions with the radical at the chiral C4 of the pentose sugar and the intramolecularly C1-tethered olefin (on radical precursors 8 and 17) gave a new diastereospecific C4-C8 bond in dimethylbicyclo[2.2.1]heptane 9, whereas the new C4-C7 bond in 7-methyl-2-oxabicyclo[2.2.1]heptanes 18a/18b gave trans and cis diastereomers, in which the chirality of the C4 center is fully retained as that of the starting material. It has been shown how the chemical nature of the fused carba-pentofuranose scaffolds, dimethylbicyclo[2.2.1]heptane 9 vis-a-vis 7-methyl-2-oxabicyclo[2.2.1]heptanes 18a/18b (C7-Me in the former versus 2-O- in the latter), dictates the stereochemical outcome both at the Grignard reaction step as well as in the free-radical ring-closure reaction. The formation of pure 1,8-trans-bicyclo[2.2.1]heptane 9 from 8 suggests that the boat-like transition state is favored due to the absence of steric clash of the bulky 1(S)-O-p-methoxybenzyl (PMB) and 7(R)-Me substituents (both in the alpha-face) with that of the 8(R)-CH2 center dot radical in the beta-face. The conversion of 17 -> 18a-7(S) and 18b-7(R) in 6:4 ratio shows that the participation of both the chair- and the boat-like transition states is likely.

  • 34.
    Karimiahmadabadi, Mansoureh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Erfan, Sayeh
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Földesi, András
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Distal Two-Bond versus Three-Bond Electronegative Oxo-Substituent Effect Controls the Kinetics and Thermodynamics of the Conversion of a C-Nitroso Function to the Corresponding Oxime in the Conformationally Locked Pentofuranose (Bicyclo[2.2.1]heptane) System2014In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 79, no 16, p. 7266-7276Article in journal (Refereed)
    Abstract [en]

    We report the high-yielding and scalable diastereospecific synthesis of isomeric bicyclo [2.2.1]heptane-7- and -8-oximes and their corresponding C-nitroso derivatives, which are the key intermediates for the synthesis of carbanucleosides. Neither the (C7-R)-nitroso- nor (C8-S)-nitrosobicycloheptane system requires any external base in DMSO-d(6) to afford the corresponding oxime, and no reverse isomerization from the oxime to the C-nitroso compound was observed. The conversion of the (C8-S)-nitroso compound to the E/Z-oximes was similar to 8 times faster (at 40 degrees C) than that of the (C7-R)-nitroso derivative. The mechanism involves first-order reaction kinetics for the conversion of either the (C7-R)- or (C8-S)-nitroso derivative to the corresponding E/Z-oximes. The lower rate of conversion of the (C7-R)-nitroso compound to the corresponding crimes compared with that of the (C8-S)-nitroso derivative is attributed to the fact that the acidic H8 ionizing center is two bonds away from the OPMB group on C1 in the latter whereas H7 is three bonds away from the C1 OMe group in the former, making the effect of the electron-withdrawing group on C1 stronger in the latter.

  • 35.
    Karimiahmadabadi, Mansoureh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Földesi, András
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Unusual strain-releasing nucleophilic rearrangement of a bicyclo[2.2.1]heptane system to a cyclohexenyl derivative2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 21, p. 9747-9755Article in journal (Refereed)
    Abstract [en]

    We report an unusual strain-releasing reaction of 1-mesyloxy-8,7- dimethylbicyclo[2.2.1]heptane (3) by a base-promoted substitution at the chiral C3 followed by spontaneous concerted ring opening involving the most strained C2-C3-C4 bonds (with bond angle 94°) and the C2 bridgehead leading to anti-endo elimination of the C1-mesyloxy group by the conjugate base of adenine or thymine to give two diastereomeric C3′(S) and C3′(R) derivatives of 1-thyminyl and 9-adeninyl cyclohexene: 3 → T-4a + T-4b and 3 → A-5a + A-5b. These products have been unambiguously characterized by detailed 1D and 2D NMR (J-coupling constants and nOe analysis), mass, and UV spectroscopy. Evidence has been presented suggesting that the origin of these diastereomeric C3′(S) and C3′(R) derivatives of 1-thyminyl and 9-adeninyl cyclohexene from 3 is most probably a rearrangement mechanism of a trigonal bipyramidal intermediate formed in the S N2 displacement-ring-opening reaction.

  • 36.
    Kocovsky, Pavel
    et al.
    Uppsala University.
    Dunn, Victoria
    Uppsala University.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry.
    Langer, Vratislav
    Uppsala University.
    An approach toward the triquinane-type skeleton via reagent-controlled skeletal rearrangements. A facile method for protection-deprotection of organomercurials, tuning the selectivity of Wagner-Meerwein migrations, and a new route to annulated lactones1999In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 64, no 1, p. 101-119p. 101-119Article in journal (Refereed)
    Abstract [en]

    Nonlinear triquinane-type building blocks have been synthesized using three strategic steps, namely, (1) Hg2+-mediated opening of a cyclopropane ring involving a skeletal rearrangement (3 --> 8), (2) an intramolecular organometallic addition across a C=O

  • 37.
    Kumar, Sangit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Engman, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Valgimigli, Luca
    Amorati, Richard
    Grazia Fumo, Maria
    Franco Pedulli, Gian
    Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 16, p. 6046-6055Article in journal (Refereed)
    Abstract [en]

    (Chemical Equation Presented) 6-(Ethylthio)-, 6-(ethylseleno)-, and 6-(ethyltelluro)-2,2,4-trimethyl-1,2-dihydroquinoline-three heavier chalcogen analogues of ethoxyquin-were prepared by dilithiation of the corresponding 6-bromodihydroquinoline followed either by treatment with the corresponding diethyl dichalcogenide (sulfur derivative) or by insertion of selenium/tellurium into the carbon-lithium bond, oxidation to a diaryl dichalcogenide, borohydride reduction, and finally alkylation of the resulting areneselenolate/ arenetellurolate. Ethoxyquin, its heavier chalcogen analogues, and the corresponding 6-PhS, 6-PhSe, and 6-PhTe derivatives were assayed for both their chain-breaking antioxidant capacity and their ability to catalyze reduction of hydrogen peroxide in the presence of a stoichiometric amount of a thiol reducing agent (thiol peroxidase activity). Ethoxyquin itself turned out to be the best inhibitor of azo-initiated peroxidation of linoleic acid in a water/chlorobenzene two-phase system. In the absence of N-acetylcysteine as a coantioxidant in the aqueous phase, it inhibited peroxidation as efficiently as α-tocopherol but with a more than 2-fold longer inhibition time. In the presence of 0.25 mM coantioxidant in the aqueous phase, the inhibition time was further increased by almost a factor of 2. This is probably due to thiol-mediated regeneration of the active antioxidant across the lipid-aqueous interphase. The ethyltelluro analogue 1d of ethoxyquin was a similarly efficient quencher of peroxyl radicals compared to the parent in the two-phase system, but less regenerable. Ethoxyquin was found to inhibit azo-initiated oxidation of styrene in the homogenous phase (chlorobenzene) almost as efficiently (k inh = (2.0 ± 0.2) × 106 M-1 s -1) as α-tocopherol with a stoichiometric factor n = 2.2 ± 0.1. At the end of the inhibition period, autoxidation was additionally retarded, probably by ethoxyquin nitroxide formed during the course of peroxidation. The N-H bond dissociation enthalpy of ethoxyquin (81.3 ± 0.3 kcal/mol) was determined by a radical equilibration method using 2,6-dimethoxyphenol and 2,6-di-tert-butyl-4-methylphenol as equilibration partners. Among the investigated compounds, only the tellurium analogues 1d and, less efficiently, 1g had a capacity to catalyze reduction of hydrogen peroxide in the presence of thiophenol. Therefore, analogue 1d is the only antioxidant which is multifunctional (chain-breaking and preventive) in character and which can act in a truly catalytic fashion to decompose both peroxyl radicals and organic hydroperoxides in the presence of suitable thiol reducing agents.

  • 38.
    Kumar, Sangit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Johansson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Engman, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Valgimigli, Luca
    Amorati, Riccardo
    Grazia Fumo, Maria
    Pedulli, Gian Franco
    Regenerable Chain-Breaking 2,3-Dihydrobenzo[b]selenophene-5-ol Antioxidants2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 7, p. 2583-2595Article in journal (Refereed)
    Abstract [en]

    A series of 2,3-dihydrobenzo[b]selenophene-5-ol antioxidants was prepared by subjecting suitably substituted allyl 4-methoxyphenyl selenides to microwave-induced seleno-Claisen rearrangement/intramolecular Markovnikov hydroselenation followed by boron tribromide-induced O-demethylation. The novel antioxidants were assayed for their capacity to inhibit azo-initiated peroxidation of linoleic acid in a water/chlorobenzene two-phase system containing N-acetylcysteine as a thiol reducing agent in the aqueous phase. Antioxidant efficiency as determined by the inhibited rate of peroxidation, Rinh, increased with increasing methyl substitution (Rinh = 46−26 μM/h), but none of the compounds could match α-tocopherol (Rinh = 22 μM/h). Regenerability as determined by the inhibition time, Tinh, in the presence of the thiol regenerating agent decreased with increasing methyl substitution. Thus, under conditions where the unsubstituted compound 5a inhibited peroxidation for more than 320 min, α-tocopherol worked for 90 min and the trimethylated antioxidant 5g for 60 min only. Sampling of the aqueous phase at intervals during peroxidation using antioxidant 5a showed that N-acetylcysteine was continuously oxidized with time to the corresponding disulfide. In the absence of the regenerating agent, compounds 5 inhibited peroxidation for 50−60 min only. A (RO)B3LYP/LANL2DZdp//B3LYP/LANL2DZ model was used for the calculation of homolytic O−H bond dissociation enthalpies (BDE) and adiabatic ionization potentials (IP) of phenolic antioxidants 5. Both BDE (80.6−76.3 kcal/mol) and IP (163.2−156.0 kcal/mol) decrease with increasing methyl substitution. The phenoxyl radical corresponding to phenol 5g gave an intense ESR signal centered at g = 2.0099. The H−O bond dissociation enthalpy of the phenol was determined by a radical equilibration method using BHA as an equilibration partner. The observed BDE (77.6 ± 0.5 kcal/mol) is in reasonable agreement with calculations (76.3 kcal/mol). As judged by calculated log P values, the lipophilicity of compounds 5 increased slightly when methyl groups were introduced into the phenolic moiety (2.9 > C log P < 4.2). The capacity of compounds 5a (kinh = 3.8 × 105 M-1 s-1) and 5g (kinh = 1.5 × 106 M-1 s-1) to inhibit azo-initiated autoxidation of styrene in the homogeneous phase (chlorobenzene) was also studied. More efficient regeneration at the lipid−aqueous interphase is the most likely explanation why the intrinsically poorest antioxidant 5a can outperform its analogues as well as α-TOC in the two-phase system. Possible mechanisms of regeneration are discussed and evaluated.

  • 39.
    Kumar, Sangit
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Johansson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Kanda, Takahiro
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Engman, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Muller, Thomas
    Bergenudd, Helena
    Jonsson, Mats
    Pedulli, Gian Franco
    Amorati, Riccardo
    Valgimigli, Luca
    Catalytic chain-breaking pyridinol antioxidants2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 3, p. 716-725Article in journal (Refereed)
    Abstract [en]

    The synthesis of 3-pyridinols carrying alkyltelluro, alkylseleno, and alkylthio groups is described together with a detailed kinetic, thermodynamic, and mechanistic Study of their antioxidant activity. When assayed for their capacity to inhibit azo-initiated peroxidation of linoleic acid in a water/chlorobenzene two-phase system, tellurium-containing 3-pyridinols were readily regenerable by N-acetylcysteine contained in the aqueous phase. The best inhibitors quenched peroxyl radicals more efficiently than alpha-tocopherol, and the duration of inhibition was limited only by the availability of the thiol reducing agent. fn homogeneous phase, inhibition of styrene autoxidation absolute rate constants k(inh) for quenching of peroxyl radical were as large as 1 x 10(7) M-1 s(-1), thus Outperforming the best phenolic antioxidants including alpha-tocopherol. Tellurium-containing 3-pyridinols could be quantitatively regenerated in homogeneous phase by N-tert-butoxycarbonyl cysteine methyl ester, a lipid-soluble analogue of N-acetylcysteine. In the presence of an excess of the thiol, a catalytic mode of action was observed, similar to the one in the two-phase system. Overall, compounds bearing the alkyltelluro moiety ortho to the OH group were much more effective antioxidants than the corresponding para isomers. The origin of the high reactivity of these compounds was explored using pulse-radiolysis thermodynamic measurements, and a mechanism for their unusual antioxidant activity was proposed. The tellurium-containing 3-pyridinols were also found to catalyze reduction of hydrogen peroxide in the presence of thiol reducing agents, thereby acting as multifunctional (preventive and chain-breaking) catalytic antioxidants.

  • 40. Larhed, M
    et al.
    Hallberg, A
    Direct synthesis of cyclic ketals of acetophenones by palladium-catalyzed arylation of hydroxyalkyl vinyl ethers1997In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 62, no 22, p. 7858-7862Article in journal (Refereed)
    Abstract [en]

    Reaction of 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, or di(ethylene glycol) vinyl ether with aryl triflates, aryl bromides, or iodobenzene in presence of a catalytical amount of palladium acetate and the bidentate ligand DPPP provides a direct entry to cyclic ketals of acetophenones. It is postulated that the reaction proceeds via an initial alpha-arylation of the vinyl ethers to give labile aryl vinyl ether intermediates, which undergo subsequent ketalization in presence of protons in the reaction media. The method merits attention due to the simplicity of the experimental procedure and the possibility of selective ketal formation in the presence of an additional carbonyl group.

  • 41. Larhed, M
    et al.
    Hallberg, A
    Microwave-promoted palladium-catalyzed coupling reactions1996In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 61, no 26, p. 9582-9584Article in journal (Refereed)
  • 42. Larhed, M
    et al.
    Hoshino, M
    Hadida, S
    Curran, D P
    Hallberg, A
    Rapid fluorous Stille coupling reactions conducted under microwave irradiation1997In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 62, no 16, p. 5583-5587Article in journal (Refereed)
    Abstract [en]

    Palladium-catalyzed fluorous Stille cross-coupling reactions with organic halides or triflates require only 90-120 s for completion when conducted under microwave irradiation. Comparable thermal reactions require about 1 day. Fourteen different coupling products were synthesized and isolated in good yields after three-phase extraction (FC-84, dichloromethane, water) and chromatography. The examples extend the scope of the fluorous Stille coupling with respect to both the tin and halide/triflate components. Applications in parallel synthesis are suggested.

  • 43.
    Li, Qing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Yuan, Fengfeng
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Zhou, Chuanzheng
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Plashkevych, Oleksandr
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
    Free-Radical Ring Closure to Conformationally Locked alpha-L-Carba-LNAs and Synthesis of Their Oligos: Nuclease Stability, Target RNA Specificity, and Elicitation of RNase H2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 18, p. 6122-6140Article in journal (Refereed)
    Abstract [en]

    A new class of conformationally constrained nucleosides, alpha-L-ribo-carbocyclic LNA thymidine (alpha-L-carba-LNA-T, LNA is an abbreviation of locked nucleic acid) analogues and a novel "double-locked" alpha-L-ribo-configured tetracyche thymidine (6,7'-methylene-bridged-alpha-L-carba-LNA-T) in which both the sugar puckering and glyeosidic torsion are simultaneously constrained, have been synthesized through a key step involving 5-exo free-radical intramolecular cyclization. These alpha-L-carba-LNA analogues have been subsequently transformed to corresponding phosphoramidites and incorporated into isosequential antisense oligonucleotides (AONs), which have then been examined for the thermal denaturation of their duplexes, nuclease stability, and RNase H recruitment capabilities. Introduction of a single 6',7'-substituted alpha-L-carba-LNA-T modification in the AON strand of AON/RNA heteroduplex led to T-m reduction by 2-3 degrees C as compared to the native heteroduplex, whereas the parent 2'-oxa-alpha-L-LNA-T modification at the identical position in the AON strand has been found to lead to an increase in the T-m by 3-5 degrees C. This suggests that the 6' and 7' substitutions lead to much reduced thermal stability for the modified heteroduplex, especially the hydrophobic 7'-methyl on alpha-L-carba-LNA, which is located in the major groove of the duplex. All of the AONs incorporating 6',7'-substituted alpha-L-earba-LNA-T have, however, showed considerably improved nuclease stability toward 3'-exonuclease (SVPDE) and in human blood serum compared to the 2'-oxa-alpha-L-LNA-T incorporated AONs. The hybrid duplexes that are formed by 6',7'-substituted alpha-L-carba-LNA-T-modified AONs with complementary RNA have been found to recruit RNase H with higher efficiency than those of the beta-D-LNA-T or beta-D-carba-LNA-T-modified counterparts. These greatly improved nuclease resistances and efficient RNasc H recruitment capabilities elevate the alpha-L-carba-LNA-modified nucleotides into a new class of locked nucleic acids for potential RNA targeting therapeutics.

  • 44.
    Li, Qing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Yuan, Fengfeng
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Zhou, Chuanzheng
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Plashkevych, Oleksandr
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Free-Radical Ring Closure to Conformationally Locked α-l-Carba-LNAs and Synthesis of Their Oligos:: Nuclease Stability, Target RNA Specificity, and Elicitation of RNase H2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 18, p. 6122-6140Article in journal (Refereed)
    Abstract [en]

    A new class of conformationally constrained nucleosides, α-L-ribo-carbocyclic LNA thymidine (α-L-carba-LNA-T, LNA is an abbreviation of locked nucleic acid) analogues and a novel "double-locked" α-L-ribo-configured tetracyclic thymidine (6,7'-methylene-bridged-α-L-carba-LNA-T) in which both the sugar puckering and glycosidic torsion are simultaneously constrained, have been synthesized through a key step involving 5-exo free-radical intramolecular cyclization. These α-L-carba-LNA analogues have been subsequently transformed to corresponding phosphoramidites and incorporated into isosequential antisense oligonucleotides (AONs), which have then been examined for the thermal denaturation of their duplexes, nuclease stability, and RNase H recruitment capabilities. Introduction of a single 6',7'-substituted α-L-carba-LNA-T modification in the AON strand of AON/RNA heteroduplex led to T(m) reduction by 2-3 °C as compared to the native heteroduplex, whereas the parent 2'-oxa-α-L-LNA-T modification at the identical position in the AON strand has been found to lead to an increase in the T(m) by 3-5 °C. This suggests that the 6' and 7' substitutions lead to much reduced thermal stability for the modified heteroduplex, especially the hydrophobic 7'-methyl on α-L-carba-LNA, which is located in the major groove of the duplex. All of the AONs incorporating 6',7'-substituted α-L-carba-LNA-T have, however, showed considerably improved nuclease stability toward 3'-exonuclease (SVPDE) and in human blood serum compared to the 2'-oxa-α-L-LNA-T incorporated AONs. The hybrid duplexes that are formed by 6',7'-substituted α-L-carba-LNA-T-modified AONs with complementary RNA have been found to recruit RNase H with higher efficiency than those of the β-D-LNA-T or β-D-carba-LNA-T-modified counterparts. These greatly improved nuclease resistances and efficient RNase H recruitment capabilities elevate the α-L-carba-LNA-modified nucleotides into a new class of locked nucleic acids for potential RNA targeting therapeutics.

  • 45.
    Lindh, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Enquist, Per-Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Pilotti, Åke
    Nilsson, Peter
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Larhed, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    Efficient palladium(II) catalysis under air. Base-free oxidative heck reactions at room temperature or with microwave heating2007In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 72, no 21, p. 7957-7962Article in journal (Refereed)
    Abstract [en]

    Scope and limitations of the base-free oxidative Heck reaction with arylboronic acids have been explored. Under our conditions, the dmphen−palladium(II)-catalyzed arylation proceeded with air or p-benzoquinone as reoxidants of palladium(0). We found that ambient temperature and mild aerobic conditions allow for the use of substrates sensitive to palladium(II)-catalyzed oxidation. Oxidative Heck couplings, employing different arylboronic acids, were smoothly and regioselectively conducted with both electron-rich and electron-poor olefins, providing high yields even with disubstituted butyl methacrylate, sensitive acrolein, and a vinylboronate ester. Controlled microwave processing was used to reduce reaction times from hours to minutes both in small scale and in 50 mmol scale batch processes.

  • 46.
    Liu, Yi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Xu, Jianfeng
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Karimiahmadabadi, Mansoureh
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Zhou, Chuanzheng
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Bioorganic Chemistry.
    Synthesis of 2',4' -Propylene-Bridged (Carba-ENA) Thymidine and Its Analogues: The Engineering of Electrostatic and Steric Effects at the Bottom of the Minor Groove for Nuclease and Thermodynamic Stabilities and Elicitation of RNase H2010In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 21, p. 7112-7128Article in journal (Refereed)
    Abstract [en]

    2',4'-Propylene-bridged thymidine (carba-ENA-T) and five 8'-Me/NH2/OH modified carba-ENA-T analogues have been prepared through intramolecular radical addition to C=N of the tethered oxime-ether. These carba-ENA nucleosides have been subsequently incorporated into 15mer oligodeoxynucleotides (AON), and their affinity toward cDNA and RNA, nuclease resistance, and RNase H recruitment capability have been investigated in comparison with those of the native and ENA counterparts. These carba-ENAs modified AONs are highly RNA-selective since all of them led to slight thermal stabilization effect for the AON: RNA duplex, but quite large destabilization effect for the AON:DNA duplex. It was found that different C8' substituents (at the bottom of the minor groove) on carba-ENA-T only led to rather small variation of thermal stability of the AON:RNA duplexes. We, however, observed that the parent carba-ENA-T modified AONs exhibited higher nucleolytic stability than those of the ENA-T modified counterparts. The nucleolytic stability of carba-ENA-T modified AONs can be further modulated by C8' substituent to variable extents depending on not only the chemical nature but also the stereochemical orientation of the C8' substituents: Thus, (1) 8'S-Me on carba-ENA increases the nucleolytic stability but 8'R-Me leads to a decreased effect; (2) 8'R-OH on carba-ENA had little, if any, effect on nuclease resistance hut 8'S-OH resulted in significantly decreased nucleolytic stability; and (3) 8'-NH2 substituted carba-ENA leads to obvious loss in the nuclease resistance. The RNA strand in all of the carba-ENA derivatives modified AON:RNA hybrid duplexes can be digested by RNase HI with high efficiency, even at twice the rate of those of the native and ENA modified counterpart.

  • 47. Martinez-Montero, Saul
    et al.
    Fernandez, Susana
    Sanghvi, Yogesh S.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Ganesan, Muthupandian
    Ramesh, Namakkal G.
    Gotor, Vicente
    Ferrero, Miguel
    Design and Divergent Synthesis of Aza Nucleosides from a Chiral Imino Sugar2012In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 77, no 10, p. 4671-4678Article in journal (Refereed)
    Abstract [en]

    Several novel nucleoside analogues as potential inhibitors of glycosidases and purine nucleoside phosphorylase (PNP) have been synthesized via selective coupling of an appropriate nucleobase at different positions of an orthogonally protected imino sugar as a common precursor. This synthetic strategy offers a straightforward protocol for the assembly of imino sugar containing nucleosides, establishing a new repertoire of molecules as potential therapeutics.

  • 48.
    Messersmith, Reid E.
    et al.
    Johns Hopkins Univ, Dept Chem, 3400 North Charles St, Baltimore, MD 21218 USA..
    Yadav, Sangeeta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Siegler, Maxime A.
    Johns Hopkins Univ, Dept Chem, 3400 North Charles St, Baltimore, MD 21218 USA..
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Tovar, John D.
    Johns Hopkins Univ, Dept Chem, 3400 North Charles St, Baltimore, MD 21218 USA.;Johns Hopkins Univ, Dept Mat Sci & Engn, 3400 North Charles St, Baltimore, MD 21218 USA..
    Benzo[b]thiophene Fusion Enhances Local Borepin Aromaticity in Polycyclic Heteroaromatic Compounds2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 24, p. 13440-13448Article in journal (Refereed)
    Abstract [en]

    This report documents the synthesis, characterization, and computational evaluation of two isomeric borepin-containing polycyclic aromatics. The syntheses of these two isomers involved symmetrical disubstituted alkynes that were reduced to Z-olefins followed by borepin formation either through an isolable stannocycle intermediate or directly from the alkene via the trapping of a transient dilithio intermediate. Comparisons of their magnetic, crystallographic, and computational characterization to literature compounds gave valuable insights about the aromaticity of these symmetrically fused [b,f]borepins. The fusion of benzo[b]thiophene units to the central borepin cores forced a high degree of local aromaticity within the borepin moieties relative to other known borepin-based polycyclic aromatics. Each isomer had unique electronic responses in the presence of fluoride anions. The experimental data demonstrate that the local borepin rings in these two compounds have a relatively high amount of aromatic character. Results from quantum chemical calculations provide a more comprehensive understanding of local and global aromatic characters of various rings in fused ring systems built upon boron heterocycles.

  • 49. Moriou, Celine
    et al.
    Denhez, Clement
    Plashkeyych, Oleksandr
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Coantic-Castex, Stephanie
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Chemical Biology.
    Guillaume, Dominique
    Clivio, Pascale
    A Minute Amount of S-Puckered Sugars Is Sufficient for (6-4) Photoproduct Formation at the Dinucleotide Level2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 1, p. 615-619Article in journal (Refereed)
    Abstract [en]

    The di-2'-alpha-fluoro analogue of thymidylyl(3',5')thymidine, synthesized to probe the effect of a minimum amount of S conformer on the photoreactivity of dinucleotides, is endowed with only 3% and 8% of S sugar conformation at its 5'- and 3'-end, respectively. This analogue gives rise to the (6-4) photoproduct as efficiently as the dithymine dinucleotide (74% and 66% at the 5'- and 3'-end, respectively) under 254 nm. Our results suggest that the 5'-N, 3'-S conformer gives rise to the (6-4) photoproduct.

  • 50.
    Moriou, Céline
    et al.
    CNRS, Inst Chim Subst Nat, Gif Sur Yvette, France.
    Da Silva, Adilson D.
    Univ Fed Juiz de Fora, Dept Quim, ICE, BR-Juiz De Fora, MG, Brazil.
    Vianelli Prado, Marcos Joel
    Univ Fed Juiz de Fora, Dept Quim, ICE, BR-Juiz De Fora, MG, Brazil.
    Denhez, Clément
    Univ Reims, Inst Chim Mol Reims, CNRS, UMR 7312,UFR Pharm, 51 Rue Cognacq Jay, Reims, France; Univ Reims, Multiscale Mol Modelling Platform, UFR Sci Exactes & Nat, Reims, France.
    Plashkevych, Oleksandr
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Biology.
    Chattopadhyaya, Jyoti
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular Biology.
    Guillaume, Dominique
    Univ Reims, Inst Chim Mol Reims, CNRS, UMR 7312,UFR Pharm, 51 Rue Cognacq Jay, Reims, France.
    Clivio, Pascale
    Univ Reims, Inst Chim Mol Reims, CNRS, UMR 7312, UFR Pharm, 51 Rue Cognacq Jay, Reims, France.
    C2 '-F Stereoconfiguration As a Puckering Switch for Base Stacking at the Dinucleotide Level2018In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 83, no 4, p. 2473-2478Article in journal (Refereed)
    Abstract [en]

    Fluorine configuration at C2′ of the bis(2′-fluorothymidine) dinucleotide is demonstrated to drive intramolecular base stacking. 2′-β F-Configuration drastically reduces stacking compared to the 2′-α series. Hence, base stacking emerges as being tunable by the C2′-F stereoconfiguration through dramatic puckering variations scrutinized by NMR and natural bond orbital analysis. Accordingly, 2′-β F-isomer photoreactivity is significantly reduced compared to that of the 2′-α F-isomer.

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