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  • 1. Agasti, Soumitra
    et al.
    Maity, Soham
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Maiti, Debabrata
    Palladium-Catalyzed Synthesis of 2,3-Disubstituted Benzofurans: An Approach Towards the Synthesis of Deuterium Labeled Compounds2015In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 357, no 10, p. 2331-2338Article in journal (Refereed)
    Abstract [en]

    Palladium-catalyzed oxidative annulations between phenols and alkenylcarboxylic acids produced a library of benzofuran compounds. Depending on the nature of the substitution of the phenol precursor, either 2,3-dialkylbenzofurans or 2-alkyl-3-methylene-2,3-dihydrobenzofurans can be synthesized with excellent regioselectivity. Reactions between conjugated 5-phenylpenta-2,4-dienoic acids and phenol gave 3-alkylidenedihydrobenzofuran alkaloid motifs while biologically active 7-arylbenzofuran derivatives were prepared by starting from 2-phenylphenols. More interestingly, selective incorporation of deuterium from D2O has been discovered, which offers an attractive one-step method to access deuterated compounds.

  • 2.
    Alam, Rauful
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Das, Arindam
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Huang, Genping
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stereoselective allylboration of imines and indoles under mild conditions. An in situ E/Z isomerization of imines by allylboroxines2014In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 5, no 7, p. 2732-2738Article in journal (Refereed)
    Abstract [en]

    Direct allylboration of various acyclic and cyclic aldimine, ketimine and indole substrates was performed using allylboronic acids. The reaction proceeds with very high anti-stereoselectivity for both E and Z imines. The allylboroxines formed by dehydration of allylboronic acids have a dual effect: promoting E/Z isomerization of aldimines and triggering the allylation by efficient electron withdrawal from the imine substrate.

  • 3.
    Alam, Rauful
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Raducan, Mihai
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diastereoselective allylboration of wide variety of carbonyl compounds using allylboronic acids: Construction of adjacent tertiary and quaternary centers2013In: Abstracts of papers of The American Chemical Society, American Chemical Society (ACS), 2013, Vol. 246, p. 364-ORGN-Conference paper (Refereed)
  • 4.
    Alam, Rauful
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Vollgraff, Tobias
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Adjacent Quaternary Stereocenters by Catalytic Asymmetric Allylboration2015In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 35, p. 11262-11265Article in journal (Refereed)
    Abstract [en]

    Allylboration of ketones with gamma-disubstituted allylboronic acids is performed in the presence of chiral BINOL derivatives. The reaction is suitable for single-step creation of adjacent quaternary stereocenters with high selectivity. We show that, with an appropriate choice of the chiral catalyst and the stereoisomeric prenyl substrate, full control of the stereo- and enantioselectivity is possible in the reaction.

  • 5.
    Aydin, Juhanes
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Larsson, Johanna M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pincer complex-catalyzed redox coupling of alkenes with iodonium salts via presumed palladium(IV) intermediates2009In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 11, no 13, p. 2852-2854Article in journal (Refereed)
    Abstract [en]

    Palladium pincer complexes directly catalyze the redox coupling reactions of functionalized alkenes and iodonium salts. The catalytic process, which is suitable for mild catalytic functionalization of allylic acetates and electron-rich alkenes, probably occurs through Pd(IV) intermediates. Due to the strong metal−ligand interactions, the oxidation of phosphine and amine ligands of the pincer complexes can be avoided in the presented reactions.

  • 6.
    Aydin, Juhanes
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanistic considerations for the enantioselective palladium pincer complex catalyzed carbon-carbon coupling reactions2008In: Abstracts of Papers, 236th ACS National Meeting, Philadelphia, PA, United States, August 17-21, 2008, Washington, DC: American Chemical Society , 2008Conference paper (Other academic)
  • 7.
    Das, Arindam
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Alam, Rauful
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Inorganic and Structural Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stereocontrol in Synthesis of Homoallylic Amines. Syn Selective Direct Allylation of Hydrazones with Allylboronic Acids2014In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 16, no 14, p. 3808-3811Article in journal (Refereed)
    Abstract [en]

    Allylboronic acids directly react with acyl hydrazones, affording homoallylic amine derivatives. The reaction proceeds with very high syn selectivity, which is the opposite of the stereochemistry observed for allylboration of imines. The reaction can be carried out with both aromatic and aliphatic acyl hydrazones. Based on our studies the excellent syn stereochemistry can be explained by chelation control of the acyl hydrazone and the B(OH)(2) moiety.

  • 8.
    Das, Arindam
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wang, Dong
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Belhomme, Marie-Charlotte
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Copper-Catalyzed Cross-Coupling of Allylboronic Acids with alpha-Diazoketones2015In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 17, no 19, p. 4754-4757Article in journal (Refereed)
    Abstract [en]

    Copper-catalyzed cross-coupling of substituted allylboronic acids with alpha-diazoketones was studied. This allylation reaction is highly regioselective, providing the branched allylic product. The process involves creation of a new C(sp(3))-C(sp(3)) bond by retaining the keto functional group of the alpha-diazoketone precursor.

  • 9.
    Deng, Hong-Ping
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wang, Dong
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Direct Allylation of Quinones with Allylboronates2015In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 80, no 6, p. 3343-3348Article in journal (Refereed)
    Abstract [en]

    Allylboronates undergo C-H allylation of unsubstituted or monosubstituted benzoquinone and naphthoquinone substrates. In the case of 2,5- or 2,6-disubstituted quinones addition involving the substituted carbon takes place. Allylation with stereodefined allylboronates occurs with retention of the configuration.

  • 10. Huang, Genping
    et al.
    Diner, Colin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Himo, Fahmi
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanism and Stereoselectivity of the BINOL-Catalyzed Allylboration of Skatoles2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 21, p. 5904-5907Article in journal (Refereed)
    Abstract [en]

    Density functional theory calculations have been performed to investigate the binaphthol-catalyzed allylboration of skatoles. The high stereoselectivity observed for the reaction is reproduced well by the calculations and was found to be mainly a result of steric repulsions in the corresponding Zimmerman-Traxler transition states. The role of the additive MeOH in enhancing the stereoselectivity was also investigated and is suggested to promote the formation of less reactive allylboronic ester intermediates, thereby suppressing the formation of allylboroxine species, which undergo the facile racemic background reaction.

  • 11.
    Ilchenko, Nadia O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cortes, Miguel A.
    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.

  • 12.
    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.

  • 13.
    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.

  • 14.
    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.

  • 15.
    Ilchenko, Nadia O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Geminal difluorination of alpha,alpha '-disubstituted styrenes using fluoro-benziodoxole reagent. Migration aptitude of the alpha-substituents2017In: Journal of fluorine chemistry, ISSN 0022-1139, E-ISSN 1873-3328, Vol. 203, p. 104-109Article in journal (Refereed)
    Abstract [en]

    alpha,alpha'-Disubstituted styrenes undergo a difluorination-rearrangement reaction with fluoro-benzoiodoxole reagent 1. The reaction is catalyzed by Pd(MeCN)(4)(BF4)(2) and Cu(MeCN)(4)PF6. We have studied the rearrangement of alpha,alpha'-diaryl substituted styrenes, in which the aryl groups have different electronic character. In the case of a aryl, alpha'-alkyl substituted styrenes, the aryl substituent has a higher migratory aptitude than the alkyl group. We have also extended the reactions to cycloalkyl styrenes, which underwent interesting ring contraction/expansion reactions. The regioselectivity of the migration can be explained on the basis of the formation of a phenonium intermediate.

  • 16.
    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.

  • 17.
    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.

  • 18.
    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.

  • 19.
    Kjellgren, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sundén, Henrik
    Szabó, Kálmán J.
    Palladium pincer complex-catalyzed stannyl and silyl transfer to propargylic substrates: Synthetic scope and mechanism2005In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 127, no 6, p. 1787-1796Article in journal (Refereed)
  • 20.
    Kjellgren, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sundén, Henrik
    Szabó, Kálmán J.
    Palladium Pincer-Complex Catalyzed Trimethyltin Substitution of Functionalized Propargylic Substrates: An Efficient Route to Propargyl- and Allenyl-Stannanes2004In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, no 2, p. 474-476Article in journal (Refereed)
  • 21.
    Kjellgren, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Synthesis of stereodefined vinyl-tetrahydropyran and vinyl-octahydrochromene derivatives via acetalization-cyclization of allylsilanes with aldehydes: Origin of the high stereoselectivity2002In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 43, no 6, p. 1123-1126Article in journal (Refereed)
  • 22.
    Larsson, Johanna M.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pathipati, Stalin R.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Regio- and Stereoselective Allylic Trifluoromethylation and Fluorination using CuCF3 and CuF Reagents2013In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 78, no 14, p. 7330-7336Article in journal (Refereed)
    Abstract [en]

    Copper-mediated trifluoromethylation of allylic chlorides and trifluoroacetates was performed using a convenient Cu-CF3 reagent. The reaction is suitable for selective synthesis of allyl trifluoromethyl species. Mechanistic studies indicate that the reaction proceeds via a nucleophilic substitution mechanism involving allyl copper intermediates. The analogous Cu-F reagent was suitable for fluorination of allyl chlorides. Stereodefined cyclic substrates reacted regio- and stereoselectively.

  • 23.
    Larsson, Johanna M.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Zhao, Tony S. N.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Oxidative Allylic C-H Silylation2011In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 13, no 7, p. 1888-1891Article in journal (Refereed)
    Abstract [en]

    Palladium-catalyzed allylic C−H silylation was performed with use of hexamethyldisilane as the silyl source. These C−H functionalization reactions occur only in the presence of hypervalent iodine reagents or other strong oxidants and proceed with excellent regioselectivity, providing the linear allylic isomer of the allylsilane products. In demonstrating the first oxidative allylic C−H silylation of alkenes, this study marks an important advance for the catalytic C−H functionalization method.

  • 24.
    Lübcke, Marvin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Karolinska Institutet, Sweden.
    Yuan, Weiming
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Karolinska Institutet, Sweden.
    Trifluoromethylthiolation-Based Bifunctionalization of Diazocarbonyl Compounds by Rhodium Catalysis2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 17, p. 4548-4551Article in journal (Refereed)
    Abstract [en]

    A new Rh-catalyzed, three-component reaction for the oxytrifluoromethylthiolation of alpha-diazoketones was developed. The SCF3 functionality was introduced using a stable dibenzenesulfonimide reagent under mild conditions. Alcohols, acetals, and ethers were used as the alkoxy sources. Cyclic ethers underwent a trifunctionalization reaction through the introduction of SCF3, OR, and N(SO2Ph)(2) substituents in a single step.

  • 25. Mao, Lujia
    et al.
    Bertermann, Rüdiger
    Emmert, Katharina
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Marder, Todd B.
    Synthesis of Vinyl-, Allyl-, and 2-Boryl Allylboronates via a Highly Selective Copper-Catalyzed Borylation of Propargylic Alcohols2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 24, p. 6586-6589Article in journal (Refereed)
    Abstract [en]

    An efficient methodology for the synthesis of vinyl-, allyl-, and (E)-2-boryl allylboronates from propargylic alcohols via Cu-catalyzed borylation under mild conditions is reported. In the presence of commercially available Cu(OAc)(2) or Cu(acac)(2) and Xantphos, the reaction affords the desired products in up to 92% yield with a broad substrate scope (43 examples). Isolation of an allenyl boronate as the reaction intermediate suggests that an insertion elimination-type reaction, followed by borylcupration, is involved in the borylation of propargylic alcohols.

  • 26. Mao, Lujia
    et al.
    Bertermann, Rüdiger
    Rachor, Simon G.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Marder, Todd B.
    Palladium-Catalyzed Oxidative Borylation of Allylic C-H Bonds in Alkenes2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 24, p. 6590-6593Article in journal (Refereed)
    Abstract [en]

    This communication describes an efficient palladium pincer complex-catalyzed allylic C-H borylation of alkenes. The transformation exhibits high regio- and stereo selectivity with a variety of linear alkenes. A synthetically useful feature of this allylic C-H borylation method is that all allyl-Bpin products can be isolated in usually high yields. Preliminary mechanistic studies indicate that this CH borylation reaction proceeds via Pd(IV) pincer complex intermediates.

  • 27. Mao, Lujia
    et al.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Marder, Todd B.
    Synthesis of Benzyl-, Allyl-, and Allenyl-boronates via Copper-Catalyzed Borylation of Alcohols2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 5, p. 1204-1207Article in journal (Refereed)
    Abstract [en]

    Alcohols are among the most abundant and readily available organic feedstocks in industrial processes. The direct catalytic functionalization of sp(3) C-O bonds of alcohols remains the main challenge in this field. Here, we report a copper-catalyzed synthesis of benzyl-, allyl-, and allenylboronates from benzylic, allylic, and propargylic alcohols, respectively. This protocol exhibits a broad reaction scope (40 examples) and high efficiency (up to 95% yield) under mild conditions, including for the preparation of secondary allylic boronates. Preliminarily mechanistic studies suggest that nucleophilic substitution is involved in this reaction.

  • 28. Miralles, Nuria
    et al.
    Alam, Rauful
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Fernandez, Elena
    Transition-Metal-Free Borylation of Allylic and Propargylic Alcohols2016In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, no 13, p. 4303-4307Article in journal (Refereed)
    Abstract [en]

    The base-catalyzed allylic borylation of tertiary allylic alcohols allows the synthesis of 1,1-disubstituted allyl boronates, in moderate to high yield. The unexpected tandem performance of the Lewis acid-base adduct, [Hbase](+)[MeO-B(2)pin(2)](-) favored the formation of 1,2,3-triborylated species from the tertiary allylic alcohols and 1-propargylic cyclohexanol at 90 degrees C.

  • 29.
    Pilarski, Lukasz T.
    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.
    Palladium-Catalyzed Selective Acyloxylation Using Sodium Perborate as Oxidant2011In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 76, no 5, p. 1503-1506Article in journal (Refereed)
    Abstract [en]

    Sodium perborate (SPB), a principal component of washing powders, was employed as an inexpensive and eco-friendly oxidant in the palladium-catalyzed C-H acyloxylation of alkenes in excellent regio- and stereochemistry. The reactions used anhydrides as acyloxy sources. The method applies to both terminal and internal alkenes, and even benzylic C-H oxidation.

  • 30.
    Pilarski, Lukasz T.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diphenyliodonium hexafluorophosphate2011In: Encyclopedia of Reagents for Organic Synthesis, John Wiley & Sons, 2011Chapter in book (Refereed)
  • 31.
    Sebelius, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Olsson, Vilhelm J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wallner, Olov A.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Coupling of Allylboronic Acids with Iodobenzenes. Selective Formation of the Branched Allylic Product in the Absence of Directing Groups2006In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 128, no 25, p. 8150-8151Article in journal (Refereed)
    Abstract [en]

    Palladium-catalyzed coupling reactions of functionalized allylboronic acids with iodobenzenes were achieved under standard Suzuki−Miyaura coupling conditions. The coupling reactions afforded selectively the branched allylic products in high to excellent yields. In contrast to palladium-catalyzed nucleophilic substitution reactions proceeding via (η3-allyl)palladium intermediates, this process does not require directing groups in the allyl moiety to achieve substitution at the congested allylic terminus. The regioselectivity of the process was largely unaffected by the substituent effects of the iodobenzenes and the allylic substrates.

  • 32.
    Seenivasaperumal, Muthu
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Federsel, Hans-Jürgen
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanism of the asymmetric sulfoxidation in the esomeprazole process: Effects of the imidazole backbone for the enantioselection2009In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 351, no 6, p. 903-919Article in journal (Refereed)
  • 33.
    Selander, Nicklas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Paasch, Jennifer R.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Palladium-Catalyzed Allylic C-OH Functionalization for Efficient Synthesis of Functionalized Allylsilanes2011In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 133, no 3, p. 409-411Article in journal (Refereed)
    Abstract [en]

    A new method is described for palladium-catalyzed allylic silylation using allylic alcohols and disilanes as precursors. The reactions proceed smoothly under mild and neutral conditions, and this method is suitable for synthesis of regio-and stereodefined allylsilanes. The presented silylation reaction can be easily extended to include synthesis of allylboronates by change of the dimetallic reagent. The presented synthetic procedure offers a broad platform for the selective synthesis of functionalized allyl metal reagents, which are useful precursors in advanced organic chemistry and natural product synthesis.

  • 34.
    Selander, Nicklas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sebelius, Sara
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Estay, Cesar
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Highly Selective and Robust Palladium-Catalysed Carbon-Carbon Coupling between Allyl Alcohols and Aldehydes via Transient Allylboronic Acids2006In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 18, p. 4085-4087Article in journal (Refereed)
    Abstract [en]

    The highly regio- and stereoselective coupling of allyl alcohols with aldehydes could be achieved with 5 mol-% of SeCSe pincer complex catalyst and p-toluenesulfonic acid in the presence of diboronic acid. The transformations have a broad synthetic scope, and the high yields were obtained without the use of an inert atmosphere and carefully dried solvents.

  • 35.
    Selander, Nicklas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalysis by Palladium Pincer Complexes2011In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 111, no 3, p. 2048-2076Article, review/survey (Refereed)
  • 36.
    Selander, Nicklas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Efficient synthesis of α-amino acids via organoboronate reagents2009In: Asymmetric Synthesis and Application of α-Amino Acids / [ed] Vadim A. Soloshonok and Kunisuke Izawa, Washington, DC, USA: American Chemical Society , 2009, p. 190-202Chapter in book (Other academic)
  • 37.
    Selander, Nicklas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis and transformation of organoboronates and stannanes by pincer-complex catalysts2009In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, no 32, p. 6267-6279Article in journal (Refereed)
  • 38.
    Selander, Nicklas
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Willy, Benjamin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selective C-H Borylation of Alkenes by Palladium Pincer Complex Catalyzed Oxidative Functionalization2010In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 49, no 24, p. 4051-4053Article in journal (Refereed)
  • 39.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Application of chiral pincer complexes in asymmetric catalysis2009In: Abstracts of Papers, 238th ACS National Meeting, Washington, DC, United States, August 16-20, 2009, American Chemical Society , 2009Conference paper (Other academic)
  • 40.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iridium catalyzed functionalization of allylic and vinylic C-H bonds2009In: Abstracts of Papers, 238th ACS National Meeting, Washington, DC, United States, August 16-20, 2009, American Chemical Society , 2009Conference paper (Other academic)
  • 41.
    Wang, Dong
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Copper-Catalyzed, Stereoselective Cross-Coupling of Cyclic Allyl Boronic Acids with alpha-Diazoketones2017In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 19, no 7, p. 1622-1625Article in journal (Refereed)
    Abstract [en]

    In this study; we present the synthesis of new, Stereodefined allylboronic adds employed to investigate the stereochemistry of the Cu-catalyzed cross-coupling of allylboronic acids with alpha-diazoketones. According to our results, this reaction proceeds with retention of the relative configurtion of the allylberonic acid substrate. We suggest that the stereoinduction step involves a syn S(E)2'-type transrnetalation of the allylboronic acid substrate with a Cu-carbene species.

  • 42.
    Yang, Yuzhu
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Synthesis of Allenes by Catalytic Coupling of Propargyl Carbonates with Aryl Iodides in the Presence of Diboron Species2016In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, no 1, p. 250-255Article in journal (Refereed)
    Abstract [en]

    Bimetallic copper-/palladium-catalyzed multicomponent reaction of propargyl carbonates, aryl iodides, and diboron species was studied. This procedure can be used for synthesis of di-, tri-, and tetra-substituted allenes. Using diboronic acid, the reaction is supposed to proceed via allenylboronic acid intermediate.

  • 43.
    Zhao, Tony S. N.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Trifluoromethylation of Propargylic Halides and Trifluoroacetates Using (Ph3P)(3)Cu(CF3) Reagent2012In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 14, no 15, p. 3966-3969Article in journal (Refereed)
    Abstract [en]

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

  • 44.
    Zhao, Tony S. N.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Yang, Yuzhu
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lessing, Timo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Borylation of Propargylic Substrates by Bimetallic Catalysis. Synthesis of Allenyl, Propargylic, and Butadienyl Bpin Derivatives2014In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 136, no 21, p. 7563-7566Article in journal (Refereed)
    Abstract [en]

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

1 - 44 of 44
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