Digitala Vetenskapliga Arkivet

Change search
Refine search result
123 1 - 50 of 110
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 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. Agasti, Soumitra
    et al.
    Mondal, Bhaskar
    Achar, Tapas Kumar
    Sinha, Soumya Kumar
    Suseelan, Anjana Sarala
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Schoenebeck, Franziska
    Maiti, Debabrata
    Orthogonal Selectivity in C–H Olefination: Synthesis of Branched Vinylarene with Unactivated Aliphatic Substitution2019In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 9, no 10, p. 9606-9613Article in journal (Refereed)
    Abstract [en]

    Oxidative coupling is a useful tool to synthesize vinylarenes. Despite remarkable successes in linear vinylarene, branched vinylarene synthesis has remained underdeveloped. Overcoming this limitation, herein, we report a chelation-assisted oxidative coupling to generate branched olefinated product in high yield. Exclusive branched selectivity was obtained using alkenyl carboxylic acid. Detailed experimental studies combined with computational investigations suggest that beta-migratory insertion, followed by a decarboxylation pathway is operative for the overall transformation.

  • 3.
    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.

    Download full text (pdf)
    fulltext
  • 4.
    Alam, Rauful
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diner, Colin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jonker, Sybrand
    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.
    Catalytic Asymmetric Allylboration of Indoles and Dihydroisoquinolines with Allylboronic Acids: Stereodivergent Synthesis of up to Three Contiguous Stereocenters2016In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, no 46, p. 14417-14421Article in journal (Refereed)
    Abstract [en]

    The catalytic asymmetric allylboration of cyclic imines with gamma,gamma-disubstituted allylboronic acids provides products with adjacent stereocenters in high yield and stereoselectivity. Various electrophiles, including 3,4-dihydroisoquinolines and indoles, were prenylated in a fully stereodivergent fashion by switching the E/Z geometry of the allylboronate and/or the enantiomer of the BINOL catalyst. 3-Methylindole provided products with three adjacent stereocenters with high stereoselectivity in one synthetic operation.

  • 5.
    Alam, Rauful
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pilarski, Lukasz T.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pershagen, Elias
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Stereoselective intermolecular allylic C-H trifluoroacetoxylation of functionalized alkenes2012In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 134, no 21, p. 8778-8781Article in journal (Refereed)
    Abstract [en]

    Pd-catalyzed allylic C-H trifluoroacetoxylation of substituted alkenes was performed using PhI(OCOCF3)(2) as the oxidant and acyloxy source. Trifluoroacetoxylation of monosubstituted cyclopentenes and cyclohexenes proceeds with excellent regio- and diastereoselectivity. Studies with one of the possible (eta(3)-allyl)Pd(II) intermediates suggest that the reaction proceeds via stereoselective formation of Pd(IV) intermediates and subsequent stereo- and regioselective reductive elimination of the product.

  • 6.
    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)
  • 7.
    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), Inorganic and Structural Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Selective Formation of Adjacent Stereocenters by Allylboration of Ketones under Mild Neutral Conditions2013In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 15, no 10, p. 2546-2549Article in journal (Refereed)
    Abstract [en]

    Allylboronic acids readily react with a broad variety of ketones, affording homoallylic alcohols with adjacent quaternary and tertiary stereocenters. The reaction proceeds with very high anti stereoselectivity even if the substituents of the keto group have a similar size. a-Keto acids react with syn stereoselectivity probably due to the formation of acyl boronate intermediates. The allylation reactions proceed without added acids/bases under mild conditions. Because of this, many functionalities are tolerated even with in situ generated allylboronic acids.

  • 8.
    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.

  • 9.
    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.

  • 10.
    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.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Pincer Complex-Catalyzed Coupling Reactions via Palladium (IV) Intermediates2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, 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.

  • 11.
    Aydin, Juhanes
    et al.
    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.
    Strategies for fine-tuning the catalytic activity of pincer-complexes2006In: Tetrahedron Letters, ISSN 0040-4039, E-ISSN 1359-8562, Vol. 47, no 50, p. 8999-9001Article in journal (Refereed)
    Abstract [en]

    Various methoxy substituted pincer-complexes were prepared in order to study the substituent effects on the catalytic activity in palladium catalyzed opening of vinyl epoxides and boronation of cinnamyl alcohol. The results clearly show that methoxy substitution at the para-position of the pincer-complex leads to up to fourfold acceleration of the catalytic reactions, while substitution of the side-arms does not change the activity of the complex or leads to a slight deceleration of the catalytic processes.

  • 12.
    Aydin, Juhanes
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Senthil, Kumar K
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sayah, Mahmoud J
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Wallner, Olov A
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J
    Synthesis and catalytic application of chiral 1,1'-Bi-2-naphthol- and biphenanthrol-based pincer complexes: selective allylation of sulfonimines with allyl stannane and allyl trifluoroborate.2007In: Journal of Organic Chemistry, Vol. 72, no 13, p. 4689-4697Article in journal (Refereed)
    Abstract [en]

    New easily accessible 1,1'-bi-2-naphthol- (BINOL-) and biphenanthrol-based chiral pincer complex catalysts were prepared for selective (up to 85% enantiomeric excess) allylation of sulfonimines. The chiral pincer complexes were prepared by a flexible modular approach allowing an efficient tuning of the selectivity of the catalysts. By employment of the different enantiomeric forms of the catalysts, both enantiomers of the homoallylic amines could be selectively obtained. Both allyl stannanes and allyl trifluoroborates can be employed as allyl sources in the reactions. The biphenanthrol-based complexes gave higher selectivity than the substituted BINOL-based analogues, probably because of the well-shaped chiral pocket generated by employment of the biphenanthrol complexes. The enantioselective allylation of sulfonimines presented in this study has important implications for the mechanism given for the pincer complex-catalyzed allylation reactions, confirming that this process takes place without involvement of palladium(0) species.

  • 13.
    Aydin, Juhanes
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Enantioselective palladium pincer complex catalyzed carbon carbon coupling reactions between tosylimines and various nucleophiles2008In: Abstracts of Papers, 236th ACS National Meeting, Philadelphia, PA, United States, August 17-21, 2008, Washington, DC: American Chemical Society , 2008Conference paper (Other academic)
  • 14.
    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)
  • 15.
    Belhomme, Marie-Charlotte
    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.
    Formation of C(sp(3))-C(sp(3)) Bonds by Palladium Catalyzed Cross-Coupling of alpha-Diazoketones and Allylboronic Acids2016In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 18, no 10, p. 2503-2506Article in journal (Refereed)
    Abstract [en]

    Palladium catalyzed cross-coupling of allylboronic acids with a-diazoketones was studied. The reaction selectively affords the linear allylic product. The reaction proceeds with formation of a new C(sp(3))-C(sp(3)) bond. The reaction was performed without an external oxidant, likely without the Pd-catalyst undergoing redox reactions.

  • 16.
    Bermejo Gómez, Antonio
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cortés González, Miguel A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lübcke, Marvin
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Karolinska Institutet, Sweden.
    Johansson, Magnus J.
    Halldin, Christer
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Karolinska Insitutet, Sweden.
    Schou, Magnus
    Efficient DBU accelerated synthesis of F-18-labelled trifluoroacetamides2016In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 52, no 97, p. 13963-13966Article in journal (Refereed)
    Abstract [en]

    Nucleophilic F-18-fluorination of bromodifluoromethyl derivatives was performed using [F-18] Bu4NF in the presence of DBU(1,8-diazabicyclo[5.4.0]undec-7-ene). This novel procedure provided a diverse set of [F-18] trifluoroacetamides in good to excellent radiochemical conversions. A mechanism where DBU acts as organomediator in this transformation is proposed.

  • 17.
    Bermejo Gómez, Antonio
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cortés González, Miguel A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Lübcke, Marvin
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Karolinska Intitutet, Sweden.
    Johansson, Magnus J.
    Schou, Magnus
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Karolinska Intitutet, Sweden.
    Synthesis of trifluoromethyl moieties by late-stage copper (I) mediated nucleophilic fluorination2017In: Journal of fluorine chemistry, ISSN 0022-1139, E-ISSN 1873-3328, Vol. 194, p. 51-57Article in journal (Refereed)
    Abstract [en]

    The nucleophilic fluorination of bromodifluoromethyl derivatives mediated by the complex (PPh3)(3)CuF is described. Under the reaction conditions, different trifluoroacetates, trifluorolcetones, trifluoroarenes and trifluoroacetamides were obtained in good yields.

  • 18.
    Brea, Oriana
    et al.
    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.
    Mechanisms of Formation and Rearrangement of Benziodoxole-Based CF3 and SCF3 Transfer Reagents2020In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 85, no 23, p. 15577-15585Article in journal (Refereed)
    Abstract [en]

    Togni's benziodoxole-based reagents are widely used in trifluoromethylation reactions. It has been established that the kinetically stable hypervalent iodine form (I-CF3) of the reagents is thermodynamically less stable than its acyclic ether isomer (O-CF3). On the other hand, the trifluoromethylthio analogue exists in the thermodynamically stable thioperoxide form (O-SCF3), and the hypervalent form (I-SCF3) has been elusive. Despite the importance of these reagents, very little is known about the reaction mechanisms of their syntheses, which has hampered the development of new reagents of the same family. Herein, we use density functional theory calculations to understand the reasons for the divergent behaviors between the CF3 and SCF3 reagents. We demonstrate that they follow different mechanisms of formation and that the metals involved in the syntheses (potassium in the case of the trifluoromethyl reagent and silver in the trifluoromethylthio analogue) play key roles in the mechanisms and greatly influence the possibility of their rearrangements from the hypervalent (I-CF3, I-SCF3) to the corresponding ether-type form (O-CF3, O-SCF3).

  • 19.
    Cortés González, Miguel A.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jian, Xingguo
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nordeman, Patrik
    Antoni, Gunnar
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Rhodium-mediated 18F-oxyfluorination ofdiazoketones using a fluorine-18-containing hypervalent iodine reagent2019In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, no 89, p. 13358-13361Article in journal (Refereed)
    Abstract [en]

    Geminal 18F-oxyfluorination of diazoketones was performed in the presence of rhodium mediators. The reactions were performed using a hypervalent iodine-based [18F]fluoro-benziodoxole reagent. By this methodology various α-[18F]fluoro ethers were obtained in high radiochemical yield (up to 98%) and molar activity (216 GBq μmol-1).

  • 20.
    Cortés González, Miguel A.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nordeman, Patrik
    Bermejo Gómez, Antonio
    Stockholm University, Faculty of Science, Department of Organic Chemistry. AstraZeneca PET Centre at Karolinska Institutet, Sweden.
    Meyer, Denise N.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Antoni, Gunnar
    Schou, Magnus
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    [F-18]fluoro-benziodoxole: a no-carrier-added electrophilic fluorinating reagent. Rapid, simple radiosynthesis, purification and application for fluorine-18 labelling2018In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 34, p. 4286-4289Article in journal (Refereed)
    Abstract [en]

    Operationally simple radiosynthesis and purification of [F-18]fluoro-benziodoxole was developed starting from a cyclotron produced [F-18]F- precursor, [F-18]TBAF, and tosyl-benziodoxole. The synthetic utility of [F-18]fluoro-benziodoxole was demonstrated by electrophilic fluorocyclization of o-styrilamides proceeding with high RCC (typically 50-90%) and high molar activity (up to 396 GBq mol(-1)).

  • 21.
    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.

    Download full text (pdf)
    fulltext
  • 22.
    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.

  • 23.
    Deliaval, Marie
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jayarajan, Ramasamy
    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.
    Three-Component Approach to Densely Functionalized Trifluoromethyl Allenols by Asymmetric Organocatalysis2023In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 145, no 18, p. 10001-10006Article in journal (Refereed)
    Abstract [en]

    We have developed a new three-component catalytic coupling reaction of alkynyl boronates, diazomethanes, and aliphatic/aromatic ketones in the presence of BINOL derivatives. The reaction proceeds with a remarkably high enantio- and diastereoselectivity (up to three contiguous stereocenters) affording tertiary CF3-allenols in a single operational step. The reaction proceeds under mild, neutral, metal-free conditions, which leads to a high level of functional group tolerance.

  • 24.
    Deng, Hong-Ping
    et al.
    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.
    Allylic sp (3) C-H borylation of alkenes via allyl-Pd intermediates: an efficient route to allylboronates2014In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 50, no 65, p. 9207-9210Article in journal (Refereed)
    Abstract [en]

    Palladium catalyzed allylic C-H functionalization was performed using exocyclic alkene substrates. Multi-component synthesis of stereodefined homoallylic alcohols could be performed using a reaction sequence involving allylic C-H borylation and allylation of aldehydes.

    Download full text (pdf)
    fulltext
  • 25.
    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.

  • 26.
    Diner, Colin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Recent Advances in the Preparation and Application of Allylboron Species in Organic Synthesis2017In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 1, p. 2-14Article, review/survey (Refereed)
    Abstract [en]

    In this Perspective we will highlight the most important recent breakthroughs in selective allylboron chemistry (both the synthesis and application of these species). In addition we will provide an outlook toward the future of this promising subfield of organic synthesis.

  • 27. Dutheuil, Guillaume
    et al.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aggarwal, Varinder K.
    Direct synthesis of functionalized allylic boronic esters from allylic alcohols and inexpensive reagents and catalysts2008In: Synthesis (Stuttgart), ISSN 0039-7881, E-ISSN 1437-210X, no 14, p. 2293-2297Article in journal (Refereed)
    Abstract [en]

    A remarkably simple and effective system for the direct conversion of allylic alcohols into high value allylic boronic esters using commercially available reagents and catalysts is described.

  • 28. Gagliardo, Marcella
    et al.
    Selander, Nicklas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mehendale, Nilesh C.
    van Koten, Gerard
    Klein Gebbink, Robertus J. M.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Catalytic performance of symmetrical and unsymmetrical sulfur-containing pincer complexes: synthesis and tandem catalytic activity of the first PCS-pincer palladium complex2008In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 14, no 16, p. 4800-4809Article in journal (Refereed)
  • 29. 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.

  • 30.
    Ilchenko, Nadia O.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cortés, 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.

  • 31.
    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.

  • 32.
    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.

  • 33.
    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.

  • 34.
    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.

  • 35.
    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.

    Download full text (pdf)
    fulltext
  • 36.
    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.

  • 37.
    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.

  • 38.
    Jayarajan, Ramasamy
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kireilis, Tautvydas
    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.
    Asymmetric Organocatalytic Homologation: Access to Diverse Chiral Trifluoromethyl Organoboron Species2022In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 28, no 58, article id e202202059Article in journal (Refereed)
    Abstract [en]

    A broad range of aliphatic, aromatic, and heterocyclic boronic acids were successfully homologated using trifluorodiazoethane in the presence of BINOL derivatives to provide the corresponding chiral trifluoromethyl containing boronic acid derivatives in high yields and excellent enantioselectivity. The in situ conversion of the chiral transient boronic acids to the corresponding alcohols or β-CF3 carboxylates are also demonstrated. 

  • 39.
    Jiang, Xingguo
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Meyer, Denise
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Baran, Dominik
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Cortés González, Miguel A.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Trifluoromethylthiolation, Trifluoromethylation, and Arylation Reactions of Difluoro Enol Silyl Ethers2020In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 85, no 13, p. 8311-8319Article in journal (Refereed)
    Abstract [en]

    This study reports a new application area of difluoro enol silyl ethers, which can be easily obtained from trifluoromethyl ketones. The main focus has been directed to the electrophilic fluoroalkylation and arylation methods. The trifluoromethylthiolation of difluoro enol silyl ethers can be used for the construction of a novel trifluoromethylthio-alpha, alpha-difluoroketone (-COCF2SCF3) functionality. The -CF2SCF3 moiety has interesting properties due to the electron-withdrawing, albeit lipophilic, character of the SCF3 group, which can be combined with the high electrophilicity of the difluoroketone motif. The methodology could also be extended to difluoro homologation of the trifluoromethyl ketones using the Togni reagent. In addition, we presented a method for transition-metal-free arylation of difluoro enol silyl ethers based on hypervalent iodines.

  • 40.
    Jonker, Sybrand J. T.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Diner, Colin
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Schulz, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Iwamoto, Hiroaki
    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.
    Catalytic asymmetric propargyl- and allylboration of hydrazonoesters: a metal-free approach to sterically encumbered chiral alpha-amino acid derivatives2018In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, no 91, p. 12852-12855Article in journal (Refereed)
    Abstract [en]

    A new asymmetric catalytic propargyl- and allylboration of hydrazonoesters is reported. The reactions utilize allenyl- and allylboronic acids in the presence of the inexpensive parent BINOL catalyst. The reactions can be performed under mild conditions (0 degrees C) without any metal catalyst or other additives affording sterically encumbered chiral -amino acids. This is the first metal-free method for the asymmetric propargyl- and allylboration of hydrazonoesters.

  • 41.
    Jonker, Sybrand
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Jayarajan, Ramasamy
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Kireilis, Tautvydas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Deliaval, Marie
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Eriksson, Lars
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Organocatalytic Synthesis of α‐Trifluoromethyl Allylboronic Acids by Enantioselective 1,2-Borotropic Migration2020In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 142, no 51, p. 21254-21259Article in journal (Refereed)
    Abstract [en]

    Chiral α-substituted allylboronic acids were synthesized by asymmetric homologation of alkenylboronic acids using CF3/TMS-diazomethanes in the presence of BINOL catalyst and ethanol. The chiral α-substituted allylboronic acids were reacted with aldehydes or oxidized to alcohols in situ with a high degree of chirality transfer. The oxygen-sensitive allylboronic acids can be purified via their isolated diaminonaphthalene (DanH)-protected derivatives. The highly reactive purified allylboronic acids reacted in a self-catalyzed reaction at room temperature with ketones, imines, and indoles to give congested trifluoromethylated homoallylic alcohols/amines with up to three contiguous stereocenters.

  • 42.
    Larsson, Johanna M.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Aydin, Juhanes
    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.
    Catalytic functionalization of allylic compounds via palladium(IV) intermediates2010In: Abstracts of Papers, 2010Conference paper (Other academic)
  • 43.
    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.

  • 44.
    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.

  • 45.
    Lübcke, Marvin
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bezhan, Dina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Szabó, Kálmán J.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Trifluoromethylthiolation-arylation of diazocarbonyl compounds by modified Hooz multicomponent coupling2019In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 10, no 23, p. 5990-5995Article in journal (Refereed)
    Abstract [en]

    A new Zn-mediated trifluoromethylthiolation-based bifunctionalization reaction is developed. In this process, simultaneous C-SCF3 and C-C bond formation takes place in a multicomponent reaction, in which an aryl and a SCF3 group arise from different reagents. Our studies show that the reaction mechanism is similar to the Hooz multicomponent coupling. The process involves in situ generation of BAr3, which reacts with a diazocarbonyl compound, and the reaction is terminated by an electrophilic SCF3 transfer. The reaction can also be extended to fluorination based bifunctionalization which proceeds with somewhat lower yield than the analogous trifluoromethylthiolation reaction.

  • 46.
    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.

  • 47.
    Mai, Binh Khanh
    et al.
    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.
    Mechanisms of Rh-Catalyzed Oxyaminofluorination and Oxyaminotrifluoromethylthiolation of Diazocarbonyl Compounds with Electrophilic Reagents2018In: Organic Letters, ISSN 1523-7060, E-ISSN 1523-7052, Vol. 20, no 21, p. 6646-6649Article in journal (Refereed)
    Abstract [en]

    Density functional theory calculations were performed to study the detailed reaction mechanisms of rhodium-catalyzed oxyaminofluorination and oxyaminotrifluoromethylthiolation of diazocarbonyl compounds with electrophilic N-F and N-SCF3-based reagents. The calculations show that the operating mechanisms for the two reactions are identical. The catalytic cycle starts with N-2 dissociation to provide a rhodium-carbene intermediate, followed by nucleophilic attack of tetrahydrofuran on the carbene and a rhodium coordination change generating a rhodium-enolate intermediate. Subsequent electrophilic attack introduces the fluorine or the SCF3 moiety, and it is followed by nucleophilic attack of the remaining amino group to yield the final product.

  • 48.
    Mai, Binh Khanh
    et al.
    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.
    Mechanisms of Rh-Catalyzed Oxyfluorination and Oxytrifluoromethylation of Diazocarbonyl Compounds with Hypervalent Fluoroiodine2018In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 5, p. 4483-4492Article in journal (Refereed)
    Abstract [en]

    The reaction mechanisms of rhodium-catalyzed geminal oxyfluorination and oxytrifluoromethylation of diazo-carbonyl compounds with fluoro-benziodoxole and Togni reagents are investigated by means of density functional theory calculations. It is shown that the two reactions follow very similar mechanisms, involving N-2 dissociation to form a Rh-carbene intermediate, alcohol insertion and proton transfer resulting in a stable Rh-enol intermediate, and concerted proton transfer/electrophilic addition of the hypervalent iodine reagent to the enol. Isomerization of the hypervalent iodine takes then place before a ligand coupling affords the final product. The role of the dirhodium catalyst in facilitating the various steps of the reaction is discussed. The presented mechanisms are consistent with available experimental information, and the obtained insights allow for extension to other reactions involving hypervalent iodine reagents.

  • 49. 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.

  • 50. 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.

123 1 - 50 of 110
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf