Journal: Beilstein Journal of Organic Chemistry

Abbreviation

Beilstein j. org. chem.

Publisher

Beilstein-Institut zur Förderung der Chemischen Wissenschaften

Journal Volumes

ISSN

1860-5397

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2011 - 201972020 - 20255
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Publications1 - 10 of 12
  • The chemistry and biology of mycolactones
    Item type: Review Article
    Gehringer, Matthias; Altmann, Karl-Heinz (2017)
    Beilstein Journal of Organic Chemistry
    Mycolactones are a group of macrolides excreted by the human pathogen Mycobacterium ulcerans, which exhibit cytotoxic, immunosuppressive and analgesic properties. As the virulence factor of M. ulcerans, mycolactones are central to the pathogenesis of the neglected disease Buruli ulcer, a chronic and debilitating medical condition characterized by necrotic skin ulcers. Due to their complex structure and fascinating biology, mycolactones have inspired various total synthesis endeavors and structure–activity relationship studies. Although this review intends to cover all synthesis efforts in the field, special emphasis is given to the comparison of conceptually different approaches and to the discussion of more recent contributions. Furthermore, a detailed discussion of molecular targets and structure–activity relationships is provided.
  • Synthesis, characterization and initial evaluation of 5-nitro-1-(trifluoromethyl)-3H-1λ3,2-benziodaoxol-3-one
    Item type: Journal Article
    Santschi, Nico; Sarott, Roman C.; Otth, Elisabeth; et al. (2014)
    Beilstein Journal of Organic Chemistry
    The synthesis of 5-nitro-1-(trifluoromethyl)-3H-1λ3,2-benziodaoxol-3-one (3), a hypervalent-iodine-based electrophilic trifluoromethylating reagent, is described. Whereas considerations based on cyclic voltammetry and X-ray structural properties would predict an inferior reactivity when compared to the non-nitrated derivative 2, 19F NMR kinetic studies showed that this new derivative is almost one order of magnitude more reactive. Furthermore, differential scanning calorimetry measurements indicated that, in addition, it is also safer to handle.
  • O-Alkylated heavy atom carbohydrate probes for protein X-ray crystallography: Studies towards the synthesis of methyl 2-O-methyl-L-selenofucopyranoside
    Item type: Journal Article
    Sommer, Roman; Hauck, Dirk; Varrot, Annabelle; et al. (2016)
    Beilstein Journal of Organic Chemistry
    Selenoglycosides are used as reactive glycosyl donors in the syntheses of oligosaccharides. In addition, such heavy atom analogs of natural glycosides are useful tools for structure determination of their lectin receptors using X-ray crystallography. Some lectins, e.g., members of the tectonin family, only bind to carbohydrate epitopes with O-alkylated ring hydroxy groups. In this context, we report the first synthesis of an O-methylated selenoglycoside, specifically methyl 2-O-methyl-L-selenofucopyranoside, a ligand of the lectin tectonin-2 from the mushroom Laccaria bicolor. The synthetic route required a strategic revision and further optimization due to the intrinsic lability of alkyl selenoglycosides, in particular for the labile fucose. Here, we describe a successful synthetic access to methyl 2-O-methyl-L-selenofucopyranoside in 9 linear steps and 26% overall yield starting from allyl L-fucopyranoside.
  • Automated synthesis of sialylated oligosaccharides
    Item type: Journal Article
    Esposito, Davide; Hurevich, Mattan; Castagner, Bastien; et al. (2012)
    Beilstein Journal of Organic Chemistry
    Sialic acid-containing glycans play a major role in cell-surface interactions with external partners such as cells and viruses. Straightforward access to sialosides is required in order to study their biological functions on a molecular level. Here, automated oligosaccharide synthesis was used to facilitate the preparation of this class of biomolecules. Our strategy relies on novel sialyl α-(2→3) and α-(2→6) galactosyl imidates, which, used in combination with the automated platform, provided rapid access to a small library of conjugation-ready sialosides of biological relevance.
  • Interaction of a pyrene derivative with cationic [60]fullerene in phospholipid membranes and its effects on photodynamic actions
    Item type: Journal Article
    Takagi, Hayato; Çelik, Çetin; Fukuda, Ryosuke; et al. (2024)
    Beilstein Journal of Organic Chemistry
    We have reported that upon visible light irradiation, ferrocene-porphyrin-[60]fullerene triad molecules yield long-lived charge-separated states, enabling the control of the plasma membrane potential (Vm) in living cells. These previous studies indicated that the localization of the triad molecules in a specific intra-membrane orientation and the suppression of the photodynamic actions of the [60]fullerene (C60) moiety are likely important to achieve fast and safe control of V m , respectively. In this study, by mimicking our previous system of triad molecules and living cells, we report a simplified model system with a cationic C 60 derivative (catC60) and a liposome with embedded 1-pyrenebutyric acid (PyBA) to demonstrate that the addition of PyBA was important to achieve fast and safer control of V m .
  • Binding of tryptophan and tryptophan-containing peptides in water by a glucose naphtho crown ether
    Item type: Journal Article
    Gallo, Gianpaolo; Lewandowski, Bartosz (2025)
    Beilstein Journal of Organic Chemistry
    Tryptophan fulfills a plethora of important functions in nature both in its free form and as a component of peptides and proteins. Selective binding of tryptophan is therefore important for diagnostic and medicinal applications. Recently, we reported a glucose naphtho crown ether which is a chemoselective receptor for the esters of aromatic amino acids, in particular tryptophan, in water. Herein, we demonstrate that the same compound also binds free tryptophan selectively in aqueous media. Furthermore, it is capable of binding to tryptophan within model tripeptides. The naphthalene functionality in the glucose-derived receptor enables the study of guest binding using fluorescence spectroscopy.
  • Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters
    Item type: Journal Article
    Hintermann, Lukas; Perseghini, Mauro; Togni, Antonio (2011)
    Beilstein Journal of Organic Chemistry
    Titanium-based Lewis acids catalyze the α-fluorination of β-ketoesters by electrophilic N–F-fluorinating reagents. Asymmetric catalysis with TADDOLato–titanium(IV) dichloride (TADDOL = α,α,α',α'-tetraaryl-(1,3-dioxolane-4,5-diyl)-dimethanol) Lewis acids produces enantiomerically enriched α-fluorinated β-ketoesters in up to 91% enantiomeric excess, with either F–TEDA (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)) in acetonitrile solution or NFSI (N-fluorobenzenesulfonimide) in dichloromethane solution as fluorinating reagents. The effects of various reaction parameters and of the TADDOL ligand structure on the catalytic activity and enantioselectivity were investigated. The absolute configuration of several fluorination products was assigned through correlation. Evidence for ionization of the catalyst complex by chloride dissociation, followed by generation of titanium β-ketoenolates as key reaction intermediates, was obtained. Based on the experimental findings, a general mechanistic sketch and a steric model of induction are proposed.
  • Synthesis and characterization of water-soluble C60–peptide conjugates
    Item type: Journal Article
    Ma, Yue; Persi, Lorenzo; Yamakoshi, Yoko (2024)
    Beilstein Journal of Organic Chemistry
    With the aim of developing biocompatible and water-soluble C60 derivatives, three types of C60-peptide conjugates consisting of hydrophilic oligopeptide anchors (oligo-Lys, oligo-Glu, and oligo-Arg) were synthesized. A previously reported Prato reaction adduct of a biscarboxylic acid-substituted C60 derivative was subjected to a solid phase synthesis for amide formation with N-terminal amines of peptides on resin to successfully provide C60-peptide conjugates with one C60 and two peptide anchors as watersoluble moieties. Among three C60-peptide conjugates prepared, C60-oligo-Lys was soluble in water at neutral pH, and C60-oligoGlu was soluble in buffer with a higher pH value, but C60-oligo-Arg was insoluble in water and most other solvents. C60-oligo-Lys and C60-oligo-Glu were characterized by 1H and 13C NMR. Photoinduced 1O2 generation was observed in the most soluble C60-oligo-Lys conjugate under visible light irradiation (527 nm) to show the potential of this highly water-soluble molecule in biological systems, for example, as a photosensitizer in photodynamic therapy.
  • Stereoselectivity of supported alkene metathesis catalysts: a goal and a tool to characterize active sites
    Item type: Review Article
    Copéret, Christophe (2011)
    Beilstein Journal of Organic Chemistry
    Stereoselectivity in alkene metathesis is a challenge and can be used as a tool to study active sites under working conditions. This review describes the stereochemical relevance and problems in alkene metathesis (kinetic vs. thermodynamic issues), the use of (E/Z) ratio at low conversions as a tool to characterize active sites of heterogeneous catalysts and finally to propose strategies to improve catalysts based on the current state of the art.
  • Catalysing (organo-)catalysis: Trends in the application of machine learning to enantioselective organocatalysis
    Item type: Journal Article
    Schmid, Stefan; Schlosser, Leon; Glorius, Frank; et al. (2024)
    Beilstein Journal of Organic Chemistry
    Organocatalysis has established itself as a third pillar of homogeneous catalysis, besides transition metal catalysis and biocatalysis, as its use for enantioselective reactions has gathered significant interest over the last decades. Concurrent to this development, machine learning (ML) has been increasingly applied in the chemical domain to efficiently uncover hidden patterns in data and accelerate scientific discovery. While the uptake of ML in organocatalysis has been comparably slow, the last two decades have showed an increased interest from the community. This review gives an overview of the work in the field of ML in organocatalysis. The review starts by giving a short primer on ML for experimental chemists, before discussing its application for predicting the selectivity of organocatalytic transformations. Subsequently, we review ML employed for privileged catalysts, before focusing on its application for catalyst and reaction design. Concluding, we give our view on current challenges and future directions for this field, drawing inspiration from the application of ML to other scientific domains.
Publications1 - 10 of 12