34 research outputs found

    Efficient C3-alkylsulfenylation of indoles under mild conditions using Lewis acid-activated 8-quinolinethiosulfonates.

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    The importance of sulfur-containing compounds in various fields, ranging from material science1-2 to medicinal chemistry, 3 has called for the development of synthetic strategies to form carbon-sulfur (C-S) bonds. Thus, numerous approaches based on the nucleophilicity of thiols have been designed over the years, which mostly use air-sensitive noble metal catalysts.4- 9 At the opposite, the use of electrophilic sulfur reagents is also a powerful, more eco-friendly approach, in particular for the sulfenylation of C-H bonds into C-S bonds.10-11 In this context, the sulfenylation of indoles (Equation 1) has become a benchmark reaction to develop and test new sulfenyl transfer reagents, because indoles are good nucleophiles and their occurrence in many natural products or biological active compounds makes them attractive synthetic targets.12-14 For instance, metal-catalyzed or metal-free protocols have been proposed, in which disulfides, sulfinic acid and their salts, sulfonyl chlorides, sulfonylhydrazine, or Nthiophtalimides are used as source of electrophilic sulfur.10,15-16 Thiosulfonates (RSO2SR’) are another class of emerging17 reagents, which were also studied for C-S bond formation18-20 and for indole sulfenylation.21 However, despite the large pool of sulfenylation agents listed above, the difficult activation of the chalcogen centre essentially limits these reagents to the formation of C-S(aryl) bonds. On the other hand, the transfer of alkylsulfenyl groups requires harsher activating conditions and is so far still limited<br /

    Reactivity of Persulfides Toward Strained Bicyclo[6.1.0]nonyne Derivatives: Relevance to Chemical Tagging of Proteins

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    Persulfides are an emerging class of cysteine oxidative post-translational modification. They react with the bioconjugation reagents bicyclo[6.1.0]­nonynes (BCNs) to engender thioethers and/or disulfides. This new reactivity of BCNs with a biologically important redox-signaling species efficiently interferes with the recent usage of strained cycloalkynes to specifically trap protein sulfenic acids

    Synthesis, Characterization, and Reactivity of Alkyldisulfanido Zinc Complexes

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    An optical H2S biosensor based on the chemoselective Hb-I protein tethered to a transparent, high surface area nanocolumnar electrode

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    International audienceSensitive and selective detection of analytes in complex biological fluids can be an extremely challenging issue. The constructive association of biomolecules and transparent mesoporous electrodes is of interest in this area, as it can lead to innovative biosensors combining optical and electrochemical detection modes. This concept, however, requires the development of appropriate surface functionalization methodologies that are robust enough for long-term operation in physiological environments. In the present work, the high-surface area of 3D transparent mesoporous indium-tin oxide (ITO) electrodes (prepared by glancing angle deposition or GLAD) has been chemically functionalized with recombinant hemoglobin I from Lucina pectinata according to a versatile 2-step process. First, 4-diazoniumbenzoic acid salt is covalently electrografted onto the ITO surface, followed by amide coupling of the protein. The resulting electrodes were quantitatively characterized by cyclic voltammetry and UV-vis absorption spectroscopy, demonstrating high surface coverages (up to 45% of a closed-packed monolayer for Hemoglobin-I) and homogeneous distribution across the entire thickness of the GLAD mesoporous structure. Good stability is also observed when the modified electrodes are immersed for prolonged times in a high ionic strength saline buffer. We also show that the hemoglobin I-modified electrode can be used as an optical biosensor for the selective, reversible, and fast detection of H 2 S in aqueous solutions over a ∼two-decade concentration range (i.e. up to 10 μM) and with a limit of detection of 0.35 μM. Good analytical performance was also achieved in human plasma without significant interference from the biological matrix
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