- Reactions of Electron-Rich Heterocycles with Derivatives of Carboxylic Ortho Acids, II: Acid Catalysed Reactions of 3-Substituted Indoles with Ethyl Orthoformate
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The indoles 1a and 1b react with the diethoxycarbenium ion 2b, generated in an acidic medium, to yield the di- and triindolylmethanes 3, 4, 5 and 7.Compound 5a is oxidized to the cyanine 6a.Tryptamine (8a) undergoes formylation with 2b.When the nucleophilicity of the amino group in 8a is reduced, formation of triindolylmethane is favored, as shown in the reaction of 8b with 2b.
- Mueller, Johann,Pindur, Ulf
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- Triple-Pnictogen Bonding as a Tool for Supramolecular Assembly
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Supramolecular assembly utilizing simultaneous formation of three pnictogen bonds around a single antimony vertex was explored via X-ray crystallography, solution NMR, and computational chemistry. An arylethynyl (AE) ligand was designed to complement the three electrophilic regions around the Sb compound. Though solution studies reveal large binding constants for individual pyridyl units with the Sb donor, the rigidity and prearrangement of the AE acceptor proved necessary to achieve simultaneous binding of three acceptors to the Sb-centered pnictogen-bond donor. Calculations and X-ray structures suggest that negative cooperativity upon sequential binding of three acceptors to a Sb center limits the utility of triple-pnictogen bonding pyridyl acceptors. These limitations can be negated, however, when positive cooperativity is designed into a complementary acceptor ligand.
- Moaven, Shiva,Andrews, Miranda C.,Polaske, Thomas J.,Karl, Brian M.,Unruh, Daniel K.,Bosch, Eric,Bowling, Nathan P.,Cozzolino, Anthony F.
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- A highly selective colorimetric probe based on 2,2′,2″- trisindolylmethene for cysteine/homocysteine
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The interaction and colorimetric sensing properties of receptor 1, tris(3-methylindole-2-yl)methene as the perchlorate salt, with amino acids in aqueous MeCN at neutral pH were investigated using UV-vis spectroscopic techniques. Specifically, receptor 1 behaves as a colorimetric probe for selective and sensitive detection of cysteine (Cys)/homocysteine (Hcy) based on the nucleophilic addition reaction between the sulphydryl group of Cys/Hcy and the meso carbon-carbon double bond of receptor 1, leading to clear color change from violet to colorless. A more quantitative determination for Cys/Hcy was preliminary performed by flow injection analysis (FIA) coupled with spectrophotometry. The selective binding ability of receptor 1 toward Cys/Hcy has also been evaluated by electrochemical techniques.
- Wei, Wei,Liang, Xiaojing,Hu, Guangzhi,Guo, Yong,Shao, Shijun
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- Spectroscopic properties of the receptors based on 2- And 3-linked tri(indolyl)methanes for anion binding
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The anion binding properties of two title tri(indolyl)methane compounds have been evaluated by using UV-vis absorption and fluorescence spectroscopy. Different from 3-linked receptor which exhibited faint even no obvious spectral response to anions, 2-linked receptor can bind F-, AcO- and H2PO4-, with the bathochromic shifts of the UV absorption and fluorescence quenching. This selectivity will be attributed to suitable steric array of NH binding sites of 2-linked receptor, which helps to form multiple hydrogen bonding interactions with anions.
- Wei, Wei,Guo, Yong,Xu, Jian,Shao, Shijun
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- A positive charge-containing unsaturated group imine of the receptor preparation method of the compound
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The invention discloses a preparation method for a receptor compound containing unsaturated group imine with positive charges. The preparation method comprises the following steps: dissolving 3-methylindole through absolute methanol, adding triethyl orthoformate and concentrated sulphuric acid for reacting to synthesize 2,2',2''-triindolylmethane, dissolving, after reaction by using sodium nitrite, adding a perchloric acid aqueous solution, removing a solvent, generating black and blue precipitates and washing, so as to obtain the receptor compound containing unsaturated group imine with positive charges. The invention further provides application of the perchlorate receptor molecules of 2,2',2''-triindolylmethane to copper ion recognition through a colorimetric method, and an experiment result shows that the perchlorate receptor molecules of 2,2',2''-triindolylmethane have a high-selectivity colorimetric recognition effect on Cu(II) and can quickly responds to Cu(II).
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Paragraph 0015; 0042; 0044; 0046
(2018/11/03)
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- Anion recognition properties of receptor based on 2-linked trisindolymethene
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A compound based on 2-linked trisindolymethene is studied as a new anion receptor. This receptor selectively F?, AcO? and H2PO4 ? recognizes by visible color changes. It binds with F?, AcO? and H2PO4 ? by double hydrogen bonding interactions, and favorable color changes of violet-to-colorless are observed clearly. The addition of excessive F? induces further deprotonation of the receptor, exhibiting the color change from violet to yellow. Due to the positive charge in the molecular structure of the receptor, it can even binding with F? and AcO? in watercontaining solution by color change.
- Wei, Wei,Shao, Shi Jun,Guo, Yong
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p. 1039 - 1043
(2015/09/28)
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- Synthesis of pharmacologically active bis(indolyl) and tris(indolyl) derivatives using chlorotrimethylsilane
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Chlorotrimethylsilane is found to be a comparatively fast and efficient catalyst for carrying out electrophilic substitution reactions of indoles with various aldehydes/ketones/triethylorthoformate, yielding excellent amount of bis(indolyl)methanes/tris(indolyl)methanes. The merits of this protocol are avoidance of any external energy source, minimal reaction time, simple and easy procedure and high yield under solvent free room temperature condition. The versatility of this method has been tested with various aldehydes/ketones and received satisfactory results. A simple, fast, efficient, cheap and versatile method for the synthesis of bis(indolyl)methanes and tris(indolyl)methanes under solvent free room temperature condition using chlorotrimethylsilane as a catalyst has been developed. Thus, we have demonstrated the utility of TMSCl not only as a protecting group but also as catalyst in electrophilic substitution reactions. Copyright
- Singh, Nongthombam G.,Kathing, Chingrishon,Rani, Jims W. S.,Nongkhlaw, Rishan L.
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p. 442 - 446
(2014/05/06)
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- Eco-friendly synthesis of condensed nitrogen heterocycles: A brief experience from our group
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In order to develop eco-friendly syntheses of condensed nitrogen heterocycles, solvent-free syntheses on solid acidic catalysts and aqueous reactions using a phase transfer catalyst (PTC) were successfully carried out. The catalysts used were (i) TLC-grade silica gel G (SiO2), (ii) SiO2 doped with 10 mol% phosphoric acid (H3PO 4-SiO2), (iii) Montmorillonite K10 clay (K10), (iv) acid-washed K10 clay (acid-clay), (v) K10 doped with one equivalent (with respect to substrate) of tosic acid (TsOH-K10) and (vi) cetylpyridinium bromide (CPB) (5 mol%) as the PTC. The reactions were carried out at room temperature (rt), at 60-70°C (oven) or under microwave irradiation (MWI).
- Chakrabarty, Manas,Mukherji, Ajanta
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p. 1681 - 1694
(2014/01/17)
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- NH4Cl-promoted synthesis of symmetrical and unsymmetrical triindolylmethanes under solvent-free conditions
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The synthesis of various triindolylmethanes from indole-3-carboxaldehyde, using indole derivatives as reactants and NH4Cl as catalyst under solvent-free conditions, is described. This methodology provides access to both symmetrical and unsymmetrical triindolylmethanes in excellent yields. With N-methylindole particularly, indole-3-carboxaldehyde appears to act as a formyl donor, leading to the exclusive formation of a symmetrically trisubstituted product. The novelty of the methodology lies in its operational simplicity, environment friendly reaction conditions, and inexpensive and easy availability of the catalyst. A plausible mechanism of formation of the products is suggested.
- Naskar, Subhendu,Hazra, Abhijit,Priyankar Paira,Sahu, Rishnendu B.,Banerjee, Sukdeb,Mondal, Nirup B.
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experimental part
p. 568 - 571
(2009/09/25)
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- First general solvent-free synthesis of symmetrical triindolylmethanes using acid-washed montmorillonite clay
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Dry reaction of indoles and alkylindoles (1a-h) with triethyl orthoformate (2.5 equiv.) on acid-washed montmorillonite K10 clay at room temperature afforded in 5 min-4 hr the respective symmetrical TIMs (2a-h) in good to high yields along with the formylindole 3 and the formyl-TIM 4 from 1g and 1h, respectively.
- Chakrabarty, Manas,Sarkar, Sandipan,Linden, Anthony,Stein, Bridget K.
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p. 1801 - 1810
(2007/10/03)
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- Novel clay-mediated, tandem addition-elimination-(Michael) addition reactions of indoles with 3-formylindole: An eco-friendly route to symmetrical and unsymmetrical triindolylmethanes
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Dry reaction of 3-formylindole (1) with indole (2a) on Montmorillonite K10 clay at room temperature furnished within minutes tris(indol-3-yl)methane (3a) in high yield. The reaction of 1 with other mono- and dialkylindoles (2b-c, skatole, 8a-c) under simi
- Chakrabarty, Manas,Sarkar, Sandipan
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p. 1351 - 1353
(2007/10/03)
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