- Some contribution to W(VI)-peroxo-chemistry: Synthesis, spectroscopic characterization, reactivity and DFT studies
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Synthesis of white microcrystalline oxodiperoxotungstate(VI) complexes, K[WO(O2)2(L)(H2O)]·H2O, (L ?= ?salicylate, 5-chlorosalicylate, 4-hydroxybenzoate) have been achieved from reaction of Na2WO4·2H2O with 30% H2O2 and the respective hetero-ligands at pH Ca. 7–7.5 in aqueous medium. The newly synthesized compounds were comprehensively characterized by elemental analyses, spectral studies, room temperature magnetic moment measurements and mass spectrometric studies. Infrared spectra suggest that, peroxo groups are bonded to the WO+4 center in a triangular bidentate (C2v) fashion and the hetero-ligands benzene-core hydroxycarboxylic acids viz. salicylic acid, 5-chlorosalicylic acid, 4-hydroxybenzoic acid in anoinic form are coordinated in monodentate manner. Compounds are fairly stable in aqueous solution for sufficient period of time. The results of mass spectrometric analysis lend support to the molecular composition of the complexes ascertained on the basis of elemental analyses and spectroscopic studies. Compound potassium(aquo)(5-chlorosalicylato)oxodiperoxotungstate(VI)monohydrate, K[WO(O2)2(5-chlorosalicylate)(H2O)]·H2O, act as an oxidant of bromide ion in aqueous phase bromination of chosen organic substrates to their corresponding bromo organics. Density Functional Theory (TD-DFT) calculations were performed on the synthesized complexes substantiated the experimentally obtained results. The TD-DFT optimized structures are in excellent agreement with the results of elemental analyses, spectral as well as mass spectrometric data.
- Bhattacharjee, M.,Boruah, S. R.,Chowdhury, S.,Das, N.,Dutta Purkayastha, R. N.
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- Synthesis, anti-HIV-1 and antiproliferative evaluation of novel 4-nitroimidazole derivatives combined with 5-hydroxy-4-pyridinone moiety
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In an effort to synthesize more effective non-nucleoside reverse transcriptase inhibitors (NNRTIs) against the HIV-1 infection, a new series of novel 4-nitroimidazole derivatives combined with 5-hydroxy-4-pyridinone moiety were designed by molecular docking studies, prepared and characterized by spectroscopic techniques. All the synthesized compounds were in vitro evaluated for their inhibitory effect against the HIV-1 replication in the MT-4 cells. Results showed that none of these synthesized compounds displayed any specific anti HIV-1 activity. Surprisingly, these compounds showed high cytotoxicity against MT-4 cells with low selectivity index (50 = 1.3 μM and EC50 = 1.8 μM respectively).
- Shirvani, Pouria,Fassihi, Afshin,Saghaie, Lotfollah,Van Belle, Siska,Debyser, Zeger,Christ, Frauke
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- Peroxo–tungstate(VI) complexes: syntheses, characterization, reactivity, and DFT studies
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Abstract: Three new oxodiperoxo–tungsten(VI) complexes containing benzene core carboxylic acids, viz., benzoic acid, 2-chlorobenzoic acid, and 3-aminobenzoic acid as co-ligands have been synthesized from reaction of Na2WO6H4, 30% H2O2 and the corresponding co-ligands in aqueous medium. The compounds have been comprehensively characterized by elemental analyses, FT-IR, 1H NMR, UV–Vis spectral studies as well as by mass spectrometric and TGA analyses. The infrared spectra suggest occurrence of terminally bonded W=O as well as triangular bidentate peroxo groups (C2v) and monodentate carboxylate group bound to the WO4+ center. The mass spectra of the compounds are in good agreement with proposed molecular formulations. Thermogravimetric analyses indicate the existence of both lattice and coordinated water molecules in the complexes. Density functional theory (DFT) calculations were used to compute the frequencies of relevant vibrational modes, electronic properties and also to investigate structure of the compounds. Compound potassium(aquo)(2-chlorobenzoato)oxodiperoxo–tungstate(VI)dihydrate acts as an oxidant for bromide ion in aqueous phase bromination of chosen organic substrates to their corresponding bromo-organics. Graphical abstract: [Figure not available: see fulltext.]
- Das, Nandita,Chowdhury, Shubhamoy,Purkayastha, Ranendra N. Dutta
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p. 1255 - 1266
(2019/07/04)
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- Reductive dehalogenation and dehalogenative sulfonation of phenols and heteroaromatics with sodium sulfite in an aqueous medium
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Prototropic tautomerism was used as a tool for the reductive dehalogenation of (hetero)aryl bromides and iodides, or dehalogenative sulfonation of (hetero)aryl chlorides and fluorides, using sodium sulfite as the sole reagent in an aqueous medium. This protocol does not require a metal or phase transfer catalyst and avoids using organic solvent as the reaction medium. This method is especially suitable for substrates that readily tautomerize (such as 2-or 4-halogenated aminophenols and 4-halogenated resorcinols), for which dehalogenation or sulfonation proceeds under mild reaction conditions (≤60 °C). As sodium sulfite is an inexpensive, safe, and environmentally less hazardous reagent, this method has at least three potential applications: (i) in the deprotection of halogens as protecting groups, using sodium sulfite as a reducing agent; (ii) in the sulfonation of aromatic halides under mild reaction conditions avoiding hazardous and corrosive reagents/solvents; and (iii) in the transformation of toxic halogenated aromatics into less harmful compounds.
- Tomanová, Monika,Jedinák, Luká?,Canka?, Petr
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supporting information
p. 2621 - 2628
(2019/06/03)
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- Preparation method of 4-halogen-1H-imidazole
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The invention discloses a preparation method of 4-halogen-1H-imidazol. The method comprises the following steps: (1), enabling imidazole and halogen elementary substance which are taken as raw materials to be in reaction at a temperature of 60 to 100 DEG C in an alkaline condition, and filtering after the reaction, so as to obtain a filter cake 4-halogen-1H-imidazol crude product; (2), enabling the 4-halogen-1H-imidazol crude product and a reducing agent to be in reaction, filling and filtering after the reaction, and performing extraction and vacuum concentration on the filter cake, so as to obtain a 4-halogen-1H-imidazol pure product. The method is simple in technology, high in reaction yield, low in cost, and free from pollution and waste liquid discharge.
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Paragraph 0037
(2017/08/28)
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- A deuterated of the IDO inhibitor and its preparation and use (by machine translation)
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The invention provides a deuterated of the IDO inhibitor and its preparation and use, as shown in formula I provide compound or its crystalline form, a pharmaceutically acceptable salt, hydrate or solvate. The preparation of the compound or its crystalline form, a pharmaceutically acceptable salt, hydrate or solvate, can be regarded as the IDO inhibitor, can be used for the treatment of IDO related diseases, in particular cancer, viral infection, depression, neurodegenerative disease, trauma, age-related cataract, organ transplant rejection and autoimmune diseases. (by machine translation)
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Paragraph 0044; 0052; 0053; 0054
(2017/04/22)
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- Highly regioselective C-5 alkynylation of imidazoles by one-pot sequential bromination and Sonogashira cross coupling
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A variety of 2-substituted 5-alkynyl-1H-imidazoles were easily prepared by a one-pot sequential procedure involving a highly regioselective electrophilic C-5 bromination of 1,2-dimethyl-1H-imidazole, 2-chloro-1-methyl-1H-imidazole, and 2-aryl-1-methyl-1H-imidazoles, followed by an efficient palladium/copper co-catalyzed Sonogashira-type alkynylation.
- Bellina, Fabio,Lessi, Marco,Marianetti, Giulia,Panattoni, Alessandro
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supporting information
p. 3855 - 3857
(2015/06/08)
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- Rapid kinetics and relative reactivity of some five membered aromatic heterocycles using hydrodynamic voltammetry
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Kinetics of the bromination of imidazole, pyrazole and thiazole by molecular bromine and N-bromosuccinimide has been studied in aqueous medium. Since the reactions are rapid special technique namely, hydrodyanamic voltammetry has been employed to follow the course of the reactions. These reactions follow second order kinetics. The comparative kinetic data determines the reactivity order for these heterocycles towards the bromination using two different brominating reagents. The study justifies the stereochemical principles ascertaining the relative reactivity of these heterocycles quantitatively using kinetics as an investigational tool.
- Walke,Bonde,Bhadane,Dangat,Jadhav
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p. 2239 - 2245
(2016/02/27)
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- Fast halogenation of some N-heterocycles by means of N,N'-dihalo-5,5- dimethylhydantoin
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An instantaneous, selective and high-yielding halogenation process is reported. The method operates with imidazoles, pyrazoles, and indoles under benign reaction conditions. The developed process involves the use of N,N'-dihalo-5,5-dimethylhydantoins (halo=chlorine, bromine, iodine) as halogenation reagents that are activated by catalytic quantities of a strong Bronsted acid. Moreover, the halogenation process is switchable to produce either the mono- or di-halogenated products. Issues related to the reaction mechanism are investigated and a proposal for a reaction mechanism is disclosed.
- Sandtorv, Alexander H.,Bjorsvik, Hans-Rene
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p. 499 - 507
(2013/05/08)
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- Regioselective, photochemical bromination of aromatic compounds using N-bromosuccinimide
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Regioselective nuclear bromination of aromatic compounds is investigated with N-bromosuccinimide as the brominating agent under UV irradiation to afford the corresponding brominated compounds. The reaction proceeds at ambient temperature (30 ± 2 °C) without any catalyst. In most of the reactions, regioselectively mono-brominated products are obtained in good to high yields. The conversion and selectivity for bromination depend on the nature of the substituent on the aromatic ring.
- Chhattise, Prakash K.,Ramaswamy,Waghmode, Suresh B.
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p. 189 - 194
(2008/03/30)
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- A novel nitroimidazole compound formed during the reaction of peroxynitrite with 2′,3′,5′-tri-O-acetyl-guanosine
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Peroxynitrite reacts with 2′,3′,5′-tri-O-acetyl-guanosine to yield a novel compound identified as 1-(2,3,5-tri-O-acetyl-β-D-erythro-pentofuranosyl) -5-guanidino-4-nitroimidazole (6). This characterization was achieved using a combination of UV/vis spectroscopy and ESI-MS. Additionally, 1 -(β-D-erythro-pentofuranosyl) 5-guanidino-4-nitroimidazole (6a) was synthesized by an independent route, characterized by UV/vis spectroscopy, ESI-MS, and 1H- and 13C NMR, and shown to be identical to deacetylated 6. This product is extremely stable in aqueous solution at both pH extremes and is formed in significant yields. These characteristics suggest that this lesion may be useful as a specific biomarker of peroxynitrite-induced DNA damage. We also observed formation of 2′,3′,5′-tri-O-acetyl-8-nitroguanosine (2′,3′,5′-tri-O-acetyl-8-NO2Guo), 2-amino-5-[(2,3,5 tri-O-acetyl-β-D-erythro-pentofuranosyl)amino]-4H-imidazol-4-one (2′,3′,5′-tri-O-acetyl-Iz), and the peroxy-nitrite-induced oxidation products of 2′,3′,5′-tri-O-acetyl-8-oxoGuo. The formation of 6 and 2′,3′,5′-tri-O-acetyl-8-NO2Guo was rationalized by a mechanism invoking formation of the guanine radical.
- Niles,Wishnok,Tannenbaum
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p. 12147 - 12151
(2007/10/03)
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- Synthesis and Reactions of Brominated 2-Nitroimidazoles
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Various approaches to the synthesis of the hitherto-unknown 4(5)-bromo-2-nitroimidazole (5) are reported.Direct bromination of 2-nitroimidazole with N-bromosuccinimide gave the unreported 4,5-dibromo-2-nitroimidazole (10) in quantitative yield, but this could be selectively debrominated to give compound (5).While 1-methyl-2-nitroimidazole readily gave 4-bromo-1-methyl-2-nitroimidazole (15) on bromination, this could not be demethylated to give (5), and bromination of various other N-protected 2-nitroimidazoles was also unsuccessful.Lithiation of 4-bromo-1-tritylimidazole (21) followed by quenching with propyl nitrate gave (after detritylation and methylation) a mixture of a dimer (28) and compound (15), indicating that the desired product (5) is produced in this reaction although it can only be isolated in derivatized form.The proposed route for formation of the dimer suggests a general reaction between 1-alkyl-4-bromo-2-nitroimidazoles and strong C- and N-nucleophiles, resulting in substitution at the 5-position.
- Palmer, Brian D.,Denny, William A.
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- ACIDIFYING EFFECTS OF AZA GROUPS IN THE NH ACIDITY OF AMINOAZINES AND THE CH ACIDITY OF ACETYLAZINES
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The pK values for a series of aminoazines and acetylazines containing one, two, or three aza groups in the ring were determined in dimethyl sulfoxide.There is a good linear correlation between pK values of the investigated NH and CH acids.The acidifying effects (ΔpK) of the aza groups at positions 2, 3, or 4 in relation to the side chain were determined and had values of 3.1, 2.4, and 4.5 logarithmic units in the aminoazines and 3.5, 2.9 and 4.8 logarithmic units respectively in the acetylazines.Except in the case of two ortho-located aza groups the effects are additive.Compared with dimethyl sulfoxide water has a differentiating effect on the acidity of the aminoazines, and this is explained by the formation of hydrogen bonds between the molecules of the proton-donating solvent and the aza groups of the anions of the aminoazines.
- Terekhova, M. I.,Petrov, E. S.,Mikhaleva, M. A.,Shkurko, O. P.,Mamaev, V. P.,Shatenshtein, A. I.
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