- S-methylation of N-containing heterocyclic thiols with conjugated acids of methoxy groups
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2-Mercaptopyridine-3-carboxylic acid reacts with methanol under acidic conditions to afford the corresponding S-methylated methyl ester, methyl 2-methylthiopyridine-2-carboxylate. Such S-methylation occurred for various N-containing heterocyclic thiols wi
- Shimizu, Masao,Shimazaki, Teruaki,Kon, Yoshihiro,Konakahara, Takeo
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- Anti-thyroid drugs and thyroid hormone synthesis: Effect of methimazole derivatives on peroxidase-catalyzed reactions
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Syntheses and characterization of the selenium analogue (MSeI) of anti-thyroid drug methimazole and a series of organoselenium compounds bearing N-methylimidazole pharmacophore are described. In contrast to the sulfur compound that exists predominantly in its thione form, the selenium analogue exists in a selenol form, which spontaneously oxidizes in air to produce the corresponding diselenide. The reduction of the diselenide by GSH or NaBH 4 affords the biologically active selenol, which effectively inhibits the lactoperoxidase (LPO) activity in vitro. The monoselenides having N-methylimidazole moiety are found to be much less active than the selenol, suggesting that the presence of a selenol moiety is important for the LPO inhibition. The kinetic and mechanistic studies reveal that MSeI inhibits the LPO activity by reducing the H2O2, providing a novel method to reversibly inhibit the enzyme. Although MSeI strongly inhibits LPO, the enzyme's activity can be completely recovered by increasing the H 2O2 concentration. On the other hand, the inhibition by methimazole (MMI), the sulfur analogue, cannot be reversed by increasing the H2O2 concentration, leading to a complete inactivation of the enzyme. The reversible inhibition of LPO by some of the selenium derivatives is correlated with their glutathione peroxidase (GPx) activity, and the high GPx activity of the selenium compounds as compared with their sulfur analogues suggests that the selenium derivatives may protect the thyroid gland from oxidative damage.
- Roy, Gouriprasanna,Mugesh
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- Applications of 15N NMR to a Study of Tautomerism in Some Monocyclic Azoles
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15N NMR shielding measurements reveal that thiolo-imidazole and -tetrazole exist almost entirely as the thione form.Quantitative estimates of the position of tautomerism in 1,2,3-triazole and tetrazole are obtained.The reported assignments are supported by means of INDO/S-SOS shielding calculations.
- Bojarska-Olejnik, E.,Stefaniak, L.,Witanowski, M.,Hamdi, B. T.,Webb, G. A.
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- Synthesis and biological activity of nitro heterocycles analogous to megazol, a trypanocidal lead
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As part of our efforts to develop new compounds aimed at the therapy of parasitic infections, we synthesized and assayed analogues of a lead compound megazol, 5-(1-methyl-5-nitro-1H-2-imidazolyl)-1,3,4-thiadiazol-2-amine, CAS no. 19622-55-0), in vitro. We first developed a new route for the synthesis of megazol. Subsequently several structural changes were introduced, including substitutions on the two rings of the basic nucleus, replacement of the thiadiazole by an oxadiazole, replacement of the nitroimidazole part by a nitrofurane or a nitrothiophene, and substitutions on the exocyclic nitrogen atom for evaluation of an improved import by the glucose or the purine transporters. Assays of the series of compounds on the protozoan parasites Trypanosoma brucei, Trypanosoma cruzi, and Leishmania donovani, as either extracellular cells or infected macrophages, indicated that megazol was more active than the derivatives. Megazol was then evaluated on primates infected with Trypanosoma brucei gambiense, including late-stage central nervous system infections in combination with suramin. Full recovery was observed in five monkeys in the study with no relapse of parasitemia within a 2 year follow-up. Because there is a lack of efficacious treatments for sleeping sickness in Africa and Chagas disease in South America, megazol is proposed as a potential alternative. The mutagenicity of this compound is at present being reevaluated, and metabolism is also under investigation prior to possible further developments.
- Chauvière, Gérard,Bouteille, Bernard,Enanga, Bertin,De Albuquerque, Cristina,Croft, Simon L.,Dumas, Michel,Périé, Jacques
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p. 427 - 440
(2007/10/03)
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- 1-dethia-2-thia-cephalosporanic acids
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Novel 1-dethia-2-thia-cephalosporanic acid derivatives of the formula STR1 wherein R is selected from the group consisting of STR2 Ra is an organic radical, Ri and Rj are individually selected from the group consisting of hydrogen, aliphatic, aromatic and heterocycle or taken together with the nitrogen atom to which they are attached form an optionally substituted cycle or Rb NH--, Rb is optionally substituted carbocyclic or heterocyclic aryl, R1 and --COM are as defined in the specification, R4 is hydrogen or methoxy, n2 is 0, 1 or 2 and their non-toxic, pharmaceutically acceptable acid addition salts in racemic or optically active form having antibiotic activity and their preparation and novel intermediates.
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- The methylation, oxidation and crystallographic characterization of imidazole derivatives
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Compounds 2, 3 and 4 were synthesized and the crystal and molecular structures of 1 and 4 were determined. An hptlc technique for studying the methylation rate of 1 and the oxidation rate of 2 was applied.
- Vampa,Benvenuti,Severi,Malmusi,Antolini
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p. 227 - 234
(2007/10/02)
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- Transfer of Alkoxycarbonyl from Alkyl Imidazolium-2-carboxylates to Benzyl Alcohol, a Cyclohexanone Enamine and Diethylamine
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Alkylimidazole-2-carboxylates may be alkylated with methyl triflate to give the corresponding N-methylimidazolium salts.These salts react with benzyl alcohol in the presence of 1,4-diazabicyclooctane, with 1-(pyrrolidin-1-yl)cyclohexene and with diethylamine to give benzyl alkyl carbonates, an enamino ester and a urethane respectively; in one case a tetrahedral intermediate is observed.The corresponding phenyl ester was consumed without attack by benzyl alcohol at the carbonyl group.A 2-cyanoimidazolium salt underwent similar ill-defined consumption whereas a 2-dimethylaminocarbonyl derivative remained unchanged. 2-Methylsulfonylimidazolium salts suffered attack by benzyl alcohol at the ring C-2.
- Bakhtiar, Cuross,Smith, Edward H.
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p. 239 - 244
(2007/10/02)
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- Reaction of Dimethyl N-Aryl- and N-Alkylcarbonimidodithioates with Aminoacetaldehyde Diethyl Acetal: A Direct Synthesis of 1-Aryl- and 1-Alkyl-2-methylthioimidazoles
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The reaction of dimethyl N-aryl- or N-alkylcarbonimidodithioates with aminoacetaldehyde diethyl acetal in refluxing acetic acid affords 1-aryl or 1-alkyl-2-methylthioimidazoles in good yields.Dimethyl N-isopropylcarbonimidodithioate gave 1-isopropylimidazole-2(3H)-thione under similar conditions.
- Pooranchand, Dinah,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
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p. 1136 - 1138
(2007/10/02)
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- STUDIES ON THE DILITHIATION OF 1-METHYLIMIDAZOLE. OPTIMISATION OF REACTION CONDITIONS FOR SYNTHESES OF 2,5-DISUBSTITUTED DERIVATIVES
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Reaction of 1-methylimidazole with an excess of n-butyllithium yields the 2,5-dilithio intermediate.The extent of dilithiation is dependent on the solvent, reaction time, temperature and molar ratio of the lithiating agent to the substrate.Use of a chelating agent for Li(+) decreases the reaction time, temperature and molar excess of the alkyllithium required for high-yielding dilithiation.Syntheses via the dilithio intermediate of 2,5-bis(hydroxydiphenylmethyl)- (3) and 2,5-bis(methylthio)-1-methylimidazole (5), of 1-methyl-5-trimethylsilylimidazole (8), and (in poor yields) of 1-methylimidazole-2,5-dicarboxylic acid (9) and methyl 1-methylimidazole-2,5-dicarboxylate (10) are reported.
- Carpenter, Andrew J.,Chadwick, Derek J.,Ngochindo Raphael I.
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p. 1913 - 1941
(2007/10/02)
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