- Unexpected reactivity of annulated 3H-benzothiazol-2-ylideneamines as an acyl transfer catalyst
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Catalytic ability of annulated 3H-benzothiazol-2-ylideneamines and 1H-pyridin-2-ylideneamines for acylation of alcohols was investigated and 3,4-dihydro-2H-9-thia-1,4a-diazafluorene (2b) was found to be an extremely effective catalyst, the reaction with which was faster than that with DMAP.
- Kobayashi, Megumi,Okamoto, Sentaro
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- Structure-activity relationships of rosiglitazone for peroxisome proliferator-activated receptor gamma transrepression
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Anti-inflammatory effects of peroxisome proliferator-activated receptor gamma (PPRAγ) ligands are thought to be largely due to PPARγ-mediated transrepression. Thus, transrepression-selective PPARγ ligands without agonistic activity or with only partial agonistic activity should exhibit anti-inflammatory properties with reduced side effects. Here, we investigated the structure-activity relationships (SARs) of PPARγ agonist rosiglitazone, focusing on transrepression activity. Alkenic analogs showed slightly more potent transrepression with reduced efficacy of transactivating agonistic activity. Removal of the alkyl group on the nitrogen atom improved selectivity for transrepression over transactivation. Among the synthesized compounds, 3l exhibited stronger transrepressional activity (IC50: 14?μM) and weaker agonistic efficacy (11%) than rosiglitazone or pioglitazone.
- Toyota, Yosuke,Nomura, Sayaka,Makishima, Makoto,Hashimoto, Yuichi,Ishikawa, Minoru
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p. 2776 - 2780
(2017/05/29)
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- Convenient and reliable routes towards 2-aminothiazoles: Palladium-catalyzed versus copper-catalyzed aminations of halothiazoles
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Two efficient methods for the amination of 2-halothiazoles are presented here. A first protocol requires a Pd/L system. Several 2-aminothiazoles were synthesized under optimized conditions and isolated in good yields. The first palladium-catalyzed C-N coupling reactions between 2-halothiazoles and primary alkylamines are presented. In a second part, ligand-free copper-catalyzed aminations of 2-halothiazoles by alkylamines and aniline in a green solvent have been developed. The protocol is very effective for primary and secondary amines and perfectly tolerates the presence of another halide moiety on the 2-halothiazole. The reaction occurs under the assistance of microwave irradiation, which drastically decreases the reaction time. The reaction leads to the formation of 2-aminothiazoles, key molecules in pharmaceutical research. Copyright
- Toulot, Stephanie,Heinrich, Timo,Leroux, Frederic R.
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supporting information
p. 3263 - 3272
(2013/12/04)
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- Laccase-catalysed homocoupling of primary aromatic amines towards the biosynthesis of dyes
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Coloured disubstituted benzoquinonimine trimeric structures are obtained as main reaction products of the oxidation of p-electron donor pri-mary aromatic amines using two different laccases, CotA-laccase from Baccilus subtilus and TvL from Trametes versicolor. These orange-red to purple products, presenting high molar extinction coeffi-cients, presumably result from oxidative homocou-pling reactions, through the formation of N-C bonds at positions 2 and 5, of the laccase oxidised inter-mediate as showed in the proposed oxidative path-way. The product of 1,4-phenylenediamine is shown to be the trimer known as Bandrowski's base which has an established role in hair and fur dyeing. Our results also show that the occurrence and/or rates of oxidation of aromatic amines are strongly dependent on the presence of p-electron releasing substituents in the aromatic ring and are independent on the properties of the enzyme used. Overall our data con-tribute for (i) understanding key features of laccase reactivity with p-substituted aromatic amines and (ii) establishing enzymatic processes that lead to the syn-thesis of coloured bio-products under mild condi-tions with potential impact in the cosmetic and dye industries.
- Sousa, Ana Catarina,Martins, Lígia O.,Robalo, M. Paula
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supporting information
p. 2908 - 2917
(2014/03/21)
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- One-pot synthesis of 2-aminobenzothiazoles using a new reagent of [Bmim]Br3 in [Bmim]BF4
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The one-pot direct synthesis of 2-aminobenzothiazoles from phenyl isothiocyanate and amines using a new reagent of 1-butyl-3-methylimidazolium tribromide ([Bmim]Br3) in ionic liquid 1-butyl-3-methyl-imidazolium tetraflouoroborate ([Bmim]BF4) is described.
- Le, Zhang-Gao,Xu, Jian-Ping,Rao, Huo-Yu,Ying, Min
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p. 1123 - 1124
(2007/10/03)
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- Efficient Conversion of Substituted Aryl Thioureas to 2-Aminobenzothiazoles Using Benzyltrimethylammonium Tribromide
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The reaction of molecular bromine (Br2) with arylthioureas is known to produce 2-aminobenzothiazoles (Hugerschoff reaction). We show here that benzyltrimethylammonium tribromide (1, PhCH2NMe 3Br3), a stable, crystalline organic ammonium tribromide (OATB), can be readily utilized as an alternative electrophilic bromine source. It is easier to control the stoichiometry of addition with an OATB, which minimizes aromatic bromination caused by excess reagent. We have developed a direct procedure from isothiocyanates and amines using tetrabutylammonium thiocyanate (Bu4NSCN) and PhCH2NMe3Br 3 to afford functionalized 2-aminobenzothiazoles.
- Jordan, Alfonzo D.,Luo, Chi,Reitz, Allen B.
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p. 8693 - 8696
(2007/10/03)
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