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Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Vilas-Boas, Miguel; Estevinho, Leticia M.; Begouin, Agathe; Kirsch, Gilbert. |
The antioxidant properties of substituted diarylamines in the benzo[b]thiophene series were evaluated by their reducing power and free radical scavenging activity. The results were compared with those of standards: acid ascorbic for the first method and BHA and BHT for the second. For both methods it was possible to establish some structure–activity relationships (SARs) based on the position of the arylamination on the benzo[b]thiophene moiety, the presence of different substituents on the phenyl ring (F, 1 or 2 OMe) and on the thiophene ring (H, CO2Et, CO2H). |
Tipo: Article |
Palavras-chave: Diarylamines; Benzothiophenes; Antioxidant activity; Structure–activity relationships. |
Ano: 2006 |
URL: http://hdl.handle.net/10198/825 |
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Queiroz, Maria João R.P.; Begouin, Agathe; Ferreira, Isabel C.F.R.; Kirsch, Gilbert; Calhelha, Ricardo C.; Barbosa, Sandra; Estevinho, Leticia M.. |
Several diarylamines in the benzo[b]thiophene series were prepared in good to high yields by palladium-catalysed amination of ethyl 3-bromobenzo[b]thiophene-2-carboxylate with anilines and 5-aminoindole in the presence of Pd(OAc)2, BINAP and Cs2CO3 in toluene. The presence of the ester group at the 2-position of the benzo[b]thiophene moiety increases the yields and lowers the heating times relative to the reactions performed with 3-bromobenzo[b]thiophene. When aminopyridines were used instead of anilines, the ligand and the solvent need to be changed to XANTHPHOS and dioxane in the amination reaction. With 2-aminopyridine a onepot C−N coupling and intramolecular cyclization involving the nitrogen atom of the pyridine ring occurred, with loss of ethanol,... |
Tipo: Article |
Palavras-chave: Amination; Antimicrobial activity; Benzothiophenes; Diarylamines; Fluorescence; Palladium. |
Ano: 2004 |
URL: http://hdl.handle.net/10198/820 |
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Abreu, Ana S.; Ferreira, Paula M.T.; Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.; Calhelha, Ricardo C.; Estevinho, Leticia M.. |
Palladium-catalyzed borylation and Suzuki coupling (BSC) in a one-pot procedure was successfully applied to the synthesis of several β-substituted dehydrophenylalanines in the benzo[b]thiophene series, with the stereochemistry of the starting materials being maintained. Bromobenzo[b]thiophenes bearing an ortho EDG (OMe or Me) were used as the components to be borylated with pinacolborane, whilst pure stereoisomers of β-bromodehydrophenylalanines were used as the other Suzuki coupling components. Treatment of the obtained methyl ester of (Z)-N-(tert-butoxycarbonyl)-β- (2,3,5-trimethylbenzo[b]thien-6-yl)dehydrophenylalanine with Pd(OAc)2 and Cu(OAc)2 in DMF at 160 °C gave two in dole derivatives (1:3), the major product resulting from isomerization and... |
Tipo: Article |
Palavras-chave: Dehydrophenylalanines; Benzothiophenes; Borylation; Suzuki coupling; Cyclization; Indoles; Fluorescence; Antimicrobial activity. |
Ano: 2005 |
URL: http://hdl.handle.net/10198/823 |
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Ferreira, Isabel C.F.R.; Calhelha, Ricardo C.; Estevinho, Leticia M.; Queiroz, Maria João R.P.. |
Gram positive (Bacillus cereus, B. subtilis), Gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria, and Candida albicans as a representative of fungi were used for screening the in vitro antimicrobial activity of diarylamines in the 2,3,5-trimethylbenzo[ b]thiophene series bearing different substituents, synthesized by us using the palladium-catalyzed C–N coupling methodology. The minimal inhibitory concentration (MIC) and structure–activity relationships (SARs) were evaluated. |
Tipo: Article |
Palavras-chave: Diarylamines; Antimicrobial activity; SAR; Benzothiophenes. |
Ano: 2004 |
URL: http://hdl.handle.net/10198/821 |
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Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.; Gaetanoa, Yannick de; Kirsch, Gilbert; Calhelha, Ricardo C.; Estevinho, Leticia M.. |
ortho-Chlorodiarylamines in the 2,3,7-trimethylbenzo[b]thiophene series were prepared in high yields (70–85%) by C–N palladium-catalyzed cross-coupling using P(t-Bu)3 as ligand and NaOt-Bu as base. A palladium-assisted C–C intramolecular cyclization of the coupling products gave thienocarbazoles and the dechlorinated diarylamines. Studies of antimicrobial activity of the compounds obtained, against representative species of bacteria (Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus and Bacillus subtilis) and fungi (Candida albicans), were performed. We have also included in the biological assays some pyridine derivatives previously prepared by us, and it was possible to establish some structure–activity relationships (SARs). |
Tipo: Article |
Palavras-chave: Benzothiophenes; Ortho-chlorodiarylamines; Palladium; Thienocarbazoles; Thienocarboline; Antimicrobial activity. |
Ano: 2006 |
URL: http://hdl.handle.net/10198/826 |
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