Sabiia Seb
PortuguêsEspañolEnglish
Embrapa
        Busca avançada

Botão Atualizar


Botão Atualizar

Ordenar por: RelevânciaAutorTítuloAnoImprime registros no formato resumido
Registros recuperados: 6
Primeira ... 1 ... Última
Imagem não selecionada

Imprime registro no formato completo
Evaluation of the antioxidant properties of diarylamines in the benzo[b]thiophene series by free radical scavenging activity and reducing power IPB - Escola Superior Agrária
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
Imagem não selecionada

Imprime registro no formato completo
Insights in the antioxidant activity of diarylamines from the 2,3-dimethylbenzo[b]thiophene by the redox profile IPB - Escola Superior Agrária
Abreu, Rui M.V.; Falcão, Soraia; Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Vilas-Boas, Miguel.
Cyclic voltammetry was used to evaluate the antioxidant activity of 7-aryl or 7-heteroarylamino-2,3-dimethylbenzo[b]thiophenes previously synthesized by some of us, comparing their oxidation potentials with those of the well-known synthetic standards (BHA, BHT). Compounds with electron-donating groups on the arylamine moiety have lower Ep/2 than compounds with electron-withdrawing groups or electron-deficient rings (pyridines). The position of the methoxy group on the arylamine moiety also changes the oxidation potential: lower Ep/2 for the diarylamines with methoxy groups in the para position. Comparing the first peak potential with the ones of BHA and BHT, the diarylamine compounds show lower oxidation potential, and therefore higher reducing power. A...
Tipo: Article Palavras-chave: Benzo[b]thiophene; Diarylamines; Antioxidant properties; Electrochemical assays.
Ano: 2009 URL: http://hdl.handle.net/10198/2717
Imagem não selecionada

Imprime registro no formato completo
Palladium-catalysed amination of electron-deficient or relatively electron-rich benzo[b]thienyl bromides: preliminary studies of antimicrobial activity and SARs IPB - Escola Superior Agrária
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
Imagem não selecionada

Imprime registro no formato completo
Screening of antimicrobial activity of diarylamines in the 2,3,5-trimethylbenzo[b]thiophene series: a structure–activity evaluation study IPB - Escola Superior Agrária
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
Imagem não selecionada

Imprime registro no formato completo
Synthesis and antioxidant activity evaluation of new 7-aryl or 7-heteroarylamino-2,3-dimethylbenzo[b]thiophenes obtained by Buchwald–Hartwig C–N cross-coupling IPB - Escola Superior Agrária
Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.; Calhelha, Ricardo C.; Estevinho, Leticia M..
New 7-aryl or 7-heteroarylamino-2,3-dimethylbenzo[b]thiophenes were prepared by palladium-catalyzed Buchwald–Hartwig cross-coupling of 7-bromo or 7-amino-2,3-dimethylbenzo[b]thiophenes, previously prepared by us, with substituted (4-methoxy or 3,4-dimethoxy) anilines and 3-aminopyridine or with substituted (3-methoxy or 4-cyano) bromobenzenes and 2-bromopyridine, respectively, using Pd(OAc)2, rac-BINAP or Xantphos as ligands, and Cs2CO3 as base. Their antioxidant properties were evaluated by several methods: reducing power, scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals, inhibition of erythrocyte hemolysis and inhibition of lipid peroxidation using the b-carotene linoleate system. EC50 values for all the methods were determined and it...
Tipo: Article Palavras-chave: Diarylamines; Benzo[b]thiophenes; Buchwald–Hartwig coupling; Antioxidant activity.
Ano: 2007 URL: http://hdl.handle.net/10198/839
Imagem não selecionada

Imprime registro no formato completo
Synthesis of diarylamines in the benzo[b]thiophene series bearing electron donating or withdrawing groups by Buchwald–Hartwig C–N coupling IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Diarylamines in the benzo[b]thiophene series bearing electron donating or withdrawing groups, were prepared by Buchwald– Hartwig C–N coupling in moderate to high yields. The conditions used were Pd(OAc)2 (3 mol%), BINAP as ligand (4 mol%) and Cs2CO3 as base (1.4 equiv.), in toluene at 1008C, being 6-bromo or amino benzo[b]thiophenes coupled, respectively, with substituted anilines or phenylbromides. The 6-aminobenzo[b]thiophene derivatives were also prepared by palladium catalyzed C–N coupling of the corresponding 6-bromo compounds with benzophenone imine, followed by acidic hydrolysis of the imino derivatives. When 4-nitrobromobenzene and 4-bromobenzonitrile were used as coupling components, triarylamines were also isolated in small amounts. The presence...
Tipo: Article Palavras-chave: Buchwald–Hartwig coupling; Palladium; Amination; Diarylamines; Benzo[b]thiophenes.
Ano: 2003 URL: http://hdl.handle.net/10198/818
Registros recuperados: 6
Primeira ... 1 ... Última
 

Empresa Brasileira de Pesquisa Agropecuária - Embrapa
Todos os direitos reservados, conforme Lei n° 9.610
Política de Privacidade
Área restrita

Embrapa
Parque Estação Biológica - PqEB s/n°
Brasília, DF - Brasil - CEP 70770-901
Fone: (61) 3448-4433 - Fax: (61) 3448-4890 / 3448-4891 SAC: https://www.embrapa.br/fale-conosco

Valid HTML 4.01 Transitional