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Registros recuperados: 16
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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
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High efficient intramolecular cyclisation of ortho-halodiarylamides or amines to tienocarbazoles and indolobenzo[b]thiophenes IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Tipo: ConferenceObject
Ano: 2002 URL: http://hdl.handle.net/10198/3498
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Novel synthetic routes to thienocarbazoles via palladium or copper catalyzed amination or amidation of arylhalides and intramolecular cyclization IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Palladium or copper catalyzed aminations or amidations were performed to obtain diarylamines and diarylacetamides precursors of thienocarbazoles. The fact that an ortho-bromodiarylamine did not cyclize to the corresponding thienocarbazole under conditions known for carbazoles from ortho-halodiphenylamines, conducted us to a highly efficient method of palladium-catalyzed intramolecular cyclization with N-deprotection of ortho-halodiarylacetamides to thienocarbazoles. Other method of intramolecular cyclization of diarylamines based on the reoxidation of the Pd(0) formed by Cu(OAc)2, avoiding the use of stoichiometric amounts of Pd(OAc)2, gave thienocarbazoles in a moderate yield, including a ring A methoxylated compound. An attempt to combine palladium and...
Tipo: Article Palavras-chave: C–N coupling; Copper; Palladium; Cyclization–deprotection.
Ano: 2002 URL: http://hdl.handle.net/10198/815
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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
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Palladium-catalyzed amination and cyclization to heteroannellated indoles and carbazoles IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
New ortho-bromodiarylamines in the benzo[b]thiophene series were prepared by palladium-catalyzed amination, either in the benzene or in the thiophene ring. These were submitted to palladium-catalyzed cyclization, under different required conditions, to give several differently substituted thieno[3,2-c] or [2,3-b]carbazoles and indolo[3,2-b]benzo[b]thiophenes. This constitutes a novel synthetic route to both tetracyclic systems
Tipo: Article Palavras-chave: Palladium; Amination; Ortho-bromodiarylamines; Cyclization.
Ano: 2003 URL: http://hdl.handle.net/10198/817
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Palladium-catalyzed amination of electron-rich or poor benzo[b]thienyl bromides IPB - Escola Superior Agrária
Begouin, Agathe; Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Recently we have applied the palladium-catalyzed amination to the synthesis of ortho-bromodiarylamincs in the benzo[blthiophene series . Here we describe the application of this methodology to the amination of electron-rich or poor 3-bromobenzo[b}thiophcnes, using the same conditions for both cases.
Tipo: ConferenceObject
Ano: 2003 URL: http://hdl.handle.net/10198/3552
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Palladium-catalyzed amination to obtain o-halodiarylamines precursors of thienocarbazoles IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Tipo: ConferenceObject
Ano: 2001 URL: http://hdl.handle.net/10198/3323
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Palladium-catalyzed cyclisation-deprotection of o-halodiarylacetamides, obtained by C-N copper assisted coupling, to the corresponding 6H-Thieno-[2,3-c]carbazole IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Tipo: ConferenceObject
Ano: 2001 URL: http://hdl.handle.net/10198/3325
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Synthesis and antimicrobial activity studies of ortho-chlorodiarylamines and heteroaromatic tetracyclic systems in the benzo[b]thiophene series IPB - Escola Superior Agrária
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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Synthesis of 6-(2’ or 4’- nitrophenyl)benzo[b]thiophenes by Palladium-catalyzed cross-coupling IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Tipo: ConferenceObject
Ano: 2000 URL: http://hdl.handle.net/10198/3328
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Synthesis of diarylamines in the benzo[b]thiophene series bearing electron donating or withdrawing groups IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
The synthesis of diarylamines has attracted a great deal of interest due to their importance in diverse fields as natural biological active products and analogues, photography and materials science. Herein we report the synthesis of diarylamines 1 bearing electron donating or withdrawing groups by palladium catalyzed amination, in good yields (50%-quantitative yield) using two different bases and choosing the right components.
Tipo: ConferenceObject
Ano: 2002 URL: http://hdl.handle.net/10198/3887
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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
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Synthesis of potential anti-tumoral ring a substituted tieno[3,2-c]carbazoles from diarylamines IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Thienocarbazoles bearing electron donating or withdrawing groups in ring a, were prepared by intramolecular oxidative cyclization of diarylamines using stoichiometric or catalytic Pd(OAc)2 amounts, in fair to moderate yields. ln the latter case Cu(OAch was added to reoxidize Pd(O) forrned. The diarylamine precursors were prepared by palladium-catalysed amination.
Tipo: ConferenceObject
Ano: 2002 URL: http://hdl.handle.net/10198/3709
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Synthesis of the first thieno-δ-carboline. Fluorescence studies in solution and in lipid vesicles IPB - Escola Superior Agrária
Queiroz, Maria João R.P.; Castanheira, Elisabete M.S.; Pinto, Ana M.R.; Ferreira, Isabel C.F.R.; Begouin, Agathe; Kirsch, Gilbert.
The first thieno-δ-carboline (6,8,9-trimethyl-5H-pyrido[3,2-b]thieno[3,2-f]indole) was prepared in good yield (70%) by intramolecular palladium-assisted cyclization of an ortho-chlorodiarylamine. The latter was in turn selectively synthesized in high yield (90%) by C–N palladiumcatalyzed cross-coupling of 3-bromo-2-chloropyridine with, the also prepared, 6-amino-2,3,7-trimethylbenzo[b]thiophene. Fluorescence studies in solution show that thieno-δ-carboline has a solvatochromic behaviour. Despite the low fluorescence quantum yields in solution, studies of its incorporation in lipid vesicles of DPPC, DOPE and DODAB indicate that thienocarboline is located mainly inside the lipid bilayer, exhibiting different behaviours in gel or liquid-crystalline phases....
Tipo: Article Palavras-chave: Palladium-assisted reactions; Thieno-δ-carboline; Fluorescence; Solvatochromic probes; Lipid vesicles.
Ano: 2006 URL: http://hdl.handle.net/10198/828
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Synthesis of thienocarbazoles by reductive cyclization of 6-(2’- nitrophenyl)benzo[b]thiophenes IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Tipo: ConferenceObject
Ano: 2000 URL: http://hdl.handle.net/10198/3327
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Tandem palladium-catalyzed borylation and suzuki coupling (BSC) to thienocarbazole precursors IPB - Escola Superior Agrária
Ferreira, Isabel C.F.R.; Queiroz, Maria João R.P.; Kirsch, Gilbert.
Substituted 2-methyl-2'-nitro diaryl compounds in the benzo[b]thiophene series were prepared by palladium-catalyzed, two-step, one-pot borylation/Suzuki coupling (BSC) reaction in good to high yields. The borylation reaction was performed on methylated 6-bromobenzo[b]thiophenes using pinacolborane and was followed by in situ Suzuki coupling with substituted (CF3, OMe) 2-bromonitrobenzenes. The compounds obtained were cyclized to the corresponding ring A substituted thienocarbazoles which can have biological activity or/and be used as biomarkers due to their fluorescence properties and possible DNA intercalation.
Tipo: Article Palavras-chave: Palladium; Borylation; Suzuki coupling; 2-methyl-2'-nitro biaryls; Benzo[b]thiophenes.
Ano: 2003 URL: http://hdl.handle.net/10198/819
Registros recuperados: 16
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