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Registros recuperados: 10
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03SRC643 eCrystals
Butler, Ian R.; Horton, Peter N.; Hursthouse, Michael B..
Tipo: Crystal Structure Data Holding Palavras-chave: C~22~H~36~Cl~2~FeP~2~Pd; Organometallic; Iron; Palladium; Catalysis.
Ano: 2003 URL: http://ecrystals.chem.soton.ac.uk/915/
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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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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 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 pure stereoisomers of benzo[b]thienyl dehydrophenylalanines by Suzuki cross-coupling. Preliminary studies of antimicrobial activity IPB - Escola Superior Agrária
Abreu, Ana S.; Ferreira, Paula M.T.; Monteiro, Luís S.; Ferreira, Isabel C.F.R.; Calhelha, Ricardo C.; Estevinho, Leticia M..
Several benzo[b]thienyldehydrophenylalanines were synthesized from pure stereoisomers of the methyl ester of N-(tertbutoxycarbonyl)- b-bromodehydrophenylalanine as an extension of our previously reported method for the synthesis of dehydrotryptophan analogues to dehydrophenylalanine derivatives. The latter were obtained in high yields by N-deprotection and bromination of N,N-bis-(tertbutoxycarbonyl)-( Z)-dehydrophenylalanine using TFA and NBS. This was carried out in two steps or in a one pot procedure resulting in different E/Z ratios. These compounds were coupled under Suzuki cross-coupling conditions [Pd(PPh3)4, Na2CO3, DME/H2O] with several boronic benzo[b]thienyl acids in good to high yields maintaining the stereochemistry of the starting materials....
Tipo: Article Palavras-chave: Amino acids; Dehydrophenylalanines; Benzo[b]thiophenes; Suzuki coupling; Palladium; Antimicrobial.
Ano: 2004 URL: http://hdl.handle.net/10198/822
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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
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The effect of precursors salts on surface state of Pd/Al2O3 and Pd/CeO2/Al2O3 catalysts Anais da ABC (AABC)
Guimarães,André L.; Dieguez,Lídia C.; Schmal,Martin.
The influence of the precursors on the promoting effect of ceria on Pd/Al2O3 catalyst, when ceria is coated over alumina was studied. The reaction of propane oxidation proceeded under different feed conditions and the surface active sites were characterized by X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance spectroscopy (DRS). XPS and DRS results show that PdO/Pd0 interface are the active sites independent of the precursor, while the catalysts containing CeO2 showed formation of palladium species in the highest oxidation state, probably PdO2 (338 eV) after the oxidation of propane. Besides, the O/Al and O/Ce ratios evidenced the increase of oxygen storage in the presence of CeO2. In addition, the precursor acetylacetonate favors the...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Palladium; Cerium oxide; Precursors; Characterization.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652004000400014
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Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science Anais da ABC (AABC)
Schmal,Martin; Freund,Hans-Joachim.
The science of catalysis and surface science have developed, independently, key information for understanding catalytic processes. One might argue: is there anything fundamental to be discovered through the interplay between catalysis and surface science? Real catalysts of monometallic and bimetallic Co/Nb2O5 and Pd-Co/Nb2O5 catalysts showed interesting selectivity results on the Fischer-Tropsch synthesis (Noronha et al. 1996, Rosenir et al. 1993). The presence of a noble metal increased the C+5 selectivity and decreased the methane formation depending of the reduction temperature. Model catalyst of Co-Pd supported on niobia and alumina were prepared and characterized at the atomic level, thus forming the basis for a comparison with "real" support...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Catalysis; Model catalysts; Cobalt; Palladium; Characterization; Niobia.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652009000200016
Registros recuperados: 10
Primeira ... 1 ... Última
 

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