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| Barbosa, Sandra; Silvestre, Armando; Simões, Mário; Estevinho, Leticia M.. |
| The lipophilic composition of honeybee pollen from Cistus ladanifer, Castanea sativa and Rubus sp. was analysed by GC-MS. The extracts are mainly composed by saturated and unsaturated fatty acids, sterols, long chain aliphatic alcohols, alkanes and alkenes. The profiles of chemical composition allow the chemical differentiation of pollen species. The biological activity of the lipophilic fractions against several Gram positive bacteria was demonstrated and related to the resistance of beehives to certain diseases when feed with such pollens. |
| Tipo: Article |
Palavras-chave: Honeybee pollen; Lipophilic composition. |
| Ano: 2006 |
URL: http://hdl.handle.net/10198/4402 |
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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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| Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.; Barbosa, Sandra; Calhelha, Ricardo C.; Estevinho, Leticia M.. |
| The palladium-catalyzed amination of arylhalides has become an important method for the synthesis of arylamines found in pharmaceuticals. Using this methodology we were able to synthesize several diarylamines in the benzo[b]thiophene series.Here we report the synthesis 01 differently substituted diarylamines derivatives 01 6-bromo or 6-amino- 2,3,5-trimethylbenzo[b]thiophene in good to high yields (50-90%) (Scheme), The amino precursor was prepared from the bromo compound using also a C-N palladium-catalyzed cross-coupling with benzophenone imine, followed by acidic hydrolysis in a 60% overall yield. |
| Tipo: ConferenceObject |
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| Ano: 2004 |
URL: http://hdl.handle.net/10198/3728 |
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