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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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Synthesis of β - benzo[b]thienyldehydrophenylalanine derivatives by one-pot palladium-catalyzed borylation and suzuki coupling (BSC) and metal-assisted intramolecular cyclization: studies of fluorescence and antimicrobial activity IPB - Escola Superior Agrária
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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