Ana S. Abreu, Natália O. Silva, P. Ferreira
Dec 1, 2003
Citations
0
Influential Citations
18
Citations
Journal
European Journal of Organic Chemistry
Abstract
The methyl ester of β,β-dibromo-N-(tert-butoxycarbonyl)dehydroalanine was synthesized by treating the methyl ester of N,N-bis(tert-butoxycarbonyl)dehydroalanine with trifluoroacetic acid, N-bromosuccinimide and triethylamine. This compound was then used in Suzuki cross-coupling reactions with several (benzo[b]thienyl)boronic acids to give the corresponding β,β-bis(benzo[b]thienyl)dehydroalanine derivatives in good to high yields (55−90 %). After several experiments, the best conditions were shown to be: (benzo[b]thienyl)boronic acid (5 equiv.), [Pd(PPh)2Cl2] (20 mol %), Na2CO3 (4 equiv.) in DME/H2O (10:1). The Suzuki cross-coupling products were treated with Pd(OAc)2 and Cu(OAc)2 in DMF at 160 °C to give the (benzo[b]thienyl)pyrroles in moderate to good yields (25−62 %). Other attempts were carried out using only Cu(OAc)2, the thienylpyrroles being, in some cases, isolated in lower yields. Preliminary fluorescence studies show that the (benzo[b]thienyl)pyrroles can be used as biomarkers. All of these compounds are non-proteinogenic amino acids that can have biological activity or can be used in conformational studies in order to establish structure-activity relationships. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)