40306-93-2Relevant academic research and scientific papers
Synthesis and properties of symmetric and unsymmetric dibenzothienopyrroles
Balaji, Ganapathy,Valiyaveettil, Suresh
supporting information; experimental part, p. 3358 - 3361 (2009/12/03)
Symmetrical and unsymmetrical heteroacenes containing thiophene and pyrrole rings were synthesized. The unsymmetrical heteroacene was synthesized in two steps involving an unexpected palladium catalyzed amination of alkyl or aryl amines with benzo[b]thiop
Sonogashira cross-couplings of dehydroamino acid derivatives and phenylacetylenes
Abreu, Ana S.,Ferreira, Paula M. T.,Queiroz, Maria-Joao R. P.,Gatto, Emanuela,Venanzi, Mariano
, p. 3985 - 3991 (2007/10/03)
Several phenylacetylenes were coupled under Sonogashira cross-coupling conditions with the methyl esters of N-(tert-butoxycarbonyl)-(E)-β-bromo- or -β,β-dibromodehydroalanine, to give β-substituted or β,β-disubstituted dehydroalanines, respectively. The β-substituted dehydroalanines were obtained in good to high yields (60-90%) under the usual Sonogashira conditions (1 equiv. of the phenylacetylene, 1 mol % of [Pd(PPh3)4], 2 mol % of CuI, 18 equiv. of NEt 3 in acetonitrile, 24 h at room temp.), with retention of stereochemistry. The β,β-disubstituted dehydroalanines were, in turn, obtained in moderate to good yields (44-63%) under modified Sonogashira conditions (4 equiv. of the phenylacetylene, 10 mol % of [PdCl 2(PPh3)2], 20 mol % of CuI, 1.4 equiv. of Cs2CO3 in acetonitrile, 2 h at reflux). In the latter reactions, some phenylacetylene dimer and the (E) isomer of the monosubstituted coupled products were also isolated to some extent. The Sonogashira products obtained from the 4-bromophenylacetylene were allowed to react with functionalized benzo[b]thiophenes under C-C or C-N palladium-catalyzed cross-coupling conditions. Preliminary fluorescence studies were performed for mono- and disubstituted (4-aminophenyl)acetylenic dehydroamino acids and for the benzo[b]-thiophene derivatives. The results showed that some of the dehydroalanines prepared can be used as fluorescent probes. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
