Orientador(es)
Resumo(s)
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 cyclization and the minor product resulting
from direct cyclization (thienoindole). Carrying out the reaction
at 100 °C gave the same products in similar amounts.
Use of the methyl ester of (Z)-N-(tert-butoxycarbonyl)-β-
(2,3,7-trimethylbenzo[b]thien-6-yl)dehydrophenylalanine as
starting material gave only one product, resulting from isomerization
and cyclization at 100 °C. Two of the cyclized compounds
were subjected to fluorescence studies; the thienoindole
could be useful as a fluorescent probe. Preliminary studies
of antimicrobial activity were performed on the precursors
and on the cyclized products.
Descrição
Palavras-chave
Dehydrophenylalanines Benzothiophenes Borylation Suzuki coupling Cyclization Indoles Fluorescence Antimicrobial activity
Contexto Educativo
Citação
Abreu, Ana S.; Ferreira, Paula M.T.; Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.; Calhelha, Ricardo C.; Estevinho, Leticia M. (2005). 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. European Journal of Organic Chemistry. ISSN 1434-193X. 2005:14. p. 2951-2957
Editora
Wiley Interscience