Authors
Ferreira, Isabel C.F.R.
Calhelha, Ricardo C.
Estevinho, Leticia M.
Advisor(s)
Abstract(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.
Description
Keywords
Dehydrophenylalanines Benzothiophenes Borylation Suzuki coupling Cyclization Indoles Fluorescence Antimicrobial activity
Citation
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
Publisher
Wiley Interscience