Beilstein J. Org. Chem.2011,7, 1533–1540, doi:10.3762/bjoc.7.180
described. The synthesis mainly relies on the ultrasound-assisted Rap–Stoermerreaction of 3-chloroacetyl- (1) or 3,6-dichloroacetyl-9-ethyl-9H-carbazole (4) with various salicylaldehydes 2a–k as well as 2-hydroxy-1-naphthaldehyde (2l) in CH3CN with the presence of PEG-400 as catalyst. The procedure offers
easy access to benzofuroylcarbazoles in short reaction times and the products are obtained in moderate to good yields.
Keywords: 2-benzofuroyl; carbazole; PEG-400; Rap–Stoermerreaction; salicylaldehydes; ultrasound-assisted; Introduction
Carbazole, and especially heterocycle-containing carbazole
. Therefore, we report herein the synthesis of a series of novel 3-(2-benzofuroyl)carbazoles and 3,6-bis(2-benzofuroyl)carbazoles.
Results and Discussion
In order to synthesize the targeted compounds through a facile and direct methodology, we devised a route that made use of the Rap–Stoermerreaction [46
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Graphical Abstract
Scheme 1:
PEG-400 catalyzed ultrasound-assisted Rap–Stoermer synthesis of 3-(2-benzofuroyl)carbazoles 3a–k.