A novel and facile synthesis of 3-(2-benzofuroyl)- and 3,6-bis(2-benzofuroyl)carbazole derivatives

Abstract

SummaryA facile synthesis of hitherto unreported 3-(2-benzofuroyl)carbazoles 3a–k, 3,6-bis(2-benzofuroyl)carbazoles 5a–k, and naphtho[2,1-b]furoylcarbazoles 3l and 5l is described. The synthesis mainly relies on the ultrasound-assisted Rap–Stoermer reaction 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.

Facile Synthesis of Novel Pyrano‐Pyrido‐Carbazole Scaffolds Using Magnetic Fe3O4 Nanoparticles as a Heterogeneous Green and Reusable Catalyst

“…Further, for a comprehensive comparison, the salient features of the work reported previously [39][40][41][42][43][44][45] along with present work are given in Table 3.…”

First Synthesis of 2-Ferrocenoyl-3-Methylbenzofuran Derivatives

“…[18][19][20][21][22][23] Our research group has synthesised 2-heteroylbenzofurans through Rap-Stoermer reaction of salicylaldehydes with α-haloketones. [24][25][26][27] Building on this expertise and in an attempt to create novel hybrids to extend the diversity of our previous work, we investigated how this reaction could be extended to 2′-hydroxyacetophenones with 1-chloroacetylferrocene for the synthesis of the desired 2-ferrocenoyl-3-methylbenzofurans. A literature search suggests that no such work has been previously reported.…”

“…Thus, we considered that in this case the use of ultrasonication was unnecessary to promote the reaction, in contrast to our previous reports. [24][25][26][27] Furthermore, a control experiment without the addition of PEG-400 was attempted but provided a modest yield of 43% of 5a, which indicated that PEG-400 was also needed for the success of this reaction. Other attempts such as the use of different bases or solvents did not result in an improved yield.…”

Aldo‐X Bifunctional Building Blocks for the Synthesis of Heterocycles

“…Salicylaldehydes are often used in the synthesis of benzo‐fused five‐membered‐ring oxygen‐containing heterocycles. Benzofurans could be generated through the condensation of salicylaldehyde with an α‐halide‐substituted ketone . This is probably the most convenient method for the synthesis of C3‐unsubstituted benzofurans, which are very important for medicinal chemistry.…”