An efficient iron/acetic acid system-mediated reductive cyclization reaction of substituted
2-aryl-3-nitro-2H-chromenes with substituted 2-nitrobenzaldehydes for the synthesis of 6-aryl-6H-chromeno[3,4-b]quinolines was developed. This reaction involves the sequential reduction, hydrolysis,
aldol condensation, intramolecular addition, and the nucleophilic addition of substituted
2-aryl-3-nitro-2H-chromenes with substituted 2-nitrobenzaldehydes to give the corresponding 6H-chromeno[3,4-b]quinolines. This transformation provides a straightforward synthetic protocol for
constructing substituted 6H-chromeno[3,4-b]quinoline derivatives. The structures of three typical products were confirmed by
X-ray crystallography.
Key words
6-aryl-6
H-chromeno[3,4-
b]quinolin-6-ol - 2-aryl-3-nitro-2
H-chromenes - reductive cyclization reaction - 2-nitrobenzaldehyde - Povarov reaction