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Chapter – 5 Synthesis and Characterization…..
4-arylaminocoumarins were prepared by treatment of an ethanolic
solution of 4-hydroxycoumarin and o-aminobenzaldehyde under reflux
condition, which on further cyclization afforded 6H-[1] benzopyrano [4, 3-b]
quinoline. 12 This has proved the way for another clean method for the
synthesis of 3, 4-fused systems on coumarin nucleus. (Fig. 5.3)
O O
OH
+
N
H 2
OHC
Fig. 5.3
4 hours
Ethanol Reflux
O O
Asherson et. al. 13 heated dicoumarol and 4-hydroxycoumarin with
aniline to yield 4-arylaminocoumarin. Which was further validated by Conlin
et. al. 14 while they heated dicoumarol and 4-hydroxycoumarin with aniline,
benzylamine and cyclohexylamine under reflux to yield corresponding anil of
4-hydroxycoumarin.
Stunic et. al.
15
synthesized N-substituted-(3-nitrocoumarinyl)
aminoacids from 4-chloro-3-nitrocoumarin in good yield. (Fig. 5.4)
Department of Chemistry, Saurashtra University, Rajkot – 360 005 279
O
N
NH
CHO
6 hours Reflux
O