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Chapter – 5 Synthesis and Characterization…..
different amines. By reacting 3 - acetylcoumarin with the strong basic amines
in dimethylsulfoxide gave 7 – alkylamino – 3 – alkylaminoethylidene - 5, 6, 8 -
trifluorobenzopyrandiones. The 3 – acetimidoyl – 4 – hydroxyl - 5, 6, 7, 8 -
tetrafluorocoumarin affords the 3 - alkylaminoethylidenebenzopyrandiones
with the monoamines, but in dimethylsulfoxide the 7-substituted 3-acetimidoyl-
5, 6, 8-trifluorobenzopyrandiones or the 7-alkylamino-3-alkylaminoethylidene-
5, 6, 8-triflurobenzopyrandiones can be obtained.
Ghosh et. al. 34 converted 2-Aminochromones into 4-chlorocoumarins
by reacting them with phosphorous oxychloride. Which on subsequent
treatment with ethylenediamine gave 2, 3, 4, 5-tetrahydro-7-(2'hydroxyphenyl)-1,
4-diazepin-5-ones and 4-[(2-aminoethyl) amino] coumarins
in ethanol. While in dimethylformamide, it gave [4-(2-formamidoethyl)
aminocoumarins].
Ganina et. al. 35 synthesized different 4-arylaminocoumarins in high
yields by reacting 4-hydroxycoumarin trifluoromethanesulfonates with different
amines in refluxing dioxane with the presence of pyridine.
Strakova et. al. 36 heated 4-hydroxycoumarin with aniline, p-toluidine,
p-anisidine and benzylamine without solvent at higher temperature to yield the
corresponding 4-arylaminocoumarins. These compounds were converted to
N-substituted 4-amino-3-(chloroacetyl) coumarins by treating them with
excess of chloroacetyl chloride. The later products while reacted with
thiourea gave 3-(2-amino-4-thiazolyl)-4-aminocoumarins.
Zhang et. al. 37 generated 4-amino-3-arylcoumarin by consecutive
Suzuki-Miyaura reaction / nucleophilic substitution of 3-aryl-4-tosyloxy
coumarin using potassium carbonate and ethanol.
Department of Chemistry, Saurashtra University, Rajkot – 360 005 283