Download (4Mb) - Etheses - Saurashtra University

Chapter – 5 Synthesis and Characterization…..
27
Andrea et. al. synthesized 4-(2'-Aminophenyl) amino-3coumarincarbaldehyde
by condensing 4-chloro-3-coumarin carbaldehyde with
o-phenylene diamine in presence of triethylamine in refluxing ethanol.
Kováč et. al. 28 synthesized substituted 4-(substituted amino)coumarin
by reacting coumarin-4-sulphonamide with phenoxy N-(substituted)carbamate
in presence of DBU (diazabicycloundecene) under reflux, while N-(4isopropylphenyl)-4-aminocoumarin
was synthesized by reacting coumarin-4sulphonamide
with 4-isopropylphenyl isocyanate in presence of DBN
(diazabicyclononene) under reflux in dioxane.
Stoyanov et. al. 29 reported that the reaction of 4-hydroxycoumarin with
some primary amines and morpholine under microwave irradiation occurred
without opening of the lactone ring to give N-substituted 4-aminocoumarins in
excellent yields. Under the same experimental conditions, 4-hydroxy-6methyl-2-pyrone
reacted with benzylamine or 2-phenylethylamine to give the
corresponding N, N'-di substituted 4-amino-6-methyl-2-pyridones. The main
advantages of this procedure are dramatically shortened reaction time, higher
amine utilization and considerably improved yields.
Soman 30 prepared 4-arylamino derivative of 4-hydroxy-11-methyl-2H-
[1] benzofuro [3, 2-g] chromen-2-one by refluxing them in dimethylformamide
for shorter time period.
Chavan 31 prepared 4-aryl- and 4-alkylaminocoumarins by reaction of
4-hydroxycoumarin with amines under microwave irradiation using solventfree
conditions in good to excellent yields.
Shcherbakov et. al. 32, 33 reported that the 4-hydroxy-5, 6, 7, 8tetrafluorocoumarin
reacts with the monoamines to form salts under the mild
conditions or the 4-alkyl (aryl) aminocoumarins on refluxing in o-xylene. The
3 – acetyl - 4- hydroxyl - 5, 6, 7, 8 - tetrafluorocoumarin reacts with the strong
basic amines in the polar solvents to give salts that can be transformed into
the 3 – alkylaminoethylidene - 5, 6, 7, 8 – tetrafluorobenzopyran - 2, 4 -
diones. The later can be obtained by reaction of the 3 - acetylcoumarin with
Department of Chemistry, Saurashtra University, Rajkot – 360 005 282