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Chapter – 4 Studies on different types of reactions…..
However, reaction of 4-hydroxycoumarin with aqueous sodium nitrite
afforded 2, 3, 4-chromantrione-3-oxime which forms a silver salt. 295 (Fig.
4.25)
4.5 USE OF 4-HYDROXYCOUMARIN IN DIHYDROPYRIMIDINE
SYNTHESIS
Three component Biginelli reaction is very well known for the synthesis
of dihydropyrimidine derivatives. P. Biginelli reported the synthesis of
functionalized 3, 4-dihydropyrimidine-(1H)-ones (DHPMs) via three
component condensation reaction of an aromatic aldehydes, urea and ethyl
acetoacetate. In the past decade, this long-neglected multicomponent
reaction has experienced a remarkable revival, mainly due to the interesting
pharmacological properties associated with this dihydropyrimidine scaffold. 296
EtOOC
O
+
H 2N
NH 2
O O
O
Fig. 4.25
O
H +
Fig. 4.26
The reaction was carried out by simply heating a mixture of the three
components dissolved in ethanol with a catalytic amount of concentrated
Department of Chemistry, Saurashtra University, Rajkot – 360 005 213
N
OH
EtOOC
N
H
NH
O