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Chapter – 4 Studies on different types of reactions…..
A simple synthesis and biological properties of 1, 3-diphenyl-2-propen-
1-ones are described by Jang et. al. 276 The key synthetic strategies involve
Grignard reaction of aldehyde and oxidation reaction in high yields. The
prepared compounds were evaluated for free-radical scavenging, suppression
of LPS-induced NO generation, and anti-excitotoxicity in vitro. It was found
that a couple of compounds were potent suppressors of NO generation and
demonstrated anti-excitotoxicity with the concentration range 10-20 µM in
vitro.
Trivedi et. al. 277 synthesized differently substituted 4-hydroxy
coumarins and its 3-acetyl derivatives. Further they condensed 3-acetyl-4hydroxy
coumarin with differently substituted aromatic benzaldehydes to
afford coumarinyl chalcones. They not only improved the synthetic
methodology of chalcones from strong alkali and alchohol to piperidine and
chloroform but they reported their antiviral activity too.
4.4 INTRODUCTION ON CHROMANE DIONES
Tautomeric form of 4-hydroxycoumarin was first established by J.
Kolsa. 278 He proposed that if 4-hydroxy coumarin is a 2, 4-dioxochroman than
its –COCH2CO group should be reactive and easily condense with ester but
show no reaction with diethylcarbonate, ethylcyanoacetate,
methylacetoacetate, ethylacetoacetate and benzylacetoacetate in presence of
sodium and sodium ethoxide. Thus it was concluded that 4-hydroxycoumarin
enolises at the lactone carbonyl and exists mainly in coumarin tautomerism in
which the enol form of coumarin is favored. (Fig. 4.15)
O O
OH
Fig. 4.15
O OH
Department of Chemistry, Saurashtra University, Rajkot – 360 005 208
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