Download (4Mb) - Etheses - Saurashtra University

Chapter – 4 Studies on different types of reactions…..
reaction of 3-acetyl-4-hydroxycoumarin with aldehydes forms chalcone at C3
position with the elimination of water molecule under basic condition. These
chalcones are excellent intermediates to build different heterocycles by
means of further cyclization using it.
Recently coumarinyl chalcones have drawn attention of chemistry
researchers towards it chemistry and antiviral activity. 4-hydroxycoumarinyl
chalcones were prepared from 3-acetyl-4-hydroxycoumarins via Claisen
condensation with benzaldehydes by Mulwad et. al., 271 which were further
cyclized on treatment with 10 % sulfuric acid in ethanol and selenium dioxide
in amyl alchohol to give 4H, 5H-2, 3-dihydro-2-phenylpyrano [3, 2 - c] – 1 –
benzopyran - 4, 5 - diones and 4H, 5H – 2 – phenylpyrano [3, 2 - c] – 1 –
benzopyran - 4, 5 – diones respectively. The chalcone oximes on refluxing
with silica gel and dichloroethane gave 2 – oxo – 3 – styryl - 4H – 1 –
benzopyran [3, 4 - d] isoxazoles.
Due to the exceptional reactivity of 4-hydroxycoumarin and the
versatile biological activity of coumarin derivatives, the synthesis of 3substituted
4-hydroxycoumarin derivatives was carried out and tested for
antibacterial and antifungal activity by Zavrsnik et. al. 272 Microbiological
activity of synthesized compounds was executed using diffusion method on
the species of bacteria Escherichia coli 113-1, Pseudomonas aeruginosa
ATCC 9027, Staphylococcus aureus SG 511, and fungi Candida albicans
ATCC 10231. The antibacterial activity of currently used antibiotics was also
carried out on the same species of bacteria for comparison point of view. The
synthesis of derivatives of 3-cinnamoyl-4-hydroxycoumarin and azomethines
of 4-hydroxycoumarin was also carried out. Both the groups of compounds
showed significant microbiological activity. All synthesized compounds
showed antimycotic and antibacterial activity. Derivatives of 3-cinnamoyl-4hydroxycoumarin
in relation to azomethines of 4-hydroxycoumarin showed
better activity in case of all the bacteria and fungi species. The best
antibacterial activity was shown by the species which had -Cl or -OCH3 as
substituents, and the best antimycotic activity was shown by the species
which contained Cl.
Department of Chemistry, Saurashtra University, Rajkot – 360 005 206