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Chapter – 4 Studies on different types of reactions…..
Various methods are utilized to prepare 2, 4-chromandiones and 2, 3,
4-chromantriones shows ketonic nature of 4-hydroxycoumarin and therefore
they were thought of interest to investigate their chemical reactivity and other
properties. So far, 2, 4-chromandiones have been isolated as crystalline
solids. Solid derivatives of 2, 3, 4-chromantriones have been reported usually
as derivatives of the 3-keto group.
Extensive work has been reported on 2, 4-chromandiones and 2, 3, 4chromanetriones.
They are regarded as analogues of 4-chromanones and 3,
4-chromanediones respectively. 279 (Fig. 4.16)
R 2
O O
O
R1 = O
R2 = Any Substituent
R 1
O O
A brief survey of literature on some 2, 4-chromandione and 2, 3, 4chromantrione
derivatives is summarized.
4-hydroxycoumarins frequently react with aromatic aldehydes to give 3benzylidene-2,
4-chromandiones. 280-283 (Fig. 4.17)
O O
OH
+
R 2
Department of Chemistry, Saurashtra University, Rajkot – 360 005 209
R 3
Fig. 4.16
CHO
Fig. 4.17
OH
R 2
R1 = H
R2, R3 = Any substituent
O O
O
R 1
R 2