MEDICINAL CHEMISTRY
MEDICINAL CHEMISTRY
MEDICINAL CHEMISTRY
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OH<br />
COOCH 3<br />
AC 2O<br />
Methyl salicylate (27)<br />
CH=CHCOCH 3<br />
Benzalacetone<br />
O<br />
O<br />
CH<br />
OH CH 2COCH 3<br />
O<br />
O - C- CH 3<br />
COOCH 3<br />
(28)<br />
Warfarin (33) R = H<br />
Nicoumalone (34) R = NO 2<br />
O<br />
OH<br />
R<br />
O<br />
i) Na, 250 o C<br />
ii) Acidification<br />
CH<br />
CH 2COCH 3<br />
Warfarin (33)<br />
O O<br />
OH<br />
(29)<br />
Taking warfarin as a prototype, a number of derivatives of 4-hydroxycoumarin have been<br />
prepared where 3 and 4'-positions have been substituted by different substituents.<br />
Cyclocoumarol (35) may be prepared by passing HCl gas in methanolic solution of<br />
warfarin<br />
Warfarin (33)<br />
O<br />
HCl gas<br />
CH 3OH<br />
O<br />
CH<br />
OH CH 2CH 3<br />
OH<br />
O O<br />
O<br />
H 3C OCH 3<br />
Cyclocoumarol (35)<br />
Phenprocoumon (36)<br />
Nicoumalone (acenocoumarol) (34), phenprocoumon (36), coumachlor, snitrom and<br />
marcoumar are other examples. In all these compounds there is chiral centre. The<br />
enantiomers differ in anticoagulant potency. These are, therefore, used as racemic<br />
mixtures, and any advantage of administering a pure enantiomer has not yet been<br />
established. They are used in the form of alkali salts, also used as rodenticide.
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