Coumarin skeleton substituents

Abstract Construction of chemical libraries is a useful approach to the discovery of better fluorescent materials, and several types, such as styryl dyes and cyanine dyes, have been reported. In this chapter, we focus on construction of a library of chemicals having a coumarin skeleton as the core structure. Coumarin and its derivatives are key structures in various bioactive or fluorescent molecules, and their fluorescence properties are dependent on the precise structure, including the positions of substituents. 

Phenolics and their functional derivatives are widely found throughout the plant kingdom. One defining characteristic of these compounds is that their aromatic ring usually contains at least one hydroxyl substituent. In a broad sense, phenolics, which are classified according to their structural skeleton, are basically derivatives from simple phenols and phenolic acids, phenylpropanoids including coumarins and lignans, flavonoids and related compounds, and stilbenes. Some of these compounds which show anti-inflammatory activity are reviewed in this section. 

Members of this group biogenetically originate from cinnamic acid derivatives via the shikimic acid pathway. They are all C-9 compounds having the 2H-l-benzopyran-2-one moiety in their skeleton. Coumarin itself has an unsubstituted basic skeleton. Compounds with hydroxyl or meth-oxyl substituents are described as simple coumarins. More... 

The main subclasses of flavonoids are the flavones, flavonols, flavan-3-ols, isoflavones, flavanones and anthocyanidins (Figure 1.1). Other flavonoid groups, which quantitatively are in comparison minor components of the diet, are dihydroflavonols, flavan-3,4-diols, coumarins, chalcones, dihydrochalcones and aurones (Figure 1.2). The basic flavonoid skeleton can have numerous substituents. Hydroxyl groups are usually present at the 4, 5 and 7 positions. Sugars are very common with the majority of flavonoids existing... 

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