Dibenzo coumarins

Other metabolites like 5,7-dihydroxy-8-methoxychroman-4-one (37) and possibly a coumarin derivative (35) have also been found in the bulb wax of E. comosa. From the bulb tissue of different Eucomis spp. a series of sterol derivatives, dibenzo-a-pyrones and a dicarboxylic acid have been isolated (69, 82). 

These include the SSA-catalyzed synthesis of heterocyclic compounds such as xanthenes, coumarins, oxazoles, and so on. Xanthenes are of great therapeutic and biological interest on account of their many biological activities such as anti-inflanunatory, antiviral, antibacterial properties, and so on. Seyyed Hamzeh et al. (2008) carried out the SSA-catalyzed synthesis of aryl-14 f-dibenzo[fl,y]xanthenes from aldehydes and P-naphthol and 1,8-dioxo-octahydro-xanthenes from aldehydes and 1,3-dicarbonyl componnd such as dimedone under solvent-free conditions (Schemes 5.25, 5.26). Reactions were carried out at 80°C. Nazeruddin et al. (2011) documented an effective method for 9,10-dihydro-12-aryl-8 f-benzo[a]xanthenes-ll(12 f)-one derivatives in excellent yield and short reaction time using SSA under solvent-free conditions (Scheme 5.27). 

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