Silphium

Because not all of the species in the world are known, it is difficult to determine the exact rate of species extinction. Unfortunately, there are plants with medicinal properties that have gone extinct. The first case of a medicinal plant extinction documented in an herbal text is silphium [37]. 

Parejko K. Pliny the Elder s Silphium First Recorded Species Extinction. Conservation Biol 2003 17 925-7. 

Andrews AG, The silphium of the ancients A lesson in crop control, Isis 33 232-236, 1941. 

Silphinene (750), an angularly fused triquinane isolated by Bohlmann and Jakupovic from Silphium perfoliatum in 1980 has a substitution pattern entirely different from that of isocomene and pentalenene. Entirely different synthetic protocols are consequently required. Two successful approaches to 750 have so far been devised. That due to Leone-Bay and Paquette makes use of an iterative annulation scheme... 

Apioside-7-rhamnosyl(l —> 6)galactoside Silphium perfoliatum leaves Compositae 203... 

El-Sayed, N.H. et al., Kaempferol triosides from Silphium perfoliatum. Phytochemistry, 60, 835, 2002. 

Silphinene (160), a constituent of the roots of Silphium perfoUatum, has attracted a considerable attention of synthetic chemists. Electrochemical methodology is used for its synthesis. On constant current electrolysis (1.18 mA -1-750-1200 mV V5. SCE) in AC2O, the phenol 161, readily prepared from 3,4-dimethoxyphenol, underwent intramolecular [5 -h 2] cycloaddition to give in 59% yield the desired tricyclic compound 162, which was successfully converted into silphinene through a bicyclic compound 163 (Scheme 32) . 

A detailed investigation of several Berkheya species has resulted in the identification of /3-isocomene (320). In certain of the species this compound co-occurs with the previously known isomer isocomene (321) and modhephene (322). These three hydrocarbons also co-occur in the roots of some Silphium... 

Sensitized photo-oxygenation of (12F)-abienol affords products oxygenated at C-12 that are reminiscent of the tobacco labdanoids. Amongst new labdane derivatives with 8,12-ether bridges are (12), which was isolated from a group of Silphium species. 

Fennel is a relative of silphium. Silphium may have looked something like this. (Redrawn from Crockett. J.U. et al.. Herbs, Time-Life Books, Alexandria, VA, 1977.)... 

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