Eremophila calamenene from

Another sesquiterpene class represented in the Eremophila genus is that of the bicyclic calamenenes. Two sesquiterpenes, (-r)-calamenene (76) and its 7-hydroxy derivative (77), were isolated from E. drummondii (69). At that time, contradictory claims regarding the absolute configuration of the known (-)-calamenene had been made. This confusion was resolved by an... 

Serrulatanes The most common diterpene skeleton found in Eremophila is that represented hy the hicarbocyclic serrulatane group of compounds (101-104). Essentially, these are isoprenologues of the calamenene sesquiterpenes in which the dimethylallyl derived unit of the acyclic precursor does not participate in cyclisation. The first example of this skeleton was found in dihydroxyserrulatic acid (120) which was isolated from E. serrulata (101). As observed for the calamenenes, the presence of the serrulatane skeleton can be inferred from nmr spectroscopic data. 

All serrulatanes so far described contain the l/ ,4S-stereochemistry in contrast to the calamenenes ( R,AR) from Eremophila species with which, in at least two cases, they co-occur. 

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