Famesane sesquiterpenes

CijHioOj, Mr 248.32, mp. 158 °C, (alp +109° (CHClj). A sesquiterpene of the drimane group, isolated from Drimys winteri (Winteraceae), a South American tree or bush now grown as an ornamental tree in Ireland and the Mediterranean region. The biosynthesis of the drimanes proceeds by direct cyclization of famesane derivatives. 

Formally, C-1 and C-6 of famesane close a cyclohexane ring in the bisabolanes, which represent a more prominent class of monocyclic sesquiterpenes. Additional cyclizations increase the diversity. More than 100 bisabolane derivatives of plant origin are known to date... 

Ring closure of C-1 and C-11 of famesane, not only formally but also in biogenesis via famesyldiphosphate, produces the sesquiterpene skeleton of more than 30 naturally oeeurring humulanes Regioisomeric a- and p-humulene occur in the leaves... 

Carbon atoms C-1 and C-10 in addition to C-2 and C-7 of famesane link up to close the eudesmane bicyclic skeleton of sesquiterpenes with trawj-decalin as core structure with corresponding numbering of the ring positions. To date, about 500 eudesmanes, formerly referred to as selinanes, have been documented in the litera-... 

Bond formation between C-2 and C-7 as well as C-6 and C-11 of famesane formally leads to the drimane basic skeleton of sesquiterpenes The accepted numbering system is derived from decalin and not from famesane. The parent hydrocarbon 5a,8a,9p,10p-drimane with irans-decalin as core stracture occurs in paraffin oil. 

Bonds from C-1 to C-7 and from C-1 to C-10 in famesane formally build up the sesquiterpene skeleton of isodaucanes which are converted to daucanes by migration of one methyl group (C-14) from C-7 to C-8. 

Culture of the phytopathogenic fungus Stereum purpureum (Basidomycetae), a parasite of some trees, produces unsaturated and hydroxylated sesquiterpenes wifli the tricyclic skeleton of sterpurane, formally arising from isolactarane by opening the C-5-C-6- and closing the C-4-C-5 bond, or directly from famesane by Unking the bonds C-l-C-11, C-2-C-9 and C-4-C-7. 

Connecting the bonds C-l-C-6 and C-6-C-10 in famesane formally produces the spiro[4,5]decane basic skeleton of acorane. The name of this class of sesquiterpenes stems from the Acorus species. (-)-4-Acoren-3-one, for example, has been isolated from Acorus calamus (Calamus, Araceae) and from the carrot Daucus carota (Umbelliferae). The oil of calamus (oil of sweet flag) from the rhizome of Acorus calamus with its warm and spicy odor and pleasant bitter taste is predominantly used in perfumery and as a minor (possibly carcinogenic) ingredient of vermouth, some flavored wines and liqueurs. (+)-3,7(ll)-Acoradiene is a constituent of juniper Juniperus rigida its enantiomer occurs in Chamaecyparis nootkatensis (Cupressaceae). 

Bonds between C-2 and C-11, C-6 and C-10 as well as C-6 and C-15 of famesane formally link up the tricyclic sesquiterpene skeleton prezizaane, which converts into zizaane by methyl shift. 

Unlike the sesquiterpenes presented so far, not all bonds between the isoprene units (boldface in the formula) within the pinguisane skeleton are attached in the usual head-to-tail manner. As a result, their structure (constitution) caimot be formally derived from cyclizations of famesane. Moreover, one mefliyl group of the isopropyl residue has migrated from the side chain to the six-membered ring. 

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