Cyclofarnesanes and Bisabolanes

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 

Oil of ginger obtained from the rhizome of Zingiber officinalis (Zingiberaceae) consists predominantly of (-)-zingiberene (20-40%), p-sesquiphellandrene and (+)- 

P-bisabolene. The latter also oeeurs in Chamaecyparis nootkatensis (Cupressaceae) and in the Sibirian pine tree Piims sibirica (Pinaceae). (+)-a- and (+)-p-bisabolol are fragrant sesquiterpenes found in the essential oils of various plants they also contribute to the odors of camomile and of bergamot oil from unripe fruits of Citrus aurantium var. bergamia (Rutaceae) growing in southern Italy. 

Sesquisabinene from pepper Piper nigrum (Piperaceae), sesquithujene from ginger Zingiber officinalis (Zingiberaceae) and sesquicarene from Schisandra chinensis represent bicyclic bisabolanes. 

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