Camphanes and Fenchanes

Naturally occurring camphanes include the bomeols with an endo hydroxy group, the isobomeols with an exo OH and 2-camphanone (2-bonanone) referred to as camphor. (+)-Bomeol from the camphor tree Cinnamomum camphora (Lauraceae) and from the roots of ginger-like Curcuma aromatica (Zingiberaceae), both of which grow in Eastern Asia, is known as Borneo camphor. (-)-Isobomeol was isolated from Achillea filipendulina (Asteraceae). 

Fenchane derivatives occur as fenchones and fenchols in several ethereal oils. Oil of fennel, obtained from the dried fruit of Foeniculum vulgare (Umbelliferae), contains up to 20 % (+)-fenchone, and is associated with limonene, phellandrene and a-pinene. (-)-Fenchone is isolated from the tree of life Thuja occidentalis (Cu-pressaceae), which is cultivated as hedges. The dextrorotatory enantiomer of a-fenchol with an endo OH, requested in perfumery, as well as its stereoisomers are found in fresh lemon juice, in oil of turpentine obtained from Pinus palustris (Pina-ceae), in ethereal oils originating from the Lawson white cedar Chamaecyparis lawsoniana (Cupressaceae) and other plant families such as Ferula, Juniperus, and Clausena species 

Camphene, with its slight camphoric odor, is used in perfumery and is derived from the isocamphane skeleton its enantiomers readily undergo racemization and occur as such or as the racemate in bergamot oil, as well as in the oils of citronella and turpentine. (+)-a-Fenchene is found in the ethereal oils of the giant tree of life Thuja plicata (Cupressaceae) and valerian Valeriana officinalis (Valerianaceae), (+)-P-fenchene in the fruits of caraway Carum carvi (Umbellifereae). 

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The bornane-, camphane- and fenchane-type monoterpenes possess the [2.1.1] bicyclic skeleton formed by different cyclisation of the terpinyl cation. Important members include borneol 47, isobornyl acetate 48, camphene 49, camphor 50, fenchone 51 (Structure 4.12). 

Cyclopentane bicyclic monoterpenoids that occur in the plant kingdom belong to three major skeletal types camphane, iso-camphane, and fenchane (Fig. 7). Camphane-type terpenoid alcohols, (+)-bomeol (Gl) and (—)-isobomeol (G2), have been isolated from Cinnamomum camphora (Lauraceae) and Achillea filipendulina (Asteraceae). A ketone derived from these, (-h)-camphor (G3), is found in the camphor tree Cinnamomum camphora) and in the leaves of rosemary Rosmarinus officinalis) and sage Salvia officinalis, Labiatae). Camphene (G4) and its enantiomer with the isocamphane carbon skeleton are known to occur in the oils of citronella and turpentine. Fenchane-type bicyclic cyclopentane monoterpenoids are commonly found in plants as their ketone derivatives. (—)-Fenchone (G5) occurs in the tree of life Thuja occidentalis, Cupres-saceae). Its enantiomer, (+)-fenchone (G6), has been isolated from the oil of fennel Foeniculum vulgare, Umbelliferae). 

Routine, but useful, interpretations of the mass spectral fragmentation patterns under electron impact have been reported for esters of the menthane and camphane series,39-40 for thioketones with the thujane, pinane, camphane, and fenchane skeleta,41 for [2H]limonene,42 for cannabinoids,43-46 and for the volatile components from Pinus seedlings.47... 

Bicyclic Compounds with Bornane, Camphane, and Fenchane Skeletons... 

Fig. 96.8 Monoterpenes with bomane, camphane, and fenchane structures...

Bicyclic cyclopropanes carane and thujane, bicyclic cyclobutane pinane, and bi-cyclo[2.2.1]heptanes such as camphane, isocamphane and fenchane are the most important skeletons of naturally occurring bicyclic monoterpenes... 

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