Pheromones nerolidol

Non-cyclic sesquiterpenes include the volatiles a- and (3-farnesene (which have alarm pheromone activity) and pleasant odorants from Citrus sinsensis (orange) (Rutaceae), namely a- and [i-sinensal (mandarin peel odour) and nerolidol from orange flower oil (oil of neroli). The epoxide JH III is produced by Cyperus iria (Cyperaceae) and acts critically on insect development. 

The famesenes are branched hydrocarbons with four double bonds (Fig. 96.9). E.E-a-famesene and E-p-famesene are widespread in essential oils, whereas E,Z-a-famesene and Z,Z-ot-famesene are not reported to occur in nature. Z, -a-famesene is a constituent of the trail pheromone of the red fire ant. The oxidation products, famesols as primary alcohols, as well as E- and Z-nerolidol as tertiary alcohol are occasional essential oil constituents. 

Sesquiterpenic alcohols Examples of sesquiterpenic alicyclic alcohols (8-24) are farnesol and nerolidol (also known as peruviol). Both alcohols, smelling of flowers, are components of many essential oils used in perfumery. Of the four possible geometric isomers, the (2 ,6B)-isomer of farnesol, is the most common in nature and occurs, for example, in basil oil and ambrette (Abelmoschus moschatus Malvaceae) seed oil. The (2Z,6 )-isomer occurs in the petit grain oil bigarade, which is derived from the bitter orange tree leaves (Citrus aurantiumvai. amara, Rutaceae). Farnesol is a natural pesticide for mites and a pheromone for several species of insects. Nerolidol with a double bond at C-6 occurs in the form of (Z)- and ( )-isomers, each of which can exist as an enantiomeric pair (chiral carbon C-3). The individual enantiomers and their mixtures are found in many essential oils. For example, the essential oil known as cabreuva oil that is used in perfumery is obtained from the bark of the South American tree Myrocarpus frondosus (Fabaceae) and contains the (-F)-(E)-isomer of nerolidol (3S,6 )-nerolidol. 

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