Monoterpenes function

Evidence for de novo synthesis of pheromone components was obtained by showing that labeled acetate and mevalonate were incorporated into ipsdienol by male Ips pini [103,104]. Similarly, labeled acetate and other labeled intermediates were shown to be incorporated into frontalin in a number of Dendroctonus species [105]. Possible precursors to frontalin include 6-methyl-6-hep-ten-2-one, which was incorporated into frontalin by D. ruffipennis [106]. The precursor 6-methyl-6-hepten-2-one also was shown to be converted to bre-vicomin in the bark beetle, Dendroctonus ponderosae [107]. In addition, the expression patterns of HMG-CoA reductase and HMG-CoA synthase are tightly correlated with frontalin production in Dendroctonus jeffreyi [108, 109]. A geranyl diphosphate synthase cDNA from I. pini was also isolated, functionally expressed, and modeled [110]. These data indicate that the de novo isoprenoid biosynthetic pathway is present in bark beetles. A variety of other monoterpene alcohols such as myrcenol, pityol, and sulcitol are probably synthesized through similar pathways [111]... 

Secondary compounds produced by plants may have other significant survival roles, such as signals to attract insects, birds, or other animals to enhance pollination or seed dispersal. In addition to any potential functions, secondary compounds may concomitantly serve a physiologic function, such as protection against ultraviolet (UV) light or frost, or provide a function in nitrogen transport and storage. In several instances, compounds can serve multiple functions in the same plant. Anthocyanins or monoterpenes can be... 

Ealdt J, Arimura G, Gershenzon J, Takabayashi J, Bohlmann J (2003) Functional identification of AtTPSOS as ( )-P-ocimene synthase a monoterpene synthase catalyzing jasmonate- and wound-induced volatile formation in Arabidopsis thaliana. Planta 216 745-751... 

Hydroxy-3-methylcarbazole (52) could also function as a precursor for the formation of carbazole alkaloids with a C23 skeleton as depicted in Scheme 3.6 (370). Insertion of a Cio unit, viz., geraniol at C-1 of 2-hydroxy-3-methylcarbazole (52) would yield mahanimbinol (mahanimbilol) (56). The geranyl monoterpene unit could undergo various transformations, thus giving rise to isomeric carbazole alkaloids with a C23 skeleton, such as mahanimbine (139), cyclomahanimbine (murrayazolidine, curryanin) (151), and bicyclomahanimbine (160). Therefore, mahanimbinol (mahanimbilol) could be considered as the representative member of the carbazoles with a C23 skeleton. The occurrence of 2-hydroxy-3-methylcarbazole (52),... 

The Lauraceae is a family from which relatively few isoprenylated chalcones have been reported, and only one new example, linderol A (40), from the bark of Linder a umbellata, is listed in Table 16.2. In this compound, the B-ring is unsubstituted (Figure 16.7), a common feature of Lauraceae chalcones. Several other unusual monoterpene-substituted chalcones have been reported previously from the Lauraceae genera Aniba and Lindera. The unusual structure of linderol A (40), in which the A-ring is functionalized by a cyclized monoterpenyl substituent, prompted the first total synthesis of this molecule. 

Citrus oils contain up to 95% monoterpene hydrocarbons (usually limonene, but others as well, e.g., lemon oil also contains a-terpinene and /3-pinene). The important aroma-determining components of citrus oils are functionalized terpenes and aliphatic compounds (predominantly carbonyl compounds and esters), present only in relatively low concentrations [358]. Thus, several methods are employed to concentrate citrus oils on an industrial scale. The monoterpene hydrocarbon... 

Monoterpenes occur in plants in various structural forms some are cyclic while the others are acyclic. They also contain various types of functional group, and depending on their functional groups they can be classified as simple hydrocarbons, alcohols, ketones, aldehydes, acids or phenols. Some examples are cited below. 

All the optically active terpenes mentioned in this chapter are commercially available in bulk (>kg) quantities and are fairly inexpensive. Although many of them are isolated from natural sources, they can also be produced economically by synthetic methods. Actually, two thirds of these monoterpenes sold in the market today are manufactured by synthetic or semi-synthetic routes. These optically active molecules usually possess simple carbocyclic rings with one or two stereo-genic centers and have modest functionality for convenient structural manipulations. These unique features render them attractive as chiral pool materials for synthesis of optically active fine chemicals or pharmaceuticals. Industrial applications of these terpenes as chiral auxiliaries, chiral synthons, and chiral reagents have increased significantly in recent years. The expansion of the chiral pool into terpenes will continue with the increase in complexity and chirality of new drug candidates in the research and development pipeline of pharmaceutical companies. 

The frass of females of the western pine beetle Dendroctonus brevicomis is enriched with endo- (XIX) and exo-7-ethyl-5-methyl-6,8-dfoxabicyclot3.2.1]octane (XX), which are assigned the trivial epithets endo- and exo-brevicomin (61). Males of 2 brevicomis synthesize 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane (frontalin) (XXI) in their hind guts (62), and this compound, in combination with the brevicomins and host-derived myrcene, constitutes a potent attractant for both sexes of J). brevicomis (63). Frontal in, also produced by females of . frontalis (62T7 is reported to function as a powerful aggregative pheromone when combined with host monoterpenes such as a-pinene (64). J). pseudotsugae... 

A monoterpenol, or monoterpene alcohol, is a monoterpene with an alcohol functional group. 

A monoterpenone, or monoterpene ketone, is a monoterpene with a ketone functional group. 

The alcohol functional group is -OH and the name ends in -ol for example, geraniol and linalool (found in geranium and lavender, respectively). If the alcohol functional group is attached to a monoterpene, the compounds are called monoterpenols (Fig. 3.5). 

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