Monocyclic monoterpene alcohol

Perllla alcohol [4-(l-methylethenyl)-l-cyclohexene-1-methanol]. Formula, see perillaldehyde. CiqHi O, Mr 152.24, oil. A monocyclic monoterpene alcohol occurring in both enantiomeric forms (/ )(+)- and (5)(-)-P bp. 119-121 °C (1.1 kPa), [a]o 68°. (-H)-P. occurs in delft grass oil Cymbopogon polyneu-ros, Poaceae) a grass indigenous to the Nilgiri mountains (Southern India) and the mountains of Sri Lanka (- )-P. occurs in false lavender oil Lavandula hybrida, Lamiaceae). For synthesis, see Lit.. P. induces apoptosis. It is in clinical development against breast and prostate cancer. 

Monoterpenoids are responsible for fragrances and flavors of many plants and thus their products are used in perfumery and as spices. To date over 1,500 monoterpenoids are known, and these constitute acyclic, monocyclic, and bicyclic monoterpenoids (32), which occur in nature as hydrocarbons, alcohols, aldehydes, and carboxylic acids and their esters. Several acyclic monoterpenoid hydrocarbons are known, and these include trienes such as 3-myrcene (Cl), a-myrcene (C2), (Z)-a-ocimene (C3), ( )-a-ocimene (C4), (Z)-3-ocimene (C5), and ( )-P-ocimene (C6). 3-Myrcene and 3-ocimene are constituents of basil (Oci-mum basilicum, Labiatae) and bay (Pimenta acris, Myrtaceae), pettitgrain (Citrus vulgaris, Rutaceae) leaves, strobiles of hops (Humulus lupulus, Cannabaceae), and several other essential oils. Unsaturated acyclic monoterpene alcohol constituents of plants and their derived aldehydes play a signihcant role in the perfume industry. Some common acyclic monoterpene alcohols and aldehydes include geraniol (C7), linalool (C8) (a... 

Epidemiological studies demonstrate that dietary monoterpenes may be effective in the prevention and treatment of cancer [31]. Monocyclic monoterpenes D-limonene (Fig. 86.2) and perillyl alcohol (Fig. 86.4) are shown to inhibit the development of liver, skin, mammary, colon, lung, prostate, forestomach, and pancreatic carcinomas in a dose-dependent manner [29, 31-35]. Moreover, the metabolites of D-limonene such as perillic acid, dihydroperillic acid. 

Molecular structures of monoterpenoids are present as three major types acyclic, monocyclic and bicyclic. Oxygenated derivatives of acyclic monoterpenes are more widespread in nature than acyclic monoterpenes themselves. Such derivatives are the monoterpene alcohols citronellol and geraniol, or the monoterpene aldehydes citronellal and geranial. Mononocyclic monoterpene hydrocarbons are exemplified by limonene, which is a major component of orange and lemon peel oils, and p-phellandrene, which is emitted by conifer trees under biotic stress. These compounds are relatively common in nature. Bicyclic monoterpenes are represented by the aforementioned a-pinene, one of the most abundant and important monoterpenes. 

The monoterpenes are subdivided into three groups acyclic, monocyclic and bicyclic (there is only one tricyclic terpene tricyclene). Each group contains hydrocarbon terpenes, terpene alcohols, terpene aldehydes, ketones, oxides etc... 

The hydration of a-pinene (1) with aqueous mineral acids leads to a complex mixture of monoterpenes known as s)mthetic pine oil [2], The main products are monocyclic terpenes, namely a-terpineol (9). The reaction mechanism has been extensively studied [3-7]. It is generally accepted that it proceeds through cation I (Scheme 1). Subsequent carbonium ion rearrangements leads to two parallel pathways. One yields bi- and tricyclic products such as camphene (2), bomeol (3) and isobomeol (4). The other )delds monocyclic products such as li-monene (5), a- (6) and y-terpinenes (7) terpinolene (8), a-terpineol (9)and 1,8-terpine (10) Products from the cyclization of terpineol, like 1,8-cineol, can also be formed. By controlling the many reaction variables the process can be directed to produce a maximum of terpene alcohol s. 

The occurrence and importance of monocyclic oxygen-containing monoterpene derivatives in nature have been known for a long time as is evidenced by a voluminous literature. The alcohols found in... 

Monoterpenes (Cio) are the simplest members of the terpene series. They result from the condensation of two isoprene units and may be acyclic, monocyclic, bicyclic or tricyclic. The monoterpenes can have another functional moiety like alcohol (geraniol, linalool, menthol, bomeol), aldehyde (geranial, cihonellal), ketone (menthone, carvone, thujone), ester (bomyl acetate, linalyl acetate), ether (1,8-cineol) and phenol (thymol, carvacol). In the case of optically active molecules, the proportions of the enantiomers vary largely from one species to another. 

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