Monoterpenoid alcohols and esters

Monocyclic Monoterpenoid Alcohols and Their Esters a-Terpineol... 

The oleoresinous exudate or "pitch of many conifers, but mainly pines, is the raw material for the major products of the naval stores industry. The oleoresin is produced in the epithelial cells which surround the resin canals. When the tree is wounded the resin canals are cut. The pressure of the epithelial cells forces die oleoresin to the surface of die wound where it is collected. The oleoresin is separated into two fractions by steam distillation. The volatile fraction is called gum turpentine and contains chiefly a mixture of monoterpenes but a smaller amount of sesquiterpenes is present also. The nonvolatile gum rosin 5 consists mainly of llie dilerpenuid resin acids and smaller amounts of esters, alcohols and steroids. Wood turpentine, wood rosin and a fraction of intermediate volatility, pine oil are obtained together by gasoline extrachon of the chipped wood of old pine stumps. Pine oil is largely a mixture of the monoterpenoids terpineol. borneol and fenchyl alcohol. Sulfate turpentine and its nonvolatile counterpart, tall oil, 5 are isolated as by-products of the kraft pulping process. Tall oil consists of nearly equal amounts of saponified fatty acid esters and resin acids. 

The reaction of linalool with boron trifluoride etherate has been re-examined no pinenes or camphene were obtained.146 Dehydrolinalool reacts with methyl iso-propenyl ether under acidic conditions by Claisen rearrangement to give the allene (58).147 Further papers in this section include reaction of monoterpenoid alcohols with paraformaldehyde-acetic anhydride-sodium acetate,148 rearrangement of the alcohol (47 X = OH) to the oxabicycloheptane (59) and the ketone (60),149 and the rearrangement of a typical monoterpenoid vicinal hydroxy-ester to an epoxide.150... 

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... 

In addition, acyl esters of terpenoid alcohols have been reported. For example, Dunphy and Allcock (1971) showed that 30-60% of the total monoterpenoid alcohol content of rose petals occurred as acyl esters with geranyl stearate predominating. 

The study involved the detection of altogether 125 volatiles. Beside monoterpenoids the following classes of metabolites were also found (species-dependent) Sesquiterpenoids (Sect. 7.3), phenylpropanoids (Sect. 6.3.3.1), aliphatic alcohols/ ketones/esters, and nitrogenous compounds such as nitriles or aldoximes (Raguso et al. 2003). 

Sakata, T, Okabe, K. and Kuwahara, Y. (2001). Structure elucidation of twelve novel esters between five fatty acids and three branched new alcohols along with four monoterpenoids from Sancassania shanghaiensis (Acari Acaridae). Bioscience, Biotechnology and Biochemistry 65 919-927. 

Little is known of the biosynthetic routes to the irregular monoterpenoids. It has been suggested that chrysanthemyl alcohol is a parent of the class that includes artemisia ketone, lavandulol, and santolinatriene, and stereochemical considerations have indicated that the (1/ , 3i )-isomer (16) of this alcohol would be the required precursor. The alcohol (16) occurs in Artemisia ludoviciana, and this is the first identification of the alcohol from a natural source. The santolinyl compound (17) also occurs in Artemisia tridentata and the 5-stereochemistry at C-3 is as expected if (16) (presumably as its pyrophosphate ester) is a precursor. 

The basic flavour of peaches Persica vulgaris, syn. Prunus persica, Rosaceae) is typified by the presence of y-lactones (Cg-Cjj) and 8-lactones (C q and Cjj). Individual varieties differ mainly in their content of esters and monoterpenoids. As with all stone fruits, an important component is benzaldehyde, while other important compounds include benzyl alcohol, ethyl cinnamate, isopentyl acetate, hnalool, a-terpineol, hexanal, (Z)-hex-3-enal, ( )-hex-2-enal and decomposition products of carotenoids. 

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