From myreene

Enone formation-aromatization has been used for the synthesis of 7-hydro-xyalkavinone (716)[456]. The isotlavone 717 was prepared by the elimina-tion[457]. The unsaturated 5-keto allyl esters 718 and 719, obtained in two steps from myreene. were subjected to enone formation. The reaction can be carried out even at room temperature using dinitriles such as adiponitrile (720) or 1,6-dicyanohexane as a solvent and a weak ligand to give the pseudo-ionone isomers 721 and 722 without giving an allylated product(458]. 

An important application of an isomerisation is found in the Takasago process for the commercial production of (-)menthol from myreene. The catalyst used is a rhodium complex of BINAP, an asymmetric ligand based on the atropisomerism of substituted dinaphthyl (Figure 5.5). It was introduced by Noyori [1],... 

Kig. (1. ). Conversion from myreene into (S)-ipsenol (7 ) and conversion from a-pinene into cis and trans-... 

The inexpensive natural alcohol ( )-menthol is obtained from the natural souree, Mentha arvensis, or from myreene via a homogenously eatalysed route (Takasago process) in multi-tonne quantities (Scheme 2.8). 

Regardless of Llieu apparent structural differences, all terpenoids are related. According to a formalism called the isoprene rule, they can be thought of as arising from head-to-tail joining of 5-carbon isoprene units (2-methyl-1,3-butadiene). Carbon 1 is the head of the isoprene unit, and carbon 4 is the tail. For example, myreene contains two isoprene units joined head to tail, forming an 8-carbon chain with two 1-carbon branches. a-Pinene similarly contains two isoprene units assembled into a more complex cyclic structure, and humulene contains three isoprene units. See if you can identify the isoprene units in a -pinene and humulene. 

While earlier it was generally thought that the acyclic monoterpene alcohols 242-245 are derived from the host tree s oleoresin component, myreene [453], more recent results clearly show that at least in some species they are produced denovo [454-456]. 

BOHLMANN, J., STEELE, C. L., CROTEAU, R. Monoterpene synthases from grand fir (Abies grandis) - cDNA isolation, characterization, and functional expression of myreene synthase, (-X4S)-limonene synthase, and (->-<1 S,5S)- pinene synthase, J. Biol. Chem., 1997, 272, 21784-21792. 

The wonderful fragrance of (eaves from the California bay tree is due primarily to myreene, a simple terpene. 

Monoterpenes, on the other hand, possess particularly desirable flavor notes. Three of them, (3-myreene (A.45), limonene (A.46) and p-cymene (A.59) are common to coffee, cocoa and tea, and to numerous plant families (3-myrcene for example constitutes 63% of hop oils. It is worth remembering that they particularly contribute to the flavor of spices. In a study of the effluvia of fresh red coffee berries, Mathieu et al. (1996) identified, in two varieties of robusta, a series of mono- and sesquiterpenes, a blend also present in cold pressed oil from pommelos. In fact, the effluvia of red berries attracts the females of the coffee berry borer, a very important pest. Without giving a list of the hydrocarbons identified in this study, let us note that limonene is the most abundant of them, caryophyllene (4,11,11-trimethyl-8-methylenebicyclo[7.2.0]undec-4-ene), followed by humulene (2,6,6,9-tetramethylundeca-1,4,8-triene) and a-pinene (2,6,6-trimethylbicyclo[3.1.1]hept-2-ene), are rather important in two robusta... 

Oil of Bay. Oil of Myrcia Volatile oil distilled from leaves of Pimento (Myrcia) acris K os tel., Myrtaceae. Constit. 40-55% eugenol myreene, chavico], methyleugenol, methyichavicoi, citral, l-phellandrene total phenols, 50-65% by volume. 

Furanoterpenes. Perillene, (3), one of the simplest furanoterpenes, has been synthesized as shown in scheme (1) from /S-myreene (1) by way of an endoperoxide (2). ... 

Perillene, a monoterpenoid furan derived from p-myreene, is a eonstituent of the essential oil obtained from Perilla citridora (Labiatae) among other monoterpenes, it also occurs in the pheromones of some mites and acts as a defense pheromone of the ant Lasius fulginosus. The isomerie rose furan is a fragrant component of the oil of rose obtained from fresh flowers of Rosa damascena (Rosaceae). 3-(4-Methyl-3-pentenyl)thiophene and derived eyclic tri- and tetrasulfides (1,2,3-trithiepine and 1,2,3,4-tetrathiocine) are found in the oil of hops. 

Vale, T.G., E.C. Furtado, J.G. Santos Jr., and and G.S.B. Viana, 2002. Central effects of citral, myreene and limonene, constituents of essential oil chemotypes from Lippia alba (Mill.) N.E. Brown. Phytomedicine, 9 709-14. 

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