Sesquiterpene monocyclic

Elemene is a monocyclic sesquiterpene resulting from the reduction of elemol, the sesquiterpene alcohol present in Manila elemi oil. It has the following characters —... 

On reduction elemol yields tetrahydroelemol, CigHg O. Elemol is a monocyclic sesquiterpene alcohol, and on dehydration yields the sesquiterpene elemene. 

This reaction is used as one step [(7) to (6)] of the multistage synthesis of the monocyclic sesquiterpenic hydrocarbon, dehydro-a-curumene (3) [6-methyl-2-(4-methylphenyl)hepta-l,5-diene].247 The overall strategy is revealed from a retrosynthetic analysis for this compound, and is of interest since it emphasises the logic of the disconnection approach and draws together a number of important reactions which are relevant to this discussion of unsaturated compounds. 

Amongst the monocyclic sesquiterpenes, the plant growth hormone (+)-abscisic acid 446 and a-humulene 451 are found which both can be synthesized by Wittig reactions. To synthesize (+)-abscisinic acid 446 D. L. Roberts et al. 239) converted a-ionone 444 into the allylic alcohol 445 by /-butyl chromate oxidation. 445 is reacted with ethoxycarbonylmethylene-triphenylphosphorane 238 and subsequently... 

Cyclization of polyenes. Reaction of nerolidol (1) with this brominating agent (1) in CH2CI2 (20°, 3 hours) yields a- and /J-snyderol, (2) and (3), in low yield. These bromine-containing monocyclic sesquiterpenes have been isolated recently from a marine red algae species. ... 

C,5H24, Mr 204.36, colorless oil, bp. 123°C(1.33 kPa). Monocyclic sesquiterpene from the essential oils of many plants such as, e.g., cloves, hops, and various Didymocarpus species. a-H. is often accompanied by the isomeric /5-humulene. The completely hydrogenated, monocyclic derivative of H. is humulane. H. is the biosynthetic precursor of various sesquiterpenoids, see hirsutanes, protoilludanes, etc. formed by basidi-omycetes. 

Formally, C-1 and C-6 of famesane close a cyclohexane ring in the bisabolanes, which represent a more prominent class of monocyclic sesquiterpenes. Additional cyclizations increase the diversity. More than 100 bisabolane derivatives of plant origin are known to date... 

Monocyclic sesquiterpenes bisabolenes in various oils, e.g. myrrh and limete oil, in perfume and fragrance products balsamic odor... 

In the past, it has been considered that a 2-Z-6- -precur-sor gives rise to monocyclic sesquiterpenes with one 6-... 

Juvebione, paper factor a monocyclic sesquiterpene ester from the wood of the North American balsam fir (Abies balsamea). (-h)-J. is an oil, M, 266, [a] +79.5° (c = 3.5, CHCI3). J. was the first juvenile hormone isolated from a plant, and its structure was the first elucidated. It is specific for Pyrrhocoris apterus and only the dextrorotatory form is biologically active. The search for J. began when it was observed that filter paper made from the wood of the balsam fir contained a factor which produced developmental anomalies in the larvae of Pyrrhocoris. In addition to... 

We present here some significant examples in cyclization using Pd-catalyzed allyla-tion, in carbocycle and macrolide chemistry. Humulene, a fundamental monocyclic sesquiterpene, is derived biologically from famesol by anti-Markownikov cyclization no synthesis of this terpene by such cyclization had been realized before the highly stereoselective synthesis presented by Yamamoto and co-workers. The acyclic sesquiterpene skeleton was constructed starting with geranyl acetate via the ( ,ii)-bromide 316, which... 

Figure 11.22. A sample of naturally occurring monocyclic sesquiterpenes.

Scheme 11.48. A representation of potential pathways to monocyclic sesquiterpenes a-elemene and a-bisaboline as examples for other sesquiterpenes in Figure 11.22. Cyclizations and proton migrations are readily accommodated to produce specific products.

The series of monocyclic sesquiterpene derivatives of the isopreno-logons /7-menthane type, includes some particularly interesting aroma components. (-)-a-Bisabolol (178) contributes substantially to the antiphlogistic and spasmolytic activity of camomile (239, 255, 345). 

Sukh Dev 1960 Studies in sesquiterpenes. XVI. Zerumbone, a monocyclic sesquiterpene ketone. Tetrahedron 8 171-180... 

An example of monocyclic sesquiterpenic alcohols is (-l-)-o(-bisabolol (8-24). It occurs in citrus essential oils along with other sesquiterpenic alcohols, and represents the major component of the essential oil of chamomile flowers (Matricaria chamomilla, Asteraceae). a-Bisabolol (0.26%) and other sesquiterpenoids, such as monocyclic sesquiterpenic alcohol (Z)-lanceol (1.7%), bicyclic sesquiterpenic alcohol (Z)-a-essential components of white sandalwood oil (Santalum album, Santa-laceae) used in perfumery, cosmetics and aromatherapy. (Z)-Lanceol is also a component of sage species (Salvia spp., Lamiaceae) essential oil. Sesquiterpenic bicyclic alcohol (-F)-P-nootkatol is the precursor of ketone (-F)-nootkatone, an important component of grapefruit essential oil. Trivial and systematic names of the main sesquiterpenic alcohols are listed in Table 8.7. 

Monocyclic sesquiterpenic ketone (-f)-flr-turmerone (8-52) is the main component (25-50%) of turmeric essential oil (see Table 8.32). It is formed by oxidation of hydrocarbon (-l-)-flr-curcumene, which is present in turmeric rhizomes at a level of about 6%. Bicyclic sesquiterpenic ketone is (-l-)-nootkatone (8-52), which is an important odorous compound of grapefruits formed by oxidation of hydrocarbon (-l-)-valencene via alcohol (-l-)-P-nootkatol. Another oxidation product of valencene is... 

Howard, B. M., and W. Fenical a- and p-Snyderol New Bromo-Monocyclic Sesquiterpenes from the Seaweed Laurencia. Tetrahedron Letters 1976, 41. 

The oil has been, however, carefully investigated by Semmler. It contains about 15 per cent, of a monocyclic sesquiterpene, Cx5Hj, boiling at IdO at 20 mm., and of specific gravity 0-8733 and refractive index 1-4920. An oxide, termed Carlina oxide, C jO, of specific gravity 1-066 and refractive index 1-5860, forms the principal constituent of the oil. It is a complex furane derivative of the constitution. CH -. C CH. (C HjO). Semmler has also isolated a sesquiterpene which... 

The oil has been, however, carefully investigated bv Seiiimler, It contains about ID per cent, of a monocyclic sesquiterpene boiling... 

Gibberodione and chabrolidione A may be the two first examples of monocyclic sesquiterpenes having the carbon skeleton of secoguaiane. These two closely related derivatives were isolated from Sinularia g bberosa and Nephthea chabrdii, respectively, both collected in the vicinity of Taiwan. These derivatives are only moderately cytotoxic. The epimer 1-epi-chabrolidione A was recently isolated from another Taiwanese soft coral Sinularia leptoclados (Su et al, 2010a). 

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