Verbenene

It is convenient to here mention the hydrocarbon verbenene, C,gH,4, on account of its relationship with pinene. It results from the action of acetic anhydride on verbenol, thei alcohol corresponding with the ketone, verbenone. So produced it is laevo-rotatory. The dextro-rotatory and racemic varieties are also known. The sesquiterpenes have the following characters when regenerated from their respective dibromides —... 

It yields ordinary pinene hydrochloride when treated in the usual manner with hydrogen chloride. Verbenene and 8-pinene have the following constitutions —... 

Verbenene 5 6,6-Dimethyl- 4-methylene bicyclo Q 3.1. l hept-2-ene 2(10),3-Pinadiene... 

Gries G., Borden J. H., Gries R., LaFontaine J. P., Dixon E. A., Wieser H. and Whitehead A. T. (1992a) 4-Methylene-6,6-dimethylbicyclo[3.1.1]hept-2-ene (verbenene) new aggregation pheromone of the scolytid beetle, Dendroctonus rufipennis. Naturwissenschaften 79, 367-368. 

A second example is the spruce beetle, Dendroctonus rufipennis (Kirby) (Coleoptera Scolytidae), a major cause of mortality in mature spruce stands. Gries et al. (1992) found that the terpene verbenene (31 in Figure 19.5), was emitted from the beetles, predominantly from females, and concluded that it is a pheromone component. The oxygenated compounds seudenol, frontalin, and l-methyl-cyclohex-2-en-l-ol, were previously identified as pheromone components in this species. Attraction to verbenene alone was demonstrated in field traps, and it enhanced captures to the other pheromone components. The absolute configuration of verbenene has not been investigated. 

In the case of verbenone tosylhydrazone (117), 8-pinene (118) is produced along with verbenene (119) following methyllithium treatment (equation 17). ... 

A mixture of o-menthanes resulted from reduction of o-cymene with Ca(NH3)6,297 and a neat route to the o-menthane skeleton involved photochemical addition of allene to 3-methylcyclohex-2-en-l-one and opening of the cyclobutyl ring with BF3.298 O-Menthadi- and tri-enes resulted from pyrolysis of verbenene.299 Acid-and base-promoted isomerizations of o-menthadienes300 and dehydration of cis- and trans- o-menthan-8-ols with a variety of reagents have been recorded.301 Optically active 2-methyl-4-isopropenylcyclohexanone (which is a useful precursor for ra-menthane derivatives) has been prepared by pyrolysis of chiral 2,2,5-trimethyl-bicyclo[3.1.1 ]heptan-2-one.302... 

The pyrolysis of verbenene (685) leading to o-menthatrienes, has been reexamined, and a number of o-menthadienes and two stereoisomers of an o-terpineol (686) have been prepared from a Diels-Alder reaction between 1,3-pentadiene and methyl acrylate, with subsequent Grignard addition. ... 

The third recorded production of bicyclo[4,l,l]octanes from the reaction of carbenes with a-pinene has appeared (see Vol. 2, p. 50), but this is clearly independent work, since it is nearly contemporary (202a). There is a fourth note describing carbene additions to pinenes. but this time including verbenene (340) (which reacts first on the exocyclic double bond and then on the other) and some oxygenated compounds. ... 

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