Aromatic compounds pheromones

Analytical Properties Separation of positional isomers of aromatic compounds and geometrical isomers of sex pheromones Reference 7... 

Male moths and butterflies have proven to be an especially rich source of interesting natural products. The sex pheromone produced in the wing glands of the lesser waxmoth, Achroia grisella, is composed of n-undecanal and (Zj-ll-octadecenal (98), whereas that of the greater waxmoth also contains n-undecanal (.99) but is dominated by n-nonanal (100). The scent brushes of male noctuid moths produce large amounts of aromatic compounds and terpenes which are believed to function as aphrodisiacs (101). Benzaldehyde, 2-phenyl ethanol, benzyl alcohol, 6-methyl-5-hepten-2-one, pinocarvone, and isobutyric acid have been identified in the secretions of different noctuid species (102), and it appears that these pheromones may possess some chemotaxonomic value. 

In addition to acyclic ketones, dolichoderine ants in the genus Azteca generate an alarm signal with 2-methylcyclopentanone (xxxi),cis-l-acetyl-2-methylcyclopentane (XXXII), and 2-acetyl-3-methylcyclopentene (XXXIII) (128). That some ant species utilize aromatic compounds as alarm pheromones is demonstrated by the identification of methyl 6-methyl salicylate (XXXIV) in the... 

R)-(-)-Hydro tycarbo)tylic acid can be widely used as a chiral building block for the synthesis of fine chemicals such as antibiotics, vitamins, aromatics, and pheromones. Its hydroxyl and carboxylic groups are amendable to modification in addition to being utilized as precursors for the synthesis of new compounds. 

Figure 8.4 Some simple aromatic compounds found in abdominal glands of adult male leaf-footed beetles, probably recognition pheromones. 2-Nitroethenylbenzene (nitrostyrene) is a defensive compound from a millipede...

It is known that primitive insects like Collembola (springtails) do produce pheromones, but so far only the alarm pheromone of Neanura muscorum has been identified as 1,3-dimethoxybenzene. Its origin is unknown. Other simple aromatic compounds like 2,4-dimethoxyaniline, phenol and 2-aminophenol were also found in whole body extracts. 

However, the components of the pheromone of a butterfly are known to give different amplitude EAG s (359). Grant (360) found that pheromones from different species elicit EAG s of similar amplitude in a common recipient. EAG s of similar amplitude were obtained when the antenna of the armyworm, Pseudaletia unipunctata, was stimulated with the male s known pheromone components, benzaldehyde, benzyl alcohol and benzoic acid, or with the related aromatic compounds, 2-phenyl-ethanol and benzyl acetate (361). The antennal response of male European corn borer moths, Ostrinia nubilalis, to their two pheromone components, (Z)- and ( )-ll-tetradecenyl acetates has recently shown that repetitive stimulation with one of the isomers results in adaptation which affects the amplitude of response in subsequent tests to both compounds (362). 

When allylic compounds are treated with Pd(0) catalyst in the absence of any nucleophile, 1,4-elimination is a sole reaction path, as shown by 492, and conjugated dienes are formed as a mixture of E and Z isomers[329]. From terminal allylic compounds, terminal conjugated dienes are formed. The reaction has been applied to the syntheses of a pheromone, 12-acetoxy-1,3-dode-cadiene (493)[330], ambergris fragrance[331], and aklavinone[332]. Selective elimination of the acetate of the cyanohydrin 494 derived from 2-nonenal is a key reaction for the formation of the 1,3-diene unit in pellitorine (495)[333], Facile aromatization occurs by bis-elimination of the l,4-diacetoxy-2-cyclohex-ene 496[334],... 

Pheromone chemistry in scarab beetles, chafers, and dung beetles covers a wide range of structures, including esters of amino acids and aromatics as well as branched and straight chain aliphatic compounds, among which a row of y-lactones forms a most characteristic group. 

Insects communicate through the use of a great variety of volatile pheromones. As mentioned in Chapter 8, Section A,l, some moths utilize acetate esters of various isomers of A7 and A11 unsaturated C14 fatty acids as sex pheromones. Some other moths convert the trans-l 1 -tetradecenyl acetate into the corresponding C14 aldehyde or alcohol, while others use similar compounds of shorter (Cn - C12) chain length.143 Some ants use ketones, such as 4-methyl-3-heptanone, as well as various isoprenoid compounds and pyrazines as volatile signaling compounds.144 Other insects also utilize isoprenoids,145 alkaloids,146 and aromatic substances as pheromones. 

The Baeyer-Villiger reaction is regioselective — the more substituted group migrates—and stereospecific — it does so with retention. Hydroxy ketone (22) was needed for insect pheromone synthesis and is a 1,6-difunctionalised compound. It could be made by nucleophilic displacement by an organo-metallic reagent (R ) on lactone (23), the Baeyer-Villiger product from (24) which can be made from aromatic (26). 

CJundecane. Lithium didecylcuprate, prepared by reacting copper(I) iodide in ether with decyllithium in hexane, has been coupled with [ C]H3l. The above [ C]-labelled aliphatic and aromatic hydrocarbons have been used to study their effects on man, since they are common components in air pollutants. Aliphatic saturated and unsaturated hydrocarbons act also as pheromones and defensive secretions among some social insects such as ants and bees. The C-labelled compounds have been applied for in vivo studies" . ... 

Liquid-crystalline stationary phases are used to analyze a great number of chemical compounds such as polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polychlorinated dibenzodioxins, polychlorinated dibenzofur-ans, polychlorinated naphthalenes, terpenes, steroids, pesticides, pheromones, etc. 

Significant aliphatic sulfur compounds are methional, 3-methyl-but-2-ene-1-thiol, 3-mercapto-3-methylbutan-l-ol (8-124), its ester 3-mercapto-3-methylbutyl formate, methanethiol and dimethyltrisulfide. 3-Mercapto-3-methyl-l-ol also occurs in passion fruit and blackcurrant, and as a putative cat pheromone in cat urine, where it is formed as a degradation product of amino acid L-felinine (see Section 2.2.1.2.2). Of more than 70 known pyrazines, the most important compounds in roasted coffee are isopropylpyrazine, 2-isobutyl-3-methoxypyrazine, 2-ethyl-3,5-dimethylpyrazine, 2,3-diethyl-5-methylpyrazine, 2,6-dimethyl-3-vinylpyrazine and 2-ethyl-6-methyl-3-vinylpyrazine. Pyridine and its alkyl derivatives and bicyclic pyridines have a negative impact on the quality of coffee aroma. Important aromatic... 

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