Pheromone acetals

In some species, male variation in response to component ratio offset from the natural blend is somewhat modulated by ambient temperature (Linn et al, 1988). The response specificity of G. molesta and P. gossypiella to off-ratios of pheromone acetate components in a wind tunnel assay was narrower at 20 °C than at 26 °C. In the field, sexual activity in both species occurs at both of these temperatures, depending on time of year. Some field evidence of this phenomenon with P gossypiella appears in the distribution of catch in traps baited with a range of ratios measured at various times of the flight season. Flint et al. (1977) found an evidently narrower response breadth early in the season (when temperatures were cool) compared with late-season responses. In the omnivorous leafroller Platynota stultana, the optimum ratio of its two components for attraction seems to shift with temperature in the... 

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],... 

The preparation of the sex pheromone of the bollworm moth, ( )-9,ll-dodecadien-l-yl acetate, from compound A has been described. Suggest suitable reagents for each step in this sequence. 

The ant Iridomyrmex pruinosus utilizes 2-heptanone as an alarm pheromone. Figure 17 illustrates the existence of a close correlation of the similarity between 2-heptanone and its analogs in molecular model silhouettes with their alarm activity45. It is noteworthy that the replacement of the methylene group in position 3 of 2-heptanone by the ether linkage yields n-butyl acetate which has the same activity as the natural pheromone. Considerable activity is still retained even when the carbonyl group is replaced by the hydroxyl group. 

In an article dealing with applications of olefin CM to a series of commercial products [138], solvent-free CM between ( )-3-hexene (produced by homocoupling of 1-butene) and 11-eicosenyl acetate 303 (produced from jojoba oil) was used to produce acetate 304 (Scheme 59), which is - as a natural 82 18 (EIZ) mixture - the pheromone of omnivorous leafroller, and serves as an environment-friendly pest controlling agent. The CM reaction was performed without solvent at 5 °C with a 4 1 mixture of ( )-3-hexene and 303, in the presence of only 0.2 mol% catalyst C, and furnished after 20 h coupling product 304 ( Z=83 17) in 50% yield. 

Recognising the acetal in frontalin (3), a pheromone of the western pine beetle," is not so easy. Nevertheless, it is Important to look for the two oxygen atoms joined to the same carbon atom ( in 3a) and disconnect the acetal before considering any other steps. 

Frontalin (18), the pheromone of the western pine beetle, is an acetal (atom has two single bonds to oxygen). Disconnection reveals diol ketone (19). 

The insect pheromone lineatin (21) contains a four-membered ring it also contains an acetal and disconnection of this reveals the carbon skeleton (22). Lineatin analysis... 

Show how organoborane intermediates can be used to synthesize the gypsy moth pheromone E, Z-CH3C02(CH2)4CH=CH(CH2)2CH=CH(CH2)3CH3 from hept-6-ynyl acetate, allyl bromide, and 1-hexyne. 

Rasmussen L.E.L., Lee T.D., Zhang A., Roelofs W.L., et al. (1997). Purification, identification, concentration and bioactivity of (Z)-7-dodecen-l-yl acetate sex pheromone of the female Asian Elephant, Elephas maximus. Chem Senses 22, 417-438. 

Scheme 14 illustrates Linstrumelle s synthesis of (9Z,11 )-9,11,13-tetradeca-trienyl acetate (8), the pheromone of the pyralid moth, Stenoma cecropia [25]. The key steps were palladium and copper-catalyzed Sonogashira couplings (A+B and C+D). Another noteworthy feature in this synthesis was the use of activated zinc dust in aqueous methanol for the reduction of the triple bonds of E to give two double bonds of 8. 

Kitching employed the titanium (Il)-based czs-reduction of alkynes in their synthesis of (3 ,8Z,llZ)-3,8,ll-tetradecatrienyl acetate (9), the pheromone of the moth Scrobipalpuloides absoluta as shown in Scheme 15 [15]. 

Scheme 27 summarizes Yamamoto s synthesis of lardolure (16), the aggregation pheromone of the acarid mite, Lardoglyphus konoi [45]. The key-step was the transformation of acetal A to hemiacetal B. 

S)-3,7-Dimethyl-2-oxo-6-octene-l,3-diol (39) was recently identified as the aggregation pheromone of the Colorado potato beetle (Leptinotarsa decem-lineata), and synthesized by Oliver et al., starting from (S)-linalool [86]. An improved synthesis of (S)-39 by Mori is shown in Scheme 57 [87]. Enzymatic acetylation of ( )-2,3-epoxynerol (A) with vinyl acetate and lipase PS gave B together with C. The acetate B was converted to a multi-gram quantity of (S)-39 according to Oliver [86]. 

Synthesis of Oxygen Heterocycles (Excluding Epoxides, Hemiacetals, Lactones and Acetals) as Pheromones... 

Fig. 9A,B GC-MS analysis of the pheromone extract of Anadevidia peponis (Noctuidae, 1 FE) treated with DMDS A TIC B mass chromatograms [141]. The mass chromatograms, which are multiplied by indicated factors, monitor the M+ of DMDS adducts derived from C10 to C16 monoenyl acetates (m/z 292,320,348, and 376) and some diagnostic fragment ions (m/z 89,117,145,173,175,203,231, and 259) to determine their double-bond position. Peaks I-VI indicate the DMDS adducts of the following components in the pheromone gland Z5-10 OAc (I),Z5-12 OAc (II),Z7-12 OAc (III), ll-12 OAc (IV),Z9-14 OAc (V), and Zll-16 OAc (VI)...

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