Natural sex pheromone

Hydroboration/protonolysis of ( )-enynes completes a route to (E, Z)-dienes. For example, the ( )-enyne generated in Figure B4.6 was converted into (IE, 9Z)-7,9-dodecadien-l-yl acetate (a natural sex pheromone of the European grape vine moth Lobesia botrana) by hydroboration with Sia2BH followed by acetic acid protonolysis (Equation B4.7). 

Many insect pheromones have conjugated cis, trans-diene system l52, l53). The versatility of these reactions is exemplified in the synthesis of many natural products l53-154, 55 In Eq. 99, the four step synthesis of a natural sex pheromone of the European grape vine moth (Lobesia botrana), (7E, 9Z)-7,9-dodecadien-l-yl acetate, is illustrated 155). 

We have prepared the optical isomers of the former (49) and the geometric and optical isomers of the latter (48) and biological evaluations have demonstrated that one isomer of each component is significantly more active than the others (50). Thus the natural sex pheromone probably consists of a mixture of (3j3,6R)-XV and (3Z,6R)-XVI (Figure 5). Field tests have also shown that the compounds XV and XVI are independently attractive to males, and that there is no synergistic effect when XV and XVI are combined. In addition, the presence of the inactive stereoisomers does not inhibit the trap catch of males. Thus synthetic compound for use in monitoring traps in the field can be either XV or XVI and need not be stereochemically pure. 

The cis-isomer that is shown is the natural sex pheromone of the gypsy moth. Disparlure is an aliphatic hydrocarbon (methyl-octadecan) with an epoxy group. It is used as an attractant and is formulated in plastic flakes. The racemic mixture may also be used. 

The cis-isomer that is shown is the natural sex pheromone of the gypsy... 

In 1952, it was reported that a constituent of excretions from female American cockroaches of the species Periplaneta ameri-cana is an extraordinarily potent sex pheromone.1 Early attempts to isolate and characterize the active compounds were hampered because individual cockroaches store only minute amounts of the pheromone ( 1 pg), and a full 25 years elapsed before Persoons et al. reported the isolation of two extremely active compounds, periplanones A and B.2 The latter substance is present in larger relative measure and its germacranoid structure (1, without stereochemistry) was tentatively assigned on the basis of spectroscopic data. Thus, in 1976, the constitution of periplanone B was known but there remained a stereochemical problem of a rather serious nature. Roughly three years intervened between the report of the gross structure of periplanone B and the first total synthesis of this substance by W. C. Still at Columbia.3... 

In addition to the synthetic applications related to the stereoselective or stereospecific syntheses of various systems, especially natural products, described in the previous subsection, a number of general synthetic uses of the reversible [2,3]-sigmatropic rearrangement of allylic sulfoxides are presented below. Several investigators110-113 have employed the allylic sulfenate-to-sulfoxide equilibrium in combination with the syn elimination of the latter as a method for the synthesis of conjugated dienes. For example, Reich and coworkers110,111 have reported a detailed study on the conversion of allylic alcohols to 1,3-dienes by sequential sulfenate sulfoxide rearrangement and syn elimination of the sulfoxide. This method of mild and efficient 1,4-dehydration of allylic alcohols has also been shown to proceed with overall cis stereochemistry in cyclic systems, as illustrated by equation 25. The reaction of trans-46 proceeds almost instantaneously at room temperature, while that of the cis-alcohol is much slower. This method has been subsequently applied for the synthesis of several natural products, such as the stereoselective transformation of the allylic alcohol 48 into the sex pheromone of the Red Bollworm Moth (49)112 and the conversion of isocodeine (50) into 6-demethoxythebaine (51)113. 

Wabnitz P., Bowie J., Tyler M., Wallace J. and Smith B. (1999). Aquatic sex pheromone from a male tree frog. Nature 401, 444-445. 

Scheme 7 summarizes the synthesis of (7JR,llS)-7,ll-dimethylheptadecane (1), the female sex pheromone of the spring hemlock looper (Lambdina athasaria) by Mori [ 18]. Enantiopure alkanes are usually synthesized by coupling enantio-pure building blocks derived from natural products or compounds prepared by asymmetric synthesis. Even among hydrocarbons, chirality is very important for pheromone activity, and in this particular case meso-1 was bioactive, while neither (7R,11R)-1 nor (7S,11S)-1 showed bio activity. 

Scheme 32 summarizes Matteson s synthesis of serricornin [(4S,6S,7S)-21], the female sex pheromone of the cigarette beetle (Lasioderma serricorne) via boronic esters [55]. Due to the highly stereoselective nature of boronic ester chemistry, this synthesis of 21 was quite efficient. 

Different from the use of ordinal insecticides, this disruption method has high target selectivity and, as would be desired, ensures the survival of natural enemies. The sex pheromone, which shows no toxicity to mammals, is an ideal insect-behavior regulator (IBR). Table 8 shows the application areas of main mating disruptants for lepidopteran insects. In addition to the use of the synthetic pheromone of P. gossypiella in large cotton fields, many disruptants are... 

By means of intracellular recording and staining methods, we have examined the responses of AL neurons to stimulation of the ipsilateral antenna with each of the sex pheromone components as well as partial and complete blends (75). In accordance with results of behavioral and sensory-receptor studies, components A and B are the most effective and potent sex pheromone components for eliciting physiological responses in the male-specific AL neurons. On the basis of these responses, we classified the neurons into two broad categories pheromone generalists and pheromone specialists (76). Pheromone generalists are neurons that respond similarly to stimulation of either the component A input channel or the component B input channel and do not respond differently when the complete, natural pheromone blend is presented to the antenna. In contrast, pheromone specialists are neurons that can discriminate between antennal stimulation with component A and stimulation with component B. There are several types of pheromone specialists. Some... 

Male sand flies release this sex pheromone to attract females for mating. The males attractant is more potent when mingled with odors from a host that can furnish a blood meal, so that a male sand fly is a more efficient lure for females when he is on an appropriate host. This host attractant in humans is some component of skin odor, but its chemical nature is still obscure. Experiments with human volunteers have revealed that individuals have widely differing levels of attraction for sand flies and that a single individual s attractiveness fluctuates over time. Male sand flies respond to these host odors just as females do, even though they do not feed on blood. In this way, flies can meet and mate on a host, and the mated female can proceed to take a blood meal at once in preparation for laying her eggs. 

Aldrich JR (1988) Chemistry and biological activity of pentatomid sex pheromones. In Cutler H (ed) Biologically active natural products potential uses in agriculture. Am Chem Soc Symposium Series 380, Washington DC, p 417... 

Females of several species use (R)-5-[(lZ)-l-octenyl]oxacyclopentan-2-one, buibuilactone 69 [ 140-144]. The first y-lactone identified from a scarab beetle was (R)-5-[(Z)-l-decenyl]oxacyclopentan-2-one, japonilure 70, the female produced sex pheromone of the Japanese beetle Popillia japonica [145]. Both 69 and 70 are components of specific blends of several species [140-143]. The Japanese beetle is extremely sensitive to the non-natural enantiomer of his pheromone as little as 1% of the (S)-enantiomer inhibits the attractiveness of the pheromone [ 145]. With respect to species discrimination, this is particularly... 

The male-produced sex pheromone of the red flour beetle, Tribolium cas-taneum>has been identified to be (4 ,81 -4,8-dimethyldecanal 164 (tribolure) [320,321]. During bioassays, a mixture of the (4R,8R) and (4.R,8S)-stereoisomers proved to be more active than the pure (4 ,810-enantiomer [322]. The exact enantiomeric composition of the natural product remains as yet unknown. 4,8-Dimethyldecanal was found in other Tribolium species, too [323]. Factors affecting the pheromone production in T castaneum have been described by Hussain et al. [324]. 

Another contact sex pheromone was identified as a component of the cuticular lipids of females of Psacothea hilaris [350,351]. Extracts of the elytra contained (Z)-21-methyl-8-pentatriacontene 189. The synthetic compounds (both enantiomers were synthesized [352,353]) induced precopulatory behaviour in males, however, its biological activity was considerably lower than that of the natural extract. 

So far in our discussion, life has been simple in one respect each action of a pheromone has been the consequence of one or two, or a few in the case of the brown algae, molecules in one species. In nature, things can be more complex. One molecule can serve as a pheromone for multiple species benzaldehyde serves as a trail pheromone for bees, Trigona genus a defense pheromone for ants, Veromessor genus and as a male sex pheromone in the moth, Pseudaletia genus. 

This long-chain unsaturated ester serves as one component of a mnlticomponent female sex pheromone for 140 species of moths as well as the Asian elephant. This is nnlikely to cause any real confnsion in nature. On the one hand, the 140 species of moths keep ont of each other s way and out of the elephant s way by varying the nature and relative concentrations of other components in the multicomponent pheromone. On the other hand, the male elephant is not likely to detect the extremely small amonnts of this pheromone released by female moths. Chemistry aside, there are other obvions difficnlties in moths mating with elephants in the wild. 

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