Oviposition attractant pheromone

Scheme 41 summarizes Couladouros s synthesis of the oviposition attractant pheromone of the Southern house mosquito (Culexpipiensfatigans)y (5R,6S)-6-acetoxy-5-hexadecanolide (28) [66]. The key-steps are (i) -selective Schlosser olefination (A B), asymmetric dihydroxylation (B C), and lactonization of carbonate C to the desired 6-lactone with inversion at C-5. 

Based on the previous work of this group on the three-component aza[4+2]/ allylboration strategy to construct polysubstituted piperidines [62], Gao and Hall developed a catalytic enantioselective version [63] of the corresponding oxygeneous process to construct a-hydroxyalkylated pyrans from 3-boronoacrolein [64], This recent variant of a Vaultier-Lallemand one-pot three-component reaction (see Scheme 12.14) was successfully applied to a concise total synthesis of (5R,6S)-6-acetoxy-5-hexadecanolide 128 (Scheme 12.20), the oviposition attractant pheromone of the female Culex mosquito [65] capable of transmitting the West Nile virus. 

The enantiospecific synthesis of ( + )-ef7r/zro-(5 S, 6i )-6-acetoxy-5-hexadecanolide (475), an optically active form of the major component of an oviposition attractant pheromone of the mosquito Culexpipiens fatigans, exploits the 6,8-dioxabicyclo[3.2.1]octane system to provide... 

A methodologically similar approach was successfully utilized independently for the synthesis of the oviposition attractant pheromone of the female Culex mosquito (—)-(5/ ,6S )-6-acetoxyhexadecanolide (28), by Kotsuki et al. 45) and Li et al. 46). While the Li group carried out a direct aldol reaction between undecanal (23) and cyclopentanone (24) to obtain the desired isomer 25 in excellent enantio- and diastereoselectivity, the Kotsuki group introduced the stereogenic centers by a reaction between 24 and the dithiane 26 under solvent-free conditions (Scheme 7). 

Of the simpler 8-lactone natural products, syntheses of malyngolide, mevalonolactone, and an oviposition-attractant pheromone of a mosquito ... 

An egg parasitoid uses the sex pheromone of the tussock moth to find the eggs, which are deposited shortly after mating.168 An oviposition attractant for the mosquito, Culexpipiens fatigans, is shown (11.38).169... 

Turning to detritivores, several species of Culex and Aedes mosquitoes are attracted to potential oviposition sites or stimulated to oviposit by pheromones emitted by conspecific eggs, larvae, or pupae (Mulla, 1979). Presumably such pheromones indicate locales of comparatively ample resources which have proved favorable to recent development of conspecifics. On the other hand, larvae of some of these same species, when overcrowded, emit chemicals which are toxic or growth-retarding to conspecifics (Mulla, 1979). How these two facets of chemical regulation of mosquito egg and larval density relate to one another and to individual fitness is uncertain and merits further study. 

Additional compounds found in the pheromone gland of female cigarette beetles are (2S,3R,l R)-2,3-dihyro-2-ethyl-3,5-dimethyl-6-(r-methyl-2 -oxo-butyl)-4ff-pyran-4-one 121 (P-serricorone), its (rs)-epimer (a-serricorone), and its reduction product, serricorole, 122 which shows (l/S,2/S)-configuration [245-247]. These compounds showed only weak attractivity [245], however, they obviously act as oviposition deterrents [248,249]. 

The use of single semiochemicals in the field is not usually sufficient for pest control, but by combining semi-ocheinicals, substantial protection can be achieved using an integrated approach called the push-pull system. The push is located in the crop and may comprise antifeedants, nonhost semiochemicals, attraction of predators or parasitoids, oviposition deterrents, or epideictic pheromones. The pull component comprises lures or trap areas away from the crop containing the sex pheromone, host odors, oviposition... 

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