Ambrosia beetle

Fpobtem Suggest a synthesis of optically active S-(+)-sulcatol (13), the aggregation pheromone of the wood-boring ambrosia beetle, from available ethyl (S)-(-)-lactate (14). 

The reaction in Entry 5 was used in the syntheses of linetin, which is an aggregation pheromone of the ambrosia beetle. In Entry 6, a transannular 5-exo cyclization occurs. Entry 7 is an example of formation of a lactone by carboxylate capture. In this case, the product was isolated as the mercurochloride. 

This structure had originally been assigned to lineatin, an aggregation pheromone of the female ambrosia beetle, which has since been shown to have structure 3. The same laboratory has effected synthesis of 3 from 4. Both 1 and 4 were obtained from a common intermediate in the total synthesis. 

Figure 6.9 Examples of pheromone components of bark beetles (Scolytidae) and ambrosia beetles (Scolytidae and Platypodidae) classified by likely biosynthetic origin (based on Francke and Schulz, 1999). (A) References for identification and/or behavioral activity of isoprenoid pheromone compounds are as follows-. 2-methyl-3-buten-2-ol (Bakke efa/., 1977 Giesen etal., 1984 Klimetzek etal., 1989a Lanne etal., 1989), 3-methyl-3-buten-1-ol (Stoakley etal., 1978 Bowers and Borden, 1990 Bowers etal, 1991 Zhang efa/., 2000), 3-methyl-1-butanol (Renw ick etal, 1977), 3-hydroxy-3-methylbutan-2-one (Francke and Heeman, 1974 Francke etal 1974), ipsenol and ipsdienol...

Figure 6.10 De novo biosynthesis of isoprenoid pheromone components by bark and ambrosia beetles through the mevalonate biosynthetic pathway. The end products are hemiterpenoid and monoterpenoid pheromone products common throughout the Scolytidae and Platypodidae (Figure 6.9A). The biosynthesis is regulated by juvenile hormone III (JH III), which is a sesquiterpenoid product of the same pathway. The stereochemistry of JH III is indicated as described in Schooley and Baker (1985). Although insects do not biosynthesize sterols de novo, they do produce a variety of derivatives of isopentenyl diphosphate, geranyl diphosphate, and farnesyl diphosphate. Figure adapted from Seybold and Tittiger (2003).

Figure 6.11 Biosyntheses of isoprenoid pheromone components by bark and ambrosia beetles from host conifer monoterpenes. (A) Conversion by the male California fivespined ips, Ips paraconfusus Lanier (Coleoptera Scolytidae), of myrcene from the xylem and phloem oleoresin of ponderosa pine, Pinus ponderosa Laws., to (4S)-(+)-ipsdienol and (4S)-(-)-ipsenol, components of the aggregation pheromone (Hendry et al., 1980). (B) Conversion by male and female I. paraconfusus of (1 S,5S)-(-)-a-pinene (2,6,6-trimethyl-bicyclo[3.1,1]hept-2-ene) from the xylem and phloem oleoresin of P. ponderosa to (1 S,2S,5S)-(+)-c/s-verbenol (c/s-4,6,6-trimethyl-bicyclo[3.1,1]hept-3-en-2-ol), an aggregation pheromone synergist and of (1 R,5R)-(+)-a-pinene to (1 fl,2S,5fl)-(+)-frans-verbenol (frans-4,6,6-trimethyl-bicyclo[3.1,1]hept-3-en-2-ol), a compound of unknown behavioral activity for /. paraconfusus. Male and female western pine beetle, Dendroctonus brevicomis LeConte (Coleoptera Scolytidae), convert (1 S,5S)-(-)-a-pinene to (1S,2ft,5S)-(-)-frans-verbenol, an aggregation pheromone interruptant and (1R,5R)-(+)-a-pinene to (1 R,2S,5R)-(+)-frans-verbenol, a compound of...

Renwick J. A. A., Vite J. P. and Billings R. F. (1977) Aggregation pheromones in the ambrosia beetle, Platypus flavicornis. Naturwissenschaften 64, 226. 

Another insect pheromone synthesis illustrates one of the drawbacks of chiral pool approaches. The ambrosia beetle aggregation pheromone is called sulcatol and is a simple secondary alcohol. This pheromone poses a rather unusual synthetic problem the beetles produce it as a 65 35 mixture of enantiomers so, in order to mimic the pheromone s effect, the chemist has to synthesize both enantiomers separately and mix them together in the right proportion. 

Figure 7. Pheromones from R or S lactone acid for beetles dermestids (y-capro-lactone), Pityogenes chalcographus (L.), Japanese beetle (I, Fig. 1), ambrosia beetle, and lesser grain borer beetle gypsy moths and block-tailed deer.

Pheromones of insect species in the order Coleoptera are characterized by considerable structural diversity. Unlike the lepidopterous sex pheromones, which are nearly all tatty acid derivatives, coleopterous sex pheromone structures range in complexity from the relatively simple 3,5-tetradecadienoic acid of the black carpet beetle to the tricyclic terpenoid, lineatin, of the striped ambrosia beetle. While the sex pheromones of many beetles consist of mixtures of compounds that act synergistically to elicit a behavioral response, other Coleoptera species appear to use only a single compound for chemical communication between the sexes. In the latter case the compound usually has at least one chiral center and chirality plays a major role in determining pheromone specificity. 

A very short asymmetric synthesis of an insect attractant, (lS,35,5f )-l,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane, has been realized with high enantio- and diastereo-selectivity by means of an (5)-3f-mediated aldol reaction strategy (Eq. 52) [43c]. This compound is a host-specific substance for the ambrosia beetle that infests the bark of the Norway spruce. 

The natural product (R)-sulcatol is a male-produced aggregation pheromone of the ambrosia beetle. This insect can devastate entire forests when its population is out of control.Various studies revealed that different species respond to the compound in different enantiomeric excess. The asymmetric synthesis of (R)-sulcatol was accomplished in the laboratory of S.G. Davies using a stereospecific [2,3]-Meisenheimer rearrangement as the key step. The treatment of the allylic amine substrate with mCPBA followed by the filtration of the reaction mixture through deactivated basic alumina afforded the desired hydroxylamine as a single diastereomer. 

A modern approach to dealing with insect pests that wreck crops is to use specific attractants to lure the pest to its doom while offering no threat to beneficial creatures. Compounds such as grandisol 34 are not themselves toxic but they are irresistible to specific insect pests. Grandisol, marketed as grandlure , an attractant for male cotton boll weevils, is one of a family of unusual monoterpenes containing a four-membered ring. Others are lineatin 35, an attractant for ambrosia beetles that bore into conifers, filifolone 36, and raikovenal 37 (a sesquiterpene). 

In 1974, Silverstein and coworkers isolated and identified sulcatol (103, Figure 4.51) as the male-produced aggregation pheromone of Gnathotrichus sulcatus, an economically important ambrosia beetle in the Pacific coast of North America. They showed the natural pheromone to be a 35 65 mixture of (R)-103 and (5)-103 by -NMR analysis of its Mosher ester (a-methoxy-a-trifhioromethylphenylacetate). The reason why the beetle produces a mixture of enantiomers was unclear at the time of its discovery. 

Other less common insects have strong symbiotic relationships. Ambrosia beetles cultivate mold in their brood chambers and can survive for only one generation without a supply of the ergosterol that is produced by... 

Reaction of 147 with the mixed cuprate of 3-methy 1-2-butene gives, in one step, (/ )-( — )-sulcatol (148) the enantiomer of an aggregation pheromone of a wood-boring ambrosia beetle [53]. Oxirane 147 has also been instrumental in the synthesis of (2S, 5/ )-2-methyl-5-hex-anolide (151), one of the antipodes of the sex pheromone of the carpenter bee [54] (Scheme 22) and the macrolide fungal metabolite (7 )-recifeiolide (155) [55] (Scheme 23). 

Oxirane 40 has been used in the synthesis of a variety of natural products, such as (5)-( + )-sulcatol (319), the aggregation pheromone of a wood-boring ambrosia beetle [53], and (2R,... 

TOMMERAS, B. a., MUSTAPARTA, H., Single cell responses to pheromones, host and non-host volatiles in the ambrosia beetle Typodendron lineatum, Entomol. Exp. Appl, 1989,52, 141-148. 

Both the enantiomers of sulcatol [21], the pheromone of the ambrosia beetle Gnathotrichus sulcatus, were totally inactive. Their mixture, however, showed strong pheromone activity. 

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