Dendroctonus brevicomins

Salom SM, Billings RE, Upton WW, Dalusky MJ, Grosman DM, Payne TI, Berisford GW, Shaver TN, Effect of verbenone enantiomers and racemic endo-brevicomin on response of Dendroctonus frontalis (Coleoptera Scolitidae) to attractant-baited traps, Can JForRes22 S2 i—3 i, 1992. 

Recently, M. Asami and T. Mukaiyama 124) synthesized ot-benzyloxyaldehydes (109) having a chiral tertiary center at the ot-carbon atom in high enantiomeric excess by successive treatment of the aminal (102) with diisobutylaluminium hydride (DIBAL-H) and Grignard reagents. The asymmetric reaction is applied to the total synthesis of exo-(+)-brevicomin (110), the principal aggregation pheromone in the frass of the female western pine beetle (Dendroctonus brevicomis). 

The western pine beetle Dendroctonus brevicomis is perhaps the most destructive insect enemy of western pine forests. The aggregation pheromone is a mixture of the terpenoid myrcene [123-35-3] (163) from the tree and the frass pheromones dv< -brevicomin [20290-99-7] (164) and frontalin [28401-39-0] (165). The Norway spruce beetle Ips typographus converts the tree terpenoid myrcene into the frass pheromone ipsdienol [35628-00-3] (166) and the beetles also produce 2-methyl-3-buten-2-ol [115-18-4]t and of-verbenol [473-67-6] (167), all of which are components of the aggregation pheromone. 

Figure 6.12 Cyclization reactions of acyclic, unbranched and methyl-branched ketones to bicyclic acetals and cyclic alcohols in bark beetles. (A) Mountain pine beetle, Dendroctonus ponderosae formation of exo-brevicomin [(1 F ,5S,7fl)-(+)-7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1]octane] from (Z)-6-nonen-2-one (Vanderwel and Oehlschlager, 1992 Vanderwel ef a/., 1992a) ...

B) Western balsam bark beetle, Dryocoetes confusus formation of endo-brevicomin [(1 F ,5S,7S)-7-ethyl-5-methyl-6,8-dioxabicyclo[3.2.1 ]octane] from ( )-6-nonen-2-one (Vanderwel et a/., 1992a) (C) Spruce beetle, Dendroctonus rufipennis formation of frontalin [(1S, 5fl)-(-)-1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane] from 6-methyl-6-hepten-2-one (Perez ef a/., 1996 Francke etai, 1995 Francke and Schulz, 1999) (D) European elm bark beetle, Scolytus multistriatus hypothetical formation of oc-multistriatin [(1 S,2F ,4S,5F )-(-)-2,4-dimethyl-5-ethyl-6,8-dioxabicyclo[3.2.1]octane] from 4,6-dimethyl-7-octen-3-one (Francke and Schulz, 1999) and E The colored... 

Ryker L. C. and Rudinsky J. A. (1982) Field bioassay of exo- and endo-brevicomin with Dendroctonus ponderosae in lodgepole pine. J. Chem. Ecol. 8, 701-707. 

If the reaction depicted in Figure Si3.8 is performed with a slightly modified diene, a dihydropyran is formed which provides the framework for exo-brevicomin, a pheromone of the western pine beetle Dendroctonus brevicomis, and dehydrobrevicomin, a compound which promotes agression in male mice (Figure Si3.9). 

The frass of females of the western pine beetle Dendroctonus brevicomis is enriched with endo- (XIX) and exo-7-ethyl-5-methyl-6,8-dfoxabicyclot3.2.1]octane (XX), which are assigned the trivial epithets endo- and exo-brevicomin (61). Males of 2 brevicomis synthesize 1,5-dimethyl-6,8-dioxabicyclo[3.2.1]octane (frontalin) (XXI) in their hind guts (62), and this compound, in combination with the brevicomins and host-derived myrcene, constitutes a potent attractant for both sexes of J). brevicomis (63). Frontal in, also produced by females of . frontalis (62T7 is reported to function as a powerful aggregative pheromone when combined with host monoterpenes such as a-pinene (64). J). pseudotsugae... 

Some of the aggregation pheromones of scolytid beetles also appear to be synthesized with great chiral specificity. The flight response of both sexes of the western pine beetle Dendroctonus brevicomis to (lR,5S,7R)-(+)-exo-brevicomin (XX), host terpenes, and racemic frontal in (XXI) was much greater than the response when the antipode of brevicomin was substituted (160). Similarly, (lS,5R)-(-)-frontalin was a much more powerful attractant than its antipode when tested in admixture with... 

The aggregation pheromone of Dendroctonus brevlcomls Leconte consists of a synergistic mixture of exo-brevicomin (IV) produced by females, myrcene (V) from the host tree, and frontalin (VI) produced by males which respond to compounds IV and V. The mixture of all three compounds then attracts males and females (10). Subsequently, verbenone (VII) and trans-verbenol (VIII) are produced and deter further attack (11.). Additionally verbenone deters the response of I. paraconfusus which utilizes the same host tree species in the same area (16,17). Thus the two species may be found colonizing different parts of the same tree. Again, as in the Ips pheromones, chirality plays a role. The naturally occurring enantiomers of exo-brevicomin and frontalin in combination with myrcene elicit a greater response from both male and female D. brevlcomls than do the other enantiomers. 

H. Redlich, W. Bruns, W. Francke, V. Schurig, T. L. Payne, and J. P. Vit6, Chiral building units from carbohydrates. XIII. Identification of the absolute configuration of endo-brevicomin from Dendroctonus frontalis and synthesis of both enantiomers from D-ribose, Tetrahedron 43 2029 (1987). 

Brevicomins, first identified by Silverstein [37] have been recognized as aggregation pheromones for the western pine bark beetles, Dendroctonus brevicomis Le Conte. (15, 75)-(— )-exo-Brevicomin (87) is prepared in high optical purity starting from 79 by selectively... 

Acetylenic ketones are useful intermediates in terpenoid synthesis. Coke and co-workers have described a novel synthesis of acetylenic ketones, inspired by, but different from, the Eschenmoser fragmentation. The procedure is illustrated in Scheme 34 by its application to the synthesis of exo-brevicomin (134) the pheromone from Dendroctonus brevicomis. Hydroboration of the double bond of oct-l-en-4-yne with 9-BBN, followed by the acetylene zipper procedure, and base-induced alkyl transfer to t-butyl bromo-methyl ketone offers an efficient route to acetylenic ketones in greater than 70% yield [(135)->(136)]. °... 

The sex attractant of the female Western pine beetle (Dendroctonus brevicotnis) is the enantiomerically pure (lR,5S,7H)-(+)-exo-brevicomin. The (-)-enan-tiomer is not biologically active. In contrast, the pheromone component (lR,5S,7S)-(+)-eMdo-Brevicomin caused variable responses in the Southern pine beetle (Dendroctonus frontalisZiiameimann). [202]... 

Brevicomin (73) and frontalin (74), probable products of fatty acid metabolism, are part of the pheromone system of bark beetles of the genus Dendroctonus. These compounds are involved in interactions of these insects with their host plants, many of which are important softwoods (gymno-sperms) (Fig. 2.30). 

Novotny et al. (293) identified a volatile substance in male mouse (Mus musculus) urine, whose concentration depends on the level of testosterone, as 7-exo-ethyl-5-methyl-6,8-oxabicyclo-[3.2.1]-3-octene (65) or ejco-3,4-dehydrobrevicomin, and suggested that it might be a pheromone or pheromone adjuvant. The proposed structure is identical, except for the 3,4 double bond, with that of the pine bark beetle Dendroctonus frontalis pheromone exo-brevicomin (66). 

Fig. 12.1 Aggregation pheromones of (a) Ips paraconfusus, three male-produced synergistic components - (+ )2-methyl-6-methylene-2,7-octadien-4-ol (ipsdienol) (-)2-methyl-6-methylene-7-octen-4-ol (ipsenol) and cw-verbenol. (b) Dendroctonus brevicomisj three attractive components, cxo-7-ethyl-5-methyl-6,8-dioxabicyclo-[3.2.1] octane (cxo-brevicomin) from the female l,5-dimethyl-6,8-dioxabicyclo-[3.2.1] octane (frontalin) from the male and myrcene released from the host tree. Verbenone and trans-verbenol, released after a male locates the female, interrupts response to the attractant blend.

Mori, K. Stereoselective synthesis of ( )-e Jo-brevicomin, a pheromone inhibitor produced by Dendroctonus bark beetles. Agric. Biol. Chem. 40, 2499—2500 (1976). 

Coke, J. L., H. J. Williams, and S. Natarajan A new preparation of acetylenic ketones and application to the synthesis of ejco-brevicomin, the pheromone from Dendroctonus brevicomis. J. Org. Chem. 42,2380— 2382 (1977). 

Successful host colonization depends on recruiting a minimum number of Dendroctonus pon-derosae to attack the tree and overcome its defenses," a process that is completed within 2-3 weeks. As the abundance of colonizing male Dendroctonus ponderosae increases, levels of male-secreted cxo-brevicomin and frontalin increase " " - while concentrations of the aggregation pheromones trans- and cis-verbenol and host monoterpenes decline."" This reduces the attractiveness of the target tree and commences latter stages of tree colonization. The secretion of 2-phenylethanol by males" " and the release of l-octen-3-ol by females may further reduce attraction to the target tree. 

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