Ipsenol

FIGURE 6.10. Pulse sequence for double-quantum filtered H— H COSY (DQF-COSY). 

We could continue to trace correlation paths from these four protons and the reader is invited to do so at the end of this section. Let us instead select another equally useful entry point the isopropyl me thine at 1.82 ppm. We again begin at the diagonal and this time we find that the isopropyl methine is correlated with three distinct resonances. Two of the correlations correspond to the two protons of one of the diastereotopic methylenes that also correlated with the carbinol methine above. In addition, we find a correlation to the two overlapping methyl doublets at 0.93 ppm. These correlations, of course, make perfect sense with the structure in fact, by only considering these two protons (i.e., at 3.83 and 1.82 ppm) we have established correlations (also called connectivities ) through three-fifths of the molecule. 

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The first compound (37) is clearly a Diels-Alder adduct and was made this way in a synthesis of Ipsenol. ... 

A number of new and asymmetric syntheses of (S)-(-)-ipsenol (34) and (S)-(+)-ipsdienol (35), the pheromone of Ips bark beetles, were reported. Scheme 49 summarizes the synthesis of ipsenol by Riedeker and Steiner [75], which enabled them to prepare 56 g of (S)-34. They employed chiral auxiliary B derived from D-glucose. 

Attempts to investigate boll weevil (Anthonomus grandis) pheromone biosynthesis have identified isomerization, dehydration, and oxidation of the pheromone alcohols, and anticipated allylic oxidation of myrcene and limonene, but no evidence for the cyclization of acyclic precursors. The aggregation pheromones of bark beetles have been reviewed. Ips calligraphus responds to ipsdienol only in the presence of the c/5-verbenol (32) large additional concentrations of the enantiomer (l/ ,4i ,5/ )-(32) reduce beetle response. 5-(-)-Ipsenol, the pheromone of Ips grandicollis, increases the response of /. avulsus to its own pheromone ipsdienol. ... 

A generous gift of 3-propyl-l,2-dithiolane and of ipsenol was received from D. Wackerchuck (Phero Tech, Inc.). J.H. Borden and L. Chong (Simon Fraser University) contributed a sample of sulcatol. 

As is indicated in Fig. 22-3, the same intermediate cation can yield a variety of end products. For example, pure geranyl diphosphate pinene cyclase catalyzes formation of several other terpenes in addition to a-pinene.89 Another aspect of terpene synthesis is that insects may convert a plant terpene into new compounds for their own use. For example, myrcene, which is present in pine trees, is converted by bark beetles to ipsenol (Fig. 22-3), a compound that acts as an aggregation pheromone.90... 

Chiral allenylboronic esters.1 The enantioselectivity in synthesis of homo-propargylic esters by the reaction of aldehydes with chiral allenylboronic esters (11, 181) is markedly increased by use of bis-2,4-dimethyl-3-pentyl esters of d- or vAaxtaric acid rather than the diethyl ester. Yields in the reaction of various saturated aldehydes are 70-90%, and optical yields are consistently greater than 90% and even higher (97-99%) when the aldehyde is present in excess. However, yields are poor in reactions with aryl and a,p-unsaturated aldehydes. This modified procedure was used in a synthesis of (S)-(—)-ipsenol (2) from d-(—)-bis(2,4-di-methyl-3-pentyl) tartrate (1) (equation I). 

Seybold S. J., Quilici D. R., Tillman J. A., Vanderwel D., Wood D. L. and Blomquist G. J. (1995) De novo biosynthesis of the aggregation pheromone components ipsenol and ipsdienol by the pine bark beetles Ips paraconfusus Lanier and Ipspini (Say) (Coleoptera Scolytidae). Proc. Natl. Acad. Sci. USA 92, 8393-8397. 

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 6.11 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...

Figure 6.13 Examples of the application of normal-phase, radio-HPLC to the analysis of de novo biosynthetic pathways in bark beetles (Scolytidae). Demonstration of sex-specific de novo biosynthesis of ipsenol, ipsdienol, and amitinol through radio-HPLC analysis of pentane extracts of Porapak-trapped volatiles from (A) male and (B) female Ips paraconfusus Lanier feeding for 168 h in Pinus ponderosa and (C) male and (D) female Ips pini (Say) feeding for 168 h in Pinus jeffreyi (Seybold et al., 1995b). Demonstration of sex-specific de novo biosynthesis of frontalin through radio-HPLC analysis of pentane extracts of Porapak-trapped volatiles from (E) male and (F) female...

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