8-methyl-2-decanol propanoate

R,R)-8-methyl-2-decanol propanoate (34). Sonnet et al. (35) synthesized the four stereoisomers of this pheromone in high stereoisomeric purity (Table I). Comparison of the captures of WCR males in the field with traps baited with the individual steroisomers and with the racemic mixture demonstrated that the males respond strongly to the (R,R)-isomer and to a lesser extent to the (2S,8R)-isomer. The other two isomers are inactive i.e., they neither attract nor inhibit the response of WCR males, nor do they synergize the activity of the (R.R)-isomer (36). The (R,R)-isomer appears to be as attractive as an equal amount of the natural pheromone in volatiles collected from females. Thus it is possible that the WCR is utilizing a single component pheromone. 

Table I. Purity of the synthesized stereoisomers of 8-methyl-2-decanol propanoate that were tested in the field for attractiveness to several species of Diabrotlca.

The structure of the western corn rootworm sex pheromone is 8-methyl-2-decanol propanoate (] 6) and four stereoisomers are possible (Figure 7). In our synthesis (3), we coupled a chiral 5-carbon unit to a 6-carbon fragment that had the requisite substitution to allow resolution at the oxygenated carbon. As mentioned earlier, (S)-2-methylbutyric acid was available to us from the alcohol. D-Isoleucine served as a source for the (R)-acid. Nitrosation, followed by decarboxylative oxidation of the intermediate hydroxyacid led to the (R)-2-methylbutyric acid in 96% ee. The process of fractional crystallization was... 

Thus, starting from ethyl (5)-p-hydroxybut5rrate, pheromones of diverse structural types, such as (5)-sulcatol [26], femilactone II [27], (25,6i )-2-methyl-l,7-dioxaspiro[5.6]-dodecane [28], (25,6/ ,S5)-2,8-dimethyl-l,7-dioxaspiro[5.5]undecane [29], (2R,5S)-2-methyl-5-hexanolide [31], and (2S,SjR)-8-methyl-2-decanol propanoate [32], have been synthesized. Methyl (5)-P-hydroxybutyrate has also been used for the synthesis of (25,35,75)-3,7-dimethylpentadecan-2-ol [33]. In these syntheses, the configurations at the... 

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