STEREOISOMERIC COMPOSITION OF THE 4-METHYL-3-HEPTANOL PRODUCED BY SCOLYTUS-SCOLYTUS AND THE PREPARATION AND BIOLOGICAL-ACTIVITY OF THE 4 SYNTHETIC STEREOISOMERS

Racemic threo and erythro 4-methyl-3-heptanol, obtained from the commercial alcohol by fractional distillation using a spinning band column, were resolved by high-pressure liquid chromatographic separation of their (-)-MTPA diastereoesters. The biological activity of the four stereoisomers towards Scolytus scolytus was examined in a laboratory bioassay and by coupled gas chromatography-electroantennography. Antennae of both male and female S. scolytus responded to all the stereoisomers but stronger responses were given by both sexes to the (-)-threo and (-)-erythro stereoisomers than to the (+)-threo and (+)-erytho stereoisomers. Both male and female beetles responded to all the stereoisomers in the laboratory bioassay, there being no statistically significant differences in the degree of response to each isomer. These results are discussed in relation to the field response of S. scolytus to the stereoisomers. A method is also described for the determination of the stereoisomeric composition of natural 4-methyl-3-heptanol, starting with 0.5-5 μg of the alcohol. Male S. scolytus beetles from two distinct laboratory cultures were found to produce trace (-)-threo and (-)-erythro steroisomers of 4-methyl-3-heptanol, while females from one of the cultures produced trace quantities of the (-)-erythro stereoisomer only. © 1979.