Ten aphid alarm pheromone mimics I (R = H, Me, Et, Pr, CH:CH2, Ph, CO2Et2 cyano, CH2OAc) were prepared from citral through the following series of reactions, namely reduction of citral with NaBH4 to give geranial which was converted to geranyl chloride by treatment with PCl3. Reaction of geranyl chloride with Et acetoacetate in the presence of base gave geranylacetone which was converted to compounds I through the Wittig reaction. I (R = H, Me, CO2Et) showed alarm activity to Aphis Laburin Karlebach, other compounds were inactive. Two isomers of I (R = H) (II) were synthesized stereoselectively. The more active mixture of (Z)-II and (E)-II (1:1) was obtained from the less active (Z)-II by isomerization.

Key words: BIOLOGICAL ACTIVITY, SESQUITERPENE, C11 COMPOUNDS, INSECT HORMONE, C12 COMPOUNDS, POLYENE P, PHEROMONE, APHIDIDAE, ALARM PHEROMONE