New chlorinated juvenile hormone analogues and their biological activity

Abstract

AbstractIn the search for new juvenile hormone analogues (JHAs), a general approach was chosen based on the substitution of the isoprene unit, that carries the epoxy function in the natural hormone JHIII, by 3,3,3‐trichloropropyl, 2,2‐dichlorocyclopropyl‐ methyl, 3,3‐dichloroallyl, or 3‐chloroprop‐2‐ynyl groups. Accordingly, several terpenoid aromatic JHAs were prepared with, or without, oxygen atoms in the aliphatic chain. Structure‐biological activity relationships of the most active compounds toward the yellow mealworm (Tenebrio molitor) and the large cabbage white butterfly (Pieris brassicae) are given. With a view to preparing synthetically accessible analogues, some alkyl phenyl ethers were also made, which were not branched in the aliphatic chain and were related terminally to the most active compounds. They were only moderately active against insects when tested for morphogenetic activity, but exhibited a good field persistence. The occurrence of a moderate acaricidal activity among these analogues prompted the examination of several 1,4‐disubstituted‐phenyl derivatives. The ovicidal effectiveness of these products against a susceptible strain of the two‐spotted spider mite, Tetranychus urticae, was ten or 100 times higher than that of the well known and highly potent JHAs.