Synthesis and insecticidal activity of lipophilic amides. Part 2: Effect of heteroatom replacements and of introducing methyl groups in the pentadiene system

Following the discovery of insecticidal activity in (2E,4E)-N-(2-methylpropyl)-6-phenylhexa-2,4-dienamide, structural analogues containing variations of the central pentadiene system have been examined. They include the five compounds with extra methyl groups on each of the five carbons in turn, and compounds in which heteroatoms have been introduced instead of, or additional to, the original CH or CH₂ groups. All were insecticidally inactive, indicating for the first time the severe limitations on this group if activity is to be retained.