Synthesis and insecticidal activity of lipophilic amides. Part 6: 6-(disubstituted-phenyl)hexa-2,4-dienamides

By using a phosphonate containing an N-(2,2-dimethylpropyl) instead of an N-(2-methylpropyl) group, rearrangement during the Wadsworth-Emmons condensation step was restricted to an acceptable level even with products from disubstituted phenylacetaldehydes. Previous results had shown that this change in N-group did not alter insecticidal activity drastically, so structure-activity relationship conclusions could be drawn from both series in combination. The presence of methyl groups on the phenyl lowered activity, confirming results in the mono-substituted series, so attention was directed primarily to the numerous possible di-halo combinations. Many were active, especialty those with 3,4 or 3,5 substitution patterns, but beyond this no simple correlations could be detected relating position or nature of substituents to activity. Varying both the phenyl substituents and amine group gave results approximately in agreement with additivity principles.