QUANTITATIVE STRUCTURE ACTIVITY STUDIES OF PYRETHROIDS .22. PHYSICOCHEMICAL SUBSTITUENT EFFECTS ON INSECTICIDAL ACTIVITY OF META-SUBSTITUTED BENZYL CHRYSANTHEMATES AND THEIR DIBROMOVINYL ANALOGS

Insecticidal activity against American cockroaches of a number of meta-substituted benzyl esters of (1R)-trans-chrysanthemic acid and (1R)-cis-2,2-dimethyl-3-(2′,2′-dibromovinyl)-cyclopropanecarboxylic acid and its trans-isomer was measured by injection under synergistic conditions with inhibitors of oxidative and hydrolytic metabolism. The insecticidal potency of the cis-carboxylates was higher than that of the corresponding esters with the trans-isomer of the carboxylic acid, which was, in turn, higher than that of the corresponding chrysanthemates. The difference between the insecticidal potency of the corresponding compounds with the same alcohol moiety was not uniform among various combinations of the series. Variations in the insecticidal potency were examined quantitatively using physiocochemical and structural parameters of the aromatic substituents and by regression analysis. The correlation equation previously derived for the chrysanthemates was revised with additional analogs. Introduction of substituents having a phenyl group at the meta-position of the benzyl-benzene ring was favorable for the activity. The greater the hydrophobicity, the higher was the insecticidal potency in both of the cis- and trans-dibromovinylcyclopropanecarboxylates. The potency of the chrysanthemates was not significantly changed by the substituent hydrophobicity. The shorter the substituents, the higher was the potency in all of the three series of compounds. Steric effects of the substituents in terms of the STERIMOL maximum width parameter were complex. There was an optimum width for the activity in the aromatic substituents of the chrysanthemates. The smaller the width of the aromatic substituents of the cis-carboxylates, the higher was the activity. Variations of the potency of the trans-isomers were not correlated with this steric parameter. © 1990.