Structure—activity relationships in pyrethroid esters derived from substituted 2‐phenoxy‐3‐methylbutanoic acids

摘要

AbstractNon‐cyclopropane pyrethroid esters of different substituted 2‐phenoxy‐3‐methylbutanoic acids have been synthesised using the three alcohols—3‐phenoxybenzyl alcohol, α‐cyano‐3‐phenoxybenzyl alcohol and 3, 4‐methylene‐dioxybenzyl alcohol. Among the 35 esters synthesised and tested againstCulex quinquefasciatusSay, the Bancroftian filariasis vector, for both larvicidal and adulticidal activities, α‐cyano‐3‐phenoxybenzyl 2‐(4‐fluorophenoxy)‐3‐methylbu‐tanoate, with an LC50value of 2.5 × 10−3mg litre−1for larvicidal activity, and α‐cyano‐3‐phenoxybenzyl‐2‐(4‐chlorophenoxy)‐3‐methylbutanoate, with an LD50value of 30 times; 10−4ug insect−1for adulticidal activity, were found to be as effective as fenvalerate, a well‐known non‐cyclopropane pyrethroid ester. Structure‐activity studies showed that the insecticidal activity is dependent on the nature and position of the substituent in th