The optical isomers of α‐cyano‐3‐phenoxybenzyl 3‐(1,2‐dibromo‐2,2‐dichloroethyl)‐2,2‐dimethylcyclo‐propanecarboxylate and their insecticidal activities

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Abstract
Bromination of the dichlorovinyl group of cypermethrin yielded a new compound which is a highly potent insecticide. This dibromo adduct has four asymmetric centres and therefore can exist as a mixture of 16 stereoisomers. To establish the influence of the absolute configuration at the chiral centres on the biological activities of these isomers, each of the isomers was isolated; their insecticidal activities against larvae of Heliothis virescens, and adult Calliphora erythrocephala and Blattella germanica were then determined and compared with those of (S)‐α‐cyano‐3‐phenoxybenzyl (1R)‐cis‐3‐(2,2‐dibromovinyl)‐2,2‐dimethylcyclopropanecarboxylate (deltamethrin NRDC 161), of fenvalerate, and of the eight stereoisomers of cyper methrin.