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

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 (1 R )‐ cis ‐3‐(2,2‐dibromovinyl)‐2,2‐dimethylcyclopropanecarboxylate (deltamethrin NRDC 161), of fenvalerate, and of the eight stereoisomers of cyper methrin.