Toru Tsuchiya

Synthesis and stereostructure–activity relationship of a synthetic pyrethroid, 2-chloro-1-methyl-3-phenylcyclopropylmethyl-3-phenoxybenzyl ether

Of the four diastereoisomers of 2-chloro-1-methyl-3-phenylcyclopropylmethyl 3-phenoxybenzyl ether 5, a new type of synthetic pyrethroid, which have been synthesized, only the (1R*,2S*,3S*)-isomer 5a showed significant insecticidal activity against the tobacco cutworm and the common mosquito. Two enantiomers (1R,2S,3S)-(–)-5a and (1S,2R,3R)-(+)-5a were prepared by the optical resolution process, and their absolute configurations were determined by chemical derivatization via predictable asymmetric cyclopropanation. Bioassay showed that the (1R,2S,3S)-(–)-5a was active, while (1S,2R,3R)-(–)-5a was not. The geometry around the asymmetric centre of the (1R,2S,3S)-enantiomer was correlated with that of representative pyrethroids which are both optically active and have insecticidal activity.