Abstract
To obtain (Z)-pyrethric acid, a geometrical isomer of pyrethric acid, the condensation between 1-methoxycarbonylethylphosphonate (II) and tert-butyl 2, 2-dimethyl-3-formylcyclopropane-1-carboxylate (I) was reinvestigated, the yield of the (Z)-isomer was increased to 61.5% in the reaction mixture. (Z)- and (E)-Isomers were separated effectively by recrystallization from acetonitrile after alkaline hydrolysis of the reaction product.
(Z)-Isomer of allethrin II was synthesized from (Z)-pyrethric acid and allethrolone. Toxicity of the (Z)-isomer to houseflies was compared with those of allethrin I and II.
