The cis- and trans-isomers of isopropyl 3,7,11-trimethyl-2,4,10-dodecatrienoate were prepared from citronellal by aldol condensation and Reformatskii reaction. After the isomeric mixture was subjected twice to the Z-E isometrization of the double bond using benzenethiol as a catalyst, the content of 2E,4E-isomer 3a was increased from 26% to 85%. The mixture of 3a and 3b was etherified to give methoprene and its isomers possess somewhat juvenile hormone activity. Among them the content of 2E,4E-stereoisomer with quite higher activity can reach 85%. The structures of all the compounds were confirmed by IR, NMR and MS spectra.

Key words: methoprene, citronellal, jvenile hormone analogue, Z-E isomerization of double bond