CONTRIBUTION TO THE SYNTHESIS OF PERMETHRIN

Several routes for the industrial synthesis of 1,1-dichloro-4-methyl-1,3-pentadiene as the key intermediate of permethrin insecticide have been developed. During the chlorination of 1,1,1-trichloro-4-methyl-pentene-3-ol new 1,3-and 1,5-rearrangements involving chlorine were observed. Radical species in the processes were detected by ESR spectroscopy and mechanisms of the rearrangements were rationalized.