Research into fluorinated pyrethroid alcohols-an episode in the history of pyrethroid discovery

An account of pyrethroid research from 1975 to 1985 at Bayer AG is given. The exploitation of fluorine chemistry for this purpose led to increased activity of known 3-phenoxybenzyl pyrethroid esters and to the commercialisation of the broad-spectrum insecticide cyfluthrin, the particularly tick-toxic flumethrin and the rapid-acting household insecticides fenfluthrin and transfluthrin. The last two constituted in 1976 a novel type of pyrethroid, based on polyfluorinated benzyl alcohols, off the mainstream of published pyrethroid research. Transfluthrin, the single isomer (1R)trans-permethric acid ester of 2,3,5,6-tetrafluorobenzyl alcohol has just been introduced to the market. The history of its discovery and structure–activity data as well as resistance considerations regarding cyfluthrin, are presented.