The history of extensive structural modifications of pyrethroids.

The structural modification of natural pyrethrins has led to a number of synthetic pyrethroid insecticides, and each compound has its own characteristics. At present, pyrethroid insecticides are applied not only for household use, the original use for pyrethrins, but also for a wide range of uses such as crop protection, pharmaceuticals, and veterinary applications. Quoting primary sources, this review describes the historical view of structural modifications of pyrethroids, with a focus on structural similarities, and their use.

Recent advances of pyrethroids for household use.

Development of pyrethroids for household use and recent advances in the syntheses of (1R)-trans-chrysanthemic acid, the acid moiety of most of the household pyrethroids, are reviewed. As another important acid moiety, we discovered norchrysanthemic acid to have a significant vapor action at room temperature when esterified with fluorobenzyl alcohols. In particular, 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl (1R)-trans-norchrysanthemate (metofluthrin) exhibits the highest potency in mosquito coil formulations as well as the vapor action at room temperature against various mosquitoes.

Metofluthrin: a potent new synthetic pyrethroid with high vapor activity against mosquitoes.

(1R)-trans-Norchrysanthemic acid fluorobenzyl esters are synthesized and their structure-activity relationships are discussed. These esters show outstanding insecticidal activity against mosquitoes. In particular, the 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl analog (metofluthrin) exhibits the highest potency, being approximately forty times as potent as d-allethrin in a mosquito coil formulation when tested against southern house mosquitoes (Culex quinquefasciatus).