Resmethrin

5-benzyl-3-[({[(3R)-2,2-dimethyl-3-(2-methylprop-1-en-1-yl) cyclopropyl]carbonyl}oxy)methyl]furan; (5-Benzyl-3-furyl)methyl-2,2-dimethyl-3-(2-methyl-1-propen-1-yl)cyclopropancarboxylate; 5-benzyl-3-furylmethyl (1RS,3RS;1RS,3SR)-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate; 5-benzyl-3-furylmethyl(1RS)-cis-trans-2,2-dimethyl-3-(2-methylprop-1-enyl)cyclopropanecarboxylate; 5-benzyl-3-furylmethyl(±)-cis-trans-chrysanthemate

Resmethrin is a pyrethroid insecticide with many uses, including control of the adult mosquito population.

The resmethrin molecule has four stereoisomers determined by cis-trans orientation around a carbon triangle and chirality. Technical resmethrin is a mixture of (1R,trans)-, (1R,cis)-, (1S,trans)-, and (1S,cis)- isomers, typically in a ratio of 4:1:4:1. The 1R isomers (both trans and cis) show strong insecticidal activity, while the 1S isomers do not. The (1R,trans)- isomer is also known as bioresmethrin,(+)-trans-resmethrin, or d-trans-resmethrin; although bioresmethrin has been used alone as a pesticide active ingredient, it is not now registered as a separate active ingredient (AI) by the U.S. EPA. The (1R,cis)- isomer is known as cismethrin, but this is also not registered in the U.S. for use alone as a pesticide AI.

Commercial trade names for products that contain resmethrin are: Chrysron, Crossfire, Lethalaire V-26, Pynosect, Raid Flying Insect Killer, Scourge, SPB-1382, Sun-Bugger #4, Synthrin, Syntox, Vectrin, and Whitmire PT-110.