Deltamethrin products are among the most popular and widely used insecticides in the world. This material is a member of one of the safest classes of pesticides: synthetic pyrethroids. There are many uses for deltamethrin, ranging from agricultural uses to home pest control. Deltamethrin is a pyrethroid composed of a single stereoisomer, of a possible 8 stereoisomers, selectively prepared by the esterification of (1R,3R)- or cis-2,2-dimethyl-3-(2,2-dibromovinyl)cyclopropanecarboxylic acid with (a,S)- or (+)-a-cyano-3-phenoxybenzyl alcohol or by selective recrystallization of the racemic esters obtained by esterification of the (1R,3R)- or cis-acid with the racemic or (a-R, a-S, or a-R/S)- or + or − alcohol. We have prepared Deltamethrin R-isomer (aR, 1R-cis) as well as several standards. This will be of interest to agrochemical sponsors and analytical labs.