The four stereoisomers of N-2'-methylbutyl-2-methylbutylamide, the sex pheromone of the longhorn beetle Migdolus fryanus, an economically important pest of sugarcane in South America, were synthesized. The key intermediate 2-methylbutan-1-ol is commercially available only in its (S)(-)-form. The (R)-(+)-enantiomer was obtained optically pure from methyl (S)-(+)-3-hydroxy-2-methylpropionate in five steps.