Manicone [(4E,6S)-(+)-4,6-dimethyl-4-octen-3-one], an alarm pheromone component ofManica ants, was synthesized by a five-step sequence starting from 2-chloro-3-pentanone. The latter α-chloro ketone was converted into the corresponding N-isopropyl ketimine, which was sequentially alkylated via its 3-chloro-1-azaallylic anion with (S)-(+)-2-methyl-1-bromobutane. 1,2-Dehydrochlorination of the resulting chiral functionalized α-chloro ketimine, followed by acid hydrolysis and final Rh(III)-chloride-mediated isomerization afforded the pheromone (S)-(+)-manicone in enantiopure form.