AN EFFICIENT SYNTHESIS OF (S)-(-MANICONE, AN ALARM PHEROMONE OF MANICA ANTS())

Manicone [(4E,6S)-(+)-4,6-dimethyl-4-octen-3-one] an alarm pheromone c omponent of Manica ants, was synthesized by a five-step sequence start ing from 2-chloro-3-pentanone. The latter alpha-chloro ketone was conv erted into the corresponding N-isopropyl ketimine, which was sequentia lly alkylated via its 3-chloro-1-azaallylic anion with (S)-(+)-2-methy l-1-bromobutane. 1,2-Dehydrochlorination of the resulting chiral funct ionalized ru-chloro ketimine, followed by acid hydrolysis and final Rh (III)-chloride-mediated isomerization afforded the pheromone (S)-(+)-m anicone in enantiopure form. Copyright (C) 1996 Elsevier Science Ltd