“…Another doubly branched ketone, 4,6-dimethyl-4-octen-3-one (''manicone''), was identified as an alarm pheromone from Manica ants, [17] and was found to have a (4E,6S)-configuration. [18] As for the biosynthesis of the compounds identified here, methyl branching in the ketones is presumably introduced by replacement of an acetate (malonate) by a propanoate (or methylmalonate) unit along a polyketide route. This is depicted in Scheme 3, where [X], [Y], and [Z] are activators.…”