Improved Syntheses of (+)-Iridomyrmecin and (-)-Isoiridomyrmecin, Major Components of Matatabilactone

Improved syntheses of iridomyrmecin and isoiridomyrmecin, major components of matatabilactone, are described. The synthesis features a direct transformation of nepetalactol into key intermediates by DIBAL-H reduction and provides an expeditious and straightforward production of iridoid lactones for biological investigations of the Matatabi phenomenon.

A general approach to iridoids by applying a new Julia olefination and a tandem anion-radical-carbocation crossover reaction

An efficient asymmetric approach to dihydronepetalactone and dolicholactone is presented featuring a Julia olefination and an anion–radical–cation crossover reaction.

Stereoselective chemical defense in the Drosophila parasitoid Leptopilina heterotoma is mediated by (-)-iridomyrmecin and (+)-isoiridomyrmecin

Chemical defense mechanisms are widespread among insects but have rarely been demonstrated in parasitoid wasps. Here, we show that the Drosophila parasitoid Leptopilina heterotoma (Hymenoptera, Figitidae) produces (-)-iridomyrmecin and (+)-isoiridomyrmecin in a cephalic gland, and that these chemicals have a highly repellent effect on ants. Stereoselective synthesis of 4 stereoisomers of iridomyrmecin allowed us to demonstrate that the repellent effect of iridomyrmecins depends on the stereochemistry. Potential food items impregnated with natural doses of (-)-iridomyrmecin were avoided by ants much longer than those impregnated with (+)-iridomyrmecin, (+)-isoiridomyrmecin, or (-)-isoiridomyrmecin, respectively. Quantitative headspace analyses revealed furthermore that females and males of L. heterotoma released iridomyrmecins in higher amounts when confronted with ants. This is the first time, that (-)-iridomyrmecin and (+)-isoiridomyrmecin are reported as natural products. Females synthesize more iridomyrmecins than males, and the most active (-)-iridomyrmecin is produced by females only. We, therefore, hypothesize that this defense mechanism is used mainly by female wasps when foraging for Drosophila larvae on rotten fruits, but also may protect male wasps during dispersal.