Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part II: Iridomyrmecins

• Robert Hilgraf,
• Nicole Zimmermann,
• Lutz Lehmann,
• Armin Tröger and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1256–1264, doi:10.3762/bjoc.8.141

• ), two major components, Y and Z, of the volatile secretions of both sexes of Alloxysta victrix (although in much higher amounts in males) gave almost identical 70 eV EI-mass spectra (Figure 2); somewhat resembling that of the trans-fused dihydronepetalactone that we had already found in the insects [1

Stereoselective synthesis of trans-fused iridoid lactones and their identification in the parasitoid wasp Alloxysta victrix, Part I: Dihydronepetalactones

• Nicole Zimmermann,
• Robert Hilgraf,
• Lutz Lehmann,
• Daniel Ibarra and
• Wittko Francke

Beilstein J. Org. Chem. 2012, 8, 1246–1255, doi:10.3762/bjoc.8.140

• synthesis; trans-fused dihydronepetalactone; Introduction The endohyperparasitoid wasp Alloxysta victrix is part of the tetratrophic system of oat plants (Avena sativa), grain aphids (Sitobion avenae), primary parasitoids (Aphidius uzbekistanicus) and hyperparasitoids (Alloxysta victrix). Chemical

• minor component X, the mass spectrum of which suggested it to be a trans-fused dihydronepetalactone. Since no synthetic reference compounds were available, we had to synthesize all eight trans-fused dihydronepetalactones to unambiguously identify the natural product X. The realization of this task is

• (Figure 2), showed some similarities to that of the known cis-fused dihydronepetalactone (6) [7], however, differences in relative abundances of fragment ions pointed to a trans-fused dihydronepetalactone as the target structure [8]. In the mass spectrum of the cis-fused compound m/z 67 and m/z 95 were of