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

• , all eight stereoisomers of trans-fused iridomyrmecins were synthesized starting from the enantiomers of limonene. Combined gas chromatography and mass spectrometry including enantioselective gas chromatography revealed that volatiles released by the endohyperparasitoid wasp Alloxysta victrix contain

• (4S,4aR,7S,7aR)-iridomyrmecin of 95–97% ee and stereochemically pure (4S,4aS,7R,7aS)-iridomyrmecin as a minor component. Keywords: Alloxysta victrix; identification; iridoid; stereoselective synthesis; trans-fused iridomyrmecin; Introduction In the course of our studies on volatile signals of the

• endohyperparasitoid wasp, Alloxysta victrix, we identified several acyclic terpenoids and the trans-fused (4S,4aR,7R,7aS)-dihydronepetalactone (X) as volatile components of cephalic secretions released by this species (Figure 1) [1][2]. However, gas chromatograms showed the presence of two additional major volatiles

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

• released by the endohyperparasitoid wasp Alloxysta victrix contain the enantiomerically pure trans-fused (4R,4aR,7R,7aS)-dihydronepetalactone as a minor component, showing an unusual (R)-configured stereogenic center at position 7. Keywords: Alloxysta victrix; identification; iridoid; stereoselective

• 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

• Alloxysta victrix by coupled gas chromatography/mass spectrometry (GC/MS). Figure 1 shows one major component and several trace components which could be identified as 6-methyl-5-hepten-2-one (1), neral (2), geranial (3), actinidine (4), and geranylacetone (5). Bioassays revealed the main compound 1 to be

Algicidal lactones from the marine Roseobacter clade bacterium Ruegeria pomeroyi

• Ramona Riclea,
• Julia Gleitzmann,
• Hilke Bruns,
• Corina Junker,
• Barbara Schulz and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2012, 8, 941–950, doi:10.3762/bjoc.8.106

• accompanying paper in this Thematic Series by Francke and co-workers on the synthesis and absolute configurations of iridomyrmecins from the parasitoid wasp Alloxysta victrix, the expected stereochemical relationships between structurally similar natural products from one species are not always met [30], and