Pheromones: synthesis and bioactivity

Abstract

Pheromones play an important role in chemical communication among organisms. Various chiral and non-racemic pheromones have been identified since the late 1960s. Their enantioselective syntheses were achieved so as to establish the absolute configuration of the naturally occurring pheromones and also to clarify the relationship between absolute configuration and the bioactivity of the chiral pheromones. Four recent examples of pheromone synthesis are given. The enantiomers of sordidin 14, the banana weevil pheromone, have been synthesized starting from (S)-propylene oxide. (-)-exo-Isobrevicomin 17 and its (-)-endo-isomer 21, the components of the volatiles of the mountain pine beetle, have been synthesized by employing the Sharpless asymmetric dihydroxylation and lipase-catalysed acetylation as the key reactions. The enantiomers of (Z)-hexadeca-7,15-dien-4-olide 24, the sex pheromone of the yellowish elongate chafer, have been synthesized via lipase-catalysed resolution. Lurlene 27, the pheromone of the green flagellate Chlamydomonas allensworthii, has been synthesized by employing a phenyl sulfone coupling reaction as the key reaction. The relationships between absolute configuration and bioactivity are diverse. For example, neither the (R)- nor the (S)-enantiomer of sulcatol 10, the aggregation pheromone of the ambrosia beetle Gnathotrichus sulcatus, is bioactive, but when combined to give an enantiomeric mixture they become active. In the case of olean 46, the olive fruit fly pheromone, (R)-46 is active for the males, while (S)-46 is active for the females.