Resolution of Epoxydienes by Reversed-Phase Chiral HPLC and its Application to Stereochemistry Assignment of Mulberry Looper Sex Pheromone.

Resolution of insect pheromonal cis-epoxydiene racemates derived from ( Z, Z, Z)-3,6,9-trienes was examined with a reversed-phase chiral HPLC column. The results showed that a Chiralcel OJ-R column was suitable for separating the enantiomers having a C₁₇–C₂₃ unsaturated straight chain except for 9,10-epoxydienes with a C₂₁–C₂₃ chain. To determine the absolute configuration of the separated enantiomers, each of the optically active epoxydienes was hydrogenated over Pd-BaSO₄ and its behavior was examined on this chiral column by cochromatography with the corresponding chiral epoxy compound having a saturated chain, which was prepared via a Sharpless epoxidation reaction. This analysis showed that the dextrorotatory C₁₇–C₂₃ 3,4- and 6,7-epoxydienes and C₁₇–C₂₀ 9,10-epoxydienes with shorter R_ts possess (3 S,4 R)-, (6 S,7 R)-, and (9 R,10 S) configurations, respectively, and the levorotatory enantiomers with longer R_ts possess the opposite configuration. An abdominal tip extract of the mulberry looper, Hemerophila artilineata Butler (Lepidoptera: Geometridae: Ennominae), included (9 S,10 R)-( Z, Z)- cis-9,10-epoxy-3,6-octadecadiene as a main sex pheromone component. The synthetic (9 S,10 R)-9,10-epoxydiene, rather than its antipode, elicited strong antennal and behavioral responses from the male moths in electrophysiological and field tests. [ABSTRACT FROM AUTHOR]