Gomadalactones A, B, and C: novel 3-oxabicyclo[3.3.0]octane compounds in the contact sex pheromone of the white-spotted longicorn beetle, Anoplophora malasiaca

The ether extract of the females of white-spotted longicorn beetle Anoplophora malasiaca showed activity as contact sex pheromone to males. The extract was fractionated, and a pheromonal activity was revealed only when three fractions; n-hexane, n-hexane/EtOAc 9:1, and EtOAc were blended. The relative structures of gomadalactone A, B, and C, three active components isolated from the EtOAc fraction, were determined by spectroscopic studies to be (1S∗,4R∗,5S∗)-5-hydroxy-4-[(E)-7-hydroxy-4-methylhept-3-enyl]-4,8-dimethyl-3-oxabicyclo[3.3.0]octan-7-en-2,6-dione, (1R∗,4R∗,5R∗)-5-hydroxy-4-[(E)-7-hydroxy-4-methylhept-3-enyl]-4,8-dimethyl-3-oxabicyclo[3.3.0]octan-7-en-2,6-dione, and (1S∗,4R∗,5S∗,8S∗)-5-hydroxy-4-[(E)-7-hydroxy-4-methylhept-3-enyl]-4,8-dimethyl-3-oxabicyclo[3.3.0]octan-2,6-dione, respectively.