Synthesis of 5-<i>epi</i>- and 10-<i>epi</i>-β-selinenes and 5-<i>epi</i>- and 10-<i>epi</i>-costals and their acaricidal activity against <i>Varroa destructor</i>

Synthesis of 5-epi- and 10-epi-β-selinenes and 5-epi- and 10-epi-costals was achieved from dihydrocarvone, involving the radical cyclization of selenoester to construct a decalone framework as the key step. The acaricidal activities of these diastereomers of (+)-costal and (+)-β-selinene were also evaluated against Varroa destructor. Among them, 10-epi-costal exhibited the most potent acaricidal activity.