The firsttotalsynthesis of both enantiomers of clavigerins B and C, insect antifeedant sesquiterpenes isolated fromNew Zealand liverwort Lepidolaena clavigera, has been achieved. The synthesis features Ireland-Claisen rearrangement for construction of bicyclo[3.1.1]heptene skeleton. By comparison of the optical rotations of both enantiomers with those of natural clavigerins, the absolute configurations