Sesquiterpene Backbones Generated by Sesquiterpene Cyclases: Formation of <i>iso</i>-Caryolan-1-ol and an Isoclovane

New sesquiterpene backbones are accessible after incubation of caryolan-synthase (GcoA) and presilphiperfolan-8-β-ol synthase (BcBOT2) with a non-natural farnesyldiphosphate in which the central olefinic double bond is isomerized toward the methyl group. Two newly formed sesquiterpenoids are reported, a constitutional isomer of caryolan-1-ol (<b>3</b>), which we name <i>iso</i>-caryolan-1-ol (<b>17</b>), and the first terpenoid based on the isoclovane ring skeleton generated enzymatically thus far.