Non-natural Elemane as the “Stepping Stone” for the Synthesis of Germacrane and Guaiane Sesquiterpenes

The synthesis of hydroxyelemane 5 from (R)-carvone and its utilization as a common synthetic scaffold to produce structurally diverse germacrane and guaiane sesquiterpenes are described. A highly enantio- and stereoselective biomimetic tandem oxy-Cope/ene rearrangement was used as the key reaction to access the 10-membered macrocyclic core of germacranes and the condensed 5–7 carbocycles of guaiane sesquiterpenes. Additionally, reactions of furanoguaianes under acidic or oxidizing reagents have been investigated, and preliminary results of these conversions are presented.