Synthesis of (+)-Omphadiol

Significance

(+)-Omphadiol is a member of the africanane family of sesquiterpenes, isolated from the basidiomycete omphalotus illudens and the edible fungus clavicorona pyxidata. This family contains a 5-7-3 tricyclic core with (+)-omphadiol itself containing six contiguous stereocenters making it a particularly synthetically challenging target. This first total synthesis was completed ­using an aldol lactonization, a tandem isomerization/ring-closing metathesis and a Simmons-Smith cyclopropanation, giving an overall yield of 16% over ten steps without the use of protecting groups.