Towards the Total Synthesis of the Norsesterterpene Diacarnoxide C

The synthesis of the norsesterterpene diacarnoxide C was achieved. The endoperoxide moiety could be prepared in nine and the norsesquiterpene moiety in five steps starting from (E)‐3‐methyl‐6‐oxohex‐2‐en‐1‐yl acetate and dihydro‐β‐ionone. The peroxide aldehyde and the norsesquiterpene sulfone were coupled in an (E)‐selective Julia–Kocienski reaction. The coupling product was transformed in three additional steps to an inseparable mixture of diacarnoxide C and three further isomers. The first total synthesis of diacarnoxide C (1) was achieved. The key step of the synthesis is the Julia–Kocienski reaction of sulfone 4 with aldehyde 5.