Revised Structure, Total Synthesis, and Absolute Configuration of Kopeolin and Kopeolone

An enantioselective total synthesis of two sesquiterpenoids, kopeolin and kopeolone, has been achieved. Using the diastereoselective addition of an organocerate as a key step, we controlled the absolute stereochemistry of a crucial stereocenter present in these natural products. This approach allowed us to confirm a structural revision that we previously proposed (Chem.Eur. J. 2013, 19, 10632−10642) and to fully characterize these natural products while elucidating their absolute stereochemistry.