Total Synthesis of ( )-Celaphanol A

The first total synthesis of (±)-Celaphanol A was accomplished starting from α-cyclocitral and 3,4-dimethoxy benzyl chloride via a six-step process, in which the intramolecular cyclization of ketone 4 with BF3@Et2O afforded an all-cis isomer intermediate for synthesis of aromatic tricyclic diterpenes.