Total Synthesis of Daphnepapytone A

The total synthesis of sesquiterpenoid daphnepapytone
A starting
from (R)-carvone is reported. The carbocyclic framework
of daphnepapytone A was formed by a one-pot Pauson–Khand/desilylative
oxidation reaction and a [2 + 2] photocycloaddition of synthetic oleodaphnone.
During the synthesis, it was discovered that wavelength-dependent
irradiation of oleodaphnone resulted in intramolecular photometathesis
to form a dicyclopentadienone. Late-stage oxidation and a highly stereo-
and regioselective reduction completed the synthesis.