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.