Daphnepapytone A (1), a structurally unique guaiane-type sesquiterpenoid, has been prepared by total synthesis. So, a (S)-carvone-derived decalindienone was subjected to a photosantonin rearrangement to afford, after additional steps, the natural product oleodaphnone (9). An intramolecular 2 + 2-cycloaddition of compound 9 followed by an allylic oxidation then gave target 1. Four other structures assigned to guaianes were prepared by related means and so identifying two errors in the recent literature.
Xiao et al. (Thu,) studied this question.
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