Biomimetic Syntheses of (−)-Gochnatiolides A–C and (−)-Ainsliadimer B

We report the first biomimetic syntheses of (−)-gochnatiolides
A–C and (−)-ainsliadimer B based on our proposed biogenetic
pathway. Our synthesis features one-pot cascade transformations including
Saegusa oxidation, intermolecular Diels–Alder cycloaddition,
and radical-mediated allylic oxidation, which allow for the rapid
generation of (−)-gochnatiolides A–C in a collective
manner. We also disclose an unprecedented “copper effect”
on the stereochemical outcome of the radical-mediated allylic oxidation.
Our synthetic endeavors led to the structural reassignment of (−)-gochnatiolide
B. Ultimately, a biomimetic transformation from gochnatiolide B to
ainsliadimer B was achieved through a remarkable direct enone hydration.