Asymmetric Total Synthesis of (-)-Vinigrol.

A new strategy was developed for the asymmetric total synthesis of (-)-vinigrol. The strategy involved a linear sequence of 15 steps from 3-methyl-butanal (14 steps from chloro-dihydrocarvone) and did not need protecting groups. The synthetically challenging 1,5-butanodecahydronaphthalene core was constructed efficiently via a type II intramolecular [5+2] cycloaddition, followed by a unique ring-contraction cascade.