Studies toward the Total Synthesis of Vinigrol. Synthesis of the Octalin Ring

Herein, we disclose our results regarding various strategies toward the assembly of the octanyl
ring of vinigrol. Attempts to generate the problematic eight-membered ring through a ring expansion
or via unification of the terminal olefins using the ring-closing metathesis were not successful.
The cyclooctane ring was created via a sequential hydroxy Diels−Alder/Claisen rearrangement
reaction of diene 55 and N-benzylmaleimide.