Ring-Rearrangement Metathetic Approach to Fused 6/5/6/5/6-Oxacyclic Ring System and Bipentalene Derivatives

We have developed a useful synthetic route to a 6/5/6/5/6-oxacyclic ring system and bipentalene derivatives from dimeric 7-oxonorbornene derivatives by using ring-rearrangement metathesis as a key step. This method provides access to fused oxacycles containing eight stereogenic centers in just three steps and to bipentalene derivatives in two steps only.