Synthesis of (+)-Didemniserinolipid B via Ketalization/Ring-Closing Metathesis

A modular synthesis of didemniserinolipid B is reported. Central to this synthesis was the use of a ketalization/ring-closing metathesis (K/RCM) strategy to establish the 6,8-dioxabicyclo[3.2.1]octane core. The C10 axial alcohol was established via a selective epoxidation, followed by reductive trans-diaxial epoxide opening. The serinol and unsaturated ester side chains were introduced by a Williamson etherification and cross metathesis, respectively.