Synthesis of the Spirotetracyclic Core of the Ginkgolides via a Malonyl Radical Cascade.

The ginkgolides are a family of terpene trilactone natural products exclusive to the tree. Here, we present a concise synthesis of their spirotetracyclic core via a manganese(III)-mediated oxidative radical cascade. Beginning from six simple starting materials, this route enables the diastereoselective synthesis of rings A, B, D and E of the natural product in nine steps, laying the foundations for their total synthesis.