Abstract
(-)-Bipolarolide D is an ophiobolin-derived sesteterpenoid with a unique tetraquinane (5/5/5/5) tetracyclic skeleton decorated with a diverse set of functionalities. Herein we report a robust, scalable, and efficient total synthesis of this natural product in 1.8% overall yield. The developed approach features a diastereoselective Pauson-Khand reaction, a highly efficient Rautenstrauch cycloisomerization, and radical cyclization to forge the carbon backbone and the installation of the side chain via crotylation with 1-methyl-2-propenylmagnesium chloride followed by Suzuki cross-coupling.