Synthesis of the tetracyclic core of berkelic acid using gold(I)-catalyzed hydroarylation and oxidative radical cyclizations.

A synthetic approach to the tetracyclic core of berkelic acid is reported using gold(I)-catalyzed intramolecular hydroarylation and oxidative radical cyclizations to effect the key ring-forming steps. The carboxylic acid was introduced via a late-stage palladium-catalyzed carbonylation to afford the core tetracycle with the correct relative stereochemistry for the natural product.