Synthesis of the pentacylic core of (+)-salvileucalin B.

A concise preparation of the prochiral pentacyclic core of (+)-salvileucalin B is presented. The key feature in the synthesis is the Cu-catalyzed intramolecular cyclopropanation of a symmetrical indane-derived α-diazo β-keto ester. This symmetry is carried through the remainder of the synthesis. This practical approach could allow the ready preparation of derivatives for further chemical and biological studies of this class of natural products.