Total Synthesis and Structure Revision of (−)-Avicennone C

All
four possible stereoisomers of the natural product (−)-avicennone
C were synthesized using two different methods for ring closure. The
absolute stereochemistry was elucidated unambiguously by comparison
of the analytical data with those of the reported natural product
and by single X-ray crystal diffraction of synthetic intermediates.
The proposed structure needed to be revised with regard to the absolute
configuration of the stereogenic center bearing the secondary hydroxyl
group. The reported synthesis offers a flexible, selective, and efficient
access to all possible stereoisomers and may be of value for the stereoselective
synthesis of other epoxyquinone natural products.