Enantioselective Synthesis of (-)-Halenaquinone.

The efficient, 12-14 step (LLS) total synthesis of (-)-halenaquinone has been achieved. Key steps in the synthetic sequence include: (a) proline sulfonamide-catalyzed, Yamada-Otani reaction to establish the C6 all-carbon quaternary stereocenter, (b) multiple, novel palladium-mediated oxidative cyclizations to introduce the furan moiety, and (c) oxidative Bergman cyclization to form the final quinone ring.