A concise approach for the synthesis of bitungolides: total syntheses of (-)-bitungolide B & E.

The first total synthesis of (-)-bitungolide B and a second-generation total synthesis of (-)-bitungolide E are described. The cornerstone of the approach comprises a convergent and flexible route involving Brown crotylation, highly diastereoselective substrate controlled Paterson anti-aldol reaction, hydroxyl-directed 1,3-syn/anti reduction, Barton-McCombie deoxygenation and RCM reactions. Via this route, a common intermediate 13 is readily accessible for the synthesis of the family of bitungolides A-E and franklinolides A-C.