Total Syntheses of the Assigned Structures of Lituarines B and C

The first syntheses of the structures assigned to the marine natural products lituarines B and C have been achieved via a highly convergent sequence. The structures comprise complex, highly oxygenated 25-membered macrolactones possessing a rare tricyclic spiroketal and a unique (E,Z)-dienamide side chain. Unfortunately, the spectral properties of the synthetic compounds did not match those reported for the natural lituarines. The total syntheses of the assigned structures of lituarines B and C, as well as evidence supporting the structural assignments, are presented in this communication.