Talaromynoids A-E: Five New Fusicoccane Diterpenoids from the Endophytic Fungus Talaromyces sp. DC-26.

Talaromynoids A-E ( 1 - 5 ), five new fusicoccane diterpenoids, were obtained from the endophytic fungus Talaromyces sp. DC-26, which was isolated from a wild leech. Talaromynoid A ( 1 ) represents the first fusicoccane diterpenoid bearing an unexpected 5-7-5 tricyclic ring system, which is possibly derived from normal 5-8-5 ones by ring contraction. Talaromynoid E ( 5 ) is characterized by an unusual oxygen bridge between C-1 and C-8 that establishes the eight-membered ring B to be a 9-oxo-bicyclo[3.3.1]nonane. Structures of 1 - 5 with absolute configurations were determined by extensive NMR spectral analyses, electronic circular dichroism (ECD) calculations, X-ray diffraction analyses, and acid hydrolysis.