Four Novel Diterpenoids, Including Nakamurol A with a Unique Thelepogane Skeleton, from the Marine Sponge Agelas nakamurai

Nakamurols A-D ( 1 − 4 ) have been isolated from the Okinawan sponge Agelas nakamurai Hoshino. The structures of 1 − 4 were proposed on the basis of extensive NMR experiments. Nakamurol A is the first non-alkaloid diterpene with the thelepogane skeleton.