Cespitulins A–D, novel diterpenoids from Taiwanese Cespitularia taeniata

Four novel diterpenoids, designated cespitulins A–D (1–4) were isolated and characterized from the Taiwanese soft coral Cespitularia taeniata. Their structures were determined by extensive spectroscopic analyses (1H-1H COSY, HMQC, HMBC, NOESY). Compounds 1–4 possess an unprecedented bond cleavage between C-9 and C-10 with a hemiacetalic lactone ring rather than a verticillane skeleton.