Verticillane and Norverticillane Diterpenoids from the Formosan Soft Coral Cespitularia hypotentaculata

Abstract Five new diterpenes, cespihypotins W–Z ( 1 – 4 , resp.) and cespihypotone ( 5 ) have been isolated from the AcOEt‐soluble fraction of the Formosan soft coral Cespitularia hypotentaculata. Two of them having the norverticillane skeleton, i.e. , 1 and 2 , and the other three, 3 – 5 , possessing a verticillane skeleton. The structures were established as (+)‐(1 β H,7 E )‐6 β ,11 β ‐dihydroxynorverticilla‐4(18),7‐diene‐10,12‐dione ( 1 ), (+)‐(1 β H,7 E )‐6 β ‐acetoxy‐11 β ‐hydroxynorverticilla‐4(18),7‐diene‐10,12‐dione ( 2 ), (−)‐(1 β H,7 E )‐6 β ‐acetoxyverticilla‐4(18),7,11‐triene‐10,12‐ γ ‐lactone ( 3 ), (+)‐(1 β H,7 E )‐6 β ‐acetoxy‐10‐hydroxyverticilla‐4(18),7,11‐triene‐10,12‐ γ ‐lactone ( 4 ), and (+)‐(1 β H,3 Z )‐10 β ‐hydroxy‐6‐oxoverticilla‐3,11‐diene‐10,12‐ γ ‐lactone ( 5 ), respectively, on the basis of 1D‐ and 2D‐NMR spectroscopic analyses.