摘要

Secoheliosphanes A ( 1 ) and B ( 2 ) and secoheliospholane A ( 3 ), possessing an unusual 7,8- seco -jatrophane skeleton and an unprecedented 9,10- seco -7,10-epoxyjatropholane skeleton, respectively, were isolated from the whole plants of Euphorbia helioscopia , along with two biogenetically precursors, a new jatrophane diterpene, 2- epi -euphornin I ( 4 ) and a known jatrophane diterpene, euphoscopin A ( 5 ). Structures of 1 – 4 including absolute configurations were elucidated on the basis of spectroscopic data, X-ray crystallography, and chemical conversion. Compounds 1 and 2 were prepared from 4 and 5 , respectively, confirming their structural assignments. Notably, 1 and 2 presented the first examples of seco -jatrophane-type diterpenoids and 3 featured a novel 5/6/7/7-fused tetracyclic ring skeleton. Among them, compound 2 showed modest activity against HSV-1 with IC_(50) value of 6.41 μM.