Secoheliosphanes A and
B and Secoheliospholane A,
Three Diterpenoids with Unusual seco-Jatrophane and seco-Jatropholane Skeletons from Euphorbia helioscopia
posted on 2017-11-30, 00:00authored byZhen-Peng Mai, Gang Ni, Yan-Fei Liu, Yu-Huan Li, Li Li, Jia-Yuan Li, De-Quan Yu
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 IC50 value of 6.41 μM.