FIVE NEW DITERPENES FROM EUPHORBIA SIEBOLDIANA

Five new diterpenes were isolated from Euphorbia sieboldiana and identified as atis-16-en-13(S)-hydroxy-3,14-dione(Ⅰ),atis-16-en- 14-oxo-13(S),3 β-diol(Ⅱ),atisane-3-oxo-16α,17-diol(Ⅳ),atisane-3β ,16α,17-triol(Ⅴ)and atisane-3β-acetyl-16α,17-diol(Ⅵ)based on the chemical,spectral evidences and X-ray diffraction.