Ent-atisane diterpenes from Euphorbia fidjiana☆

The heartwood of the Fijian species Euphorbia fidjiana has yielded seven new ent-14-oxo-atisenes, four ent- atisane-16,17-diols, a 4,5-seco-atisene, and a 3,4-seco- atisene-ent-13[S]-hydroxy-14-oxo-3,4-seco-atis-16-en- 3,4-olide, as well as two chlorinated ent-atisanes which were identified as artifacts. Their structures and relative stereochemistry have been determined by detailed high field NMR studies and from an X-ray structure analysis of ent-13-[S]- hydroxyatis-16-ene-3,14-dione. Their absolute configuration is inferred from an X-ray structure of ent-17-p- bromobenzoyloxy-16α-hydroxyatisan-3-one.