Constituents of Sindora sumatrana MIQ. III. New trans-Clerodane Diterpenoids from the Dried Pods.

Seven new trans-clerodane-type diterpenoids and three known ones have been identified from the chloroform-soluble fraction of the methanolic extract of Sindora sumatrana MIQ. The new compounds, each of which has a β-acetoxy group at the C-7 position, comprise three acid diterpenoids (3, 5, 6) and three neutral ones(8, 9, 10). The remaining one (7) is a dimethyl ester, which was obtained from an acid fraction after methylation with diazomethane. The structures of the isolated compounds were detemined by means of spectroscopic methods, mainly two-dimensional NMR techniques, and their relative stereochemistries were determined with the aid of difference nuclear Ovverhauser effect experiments.