Our previous reports described the isolation and structures of toxic principle and abietane-type diterpenes from the title plant. Further investigation from biogenetic interests of ingenol and high-oxygenated diterpnes gave four new diterpenes, which were named jolkinols A (1), B (2), C (3), and D (4). The structures of these new diterpenes on the basis of the chemical interrelation of jolkinols, the chemical transformation of jolkinol B (2) to lathyrol (20) whose structure has been determined by E. Hecker, NOE experiments with jolkinol C (3), and epoxidation of the isolated carbon-carbon double bond in jolkinol D (4). Furthermore, the pattern of the cleavage of the epoxide in jolkinols A and B, and the stereospecific epoxidation of jolkinol D indicate that some lathyrane-type diterpenes may be oxidatively derived from jolkinols in their biosynthetic process, as shown in Fig.2. Moreover, the atructure of jolkinolide B possessing the novel oxidolactone was determined by X-ray analysis.
