Abstract: The tri-ring diterpenes with trans-configuration showed the antitumor potency from many previous inverstigations, but the research for the tri-ring diterpene with cis-configuration has not been regarded so far. During our chemical studies on the bioactive compounds from the plants, a novel tri-ring diterpene (+)-7-deoxynimbidiol which attracts our intensive interest for its good anti-tumor activity was isolated from Celastrus hypoleucus. cis-(±)-7-Deoxynimbidiol(compound 4), the diastereoisomer of (+)-7-deoxynimbidiol, was total synthesized via eight-step reactions with geranic acid as the starting material, and modified by etherification of the phenolic hydroxyl with the substituted benzyl bromide. Eight novel tri-ring diterpenes(compounds 5a—5h) were obtained. The anti-tumor activities of all the new compounds were evaluated. Compound 5d was found to have potency against the cultured human-tumor cell line MCF7(IC₅₀=7.49 μg/mL). The fluorine atom on the benzyl group was speculated to enhancethe anti-tumor activities.

Key words: Tri-ring diterpene, Synthesis, Anti-tumor act ivity