Asymmetric Synthesis Of Two Fragments Of Clavulactone, A Natural Marine Diterpenoid Having Antitumor Activity

Clavulactone, a member of dolabellane diterpenoids, was first isolated from soft coral Clavularia Viridis collected form South China Sea by Prof. Yu-Lin Wu and coworkers in 1987. Its unique molecular architecture and remarkable antitumor activity attracted our synthetic interests.This dissertation describes our studies on the total synthesis of clavulactone. In the first part, a convenient and efficient approach to the multifunctional cyclopentane, which may serve as a versatile building block for the enantioselective synthesis of clavulactone as well as many other dolabellanes, was completed. In this synthesis, the Sharpless asymmetric epoxidation, the Yamamoto epoxide rearrangement and the SmI2-based free radical cyclization served key reactions and furnished the target intermediate.In the second part, a feasible and efficient synthesis of the linear precursor 15 with an isolated chiral methyl group was achieved in 8 step of transformations, starting from natural material citronellol.