An efficient and stereoselective synthetic procedure for (3S,5S,6R)-3,7-dimethyl-5,6,7-trihydroxy-octanal derivative, the intermediate for synthetic of the HIV-active didemnaketals analogue, was developed via a series of reactions from the natural (+)-Pulegone. In this approach, an efficient diastereoselective reaction of the epoxides 8 and 9 with PCC has been accomplished.