Synthetic studies of the HIV-1 protease inhibitive didemnaketals: Stereocontrolled synthetic approach to the key mother spiroketals

[GRAPHICS] The stereocontrolled synthesis of (2S,4R,6R,8S,10S,1'R,1"R)-2(acetylhydroxy methyl)-4,10-dimethyl-8(isopropenylhydroxymethyl)-1,7-dioxaspiro[5,5]-undec ane (4a) and its C1"-epimer (4b), the key mother spiroketals of the HIV-1 p rotease inhibitive didemnaketals from the ascidian Didemnum sp., has been c arried out through multisteps from the natural (R)-(+)-pulegone, which invo lved the diastereoselective construction of four chiral carbon centers(C-2, C-6, C-8, and C-1') by intramolecular chiral induce.