A convergent synthesis of the spiroketal moiety of the HIV-1 protease inhibitors didemnaketals

The stereoselective synthesis of the spiroketal fragment and its C1″-epimer of the HIV-1 protease inhibitors didemnaketals has been carried out through multisteps from the natural (R)-(+)-pulegone, which involved the diastereoselective construction of four chiral carbon centers by intramolecular chiral induction.