Synthesis of chiral intermediate (3S,5S,6S)-3,7-dimethyl-5,6-dihydroxy-7-en-octanal of didemnaketals analogue

A stereoselective synthesis of (3S,5S,6S)-3,7-dimethyl-5,6-dihydroxy-7-en-o ctanal, a key intermediate, for the synthesis of the HIV-inhibitory didemna ketals analogue, was performed via a series of reactions from the natural()-pulegone. In this approach, an interesting and valuable diastereo-recogni zable reaction between tertiary hydroxyepoxides and PCC was found. Therefor e, the mixture of compounds 8 and 9 was treated with PCC to recover 8 in 93 % yield and de 98% purity.