Determination of the absolute configuration of vibsanin F by asymmetric synthesis via π-allylpalladium complex

The absolute configuration of vibsanin F (1), one of the simplest 11-membered ring vibsane-type diterpene, was established to be 6R, 7S and 11S by asymmetric synthesis. A diastereomer (1a) with a 6S, 7S and 11S configuration was synthesized starting from myrcene by procedures featuring a Sharpless asymmetric epoxidation and a high diastereoselective eleven-membered ring formation between a π-allylpalladium complex and a β-ketoester nucleophile. Subsequent reduction of epoxide in 1a with LiAlH4 gave a diol, which was identical with that derived from vibsanin F.