Asymmetric reduction of diynones and the total synthesis of (S)-panaxjapyne A.

The asymmetric transfer hydrogenation of a series of diynones has been achieved in high conversion and enantiomeric induction. When R(1) is a phenyl group, a competing alkyne reduction takes place; however, when R(1) is an alkyl group, this side-reaction is not observed. The application of the reduction to the total synthesis of the natural product (S)-panaxjapyne A in high enantiomeric excess is described.