Asymmetric total synthesis of diosniponols A and B.

A concise asymmetric total synthesis of diosniponols A and B has been achieved based on an enantioselective Jacobsen kinetic resolution of racemic epoxide and the important 2,3-dihydro-4 H -pyran-4-one moiety being installed by the metal-free δ-hydroxyalkynone rearrangement catalyzed by p -TsOH. A diastereoselective catalytic hydrogenation set the required all- syn stereochemistry leading to diosniponol A, which then, under the Mitsunobu inversion conditions, provided diosniponol B. The structure and absolute stereochemistry of the natural products were further confirmed.