Palladium-Catalyzed Stereoselective Cyclization of in Situ Formed Allenyl Hemiacetals: Synthesis of Rosuvastatin and Pitavastatin.

A diastereoselective palladium-catalyzed cyclization of allenyl hemiacetals is described. It permits the selective synthesis of 1,3-dioxane derivatives, precursors for syn-configured 1,3-diols which make an appearance in all of the statin representatives. The reaction allows the total synthesis of Rosuvastatin and Pitavastatin in a straightforward fashion.