Synthesis of Pyrone-annulated 2-Oxabicyclo[3.3.1]nonanes by Palladium-Catalyzed Cyclization of 4-Hydroxy-2-pyrones with Allylic Bisacetates

Abstract Cyclization of 4-hydroxy-2-pyrones with allylic bisacetates by a palladium catalyst is described. Pyrone-annulated 2-oxabicyclo[3.3.1]nonane derivatives were regioselectively produced from the reaction of 4-hydroxy-2-pyrones with 1,4-diacetoxy-2-cyclohexene at high temperature. The reaction would proceed via a migration of the π-allylpalladium intermediate.