Gold-Catalyzed Stereocontrolled Oxacyclization/[4+2]-Cycloaddition Cascade of Ketone-Allene Substrates

We report the first success on the Au-catalyzed tandem oxacyclization/[4+2]-cycloaddition cascade using ketone-allene substrates to give highly substituted oxacyclics with excellent stereocontrol. In contrast to oxo-alkyne substrates, the resulting cycloadducts are isolable and efficiently produced from a reasonable scope of enol ethers.