Palladium-Catalyzed One-Pot Highly Regioselective 6- Endo Cyclization and Alkylation of Enynoates: Synthesis of 2-Alkanone Pyrones.

The Pd(II)-catalyzed one-pot tandem cyclization/alkylation reactions of enynoates with allylic alcohols have been demonstrated. In this reaction, an innovative protocol proceeded well through Pd-catalyzed intramolecular selective 6- endo cyclization, insertion of allylic alcohols into the Pd-C bond of vinylpalladium species generated in situ, and β-hydrogen elimination processes. This conversion provides a convenient and efficient methodology for the synthesis of 2-alkanone pyrones in moderate to good yields.