4-Pyrones (γ-Pyrones) are important oxygenated heterocyclic compounds that are found widely in nature. Various 4-pyrones are known to possess biological activities, acting as anticancer, antifungal, antibacterial, insecticidal, and immunosuppressive agents. Hence, members of this class have been evaluated and utilized as drug molecules. These compounds have been also used as valuable building blocks for the construction of bioactive natural products.
Owing to their importance and usefulness, various methods have been demonstrated for their construction. Although a number of methods for the synthesis of substituted 4-pyrones have been reported, more facile and efficient protocols are still highly desirable. In our continued efforts to develop new synthetic methodologies based on the Wolff rearrangement, we have been investigating transition-metal-free thermal cascade reactions of diazodicarbonyl compounds and β-enamino esters or β-enamino ketones. Herein, we report on a novel and direct regioselective construction of diverse 3-carbonyl functionalized 4-pyrones via thermal Wolff-rearrangement of diazodicarbonyl compounds.