Base‐Catalyzed [4+2] Annulation of Ynones and Acetates for the Synthesis of 2‐Pyrones

Abstract An efficient, practical, and scalable Cs 2 CO 3 ‐catalyzed [4+2] annulation reaction between ynones and acetates is presented, wherein ynones serve as the four‐atom annulation partners. This methodology facilitates the synthesis of substituted 2‐pyrones with yields ranging from good to excellent. The ready availability of the starting materials, coupled with the simplicity of the annulation protocol, renders this approach highly amenable to the preparation of a diverse range of 2‐pyrones. Furthermore, the feasibility of the reaction on a gram scale and its application in the synthesis of a potent and selective cyclooxygenase‐2 inhibitor underscore the practical significance and utility of this method.