Synthesis of 2‐Pyrones by Base‐Induced [3+3] Annulation Reaction of Phenacyl Phosphonium Ylides with Cyclopropenones

Abstract The base‐induced [3+3] annulation reaction of phenacyl phosphonium ylides with cyclopropenones has been proposed. Various polysubstituted 2‐pyrones are achieved in moderate to good yields through C−P bond cleavage and C−O/C−C coupling under simple and easy‐to‐operate conditions. The synthetic application and reaction mechanism have also been preliminarily explored to gain a deeper understanding of this strategy in practicality and reaction details. This protocol offers an alternative approach for the synthesis of useful 2‐pyrone derivatives.