Synthesis of alpha-pyrones via gold-catalyzed cycloisomerization/[2+1] cycloaddition/rearrangement of enyne-amides and sulfur ylides

A novel gold-catalyzed cycloisomerization/[2 + 1]cycloaddition/[1,3]-sigmatropic rearrangement sequence of readily available acyclic enyne-amides and sulfur ylides is reported. This strategy enables rapid and efficient construction of a series of alpha-pyrone derivatives with diverse substituents. Based on several control experiments, a possible mechanism was also proposed to rationalize the cascade process.