The Ferrier carbocyclization (or Ferrier II reaction) is an organic reaction that was first reported by the carbohydrate chemist Robert J. Ferrier in 1979.  It is a metal-mediated rearrangement of enol ether pyrans to cyclohexanones.  Typically, this reaction is catalyzed by mercury salts, specifically mercury(II) chloride.
Several reviews have been published.