Dienone‐Phenol Rearrangement

Abstract The dienone‐phenol rearrangement is, in most cases, the transformation of 4,4‐disubstituted cyclohexadienone into a 3,4‐disubstituted phenol upon treatment of acid; however, 2,2‐disubstituted cyclohexadienone and cyclohexadienone with exocyclic double bond can also be converted into the corresponding disubstituted phenol under similar conditions. It has been reported that the driving force for all of these rearrangements is aromatization. It has been found that the reaction media have strong effects on the rearrangement and the regioselectivity is completely controlled by the electronic factors. The migration tendency of groups at either 4,4 position or 2,2 position has been analyzed using different acid‐promoted conditions. The importance of this reaction has been evidenced in the preparation of steroids, anthracene, phenanthrene, and a variety of phenols.