A dienone is a class of organic compounds that are formally "derived from diene compounds by conversion of a –CH2– groups into –C(=O)– group .", resulting in "a conjugated structure". The class includes some heterocyclic compounds.
See main article: Dienone–phenol rearrangement. Rearrangement reaction of 6-membered cyclic dienones generate phenols[1] through the dienone–phenol rearrangement:[2]