Dienone–phenol rearrangement

A common example of dienone–phenol rearrangement is 4,4-disubstituted cyclohexadienone [de] converting into a stable 3,4-disubstituted phenol in presence of acid.

Usually this type of rearrangement is spontaneous unless a dichloromethyl group is present at the 4th position or the process is otherwise blocked.

The migration tendency for the two different groups (R) present at either 4,4 position or 2,2 position can be determined by comparing the relative stability of the intermediate carbocation formed during rearrangement.

[7][8] Apart from acid catalysis, the dienone–phenol rearrangement is also possible in presence of base.

The dienone–phenol rearrangement has been used in the synthesis of steroids,[9] anthracenes,[10] and phenanthrenes.