Pinacol Rearrangement

Abstract

The reaction represents the acid‐promoted 1,2‐rearrangement of vicinal diols to corresponding aldehydes or ketones. Because the vicinal diols are commonly called the pinacols, this transformation is generally known as the pinacol rearrangement or pinacol‐pinacolone rearrangement. Several conditions of the reaction have been discussed, which enhance the yield of the reaction. It has been reported that the reaction involves the stepwise rearrangement. The regioselectivity for this rearrangement has been determined and explained the migratory aptitudes of substituents on diols. In addition, it has been established that the migration is stereospecific, with retention of the configuration of the migrating group. Beside pinacols, some other molecules can also undertake a similar reaction through the formation of a carbocation and migration of a group to the carbocation. This reaction has very broad application in organic synthesis.