The migratory aptitude of the s-butyl group in a cationic rearrangement

Abstract

The acid-induced dienone–phenol rearrangement of 4-s-butyl-4-methylcyclohexa-2,5-dienone (1) gives 3-s-butyl-4-methylphenol, and 4-methylphenol by fragmentation. Kinetic measurements in aqueous and in methanolic aqueous sulphuric acid, and product studies in the latter, allow the migratory aptitude of the s-butyl group in this cationic rearrangement to be estimated at ca. 7 000 relative to methyl as unity and n-propyl as 50.