The Base-Promoted Rearrangements of Quaternary Ammonium Salts

The based-promoted rearrangements of quaternary ammonium salts can be divided into two categories. In the Stevens rearrangement one-alkyl group migrates from the quaternary nitrogen group to the alpha carbon atom of a second alkyl group. The Somelet-Hayser rearrangement involves migration to the ortho position of a benzyl quaternary ammonium salt. When structurally feasible, both rearrangements may occur simultaneously although experimental conditions markedly affect the competing pathways.

Keywords: Sommelet-Hauser rearrangements; Stevens rearrangements; quaternary ammonium salts; competitive rearrangements. experimental conditions