Chapter 8 - Sigmatropic Rearrangements 1: [1,j] Shifts

Abstract

This chapter deals with [1,j] sigmatropic rearrangements in neutral and charged systems. The [1,j] rearrangements are described in two parts: [1,j] hydrogen shifts when the migrating hydrogen has no stereochemistry, and [1,j] carbon shifts when the migrating carbon group can possess stereochemistry. In neutral systems, [1,3], [1,5] and [1,7] hydrogen shifts are presented in terms of their molecular isomerization and stereochemical outcome. Examples of [1,2] and [1,6] hydrogen shifts in cations and a [1,4] hydrogen shift in anion are provided. For sigmatropic carbon shifts in neutral systems, [1,3] and [1,5] rearrangements are described with particular reference to inversion or retention stereochemistry of the products. The vinylcyclopropane rearrangement as a type of [1,3] carbon shift is included. The [1,2] and [1,4] carbon shifts in cations are also presented. Finally ‘walk’ rearrangements are discussed in terms of a series of [1,3], [1,4], [1,5] or [1,7] sigmatropic carbon migrations.