March's Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 7th Edition (2013)

Chapter 18. Rearrangements

18.E. Electrophilic Rearrangements⁹⁴

Rearrangements in which a group migrates without its electrons are rarer than the two kinds previously considered, but the general principles are the same. A carbanion (or other negative ion) is created first, and the actual rearrangement step involves migration of a group without its electrons:

The product of the rearrangement may be stable or may react further, depending on its nature (see also, Reaction 18-2). An ab initio study predicts that a [1,2]-alkyl shift in alkyne anions should be facile.⁹⁵