Category: Molecular Rearrangements

In most of the cationic shifts described so far, a hydrogen atom migrates with a pair of bonding electrons (hydride migration). However, alkyl groups also can shift (along with the electrons from the σ bond that connects the group to the adjacent atom). It was George Wagner who observed in 1899 that terpenes undergo skeletal…

The shift of a hydrogen atom from one carbon atom in a carbocation to a neighbouring carbon atom is often quite rapid when a more stable carbocation can be formed from a less stable one. For example, when 2-methyl-1-propanol is treated with aqueous acid, water is lost and a tertiary carbocation is formed, as hydrogen…

There are two types of rearrangements: the first that involves the one-step migration of a hydrogen atom or of a group of atoms within a relatively short-lived intermediate. The second one may be a multistep reaction, including the migration of a hydrogen atom or of a larger molecule fragment in one of its steps. The…