Rearrangement: Sigmatropic
Sigmatropic rearrangements involve the intramolecular migration of an atom or functional group without net change in the number of sigma or pi-bonds.

Sigmatropic rearrangement reactions exhibit great stereochemical control over the product isomer distribution.

For more information look in the Chemogenesis webbook sections on rearrangement reactions and pericyclic reactions.