The Cope rearrangement is an extensively studied organic reaction involving the rearrangement reaction of 1,5-dienes. It was first reported in the Journal of the American Chemical Society by Arthur C. Cope and Elizabeth M. Hardy in 1940. For example 3-methyl-1,5-hexadiene heated to 300°C yields 1,5-heptadiene.
The most spectacular example of the Cope rearrangement is the fluxional molecule bullvalene .