Thermal and photochemical rearrangements of methyl-substituted cyclopentadienes

Abstract

5,5-Dimethylcyclopentadiene undergoes a thermal rearrangement by migration of a methyl group, the kinetics of which have been studied, but no rearrangement product was observed on u.v. irradiation. However, methylcyclopentadiene is converted photochemically to 2-methylbicyclo[2.1.0]pentene, which is thermally unstable.