AbstractThe intrinsic mechanism of circumambulatory rearrangements of 5‐bromo‐5‐methyl‐1,2,3,4‐tetramethoxycarbonylcyclopentadiene, 5‐bromo‐1,2,3,4 5‐pentamethoxycarbonylcyclopentadien and 5‐bromo‐ 1,2,3,4,5‐pentaphenylcyclopentadiene due to sigmatropic shifts of bromine over the cyclopentadiene ring was proved, using the dynamic13C and1HNMRtechnique, to be governed by successive intramolecular 1,5‐sigmatropic shifts. Semi‐empiricalAM1andMINDO/3calculations of reactions paths performed for fluoro‐, chloro‐ and bromocyclopentadienes are in accord with the conclusion of a preference for a 1,5‐ over a 1,3‐shift reaction path of halogen migration over a cyclopentadiene system. Intramolecular 1,5‐sigmatropic shifts of chlorine in 5‐chloro‐5‐methyl‐1,2,3,4‐tetramethoxycarbonylcyclopentadiene with the free energy barrier of ΔG 298+= 26