19057-26-2Relevant academic research and scientific papers
STRUCTURE AND TAUTOMERISM OF CYCLOPENTADIENE DERIVATIVES. II.REVERSIBLE MIGRATIONS OF BROMINE IN THE CYCLOPENTADIENE RING
Mikhailov, I. E.,Minkin, V. I.,Dushenko, G. A.,Klenkin, A. A.,Olekhnovich, L. P.
, p. 1061 - 1070 (2007/10/02)
The intramolecular and intermolecular migrations of bromine around the perimeter of the cyclopentadiene ring in the 5-bromo derivatives of pentasubstituted cyclopentadienes were investigated for the first time by 1H and 13C NMR methods.The free energy of activation of the process (ΔG298) lies in the range of 67.7-95.7 kJ/mole.The introduction of aryl and electron-donating substituents into the cyclopentadiene ring promotes migration of the bromine by the intramolecular mechanism of a -sigmatropic shift.The accumulation of electron-withdrawing substituents in the cyclopentadien e ring promotes the bimolecular mechanism of bromine migrations.
