Isomerization of Halogenated Cyclopentene over a NH4F Catalyst

The mechanism of the halogen-transfer isomerization of halogenated cyclopentene was investigated over a NH4F catalyst in DMF. This catalytic system was to have the unique ability to isomerize halogenated cyclopentene selectively. The process of migration of the F atom in the 3-position on the C(sp3) atom to the 4-position on the C(sp3) atom is in chemical equilibrium, whereas the process of migration of the F atom in the 2-position on the C(sp2) atom to the 3-position on the C(sp3) atom is not. Therefore, halogenated cyclopentene containing fluorine on either the C(sp3) or C(sp2) atom could be prepared selectively in terms of the NH4F catalyst.