The products of the reaction between various β-(N-acylamino) ethoxides and β-(amino) ethoxides with 2, 4-dinitrofluorobenzene resulted from an intramolecular nucleophilic aromatic substitution (the Smiles reaction) combined with acyl group migration from nitrogen to oxygen. Stepwise and concerted mechanisms were considered, and evidence for the stepwise mechanism was provided by the synthesis of an intermediate.