Two different reaction pathways were observed in the sulfonylation of N-phenylbenzamidoximes. The reaction with o-NsCl at a heating temperature gave N,N′-diphenylureas via Tiemann rearrangement, while the reaction with Ts2O at a lower temperature formed 2-phenylbenzimidazoles via intramolecular electrophilic aromatic substitution. When the amide nitrogen was replaced with carbon substituents, oxime derivatives of benzoins and benzils underwent Beckmann fragmentation reactions upon sulfonylation, whereas sulfonylation of 2-phenylacetophenone oxime afforded exclusively the Beckmann rearrangement adduct.
- Beckmann fragmentation
- Beckmann rearrangement
- Electrophilic aromatic substitution
- Tiemann rearrangement
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