Reaction of arylhalodiazirines with thiophenoxide: A redox process

Article abstract of DOI:10.1021/ja00070a003

Phenylbromodiazirine reacts with thiophenoxide ion in methanol to give benzonitrile, benzamidine, ammonia, and diphenyl disulfide. The reaction is general for arylhalodiazirines, with electron-withdrawing groups on the aromatic ring exerting a small rate-enhancing effect. Three potential mechanisms are suggested for this redox process. These mechanisms include an N-sulfenylated diazirine, a diazirinyl radical, and a diazirinyl anion. Ring opening of these intermediates and subsequent transformations would lead to benzonitriles, benzamidine, and ammonia. A key intermediate in these transformations is PhSNH₂, 32. This intermediate has been independently generated and found to rapidly convert to ammonia and diphenyl disulfide under the reaction conditions. Another proposed intermediate, N-(phenylthio)benzamidine, 38, has also been independently generated and subjected to the reaction conditions, where benzamidine and more diphenyl disulfide result. Theoretical calculations suggest the existence of isomeric diazirinyl anions. In addition to a diazirinyl ion with charge essentially on carbon, there is also an allylic-type ion with charge on the two nitrogen atoms. Single-electron reduction of a diazirinyl radical necessarily leads to a nitrogen-centered diazirinyl anion. Conversion of this anion to the carbon-centered diazirinyl anion is a forbidden process. These theoretical studies suggest that the diazirinyl anion may be a viable intermediate in solution.