摘要:
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.