Imination of Sulfides and Sulfoxides with Sulfonylimino‐λ3‐Bromane under Mild,Metal‐Free Conditions

Exposure of sulfides and sulfoxides to trifluoromethanesulfonylimino(aryl)‐λ³‐bromane in dichloromethane at 0 °C results in a facile transfer of the sulfonylimino group to sulfur atoms and affords N‐triflylsulfilimines and ‐sulfoximines in high yields under transition‐metal‐free conditions. Imination of (R)‐methyl p‐tolyl sulfoxide proceeded with predominant retention of configuration at the stereogenic sulfur center. The Hammett plot afforded ρ values of ?0.58 for para‐substituted thioanisoles and ?0.49 for their equivalent sulfoxides, which suggests a buildup of positive charge on the sulfur atoms of sulfides and sulfoxides in the transition state. Calculations suggest a bimolecular nucleophilic‐substitution mechanism on the negatively charged nitrogen atom of the sulfonylimino‐λ³‐bromane, which involves the attack of a sulfide from the opposite side to bromine(III).