Mechanistic insights into the Ag(I)-catalyzed aryl migration

Theoretical investigation has been conducted into the mechanism for the Ag(I)/PhI(OTFA)2-catalyzed 1,4-radical aryl migration from carbon center to nitrogen center in sulfonamides by using density functional theory (DFT). The calculations show that 11 elementary reactions compose the whole catalytic reaction, which includes the deprotonation, the oxidation of Ag(I) intermediate to Ag(II) intermediate, the formation of nitrogen radical, the 1,4-radical aryl migration, the oxidation of benzyl radical to benzyl cation, etc. The difference between sulfonamides and other amides in the deprotonation process accounts for the experimental phenomenon that only the sulfonamides perform the deprotonation and subsequent 1,4-radical aryl migrations. Moreover, migrations of this kind proceed via a five-membered spirocyclic radical intermediate and favor the electron-rich phenyl group.