Practical N-Hydroxyphthalimide-Mediated Oxidation of Sulfonamides to N-Sulfonylimines

A new method to prepare sulfonylimines through the oxidation of sulfonamides mediated by N-hydroxyphthalimide under mild conditions has been developed. Compared to reported oxidation methods, broader substrates scope and milder conditions were achieved in our method. Importantly, this oxidation method can afford N-sulfonyl enaminones using Mannich products as starting materials. Additionally, the one-pot Friedel–Crafts arylation reaction of unseparated N-sulfonylimine formed in our system with 1,3,5-trimethoxybenzene was successful without any additional catalyst.