Synthesis of Sultams and Cyclic N‑Sulfonyl Ketimines via Iron-Catalyzed Intramolecular Aliphatic C–H Amidation

Cyclic sulfonamides (sultams) play a unique role in drug discovery and synthetic chemistry. A direct synthesis of sultams by an intramolecular C­(sp³)–H amidation reaction using an iron complex in situ derived from Fe­(ClO₄)₂ and aminopyridine ligand is reported. This strategy features a readily available catalyst and tolerates a broad variety of substrates as demonstrated by 22 examples (up to 89% yield). A one-pot iron-catalyzed amidation/oxidation procedure for the synthesis of cyclic N-sulfonyl ketimines is also realized with up to 92% yield (eight examples). The synthetic utility of the method is validated by a gram-scale reaction and derivatization of the products to ring-fused sultams.