Iodine-Mediated Oxidative N–N Bond Formations Providing Fused 1,2,3,5-Thiatriazole Derivatives from N -Pyridinyl Sulfonimidamides

Abstract An iodine-mediated oxidative annulation of N-pyridyl sulfonimidamides is reported, providing access to 2-substituted [1,2,3,5]thiatriazolo[3,4-a]pyridine 2-oxides through intramolecular N–N bond formation. This transition metal-free process offers a concise entry to bench-stable, highly heteroatom-rich sulfur(VI) heterocycles. In addition, divergent cyclizations during the preparation of alkyl sulfonimidamide precursors afford structurally distinct sulfur(IV) thiadiazole derivatives. The results of radical-trapping experiments suggest a pathway via an N-centered radical leading to cyclization followed by oxidative aromatization.