Facile Access to Polycyclic Fused Azo[2,1‐b] [1,3]‐benzothiazinone via Iron‐Catalyzed Cascade Reaction

FeCl3-catalyzed cross-coupling of o-iodobenzoic acids with azole-2-thiols and amidation followed by in situ acidic condensation delivered azo[2,1-b][1,3]-benzothiazinones. A simple “one-pot” operation is conducted for this reaction. This reaction avoids the use of expensive catalytic reagents and provides the desired products containing different azole rings and substituents in good yields.