Chemoselective Ullmann Reaction of α‑Trisubstituted Thioamides: Synthesis of Novel 2‑Iminobenzothiolanes

New classes of unexplored benzo­[b]­thiolanes are synthesized from trisubstituted thioamides through copper-catalyzed intramolecular S-arylation of thioamides for the first time. This method provides good to excellent yields with fully controlled chemoselectivity. Unusually, iminobenzo­[b]­thiolanes are very stable under mild acidic conditions. A plausible mechanism is proposed for the chemoselective S-arylation process.