A Synthetic Route to Benzothiazocines with Two or Three Carbon Stereocenters via Copper‐Catalyzed Intramolecular N‐Arylation

A new structural family of benzothiazocines bearing two or three carbon stereogenic centers on the 8‐membered ring was synthesized by intramolecular Cu‐catalyzed N‐arylation. The chiral racemic 1,3‐aminothioethers precursors have been prepared from easily available starting materials. An ionic organic base was used for the first time in an intramolecular C−N coupling, in medium‐ring series, leading to higher yields than those obtained with an inorganic base, and a partial epimerization in some cases. The synthetic sequence was successfully performed on one example in asymmetric version, demonstrating the accessibility of enantioenriched benzothiazocines.