Synthesis of phenothiazines via ligand-free CuI-catalyzed cascade C-S and C-N coupling of aryl ortho-dihalides and ortho-aminobenzenethiols

A ligand-free CuI-catalyzed cascade C-S and C-N cross coupling of (hetero)aryl ortho-dihalides and ortho-aminobenzenethiols has been developed, and various phenothiazines were synthesized with excellent regioselectivity. A possible mechanism is proposed for the cascade coupling.