Synthesis of 2-Cyanobenzothiazoles via Pd-Catalyzed/Cu-Assisted C-H Functionalization/Intramolecular C-S Bond Formation from N -Arylcyanothioformamides.

We report herein on a catalytic system involving palladium and copper to achieve the cyclization of N -arylcyanothioformamides and the synthesis of 2-cyanobenzothiazoles. The C-H functionalization/intramolecular C-S bond formation reaction was achieved in the presence of air, using 2.0 equiv of an inorganic additive (KI). In many cases, the reaction led to a sole product regioselectively obtained in good yields, allowing the synthesis of a wide range of substituted 2-cyanobenzothiazole derivatives, providing valuable building blocks for the design of more complex heterocyclic or molecular labeling systems.