Palladium-Catalyzed Regioselective C-H Bond Arylations of Benzoxazoles and Benzothiazoles at the C7 Position

We report herein, a very simple catalytic system for the direct arylation of benzoxazole and benzothiazole derivatives at C7 position, namely, phosphine-free PdCl2 associated with PivOK in NMP at 150 degrees C. (Thio)phenoxy chelation-assisted Pd-catalyzed C-H bond cleavage, from an opened intermediate, was proposed to explain this unique regioselectivity. This reaction allows the synthesis of 2-amino-6-arylphenols through the ring opening of the benzoxazole.