Quinoxaline as an integrated directing group in palladium-catalyzed ortho-C–H bond arylation of the aryl unit of 2-arylquinoxalines†
We report the Pd-catalyzed C–H bond arylation at the ortho-position of the aryl unit of 2-arylquinoxalines. The reaction proceeds with complete regioselectivity using phosphine-free Pd(OAc)2 as the catalyst and potassium acetate as inexpensive base. In contrast to previously employed directing groups, quinoxaline is an integrated directing group in the final product that only promotes ortho-mono-arylation without the formation of bis-arylated products. A wide variety of (hetero)aryl bromides, including bromopyridine derivatives, has been successfully employed.