Iron-Catalyzed Nitrogen-Directed Coupling of Arene and Aryl Bromides Mediated by Metallic Magnesium

2-Arylpyridines, 2-alkenylpyridine, and aromatic imines can be coupled with aryl bromides in the presence of an iron catalyst, metallic magnesium, a diamine ligand and an organic dihalide oxidant at 0 degrees C. The use of a 1:1 mixture of tetrahydrofuran and 1,4-dioxane is essential for this C-H bond activation reaction. The reaction has wider scope of the substrate compared with the reaction using a separately prepared Grignard reagent, and proceeds with lower catalyst loading (2.5 mol%).