Photoinduced Ullmann C–N Coupling: Demonstrating the Viability of a Radical Pathway

Ullman Upgrade Precious metals may dominate contemporary catalysis, but the early development of synthetic organic chemistry relied on more abundant elements—a strategy that chemists are returning to now for the sake of sustainability. Copper-mediated coupling of aryl halides with amines was reported by Ullman more than a century ago and remains in use today for the synthesis of certain organic compounds. However, the reaction generally requires high temperature to proceed efficiently. Creutz et al. (p. 647 ) have developed a photochemical variant that uses copper and reacts at room temperature or below, apparently by a radical mechanism.