Organometallic chemistry may involve reactions being catalyzed by variety of metals. First Copper catalyzed biaryl coupling reactions reported by Fritz Ullmann in 1901. To commemorate his name, all the coupling reactions using this concept are, nowadays, called ‘Ullmann Coupling’ and in some cases ‘Ullmann Condensation’ if the organic substrate is an amine. When these types of reactions first introduced, they were requiring difficult reaction conditions, such as high temperature and high catalytic loading; and only resulting in moderate to poor yields with limited number of organic substrates. However, the importance of Ullmann Reactions has increased in the last couple decades due to their new applications in which various ligands have been used with different sources of bases and copper catalysts, reducing formerly required high catalytic loading. As a result, Ullmann reactions became useful practices in both medicinal and natural product chemistry.
Unlike nickel or palladium, copper is less toxic, cheap and reusable. Moreover, while coordinating with various ligands, it registers remarkable yields. Previously, our organic research team applied and reported a new modification of Ullmann Reactions for carbon-carbon homo- and heterocouplings. During the research, our team was able to obtain moderate to high yields with different substrates. Now, we are looking forward to employing a similar modification to Ullman type carbon-oxygen couplings using copper iodide, different sources of bases and our ligand; N-phenyl-2-pyridinecarboxamide-1-oxide (NPPA-oxide.) We are aiming to prove a broad range of applications for the ligand, NPPA-oxide which is being studied by our organic research team for the last few years under the supervision of Dr. Fehmi Damkaci at the Chemistry department in Oswego.
Keywords: Organocatalysis, Ullmann Coupling, Ullmann Condensation, N-phenyl-2-pyridinecarboxamide-1-oxide