Iridium catalyzed reversible dehydrogenation - Hydrogenation of quinoline derivatives under mild conditions

The potential of a hydrogen-based energy economy is limited by the fact that hydrogen gas is difficult to store and transport. Storing hydrogen in the form of liquid organic hydrogen-carriers (LOHCs) is a highly attractive alternative to current options but it requires the development of catalytic means of reversibly hydrogenating and dehydrogenating these carriers under mild conditions and ideally using a single catalyst for both processes. We report the optimization of two families of previously reported hydrogenation catalysts for the reverse reaction, dehydrogenation of N-heterocyclic substrates. These complexes are capable of catalyzing both dehydrogenation and hydrogenation reactions in alternation, giving high yields in both directions. Importantly, our complexes do not require high temperatures, high pressures of H-2 or strong base for the hydrogenation step. (C) 2015 Elsevier B.V. All rights reserved.