Adaptive Catalytic Synthesis of Aromatic and Aliphatic Amines via CO2-Induced Feedback Inhibition Using Standard Hydrogenation Catalysts

Abstract Adaptive catalytic systems, able to adjust or be adjusted reversibly in their performance, are finding increasing interest in science and technology. Yet, their development is currently associated with sophisticated catalyst designs integrating catalytic and stimuli-responsive functions on the same material, limiting scalability and practical application. We now demonstrate adaptive selectivity control over standard heterogeneous catalysts using CO2 as a molecular trigger for catalytic hydrogenation. In particular, quinoline, benzonitrile, and nitroarene derivatives are selectively hydrogenated using a commercial Ru/C catalyst to deliver either fully saturated amine products under H2 or partially saturated products under H2/CO2 as feed gas. The selectivity control through the presence or absence of CO2 has proven fully reversible, rapid, and robust and generalized over ten different commercial metal nanoparticle catalysts. The adaptivity originates from in situ modification of the catalyst surface with formate adducts generated reversibly from CO2 hydrogenation, which is facilitated by the basic amine functionalities of the intermediates or products along the reaction sequence. The synthetic potential of this simple and versatile approach is demonstrated for a wide variety of substrates, enabling the synthesis of aromatic or aliphatic amines found in valuable drug molecules (e.g., aspernigerin, angustureine, and galipinine) and as useful synthons for fine chemicals and pharmaceuticals.