Aerobic Dehydrogenative Aromatization in the Preparation of 4-Aminoquinoline Derivatives by Synergistic Pd/Cu Catalysis

The 4-aminoquinoline moiety is widely present in various bioactive compounds and marketed drugs, while the preparation of this target structure relies heavily on the amination of 4-chloroquinolines. Herein, an atom and step economic procedure was developed based on an aerobic dehydrogenative aromatization strategy. Unlike the well-known palladium-catalyzed dehydrogenative aromatization of cyclohexanones with amines, synergistic Pd/Cu catalysis is crucial for 2,3-dihydroquinolin-4(1 H )-one type of substrates. Under the optimized conditions, a range of aromatic/aliphatic amines and 2,3-dihydroquinolin-4(1 H )-ones were coupled to give the corresponding 4-aminoquinoline products in moderate to high yields, and the application of the current methodology for the preparation and late-stage diversification of marketed drugs was also demonstrated.