Several new ligands were designed to promote copper-catalyzed Ullman C-N coupling reactions. In this group, 8-hydroxyquinolin-N-oxide was found to serve as a superior ligand for CuBr-catalyzed coupling reactions of aryl iodides, bromides, and chlorides with aliphatic amines and N-heterocycles under a low catalyst loading (1% [Cu] mol). Reactions with the inexpensive catalytic system display a high functional group tolerance as well as excellent chemoselectivity.
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