Photochemical Ni-Catalyzed Selective Mono- <i>N</i> -Arylation

The selective synthesis of <i>N</i>-monomethyl arylamines presents an important challenge in synthetic chemistry. Furthermore, small molecule amines readily coordinate with metal catalysts, causing catalyst deactivation. In this work, we report an efficient C-N coupling reaction of (hetero)aryl halides with small molecule amine salts. Without the need for an external photosensitizer in the presence of a soluble organic base, a bipyridine-Ni(II) complex serving as a catalyst successfully enables the selective C-N coupling of (hetero)aryl halides with methylamine, deuterated methylamine, ethylamine, and dimethylamine under purple light irradiation (390-395 nm), thus preventing catalyst deactivation. Mechanistic studies reveal that the reaction proceeds via a Ni(I)-Ni(III) catalytic cycle, and more than 100 examples showcase its feasibility and versatility in organic synthesis.