Copper-Mediated Difunctionalization of Alkenylboronic Acids: Synthesis of α-Imino Ketones

Various alpha-imino ketones were prepared in good yields through a copper-mediated difunctionalization of alkenylboronic acids with benzotriazolamine in air. Mechanistic studies showed that alpha-imino ketones formation occurred through an initial copper-mediated coupling reaction to form an enamine, followed by homolysis of the C-Cu bond to produce an alpha-radical imine, and finally radical oxidation by air. The alpha-imino ketones were easily converted to various useful scaffolds through further transformations.