<scp>l</scp> -Proline-Derived Chiral Primary Amine/Copper Dual Catalysis: Highly Chemo- and Enantioselective α-Amination Reactions of Branched β-Ketocarbonyls

Herein, we report the development of an emerging class of l-proline-derived chiral primary amine catalysts and demonstrate their high efficiency in the α-amination of a broad range of branched acyclic β-keto esters, amides and 1,3-diketones using <i>N</i>-hydroxycarbamates. The reaction exhibits excellent <i>N</i>-selectivity with up to 99% yields and 99% <i>ee</i> across a diverse substrate range. Furthermore, the catalytic efficiency of the newly synthesized system was also evaluated in the <i>α</i>-amination of branched β-keto esters with azodicarboxylate in high yields and <i>ee</i>. Mechanistic insights, including the observed <i>N</i>-selectivity toward the <i>in situ</i> generated nitrosocarbonyl intermediate and the excellent asymmetric induction, are elucidated by density functional theory (DFT) calculations.