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

초록

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

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