Volume 60, Issue 52 pp. 27307-27311
Communication

An Iridium Catalytic System Compatible with Inorganic and Organic Nitrogen Sources for Dual Asymmetric Reductive Amination Reactions

Zhaofeng Gao

Zhaofeng Gao

Department of Chemistry, Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100 P. R. China

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Jingwen Liu

Jingwen Liu

Department of Chemistry, Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100 P. R. China

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Haizhou Huang

Haizhou Huang

Department of Chemistry, Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100 P. R. China

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Huiling Geng

Corresponding Author

Huiling Geng

Department of Chemistry, Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100 P. R. China

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Mingxin Chang

Corresponding Author

Mingxin Chang

Department of Chemistry, Shaanxi Key Laboratory of Natural Products & Chemical Biology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100 P. R. China

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First published: 26 October 2021
Citations: 24

Graphical Abstract

Two successive asymmetric reductive aminations (ARAs) have been merged into one reaction system to generate enantiopure C2-symmetric secondary amines. The iridium-phosphoramidite complex successfully manages the dual ARAs by using two distinctly different types of amine sources: an inorganic ammonium salt and an organic primary amine.

Abstract

Asymmetric reductive amination (ARA) is one of the most promising methods for the synthesis of chiral amines. Herein we report our efforts on merging two ARA reactions into a single-step transformation. Catalyzed by a complex formed from iridium and a steric hindered phosphoramidite, readily available and inexpensive aromatic ketones initially undergo the first ARA with ammonium acetate to afford primary amines, which serve as the amine sources for the second ARA, and finally provide the enantiopure C2-symmetric secondary amine products. The developed process competently enables the successive coupling of inorganic and organic nitrogen sources with ketones in the same reaction system. The Brønsted acid additive plays multiple roles in this procedure: it accelerates the formation of imine intermediates, minimizes the inhibitory effect of N-containing species on the iridium catalyst, and reduces the primary amine side products.

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