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Choi H, Ham WS, van Bonn P, Zhang J, Kim D, Chang S. Mechanistic Approach Toward the C4-Selective Amination of Pyridines via Nucleophilic Substitution of Hydrogen. Angew Chem Int Ed Engl 2024; 63:e202401388. [PMID: 38589725 DOI: 10.1002/anie.202401388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 03/25/2024] [Accepted: 04/08/2024] [Indexed: 04/10/2024]
Abstract
The development of site-selective functionalization of N-heteroarenes is highly desirable in streamlined synthesis. In this context, direct amination of pyridines stands as an important synthetic methodology, with particular emphasis on accessing 4-aminopyridines, a versatile pharmacophore in medicinal chemistry. Herein, we report a reaction manifold for the C4-selective amination of pyridines by employing nucleophilic substitution of hydrogen (SNH). Through 4-pyridyl pyridinium salt intermediates, 4-aminopyridine products are obtained in reaction with aqueous ammonia without intermediate isolation. The notable regioselectivity was achieved by the electronic tuning of the external pyridine reagents along with the maximization of polarizability in the proton elimination stage. Further mechanistic investigations provided a guiding principle for the selective C-H pyridination of additional N-heteroarenes, presenting a strategic avenue for installation of diverse functional groups.
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Affiliation(s)
- Hoonchul Choi
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, South Korea
| | - Won Seok Ham
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, South Korea
| | - Pit van Bonn
- Institute of Organic Chemistry, RWTH Aachen University, Aachen, 52074, Germany
| | - Jianbo Zhang
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, South Korea
| | - Dongwook Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, South Korea
| | - Sukbok Chang
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
- Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon, 34141, South Korea
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Asahara H, Kataoka A, Hirao S, Nishiwaki N. Functionalization of a Pyridine Framework through Intramolecular Reissert-Henze Reaction ofN-(Carbamoyloxy)pyridinium Salts and Unexpected Insertion of Ethereal Solvents. European J Org Chem 2015. [DOI: 10.1002/ejoc.201500443] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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