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Eckhardt P, Elliot Q, Alabugin IV, Opatz T. Two Paths to Oxidative C-H Amination Under Basic Conditions: A Theoretical Case Study Reveals Hidden Opportunities Provided by Electron Upconversion. Chemistry 2022; 28:e202201637. [PMID: 35880945 PMCID: PMC9804812 DOI: 10.1002/chem.202201637] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Indexed: 01/09/2023]
Abstract
Traditionally, cross-dehydrogenative coupling (CDC) leads to C-N bond formation under basic and oxidative conditions and is proposed to proceed via a two-electron bond formation mediated by carbenium ions. However, the formation of such high-energy intermediates is only possible in the presence of strong oxidants, which may lead to undesired side reactions and poor functional group tolerance. In this work we explore if oxidation under basic conditions allows the formation of three-electron bonds (resulting in "upconverted" highly-reducing radical-anions). The benefit of this "upconversion" process is in the ability to use milder oxidants (e. g., O2 ) and to avoid high-energy intermediates. Comparison of the two- and three-electron pathways using quantum mechanical calculations reveals that not only does the absence of a strong oxidant shut down two-electron pathways in favor of a three-electron path but, paradoxically, weaker oxidants react faster with the upconverted reductants by avoiding the inverted Marcus region for electron transfer.
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Affiliation(s)
- Paul Eckhardt
- Department of ChemistryJohannes Gutenberg University MainzDuesbergweg 10–1455128MainzGermany
| | - Quintin Elliot
- Department of Chemistry and BiochemistryFlorida State UniversityTallahasseeFlorida 32306USA
| | - Igor V. Alabugin
- Department of Chemistry and BiochemistryFlorida State UniversityTallahasseeFlorida 32306USA
| | - Till Opatz
- Department of ChemistryJohannes Gutenberg University MainzDuesbergweg 10–1455128MainzGermany
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Xiong J, He HT, Yang HY, Zeng ZG, Zhong CR, Shi H, Ouyang ML, Tao YY, Pang YL, Zhang YH, Hu B, Fu ZX, Miao XL, Zhu HL, Yao G. Synthesis of 4-Tetrazolyl-Substituted 3,4-Dihydroquinazoline Derivatives with Anticancer Activity via a One-Pot Sequential Ugi-Azide/Palladium-Catalyzed Azide-Isocyanide Cross-Coupling/Cyclization Reaction. J Org Chem 2022; 87:9488-9496. [PMID: 35881945 DOI: 10.1021/acs.joc.2c00382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
A new one-pot preparation of 4-tetrazolyl-3,4-dihydroquinazolines has been reported. The Ugi-azide reactions of 2-azidobenzaldehydes, amines, trimethylsilyl azide, and isocyanides produced azide intermediates without separation, which were treated with isocyanides to give 4-tetrazolyl-3,4-dihydroquinazoline derivatives through a sequential Palladium-catalyzed azide-isocyanide cross-coupling/cyclization reaction in moderate to good yields. The biological evaluation demonstrated that compound 6c inhibited breast cancer cells well and displayed broad applications for synthesis and medicinal chemistry.
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Affiliation(s)
- Jun Xiong
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Hui-Ting He
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - He-Yu Yang
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Zhi-Gang Zeng
- School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning 437100, P. R. China
| | - Cheng-Ran Zhong
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Hang Shi
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Meng-Ling Ouyang
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Yuan-Yuan Tao
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Yong-Long Pang
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Yang-Hong Zhang
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Bo Hu
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Zi-Xiang Fu
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Xiao-Lei Miao
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
| | - Hai-Li Zhu
- School of Basic Medical Sciences, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, P. R. China
| | - Gang Yao
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning 437100, Hubei, P. R. China
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