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Room temperature Cu(II) radical-triggered Alkyne C−H activation

Room temperature Cu(II) radical-triggered Alkyne C−H activation

Devonport, Jack, Sully, Lauren, Boudalis, Athanassios K., Hassell-Hart, Storm, Leech, Matthew C., Lam, Kevin ORCID: 0000-0003-1481-9212, Abdul-Sada, Alaa, Tizzard, Graham J., Coles, Simon J., Spencer Evans, John, Vargas, Alfredo and Kostaki, George E. (2021) Room temperature Cu(II) radical-triggered Alkyne C−H activation. Journal of the American Chemical Society AU. ISSN 2691-3704 (Print), 2691-3704 (Online) (doi:https://doi.org/10.1021/jacsau.1c00310)

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Abstract

A dimeric Cu(II) complex [Cu(II)2L2(μ2-Cl)Cl] (1) built from an asymmetric tridentate ligand (2-(((2-aminocyclohexyl)imino)methyl) -4,6-di-tert-butylphenol) and weakly coordinating anions has been synthesized and structurally characterized. In dichloromethane solution, 1 exists in a monomeric [Cu(II)LCl] (1′) (85%)–dimeric (1) (15%) equilibrium, and cyclic voltammetry (CV) and electron paramagnetic resonance (EPR) studies indicate structural stability and redox retention. Addition of phenylacetylene to the CH2Cl2 solution populates 1′ and leads to the formation of a transient radical species. Theoretical studies support this notion and show that the radical initiates an alkyne C–H bond activation process via a four-membered ring (Cu(II)–O···H–Calkyne) intermediate. This unusual C–H activation method is applicable for the efficient synthesis of propargylamines, without additives, within 16 h, at low loadings and in noncoordinating solvents including late-stage functionalization of important bioactive molecules. Single-crystal X-ray diffraction studies, postcatalysis, confirmed the framework’s stability and showed that the metal center preserves its oxidation state. The scope and limitations of this unconventional protocol are discussed.

Item Type: Article
Uncontrolled Keywords: copper ligand design C−H activation catalysis radical DFT EPR propargylamines
Subjects: Q Science > QD Chemistry
R Medicine > RS Pharmacy and materia medica
Faculty / School / Research Centre / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > Medway Centre for Pharmaceutical Science
Faculty of Engineering & Science > Medway Centre for Pharmaceutical Science > Pharmaceutical and Medicinal Science Research Group
Faculty of Engineering & Science > School of Science (SCI)
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Last Modified: 07 Oct 2021 13:34
Selected for GREAT 2016: None
Selected for GREAT 2017: None
Selected for GREAT 2018: None
Selected for GREAT 2019: None
Selected for REF2021: None
URI: http://gala.gre.ac.uk/id/eprint/34027

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