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Pharande PS, Rashinkar GS, Pore DM. Silica-grafted DBU-supported NiCl2: a sustainable heterogeneous catalyst for A3 coupling. RESEARCH ON CHEMICAL INTERMEDIATES 2023. [DOI: 10.1007/s11164-023-04980-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
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Metal-Catalysed A3 Coupling Methodologies: Classification and Visualisation. Catalysts 2022. [DOI: 10.3390/catal12060660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The multicomponent reaction of aldehydes, amines, and alkynes, known as A3 coupling, yields propargylamines, a valuable organic scaffold, and has received significant interest and attention in the last years. In order to fully realise the potential of the metal-based catalytic protocols that facilitate this transformation, we summarise substrates, in situ and well-characterised synthetic methods that provide this scaffold and attempt a monumental classification considering several variables (Metal, Coordinating atom(s), Ligand type and name, in-situ or well-characterised, co-catalyst, catalyst and ligand Loading (mol%), solvent, volume, atmosphere, temperature, microwave, time, yield, selectivity (e.e. d.r.), substrate name, functionality, loading (amines, aldehydes, alkynes), and use of molecular sieves). This pioneering work creates a valuable database that contains 2376 entries and allows us to produce graphs and better visualise their impact on the reaction.
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Devonport J, Sully L, Boudalis AK, Hassell-Hart S, Leech MC, Lam K, Abdul-Sada A, Tizzard GJ, Coles SJ, Spencer J, Vargas A, Kostakis GE. Room-Temperature Cu(II) Radical-Triggered Alkyne C-H Activation. JACS AU 2021; 1:1937-1948. [PMID: 34841411 PMCID: PMC8611675 DOI: 10.1021/jacsau.1c00310] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Indexed: 06/13/2023]
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.
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Affiliation(s)
- Jack Devonport
- Department
of Chemistry, School of Life Sciences, University
of Sussex, Brighton BN1 9QJ, U.K.
| | - Lauren Sully
- Department
of Chemistry, School of Life Sciences, University
of Sussex, Brighton BN1 9QJ, U.K.
| | - Athanassios K. Boudalis
- Institut
de Chimie de Strasbourg (UMR 7177, CNRS-Unistra), Université
de Strasbourg, 4 rue Blaise Pascal, CS 90032, F-67081 Strasbourg, France
- Université
de Strasbourg, CNRS, Institut de Physique et Chimie des Matériaux
de Strasbourg (IPCMS), UMR 7504, F-67000 Strasbourg, France
| | - Storm Hassell-Hart
- Department
of Chemistry, School of Life Sciences, University
of Sussex, Brighton BN1 9QJ, U.K.
| | - Matthew C. Leech
- School
of Science, Department of Pharmaceutical Chemical and Environmental
Sciences, University of Greenwich, Central Avenue, Chatham Maritime ME4 4TB, U.K.
| | - Kevin Lam
- School
of Science, Department of Pharmaceutical Chemical and Environmental
Sciences, University of Greenwich, Central Avenue, Chatham Maritime ME4 4TB, U.K.
| | - Alaa Abdul-Sada
- Department
of Chemistry, School of Life Sciences, University
of Sussex, Brighton BN1 9QJ, U.K.
| | - Graham J. Tizzard
- UK
National Crystallography Service, Chemistry, University of Southampton, Southampton SO1 71BJ, U.K.
| | - Simon J. Coles
- UK
National Crystallography Service, Chemistry, University of Southampton, Southampton SO1 71BJ, U.K.
| | - John Spencer
- Department
of Chemistry, School of Life Sciences, University
of Sussex, Brighton BN1 9QJ, U.K.
| | - Alfredo Vargas
- Department
of Chemistry, School of Life Sciences, University
of Sussex, Brighton BN1 9QJ, U.K.
| | - George E. Kostakis
- Department
of Chemistry, School of Life Sciences, University
of Sussex, Brighton BN1 9QJ, U.K.
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Nasibipour M, Safaei E, Moaddeli A, Masoumpour MS, Wojtczak A. Biradical o-iminobenzosemiquinonato(1-) complexes of nickel(ii): catalytic activity in three-component coupling of aldehydes, amines and alkynes. RSC Adv 2021; 11:12845-12859. [PMID: 35423810 PMCID: PMC8697240 DOI: 10.1039/d0ra10248b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 03/22/2021] [Indexed: 11/21/2022] Open
Abstract
The six-coordinated bis-o-iminosemiquinone complex, NiL2 BIS, in which LBIS is the o-iminosemiquinone 1-electron oxidized form of the tridentate o-aminophenol benzoxazole-based ligand H2LBAP, was synthesized and characterized. The crystal structure of the complex reveals octahedral geometry with a NiN4O2 coordination sphere in which Ni(ii) has been surrounded by two tridentate LBIS ligands. This compound exhibits (S Ni = 1) with both spin and orbital contribution to the magnetic moment and antiferromagnetic coupling between two electrons on two LBIS ligands which results in a triplet spin ground state (S = 1). The electronic transitions and the electrochemical behavior of this open-shell molecule are presented here, based on experimental observations and theoretical calculations. The electrochemical behavior of NiL2 BIS was investigated by cyclic voltammetry and indicates ligand-centered redox processes. Three-component coupling of aldehydes, amines and alkynes (A3-coupling) was studied in the presence of the NiL2 BIS complex, and the previously reported four-coordinated bis-o-iminosemiquinone NiL2 NIS. Furthermore, among these two o-iminobenzosemiquinonato(1-) complexes of Ni(ii) (NiL2 NIS and NiL2 BIS), NiL2 NIS was found to be an efficient catalyst in A3-coupling at 85 °C under solvent-free conditions and can be recovered and reused for several cycles with a small decrease in activity.
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Affiliation(s)
- Mina Nasibipour
- Department of Chemistry, College of Sciences, Shiraz University 71454 Shiraz Iran
| | - Elham Safaei
- Department of Chemistry, College of Sciences, Shiraz University 71454 Shiraz Iran
| | - Ali Moaddeli
- Department of Chemistry, College of Sciences, Shiraz University 71454 Shiraz Iran
| | | | - Andrzej Wojtczak
- Nicolaus Copernicus University, Faculty of Chemistry 87-100 Torun Poland
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