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Kondo K, Kubota K, Ito H. Mechanochemistry enabling highly efficient Birch reduction using sodium lumps and d-(+)-glucose. Chem Sci 2024; 15:4452-4457. [PMID: 38516077 PMCID: PMC10952065 DOI: 10.1039/d3sc06052g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Accepted: 02/10/2024] [Indexed: 03/23/2024] Open
Abstract
In this study, a mechanochemical protocol for highly efficient and ammonia-free sodium-based Birch reduction was developed, leveraging the use of cheap and easy-to-handle sodium lumps. The key to achieving this transformation is the use of d-(+)-glucose as a proton source, which solidifies the reaction mixture in bulk state, enhancing the efficiency of the in situ mechanical activation of sodium lumps through the ball-milling process. Under the developed conditions, a diverse array of aromatic and heteroaromatic compounds were selectively reduced to produce the corresponding 1,4-cyclohexadiene derivatives in high yields within 30 min. Notably, all synthetic operations can be carried out without inert gases or the need for dry or bulk organic solvents. Furthermore, a scaled-up synthesis can be conducted without any yield losses. These results suggest that the present mechanochemical approach offers a more convenient, economically attractive, and sustainable alternative to previously established Birch reduction protocols.
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Affiliation(s)
- Keisuke Kondo
- Division of Applied Chemistry, Faculty of Engineering, Hokkaido University Sapporo Hokkaido Japan
| | - Koji Kubota
- Division of Applied Chemistry, Faculty of Engineering, Hokkaido University Sapporo Hokkaido Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University Sapporo Hokkaido Japan
| | - Hajime Ito
- Division of Applied Chemistry, Faculty of Engineering, Hokkaido University Sapporo Hokkaido Japan
- Institute for Chemical Reaction Design and Discovery (WPI-ICReDD), Hokkaido University Sapporo Hokkaido Japan
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Nallaparaju JV, Satsi R, Merzhyievskyi D, Jarg T, Aav R, Kananovich DG. Mechanochemical Birch Reduction with Low Reactive Alkaline Earth Metals. Angew Chem Int Ed Engl 2024:e202319449. [PMID: 38436590 DOI: 10.1002/anie.202319449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/14/2024] [Accepted: 03/04/2024] [Indexed: 03/05/2024]
Abstract
Birch reduction and similar dissolved metal-type transformations hold significant importance in the organic synthesis toolbox. Historically, the field has been dominated by alkali metal reductants. In this study, we report that largely neglected, low-reactive alkaline earth metals can become powerful and affordable reductants when used in a ball mill under essentially solvent-free conditions, in the presence of ethylenediamine and THF as liquid additives. Calcium can reduce both electron-deficient and electron-rich arenes, with yields of products similar to those obtained with lithium metal. Magnesium reveals enhanced reducing power, enabling the reduction of benzoic acids while keeping electron-rich aromatic moieties intact and allows for chemoselective transformations. The developed mechanochemical approach uses readily available and safer-to-handle metals, operates under air and ambient temperature conditions, and can be used for gram-scale preparations. Finally, we demonstrate that the developed conditions can be used for other dissolved metal-type reductive transformations, including reductive amination, deoxygenation, dehalogenation, alkene and alkyne reductions.
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Affiliation(s)
- Jagadeesh Varma Nallaparaju
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Riin Satsi
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Danylo Merzhyievskyi
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
- Department of Chemistry of Bioactive Nitrogen-containing Heterocyclic Bases, V. P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Academician Kukhar Str. 1, 02094, Kyiv, Ukraine
| | - Tatsiana Jarg
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Riina Aav
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
| | - Dzmitry G Kananovich
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Akadeemia tee 15, 12618, Tallinn, Estonia
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Sala J, Capdevila L, Berga C, de Aquino A, Rodríguez L, Simon S, Ribas X. Luminescent Chiral Furanol-PAHs via Straightforward Ni-Catalysed C sp2 -F Functionalization: Mechanistic Insights into the Scholl Reaction. Chemistry 2024; 30:e202303200. [PMID: 37903141 DOI: 10.1002/chem.202303200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/01/2023]
Abstract
Here we report the stepwise synthesis of new nanographenes (NGs) and polycyclic aromatic hydrocarbons (PAHs) obtained via Scholl ring fusion applied at aromatic homologation compounds, which are obtained through one-step Ni-catalysed Csp2 -F functionalization. The latter are rapidly accessed valid precursors for the Scholl reaction, and screening of experimental conditions allowed us to describe for the first time furanol-bearing PAHs. Mechanistic insights are obtained by DFT to rationalize the formation of the furanol PAHs under moderately acidic conditions. All PAHs and NGs synthesized show moderate/weak fluorescent properties, and all PAHs crystallized show some degree of curvature and are obtained as racemic mixtures. Enantiomeric separation by chiral HPLC of one furanol-bearing PAH allowed the study of their chiroptical CD properties.
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Affiliation(s)
- Judith Sala
- Institut de Química Computacional i Catàlisi (IQCC) and, Departament de Química, Universitat de Girona, Campus Montilivi, 17003, Girona, Catalonia, Spain
| | - Lorena Capdevila
- Institut de Química Computacional i Catàlisi (IQCC) and, Departament de Química, Universitat de Girona, Campus Montilivi, 17003, Girona, Catalonia, Spain
| | - Cristina Berga
- Institut de Química Computacional i Catàlisi (IQCC) and, Departament de Química, Universitat de Girona, Campus Montilivi, 17003, Girona, Catalonia, Spain
| | - Araceli de Aquino
- Departament de Química Inorgànica i Orgànica, Secció de Química Inorgànica, Universitat de Barcelona, 08028 Barcelona (Spain), Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, 08028, Barcelona, Catalonia, Spain
| | - Laura Rodríguez
- Departament de Química Inorgànica i Orgànica, Secció de Química Inorgànica, Universitat de Barcelona, 08028 Barcelona (Spain), Institut de Nanociència i Nanotecnologia (IN2UB), Universitat de Barcelona, 08028, Barcelona, Catalonia, Spain
| | - Sílvia Simon
- Institut de Química Computacional i Catàlisi (IQCC) and, Departament de Química, Universitat de Girona, Campus Montilivi, 17003, Girona, Catalonia, Spain
| | - Xavi Ribas
- Institut de Química Computacional i Catàlisi (IQCC) and, Departament de Química, Universitat de Girona, Campus Montilivi, 17003, Girona, Catalonia, Spain
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Báti G, Csókás D, Stuparu MC. Mechanochemical Scholl Reaction on Phenylated Cyclopentadiene Core: One-Step Synthesis of Fluoreno[5]helicenes. Chemistry 2024; 30:e202302971. [PMID: 37870299 DOI: 10.1002/chem.202302971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/16/2023] [Accepted: 10/23/2023] [Indexed: 10/24/2023]
Abstract
In this study, we explore feasibility of the mechanochemical approach in the synthesis of tetrabenzofluorenes (fluoreno[5]helicenes). For this, commercially available phenylated cyclopentadiene precursors are subjected to the Scholl reaction in the solid state using FeCl3 as an oxidant and sodium chloride as the solid reaction medium. This ball milling process gave access to the 5-membered ring containing-helicenes in one synthetic step in high (95-96 %) isolated yields. The solution-phase reactions, however, were found to be moderate to low yielding in this regard (10-40 %).
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Affiliation(s)
- Gábor Báti
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore, Singapore
| | - Dániel Csókás
- Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Mihaiela C Stuparu
- School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore, Singapore
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Abstract
Solvents are so nearly omnipresent in synthetic chemistry that a classic question for their use has been: "What is the best solvent for this reaction?" The increasing use of mechanochemical approaches to synthesis-by grinding, milling, extrusion, or other means-and usually with no, or only limited, amounts of solvent, has raised an alternative question for the synthetic chemist: "What happens if there is no solvent?" This review focuses on a three-part answer to that question: when there is little change ("solvent-optional" reactions); when solvent needs to be present in some form, even if only in the amounts provided by liquid-assisted (LAG) or solvate-assisted grinding; and those cases in which mechanochemistry allows access to compounds that cannot be obtained from solution-based routes. The emphasis here is on inorganic and organometallic systems, including selected examples of mechanosynthesis and mechanocatalysis. Issues of mechanochemical depictions and the adequacy of LAG descriptions are also reviewed.
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Affiliation(s)
- Lauren E Wenger
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, 37235, USA.
| | - Timothy P Hanusa
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, 37235, USA.
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