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Reusable Immobilized Iron(II) Nanoparticle PreCatalysts for Ligand-Free Kumada Coupling Toshiki Akiyama, Yuki WADA, Kellie Jenkinson, Tetsuo Honma, Kazuki TSURUTA, Yusuke Tamenori, Hitoshi HANEOKA, Tsunayoshi TAKEHARA, Takeyuki Suzuki, Kenichi Murai, Hiromichi Fujioka, Yoshihiro Sato, Andrew E. H. Wheatley, and Mitsuhiro Arisawa ACS Appl. Nano Mater., Just Accepted Manuscript • DOI: 10.1021/acsanm.8b01742 • Publication Date (Web): 09 Nov 2018 Downloaded from http://pubs.acs.org on November 13, 2018
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ACS Applied Nano Materials
Reusable Immobilized Iron(II) Nanoparticle Pre-Catalysts for Ligand-Free Kumada Coupling Toshiki Akiyama,a Yuki Wada,a Kellie Jenkinson,b Tetsuo Honma,c Kazuki Tsuruta,c Yusuke Tamenori,c Hitoshi Haneoka,d Tsunayoshi Takehara,d Takeyuki Suzuki,d Kenichi Murai,a Hiromichi Fujioka,a Yoshihiro Sato,e Andrew E. H. Wheatleyb and Mitsuhiro Arisawaa* a
Graduate School of Pharmaceutical Sciences, Osaka University, Yamada-oka 1-6, Suita, Osaka 565-
0871, Japan b c
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK
Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198,
Japan d
The Institute of Scientific and Industrial Research , Osaka University, Mihoga-oka Ibaraki Osaka 567-
0047, Japan e
Faculty of Pharmaceutical Sciences, Hokkaido University, Kuta-12, Nishi-6, Kita-ku, Sapporo 060-
0812, Japan *Corresponding author:
[email protected] Abstract: A nanoparticle (NP)-based pre-catalyst has been developed for organic synthesis; sulfurmodified Au-supported Fe (SAFe). The SAFe was easily prepared through a three-step procedure involving simultaneous in situ metal NP and nanospace organization (PSSO). This method avoids the need for preformed templates for immobilizing and stabilizing the metal nanoparticles. On account of the relative safety and enormous earth abundance of iron, SAFe potentially represents an ideal precatalyst for carbon-carbon bond-forming cross-coupling reactions. As such it has been applied as a pre-catalyst to Kumada coupling, under ligand-free conditions, proving capable of being recycled and used repeatedly for this reaction. Analysis of SAFe and of reaction mixtures suggested that the active species in these reactions are produced in situ by assemblies of iron-based NPs. Keywords: iron, nanoparticle, pre-catalyst, reusable catalyst, Kumada coupling, ligand-free Introduction Biaryls constitute core structural units for an enormous range of functional molecules, including medicines, antibacterial agents and electroluminescent materials1. They are easily synthesized by transition metal-catalyzed cross-coupling reactions2. Of these, Kumada coupling is one of the most 1 ACS Paragon Plus Environment
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powerful; its use of easily accessible organomagnesium reagents and aryl halides having enabled it to be developed widely3. Palladium and nickel catalysts have, in the past, been the dominant choices for Kumada coupling as well as other transition metal-catalyzed cross-coupling reactions, although they are expensive and/or toxic3e. In order to overcome these significant drawbacks, as well as employing a more readily accessible transition element, recent efforts have sought to develop iron catalysts for cross-coupling in general4, and Kumada coupling specifically5-8. Iron catalysts are ideal transition metal catalysts because iron is relatively safe and enormously earth abundant. Tamura and Kochi reported the first example of iron-catalyzed Kumada coupling, using alkenyl bromides and alkyl Grignard reagents, in 19715a. Fürstner et al then reported the cross-coupling reactions of aryl chlorides, tosylates, and triflates with alkyl Grignard reagents in 20025b. Hayashi6, Fürstner7, Bedford8, and Nakamura9 have subsequently independently reported the iron-catalyzed Kumada coupling of alkyl halides and aromatic Grignard reagents. Senanayake et al5c disclosed iron-catalyzed Kumada coupling with 2-chloropyrazine and aromatic Grignard reagents, while Wang et al5d employed pyrimidine derivatives and aromatic and alkyl Grignard reagents. However, in spite of this extensive body of research, the literature contains very few reports of environmentally-friendly, ligand-free, ironcatalyzed cross coupling between easily accessible aryl halides and aromatic Grignard reagents5e.
We recently developed a sulfur-modified Au-supported Pd catalyst (SAPd) and used it to achieve Suzuki–Miyaura coupling, Buchwald–Hartwig coupling, C–H functionalization, double carbonylation, removal of the allyl protecting groups of allyl esters and redox switching10. We found SAPd to consist of approximately ten layers of self-assembled Pd(0) nanoparticles (NPs) with a mean size
