- Nickel-Catalyzed Kumada Coupling of Benzyl Chlorides and Vinylogous Derivatives
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Conditions for the fast Ni-catalyzed Kumada-type cross-coupling of functionalized benzyl and allyl chlorides with alkylmagnesium reagents were discovered. The use of Ni(acac)2-TMEDA (acac = acetylacetonate, TMEDA = N,N,N′,N′-tetramethyl-1,2-ethylenediamine) allows the presence of reactive functional groups on the electrophile. On the other hand, the use of diallyl ether was shown to provide fast coupling at low temperature with a low catalyst loading. The reaction seems to follow a radical pathway.
- Soler-Yanes, Rita,Guisán-Ceinos, Manuel,Bu?uel, Elena,Cárdenas, Diego J.
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- A Ball-Milling-Enabled Cross-Electrophile Coupling
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The nickel-catalyzed cross-electrophile coupling of aryl halides and alkyl halides enabled by ball-milling is herein described. Under a mechanochemical manifold, the reductive C-C bond formation was achieved in the absence of bulk solvent and air/moisture sensitive setups, in reaction times of 2 h. The mechanical action provided by ball milling permits the use of a range of zinc sources to turnover the nickel catalytic cycle, enabling the synthesis of 28 cross-electrophile coupled products.
- Jones, Andrew C.,Nicholson, William I.,Leitch, Jamie A.,Browne, Duncan L.
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supporting information
p. 6337 - 6341
(2021/08/23)
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- Metal-Reductant-Free Electrochemical Nickel-Catalyzed Couplings of Aryl and Alkyl Bromides in Acetonitrile
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While reductive cross-electrochemical coupling is an attractive approach for the synthesis of complex molecules at both small and large scale, two barriers for large-scale applications have remained: the use of stoichiometric metal reductants and a need for amide solvents. In this communication, new conditions that address these challenges are reported. The nickel-catalyzed reductive cross-coupling of aryl bromides with alkyl bromides can be conducted in a divided electrochemical cell using acetonitrile as the solvent and diisopropylamine as the sacrificial reductant to afford coupling products in synthetically useful yields (22-80%). Additionally, the use of a combination of the ligands 4,4′,4″-tri-tert-butyl-2,2′:6′,2′-terpyridine and 4,4′-di-tert-butyl-2,2′-bipyridine is essential to achieve high yields.
- Perkins, Robert J.,Hughes, Alexander J.,Weix, Daniel J.,Hansen, Eric C.
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supporting information
p. 1746 - 1751
(2019/08/20)
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- Visible-Light-Mediated Liberation and In Situ Conversion of Fluorophosgene
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The first example for the photocatalytic generation of a highly electrophilic intermediate that is not based on radical reactivity is reported. The single-electron reduction of bench-stable and commercially available 4-(trifluoromethoxy)benzonitrile by an organic photosensitizer leads to its fragmentation into fluorophosgene and benzonitrile. The in situ generated fluorophosgene was used for the preparation of carbonates, carbamates, and urea derivatives in moderate to excellent yields via an intramolecular cyclization reaction. Transient spectroscopic investigations suggest the formation of a catalyst charge-transfer complex-dimer as the catalytic active species. Fluorophosgene as a highly reactive intermediate, was indirectly detected via its next downstream carbonyl fluoride intermediate by NMR. Furthermore, detailed NMR analyses provided a comprehensive reaction mechanism including a water dependent off-cycle equilibrium.
- Petzold, Daniel,Nitschke, Philipp,Brandl, Fabian,Scheidler, Veronica,Dick, Bernhard,Gschwind, Ruth M.,K?nig, Burkhard
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supporting information
p. 361 - 366
(2018/11/23)
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- Mechanochemical Activation of Zinc and Application to Negishi Cross-Coupling
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A form independent activation of zinc, concomitant generation of organozinc species and engagement in a Negishi cross-coupling reaction via mechanochemical methods is reported. The reported method exhibits a broad substrate scope for both C(sp3)–C(sp2) and C(sp2)–C(sp2) couplings and is tolerant to many important functional groups. The method may offer broad reaching opportunities for the in situ generation organometallic compounds from base metals and their concomitant engagement in synthetic reactions via mechanochemical methods.
- Cao, Qun,Howard, Joseph L.,Wheatley, Emilie,Browne, Duncan L.
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supporting information
p. 11339 - 11343
(2018/08/28)
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- Synthesis of Alkyl Indium Reagents by Using Unactivated Alkyl Chlorides and Their Applications in Palladium-Catalyzed Cross-Coupling Reactions with Aryl Halides
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An efficient method for the preparation of alkyl indium reagents by using unactivated and cheap alkyl chlorides as substrates in the presence of indium and LiI was developed. The thus-formed alkyl indium species effectively underwent palladium-catalyzed cross-coupling reactions with aryl halides with wide functional group tolerance.
- Chen, Bing-Zhi,Zhi, Man-Ling,Wang, Chuang-Xin,Chu, Xue-Qiang,Shen, Zhi-Liang,Loh, Teck-Peng
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supporting information
p. 1902 - 1905
(2018/04/16)
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- Iron-catalyzed cross-coupling of aryltrimethylammonium triflates and alkyl Grignard reagents
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Fe(acac)3 effectively catalyzes reaction of aryltrimethylammonium triflates with β-hydrogen-containing primary or secondary alkyl Grignard reagents in a mixed solvent of THF and NMP at room temperature. A series of functional groups are tolerated under the reaction conditions.
- Guo, Wang-Jun,Wang, Zhong-Xia
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supporting information
p. 9580 - 9585
(2013/10/22)
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- Direct method for carbon-carbon bond formation: The functional group tolerant cobalt-catalyzed alkylation of aryl halides
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(Figure Presented). A new protocol for the direct cobaltcatalyzed alkylation of aryl halides has been developed that proceeds smoothly in the presence of phosphanes or bipyridines as ligands with a variety of alkyl halides, including challenging alkyl electrophiles bearing β hydrogen atoms (see scheme). Sensitive functional groups are tolerated on both coupling partners, thus, significantly extending the general scope of transition-metal-catalyzed alkylation of aryl halides.
- Amatore, Muriel,Gosmini, Corinne
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supporting information; experimental part
p. 5848 - 5852
(2010/09/03)
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