2189-60-8Relevant articles and documents
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Petrow,Laptewa,Ptschelkina
, (1945)
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Ligand redox effects in the synthesis, electronic structure, and reactivity of an alkyl-alkyl cross-coupling catalyst
Jones, Gavin D.,Martin, Jason L.,McFarland, Chris,Allen, Olivia R.,Hall, Ryan E.,Haley, Aireal D.,Brandon, R. Jacob,Konovalova, Tatyana,Desrochers, Patrick J.,Pulay, Peter,Vicic, David A.
, p. 13175 - 13183 (2006)
The ability of the terpyridine ligand to stabilize alkyl complexes of nickel has been central in obtaining a fundamental understanding of the key processes involved in alkyl-alkyl cross-coupling reactions. Here, mechanistic studies using isotopically labeled (TMEDA)NiMe2 (TMEDA = N,N,N′,N′-tetramethylethylenediamine) have shown that an important catalyst in alkyl-alkyl cross-coupling reactions, (tpy′)NiMe (2b, tpy′ = 4,4′,4″-tri-tert-butylterpyridine), is not produced via a mechanism that involves the formation of methyl radicals. Instead, it is proposed that (terpyridine)NiMe complexes arise via a comproportionation reaction between a Ni(II)-dimethyl species and a Ni(0) fragment in solution upon addition of a terpyridine ligand to (TMEDA)NiMe2. EPR and DFT studies on the paramagnetic (terpyridine)NiMe (2a) both suggest that the unpaired electron resides heavily on the terpyridine ligand and that the proper electronic description of this nickel complex is a Ni(II)-methyl cation bound to a reduced terpyridine ligand. Thus, an important consequence of these results is that alkyl halide reduction by (terpyridine)NiRalkyl complexes appears to be substantially ligand based. A comprehensive survey investigating the catalytic reactivity of related ligand derivatives suggests that electronic factors only moderately influence reactivity in the terpyridine-based catalysis and that the most dramatic effects arise from steric and solubility factors.
Cobalt(II) complexes bearing a bulky N-heterocyclic carbene for catalysis of Kumada-Tamao-Corriu cross-coupling reactions of aryl halides
Matsubara, Kouki,Sueyasu, Tsukasa,Esaki, Mariko,Kumamoto, Aya,Nagao, Shinya,Yamamoto, Hitomi,Koga, Yuji,Kawata, Satoshi,Matsumoto, Taisuke
, p. 3079 - 3086 (2012)
Cobalt(II) iodide, bromide, and chloride react with 1 equiv. of IPr [1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] to form a series of tetrahedral dimeric (30e) complexes of cobalt(II) in good yields. These were transformed into the monomeric forms in the presence of pyridine. These complexes were characterized by SQUID, XPS, UV/Vis spectroscopy, elemental analysis, and X-ray crystallography, and were found to have high catalytic activity for Kumada-Tamao-Corriu cross-coupling reactions of aryl halides. Copyright
Air-Stable Iron-Based Precatalysts for Suzuki-Miyaura Cross-Coupling Reactions between Alkyl Halides and Aryl Boronic Esters
Wong, Alexander S.,Zhang, Bufan,Li, Bo,Neidig, Michael L.,Byers, Jeffery A.
, p. 2461 - 2472 (2021/11/01)
The development of an air-stable iron(III)-based precatalyst for the Suzuki-Miyaura cross-coupling reaction of alkyl halides and unactivated aryl boronic esters is reported. Despite benefits to cost and toxicity, the proclivity of iron(II)-based complexes to undergo deactivationviaoxidation or hydrolysis is a limiting factor for their widespread use in cross-coupling reactions compared to palladium-based or nickel-based complexes. The new octahedral iron(III) complex demonstrates long-term stability on the benchtop as assessed by a combination of1H NMR spectroscopy, M?ssbauer spectroscopy, and its sustained catalytic activity after exposure to air. The improved stability of the iron-based catalyst facilitates an improved protocol in which Suzuki-Miyaura cross-coupling reactions of valuable substrates can be assembled without the use of a glovebox and access a diverse scope of products similar to reactions assembled in the glovebox with iron(II)-based catalysts.
Non-innocent Radical Ion Intermediates in Photoredox Catalysis: Parallel Reduction Modes Enable Coupling of Diverse Aryl Chlorides
Chernowsky, Colleen P.,Chmiel, Alyah F.,Wickens, Zachary K.,Williams, Oliver P.,Yeung, Charles S.
supporting information, p. 10882 - 10889 (2021/07/31)
We describe a photocatalytic system that elicits potent photoreductant activity from conventional photocatalysts by leveraging radical anion intermediates generated in situ. The combination of an isophthalonitrile photocatalyst and sodium formate promotes diverse aryl radical coupling reactions from abundant but difficult to reduce aryl chloride substrates. Mechanistic studies reveal two parallel pathways for substrate reduction both enabled by a key terminal reductant byproduct, carbon dioxide radical anion.