Subtle Steric Effects in Nickel-Catalysed Kumada-Tamao-Corriu Cross-Coupling Using Resorcinarenyl-Imidazolium Salts - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue European Journal of Organic Chemistry Année : 2013

Subtle Steric Effects in Nickel-Catalysed Kumada-Tamao-Corriu Cross-Coupling Using Resorcinarenyl-Imidazolium Salts

Eric Brenner
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Ismail Ozdemir
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Cemal Kaya
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Loïc Toupet

Résumé

Three resorcinarene-cavitands bearing a 3-R-1-imidazolylium substituent (R = alkyl) grafted to the wider rim of the cavitand (1-3) were assessed in the Kumada-Tamao-Corriu cross-coupling of aryl halides with arylmagnesium halides. Their combination with [Ni(cod)2] (cod = 1,5-cyclooctadiene; 1:1 stoichiometry) resulted in highly efficient catalysts, the activities of which varied in the following order: R = n-propyl (1) < isopropyl (2) ≈ benzyl (3). A remarkable turnover frequency of 60400 mol(ArX) mol(Ni)-1 h-1 was obtained in the coupling of 2-bromo-6-methoxynaphthalene with PhMgBr (100 °C in dioxane, with precursor 2). The high activities of the cavitand derivatives were attributed to steric effects that facilitate the reductive-elimination/product decoordination step. Comparative experiments carried out with a structurally modified resorcinarene, as well as cavity-free imidazolium salts bearing 2-methoxyaryl substituents, suggest that the efficiency of the catalysts mainly relies on steric interactions between the metal and the flexible substituents attached to two methine carbon atoms. These steric interactions are probably reinforced each time the metal binds one of the two oxygen atoms located next to the catalytic centre.

Domaines

Chimie organique

Dates et versions

hal-00854620 , version 1 (27-08-2013)

Identifiants

Citer

Neslihan Sahin, David Semeril, Eric Brenner, Dominique Matt, Ismail Ozdemir, et al.. Subtle Steric Effects in Nickel-Catalysed Kumada-Tamao-Corriu Cross-Coupling Using Resorcinarenyl-Imidazolium Salts. European Journal of Organic Chemistry, 2013, 2013 (20), pp.4443-4449. ⟨10.1002/ejoc.201300347⟩. ⟨hal-00854620⟩
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