Oxidative addition of aryl halides to transient anionic σ-aryl-palladium(0) intermediates - Application to palladium-catalyzed reductive coupling of aryl halides

Chemistry - A European Journal

Volumn 2, Issue 8, 1996, Pages 957-966

  Amatore, Christian ^a   Carré, Emmanuelle ^a   Jutand, Anny ^a   Tanaka, Hideo ^b   Ren, Qinghua ^b   Torii, Sigeru ^b  

^a ECOLE NORMALE SUPÉRIEURE   (France)

^b OKAYAMA UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

ELECTRONIC FACTORS; HAMMETT CORRELATION; OXIDATIVE ADDITIONS; PALLADIUM COMPLEXES; PALLADIUM-CATALYZED; REDUCTIVE COUPLINGS; REDUCTIVE ELIMINATION; TWO-ELECTRON REDUCTION;

CATALYSIS; METAL HALIDES; MOLECULES; ORGANOMETALLICS;

PALLADIUM COMPOUNDS;

EID: 0000879431     PISSN: 09476539     EISSN: 15213765     Source Type: Journal    
DOI: 10.1002/chem.19960020810     Document Type: Article

References (63)

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31. 1 is present in the diffusion layer in a non-oxidizable form [Eq. (24)].
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38. +], M = Li, Na, K, etc.). For reactivity of electrogenerated bases, see e.g., M. Baizer, Organic Electrochemistry (Eds.: H. Lund, M. Baizer), Dekker, New York, 1991, Chap. 30, pp. 1265-1277.
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43. 2.
44. 0.
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50. b) Such intermediates are expected to be reducible. However, in this study, examination of the reductive side of the voltammograms was hampered because of the excess of iodobenzene or para-substituted iodobenzene under our experimental conditions.
51. c) Since we have no structural information on the bisarylpalladium(II) intermediate, we postulate that this is a classical trans complex only to remain in agreement with previous authors (see [25a]). This species may, however, be, for example, a cis complex or a solvent-coordinated neutral pentacoordinate species [24]. Note that our conclusion must remain true because of stoichiometry, even when the final product of Scheme 4 is not a classical bisarylpalladium(II) complex.
52. 2 (Y = X or X′), which is reducible at this potential [24].
53. The yields of homo- or heterocoupling products were less than 10%, and a few percent of products resulting from coupling with the phenyls borne by the phosphine ligands were also produced. Moreover, most of the aryl halides reactants underwent reduction. This indicates that the palladium catalyst is rapidly decomposed when the reaction is performed on a preparative scale in THF. The same occurs when the reaction is performed in a batch procedure in THF (compare Table 1, last row, in DMF).
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62. 1/2 [12]. Yet, for a given experiment, δ is a constant term since D, ΔE, and ν are constant. This allows straight divisions by δ to be performed under derivative and integral operators.
63. 2 is reached and is not complete after this peak is scanned. The real reaction time to be considered is therefore not ΔE/ν, but βΔE/ν. An average value β = 0.97 has been evaluated empirically by using simulations based on an ECEC mechanism with average ΔE and half-peak widths values comparable to those found in this study (cf. Fig. 1).